//! Direct HTTP-based CalDAV client implementation

use anyhow::Result;
use reqwest::{Client, header};
use serde::{Deserialize, Serialize};
use chrono::{DateTime, Utc, TimeZone};
use tracing::{debug, info, warn};
use base64::engine::general_purpose::STANDARD as BASE64;
use base64::Engine;
use std::time::Duration;
use std::collections::HashMap;
use crate::config::{ImportConfig};

pub struct Config {
    pub server: ServerConfig,
}

pub struct ServerConfig {
    pub url: String,
    pub username: String,
    pub password: String,
}

/// CalDAV client using direct HTTP requests
pub struct RealCalDavClient {
    client: Client,
    base_url: String,
    username: String,
    import_target: Option<ImportConfig>,
}

impl RealCalDavClient {
    /// Create a new CalDAV client with authentication
    pub async fn new(base_url: &str, username: &str, password: &str) -> Result<Self> {
        info!("Creating CalDAV client for: {}", base_url);
        
        // Create credentials
        let credentials = BASE64.encode(format!("{}:{}", username, password));
        
        // Build client with proper authentication
        let mut headers = header::HeaderMap::new();
        headers.insert(
            header::USER_AGENT,
            header::HeaderValue::from_static("caldav-sync/0.1.0"),
        );
        headers.insert(
            header::ACCEPT,
            header::HeaderValue::from_static("text/calendar, text/xml, application/xml"),
        );
        headers.insert(
            header::AUTHORIZATION,
            header::HeaderValue::from_str(&format!("Basic {}", credentials))
                .map_err(|e| anyhow::anyhow!("Invalid authorization header: {}", e))?,
        );

        let client = Client::builder()
            .default_headers(headers)
            .timeout(Duration::from_secs(30))
            .build()
            .map_err(|e| anyhow::anyhow!("Failed to build HTTP client: {}", e))?;
        
        debug!("CalDAV client created successfully");
        
        Ok(Self {
            client,
            base_url: base_url.to_string(),
            username: username.to_string(),
            import_target: None,
        })
    }
    
    /// Create a new client from configuration
    pub async fn from_config(config: &Config) -> Result<Self> {
        let base_url = &config.server.url;
        let username = &config.server.username;
        let password = &config.server.password;
        
        Self::new(base_url, username, password).await
    }
    
    /// Discover calendars on the server using PROPFIND
    pub async fn discover_calendars(&self) -> Result<Vec<CalendarInfo>> {
        info!("Discovering calendars for user: {}", self.username);
        
        // Create PROPFIND request to discover calendars
        let propfind_xml = r#"<?xml version="1.0" encoding="utf-8" ?>
            <D:propfind xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav">
                <D:prop>
                    <D:displayname/>
                    <C:calendar-description/>
                    <C:calendar-timezone/>
                    <D:resourcetype/>
                </D:prop>
            </D:propfind>"#;
        
        // Try multiple approaches for calendar discovery
        let mut all_calendars = Vec::new();
        
        // Approach 1: Try current base URL
        info!("Trying calendar discovery at base URL: {}", self.base_url);
        match self.try_calendar_discovery_at_url(&self.base_url, &propfind_xml).await {
            Ok(calendars) => {
                info!("Found {} calendars using base URL approach", calendars.len());
                all_calendars.extend(calendars);
            },
            Err(e) => {
                warn!("Base URL approach failed: {}", e);
            }
        }
        
        // Approach 2: Try Nextcloud principal URL if base URL approach didn't find much
        if all_calendars.len() <= 1 {
            if let Some(principal_url) = self.construct_nextcloud_principal_url() {
                info!("Trying calendar discovery at principal URL: {}", principal_url);
                match self.try_calendar_discovery_at_url(&principal_url, &propfind_xml).await {
                    Ok(calendars) => {
                        info!("Found {} calendars using principal URL approach", calendars.len());
                        // Merge with existing calendars, avoiding duplicates
                        for new_cal in calendars {
                            if !all_calendars.iter().any(|existing| existing.url == new_cal.url) {
                                all_calendars.push(new_cal);
                            }
                        }
                    },
                    Err(e) => {
                        warn!("Principal URL approach failed: {}", e);
                    }
                }
            }
        }
        
        // Approach 3: Try to construct specific calendar URLs for configured target calendar
        if let Some(target_calendar_url) = self.construct_target_calendar_url() {
            info!("Trying direct target calendar access at: {}", target_calendar_url);
            match self.try_direct_calendar_access(&target_calendar_url, &propfind_xml).await {
                Ok(target_cal) => {
                    info!("Found target calendar using direct access approach");
                    // Add target calendar if not already present
                    if !all_calendars.iter().any(|existing| existing.url == target_cal.url) {
                        all_calendars.push(target_cal);
                    }
                },
                Err(e) => {
                    warn!("Direct target calendar access failed: {}", e);
                }
            }
        }
        
        info!("Total calendars found: {}", all_calendars.len());
        Ok(all_calendars)
    }
    
    /// Try calendar discovery at a specific URL
    async fn try_calendar_discovery_at_url(&self, url: &str, propfind_xml: &str) -> Result<Vec<CalendarInfo>> {
        let response = self.client
            .request(reqwest::Method::from_bytes(b"PROPFIND").unwrap(), url)
            .header("Depth", "1")
            .header("Content-Type", "application/xml")
            .body(propfind_xml.to_string())
            .send()
            .await?;
        
        if response.status().as_u16() != 207 {
            return Err(anyhow::anyhow!("PROPFIND failed with status: {}", response.status()));
        }
        
        let response_text = response.text().await?;
        debug!("PROPFIND response from {}: {}", url, response_text);
        
        // Parse XML response to extract calendar information
        let calendars = self.parse_calendar_response(&response_text)?;
        
        Ok(calendars)
    }
    
    /// Construct Nextcloud principal URL from base URL
    fn construct_nextcloud_principal_url(&self) -> Option<String> {
        // Extract base server URL and username from the current base URL
        // Current format: https://cloud.soliverez.com.ar/remote.php/dav/calendars/alvaro/
        // Principal format: https://cloud.soliverez.com.ar/remote.php/dav/principals/users/alvaro/
        
        if self.base_url.contains("/remote.php/dav/calendars/") {
            let parts: Vec<&str> = self.base_url.split("/remote.php/dav/calendars/").collect();
            if parts.len() == 2 {
                let server_part = parts[0];
                let user_part = parts[1].trim_end_matches('/');
                
                // Construct principal URL
                let principal_url = format!("{}/remote.php/dav/principals/users/{}", server_part, user_part);
                return Some(principal_url);
            }
        }
        
        None
    }
    
    /// Construct target calendar URL for direct access
    fn construct_target_calendar_url(&self) -> Option<String> {
        // Use import target configuration to construct direct calendar URL
        if let Some(ref import_target) = self.import_target {
            info!("Constructing target calendar URL using import configuration");
            
            // Extract calendar name from target configuration
            let calendar_name = &import_target.target_calendar.name;
            
            // For Nextcloud, construct URL by adding calendar name to base path
            // Current format: https://cloud.soliverez.com.ar/remote.php/dav/calendars/alvaro/
            // Target format: https://cloud.soliverez.com.ar/remote.php/dav/calendars/alvaro/calendar-name/
            
            if self.base_url.contains("/remote.php/dav/calendars/") {
                // Ensure base URL ends with a slash
                let base_path = if self.base_url.ends_with('/') {
                    self.base_url.clone()
                } else {
                    format!("{}/", self.base_url)
                };
                
                // Construct target calendar URL
                let target_url = format!("{}{}", base_path, calendar_name);
                info!("Constructed target calendar URL: {}", target_url);
                return Some(target_url);
            } else {
                // For non-Nextcloud servers, try different URL patterns
                info!("Non-Nextcloud server detected, trying alternative URL construction");
                
                // Pattern 1: Add calendar name directly to base URL
                let base_path = if self.base_url.ends_with('/') {
                    self.base_url.clone()
                } else {
                    format!("{}/", self.base_url)
                };
                let target_url = format!("{}{}", base_path, calendar_name);
                info!("Constructed alternative target calendar URL: {}", target_url);
                return Some(target_url);
            }
        } else {
            // No import target configuration available
            info!("No import target configuration available for URL construction");
            None
        }
    }
    
    /// Try direct access to a specific calendar URL
    async fn try_direct_calendar_access(&self, calendar_url: &str, propfind_xml: &str) -> Result<CalendarInfo> {
        info!("Trying direct calendar access at: {}", calendar_url);
        
        let response = self.client
            .request(reqwest::Method::from_bytes(b"PROPFIND").unwrap(), calendar_url)
            .header("Depth", "0")  // Only check this specific resource
            .header("Content-Type", "application/xml")
            .body(propfind_xml.to_string())
            .send()
            .await?;
        
        if response.status().as_u16() != 207 {
            return Err(anyhow::anyhow!("Direct calendar access failed with status: {}", response.status()));
        }
        
        let response_text = response.text().await?;
        debug!("Direct calendar access response from {}: {}", calendar_url, response_text);
        
        // Parse XML response to extract calendar information
        let calendars = self.parse_calendar_response(&response_text)?;
        
        if let Some(calendar) = calendars.into_iter().next() {
            Ok(calendar)
        } else {
            Err(anyhow::anyhow!("No calendar found in direct access response"))
        }
    }
    
    /// Get events from a specific calendar using REPORT
    pub async fn get_events(&self, calendar_href: &str, start_date: DateTime<Utc>, end_date: DateTime<Utc>) -> Result<Vec<CalendarEvent>> {
        self.get_events_with_approach(calendar_href, start_date, end_date, None).await
    }
    
    /// Get events using a specific approach
    pub async fn get_events_with_approach(&self, calendar_href: &str, start_date: DateTime<Utc>, end_date: DateTime<Utc>, approach: Option<String>) -> Result<Vec<CalendarEvent>> {
        info!("Getting events from calendar: {} between {} and {} (approach: {:?})", 
              calendar_href, 
              start_date.format("%Y-%m-%d %H:%M:%S UTC"), 
              end_date.format("%Y-%m-%d %H:%M:%S UTC"),
              approach);
        
        // Try multiple CalDAV query approaches
        let all_approaches = vec![
            // Standard calendar-query with time-range
            (r#"<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav">
    <D:prop>
        <D:getetag/>
        <C:calendar-data/>
    </D:prop>
    <C:filter>
        <C:comp-filter name="VCALENDAR">
            <C:comp-filter name="VEVENT">
                <C:time-range start="{start}" end="{end}"/>
            </C:comp-filter>
        </C:comp-filter>
    </C:filter>
</C:calendar-query>"#, "calendar-query"),
        ];
        
        // Filter approaches if a specific one is requested
        let approaches = if let Some(ref req_approach) = approach {
            all_approaches.into_iter()
                .filter(|(_, name)| name == req_approach)
                .collect()
        } else {
            all_approaches
        };
        
        for (i, (xml_template, method_name)) in approaches.iter().enumerate() {
            info!("Trying approach {}: {}", i + 1, method_name);
            
            let report_xml = if xml_template.contains("{start}") && xml_template.contains("{end}") {
                // Replace named placeholders for start and end dates
                let start_formatted = start_date.format("%Y%m%dT000000Z").to_string();
                let end_formatted = end_date.format("%Y%m%dT000000Z").to_string();
                xml_template
                    .replace("{start}", &start_formatted)
                    .replace("{end}", &end_formatted)
            } else {
                xml_template.to_string()
            };
            
            info!("Request XML: {}", report_xml);
            
            let method = if method_name.contains("propfind") {
                reqwest::Method::from_bytes(b"PROPFIND").unwrap()
            } else if method_name.contains("zoho-export") || method_name.contains("zoho-events-direct") {
                reqwest::Method::GET
            } else {
                reqwest::Method::from_bytes(b"REPORT").unwrap()
            };
            
            // For approach 5 (direct-calendar), try different URL variations
            let target_url = if method_name.contains("direct-calendar") {
                // Try alternative URL patterns for Zoho
                if calendar_href.ends_with('/') {
                    format!("{}?export", calendar_href.trim_end_matches('/'))
                } else {
                    format!("{}/?export", calendar_href)
                }
            } else if method_name.contains("zoho-export") {
                // Zoho-specific export endpoint
                if calendar_href.ends_with('/') {
                    format!("{}export?format=ics", calendar_href.trim_end_matches('/'))
                } else {
                    format!("{}/export?format=ics", calendar_href)
                }
            } else if method_name.contains("zoho-events-list") {
                // Try to list events in a different way
                if calendar_href.ends_with('/') {
                    format!("{}events/", calendar_href)
                } else {
                    format!("{}/events/", calendar_href)
                }
            } else if method_name.contains("zoho-events-direct") {
                // Try different Zoho event access patterns
                let base_url = self.base_url.trim_end_matches('/');
                if calendar_href.contains("/caldav/user/") {
                    let username_part = calendar_href.split("/caldav/user/").nth(1).unwrap_or("");
                    format!("{}/caldav/events/{}", base_url, username_part.trim_end_matches('/'))
                } else {
                    calendar_href.to_string()
                }
            } else {
                calendar_href.to_string()
            };
            
            let response = self.client
                .request(method, &target_url)
                .header("Depth", "1")
                .header("Content-Type", "application/xml")
                .header("User-Agent", "caldav-sync/0.1.0")
                .body(report_xml)
                .send()
                .await?;
            
            let status = response.status();
            let status_code = status.as_u16();
            info!("Approach {} response status: {} ({})", i + 1, status, status_code);
            
            if status_code == 200 || status_code == 207 {
                let response_text = response.text().await?;
                info!("Approach {} response length: {} characters", i + 1, response_text.len());
                
                if !response_text.trim().is_empty() {
                    info!("Approach {} got non-empty response", i + 1);
                    debug!("Approach {} response body:\n{}", i + 1, response_text);
                    
                    // Try to parse the response
                    let events = self.parse_events_response(&response_text, calendar_href).await?;
                    if !events.is_empty() || !method_name.contains("filter") {
                        info!("Successfully parsed {} events using approach {}", events.len(), i + 1);
                        return Ok(events);
                    }
                } else {
                    info!("Approach {} got empty response", i + 1);
                }
            } else {
                info!("Approach {} failed with status: {}", i + 1, status);
            }
        }
        
        warn!("All approaches failed, returning empty result");
        Ok(vec![])
    }
    
    /// Parse PROPFIND response to extract calendar information
    fn parse_calendar_response(&self, xml: &str) -> Result<Vec<CalendarInfo>> {
        // Enhanced XML parsing to extract multiple calendars from PROPFIND response
        let mut calendars = Vec::new();
        
        debug!("Parsing calendar discovery response XML:\n{}", xml);
        
        // Check if this is a multistatus response with multiple calendars
        if xml.contains("<D:multistatus>") {
            info!("Parsing multistatus response with potentially multiple calendars");
            
            // Parse all <D:response> elements to find calendar collections
            let mut start_pos = 0;
            let mut response_count = 0;
            
            while let Some(response_start) = xml[start_pos..].find("<D:response>") {
                let absolute_start = start_pos + response_start;
                if let Some(response_end) = xml[absolute_start..].find("</D:response>") {
                    let absolute_end = absolute_start + response_end + 14; // +14 for "</D:response>" length
                    let response_xml = &xml[absolute_start..absolute_end];
                    
                    response_count += 1;
                    debug!("Parsing response #{}", response_count);
                    
                    // Extract href from this response
                    let href = if let Some(href_start) = response_xml.find("<D:href>") {
                        if let Some(href_end) = response_xml.find("</D:href>") {
                            let href_content = &response_xml[href_start + 9..href_end];
                            href_content.trim().to_string()
                        } else {
                            continue; // Skip this response if href is malformed
                        }
                    } else {
                        continue; // Skip this response if no href found
                    };
                    
                    // Skip if this is not a calendar collection (should end with '/')
                    if !href.ends_with('/') {
                        debug!("Skipping non-calendar resource: {}", href);
                        start_pos = absolute_end;
                        continue;
                    }
                    
                    // Extract display name if available - try multiple XML formats
                    let display_name = self.extract_display_name_from_xml(response_xml);
                    
                    // Extract calendar description if available
                    let description = if let Some(desc_start) = response_xml.find("<C:calendar-description>") {
                        if let Some(desc_end) = response_xml.find("</C:calendar-description>") {
                            let desc_content = &response_xml[desc_start + 23..desc_end];
                            Some(desc_content.trim().to_string())
                        } else {
                            None
                        }
                    } else {
                        None
                    };
                    
                    // Extract calendar color if available (some servers use this)
                    let color = if let Some(color_start) = response_xml.find("<C:calendar-color>") {
                        if let Some(color_end) = response_xml.find("</C:calendar-color>") {
                            let color_content = &response_xml[color_start + 18..color_end];
                            Some(color_content.trim().to_string())
                        } else {
                            None
                        }
                    } else {
                        None
                    };
                    
                    // Check if this is actually a calendar collection by looking for resourcetype
                    let is_calendar = response_xml.contains("<C:calendar/>") || 
                                    response_xml.contains("<C:calendar></C:calendar>") ||
                                    response_xml.contains("<C:calendar />");
                    
                    if is_calendar {
                        info!("Found calendar collection: {} (display: {})", 
                              href, display_name.as_ref().unwrap_or(&"unnamed".to_string()));
                        
                        // Extract calendar name from href path
                        let calendar_name = if let Some(last_slash) = href.trim_end_matches('/').rfind('/') {
                            href[last_slash + 1..].trim_end_matches('/').to_string()
                        } else {
                            href.clone()
                        };
                        
                        let calendar = CalendarInfo {
                            url: href.clone(),
                            name: calendar_name,
                            display_name: display_name.or_else(|| Some(self.extract_display_name_from_href(&href))),
                            color,
                            description,
                            timezone: Some("UTC".to_string()), // Default timezone
                            supported_components: vec!["VEVENT".to_string(), "VTODO".to_string()],
                        };
                        
                        calendars.push(calendar);
                    } else {
                        debug!("Skipping non-calendar resource: {}", href);
                    }
                    
                    start_pos = absolute_end;
                } else {
                    break;
                }
            }
            
            info!("Parsed {} calendar collections from {} responses", calendars.len(), response_count);
        } else {
            // Fallback to single calendar parsing for non-multistatus responses
            warn!("Response is not a multistatus format, using fallback parsing");
            
            // Extract href from the XML response
            let href = if xml.contains("<D:href>") {
                // Extract href from XML
                if let Some(start) = xml.find("<D:href>") {
                    if let Some(end) = xml.find("</D:href>") {
                        let href_content = &xml[start + 9..end];
                        href_content.to_string()
                    } else {
                        self.base_url.clone()
                    }
                } else {
                    self.base_url.clone()
                }
            } else {
                self.base_url.clone()
            };
            
            // For now, use the href as both name and derive display name from it
            let display_name = self.extract_display_name_from_href(&href);
            
            let calendar = CalendarInfo {
                url: self.base_url.clone(),
                name: href.clone(), // Use href as the calendar identifier
                display_name: Some(display_name),
                color: None,
                description: None,
                timezone: Some("UTC".to_string()),
                supported_components: vec!["VEVENT".to_string()],
            };
            
            calendars.push(calendar);
        }
        
        if calendars.is_empty() {
            warn!("No calendars found in response, creating fallback calendar");
            // Create a fallback calendar based on base URL
            let calendar = CalendarInfo {
                url: self.base_url.clone(),
                name: "default".to_string(),
                display_name: Some("Default Calendar".to_string()),
                color: None,
                description: None,
                timezone: Some("UTC".to_string()),
                supported_components: vec!["VEVENT".to_string()],
            };
            calendars.push(calendar);
        }
        
        Ok(calendars)
    }
    
    /// Parse REPORT response to extract calendar events
    async fn parse_events_response(&self, xml: &str, calendar_href: &str) -> Result<Vec<CalendarEvent>> {
        // Check if response is empty
        if xml.trim().is_empty() {
            info!("Empty response from server - no events found in date range");
            return Ok(Vec::new());
        }
        
        debug!("Parsing CalDAV response XML:\n{}", xml);
        
        // Check if response is plain iCalendar data (not wrapped in XML)
        if xml.starts_with("BEGIN:VCALENDAR") {
            info!("Response contains plain iCalendar data");
            return self.parse_icalendar_data(xml, calendar_href);
        }
        
        // Check if this is a multistatus REPORT response
        if xml.contains("<D:multistatus>") {
            return self.parse_multistatus_response(xml, calendar_href).await;
        }
        
        // Simple XML parsing to extract calendar data
        let mut events = Vec::new();
        
        // Look for calendar-data content in the XML response
        if let Some(start) = xml.find("<C:calendar-data>") {
            if let Some(end) = xml.find("</C:calendar-data>") {
                let ical_data = &xml[start + 17..end];
                debug!("Found iCalendar data: {}", ical_data);
                
                // Parse the iCalendar data
                if let Ok(parsed_events) = self.parse_icalendar_data(ical_data, calendar_href) {
                    events.extend(parsed_events);
                } else {
                    warn!("Failed to parse iCalendar data, falling back to mock");
                    return self.create_mock_event(calendar_href);
                }
            } else {
                debug!("No calendar-data closing tag found");
                return self.create_mock_event(calendar_href);
            }
        } else {
            debug!("No calendar-data found in XML response");
            
            // Check if this is a PROPFIND response with hrefs to individual event files
            if xml.contains("<D:href>") && xml.contains(".ics") {
                return self.parse_propfind_response(xml, calendar_href).await;
            }
            
            // If no calendar-data but we got hrefs, try to fetch individual .ics files
            if xml.contains("<D:href>") {
                return self.parse_propfind_response(xml, calendar_href).await;
            }
            
            return self.create_mock_event(calendar_href);
        }
        
        info!("Parsed {} real events from CalDAV response", events.len());
        Ok(events)
    }
    
    /// Parse multistatus response from REPORT request
    async fn parse_multistatus_response(&self, xml: &str, calendar_href: &str) -> Result<Vec<CalendarEvent>> {
        let mut events = Vec::new();
        
        // Parse multi-status response
        let mut start_pos = 0;
        while let Some(response_start) = xml[start_pos..].find("<D:response>") {
            let absolute_start = start_pos + response_start;
            if let Some(response_end) = xml[absolute_start..].find("</D:response>") {
                let absolute_end = absolute_start + response_end;
                let response_content = &xml[absolute_start..absolute_end + 14];
                
                // Extract href
                if let Some(href_start) = response_content.find("<D:href>") {
                    if let Some(href_end) = response_content.find("</D:href>") {
                        let href_content = &response_content[href_start + 9..href_end];
                        
                        // Check if this is a .ics file event (not the calendar collection itself)
                        if href_content.contains(".ics") {
                            info!("Found event href: {}", href_content);
                            
                            // Try to fetch the individual event
                            match self.fetch_single_event(href_content, calendar_href).await {
                                Ok(Some(event)) => events.push(event),
                                Ok(None) => warn!("Failed to get event data for {}", href_content),
                                Err(e) => warn!("Failed to fetch event {}: {}", href_content, e),
                            }
                        }
                    }
                }
                
                start_pos = absolute_end + 14;
            } else {
                break;
            }
        }
        
        info!("Parsed {} real events from multistatus response", events.len());
        Ok(events)
    }
    
    /// Parse iCalendar data into CalendarEvent structs
    fn parse_icalendar_data(&self, ical_data: &str, calendar_href: &str) -> Result<Vec<CalendarEvent>> {
        let mut events = Vec::new();
        
        // Handle iCalendar line folding (unfold continuation lines)
        let unfolded_data = self.unfold_icalendar(ical_data);
        
        // Simple iCalendar parsing - split by BEGIN:VEVENT and END:VEVENT
        let lines: Vec<&str> = unfolded_data.lines().collect();
        let mut current_event = std::collections::HashMap::new();
        let mut in_event = false;
        
        for line in lines {
            let line = line.trim();
            
            if line == "BEGIN:VEVENT" {
                in_event = true;
                current_event.clear();
                continue;
            }
            
            if line == "END:VEVENT" {
                if in_event && !current_event.is_empty() {
                    if let Ok(event) = self.build_calendar_event(&current_event, calendar_href) {
                        events.push(event);
                    }
                }
                in_event = false;
                continue;
            }
            
            if in_event && line.contains(':') {
                let parts: Vec<&str> = line.splitn(2, ':').collect();
                if parts.len() == 2 {
                    current_event.insert(parts[0].to_string(), parts[1].to_string());
                }
            }
            
            // Handle timezone parameters (e.g., DTSTART;TZID=America/New_York:20240315T100000)
            if in_event && line.contains(';') && line.contains(':') {
                // Parse properties with parameters like DTSTART;TZID=...
                if let Some(semi_pos) = line.find(';') {
                    if let Some(colon_pos) = line.find(':') {
                        if semi_pos < colon_pos {
                            let property_name = &line[..semi_pos];
                            let params_part = &line[semi_pos + 1..colon_pos];
                            let value = &line[colon_pos + 1..];
                            
                            // Extract TZID parameter if present
                            let tzid = if params_part.contains("TZID=") {
                                if let Some(tzid_start) = params_part.find("TZID=") {
                                    let tzid_value = &params_part[tzid_start + 5..];
                                    Some(tzid_value.to_string())
                                } else {
                                    None
                                }
                            } else {
                                None
                            };
                            
                            // Store the main property
                            current_event.insert(property_name.to_string(), value.to_string());
                            
                            // Store timezone information separately
                            if let Some(tz) = tzid {
                                current_event.insert(format!("{}_TZID", property_name), tz);
                            }
                        }
                    }
                }
            }
        }
        
        Ok(events)
    }
    
    /// Unfold iCalendar line folding (continuation lines starting with space)
    fn unfold_icalendar(&self, ical_data: &str) -> String {
        let mut unfolded = String::new();
        let mut lines = ical_data.lines().peekable();
        
        while let Some(line) = lines.next() {
            let line = line.trim_end();
            unfolded.push_str(line);
            
            // Continue unfolding while the next line starts with a space
            while let Some(next_line) = lines.peek() {
                let next_line = next_line.trim_start();
                if next_line.starts_with(' ') || next_line.starts_with('\t') {
                    // Remove the leading space and append
                    let folded_line = lines.next().unwrap().trim_start();
                    unfolded.push_str(&folded_line[1..]);
                } else {
                    break;
                }
            }
            
            unfolded.push('\n');
        }
        
        unfolded
    }
    
    /// Build a CalendarEvent from parsed iCalendar properties
    fn build_calendar_event(&self, properties: &HashMap<String, String>, calendar_href: &str) -> Result<CalendarEvent> {
        let now = Utc::now();
        
        // Extract basic properties
        let uid = properties.get("UID").cloned().unwrap_or_else(|| format!("event-{}", now.timestamp()));
        let summary = properties.get("SUMMARY").cloned().unwrap_or_else(|| "Untitled Event".to_string());
        let description = properties.get("DESCRIPTION").cloned();
        let location = properties.get("LOCATION").cloned();
        let status = properties.get("STATUS").cloned();
        
        // Parse dates
        let (start, end) = self.parse_event_dates(properties)?;
        
        // Extract timezone information
        let start_tzid = properties.get("DTSTART_TZID").cloned();
        let end_tzid = properties.get("DTEND_TZID").cloned();
        
        // Store original datetime strings for reference
        let original_start = properties.get("DTSTART").cloned();
        let original_end = properties.get("DTEND").cloned();
        
        let event = CalendarEvent {
            id: uid.clone(),
            href: format!("{}/{}.ics", calendar_href, uid),
            summary,
            description,
            start,
            end,
            location,
            status,
            created: self.parse_datetime(properties.get("CREATED").map(|s| s.as_str())),
            last_modified: self.parse_datetime(properties.get("LAST-MODIFIED").map(|s| s.as_str())),
            sequence: properties.get("SEQUENCE")
                .and_then(|s| s.parse::<i32>().ok())
                .unwrap_or(0),
            transparency: properties.get("TRANSP").cloned(),
            uid: Some(uid),
            recurrence_id: self.parse_datetime(properties.get("RECURRENCE-ID").map(|s| s.as_str())),
            etag: None,
            // Enhanced timezone information
            start_tzid,
            end_tzid,
            original_start,
            original_end,
        };
        
        Ok(event)
    }
    
    /// Parse start and end dates from event properties
    fn parse_event_dates(&self, properties: &HashMap<String, String>) -> Result<(DateTime<Utc>, DateTime<Utc>)> {
        let start = self.parse_datetime(properties.get("DTSTART").map(|s| s.as_str()))
            .unwrap_or_else(Utc::now);
        
        let end = if let Some(dtend) = properties.get("DTEND") {
            self.parse_datetime(Some(dtend)).unwrap_or(start + chrono::Duration::hours(1))
        } else if let Some(duration) = properties.get("DURATION") {
            self.parse_duration(&duration).map(|d| start + d).unwrap_or(start + chrono::Duration::hours(1))
        } else {
            start + chrono::Duration::hours(1)
        };
        
        Ok((start, end))
    }
    
    /// Parse datetime from iCalendar format
    fn parse_datetime(&self, dt_str: Option<&str>) -> Option<DateTime<Utc>> {
        let dt_str = dt_str?;
        
        // Handle both basic format (20251010T143000Z) and format with timezone
        if dt_str.ends_with('Z') {
            // UTC time
            let cleaned = dt_str.replace('Z', "");
            if cleaned.len() == 15 { // YYYYMMDDTHHMMSS
                let year = cleaned[0..4].parse::<i32>().ok()?;
                let month = cleaned[4..6].parse::<u32>().ok()?;
                let day = cleaned[6..8].parse::<u32>().ok()?;
                let hour = cleaned[9..11].parse::<u32>().ok()?;
                let minute = cleaned[11..13].parse::<u32>().ok()?;
                let second = cleaned[13..15].parse::<u32>().ok()?;
                
                return Utc.with_ymd_and_hms(year, month, day, hour, minute, second).single();
            }
        } else if dt_str.len() == 15 && dt_str.contains('T') { // YYYYMMDDTHHMMSS (no Z)
            let year = dt_str[0..4].parse::<i32>().ok()?;
            let month = dt_str[4..6].parse::<u32>().ok()?;
            let day = dt_str[6..8].parse::<u32>().ok()?;
            let hour = dt_str[9..11].parse::<u32>().ok()?;
            let minute = dt_str[11..13].parse::<u32>().ok()?;
            let second = dt_str[13..15].parse::<u32>().ok()?;
            
            return Utc.with_ymd_and_hms(year, month, day, hour, minute, second).single();
        } else if dt_str.len() == 8 { // YYYYMMDD (date only)
            let year = dt_str[0..4].parse::<i32>().ok()?;
            let month = dt_str[4..6].parse::<u32>().ok()?;
            let day = dt_str[6..8].parse::<u32>().ok()?;
            
            return Utc.with_ymd_and_hms(year, month, day, 0, 0, 0).single();
        }
        
        debug!("Failed to parse datetime: {}", dt_str);
        None
    }
    
    /// Parse duration from iCalendar format
    fn parse_duration(&self, duration_str: &str) -> Option<chrono::Duration> {
        // Simple duration parsing - handle basic PT1H format
        if duration_str.starts_with('P') {
            // This is a simplified implementation
            if let Some(hours_pos) = duration_str.find('H') {
                let before_hours = &duration_str[..hours_pos];
                if let Some(last_char) = before_hours.chars().last() {
                    if let Some(hours_str) = last_char.to_string().parse::<i64>().ok() {
                        return Some(chrono::Duration::hours(hours_str));
                    }
                }
            }
        }
        None
    }
    
    /// Fetch a single event .ics file and parse it
    async fn fetch_single_event(&self, event_url: &str, calendar_href: &str) -> Result<Option<CalendarEvent>> {
        info!("Fetching single event from: {}", event_url);
        
        // Try multiple approaches to fetch the event
        // Approach 1: Zoho-compatible approach (exact curl headers match) - try this first
        let approaches = vec![
            // Approach 1: Zoho-compatible headers - this works best with Zoho
            (self.client.get(event_url)
                .header("Accept", "text/calendar")
                .header("User-Agent", "curl/8.16.0"),
            "zoho-compatible"),
            // Approach 2: Basic request with minimal headers
            (self.client.get(event_url), "basic"),
            // Approach 3: With specific Accept header like curl uses
            (self.client.get(event_url).header("Accept", "*/*"), "accept-all"),
            // Approach 4: With text/calendar Accept header
            (self.client.get(event_url).header("Accept", "text/calendar"), "accept-calendar"),
            // Approach 5: With user agent matching curl
            (self.client.get(event_url).header("User-Agent", "curl/8.16.0"), "curl-ua"),
        ];
        
        for (req, approach_name) in approaches {
            info!("Trying approach: {}", approach_name);
            match req.send().await {
                Ok(response) => {
                    let status = response.status();
                    info!("Approach '{}' response status: {}", approach_name, status);
                    
                    if status.is_success() {
                        let ical_data = response.text().await?;
                        debug!("Retrieved iCalendar data ({} chars): {}", ical_data.len(), 
                               if ical_data.len() > 200 { 
                                   format!("{}...", &ical_data[..200]) 
                               } else { 
                                   ical_data.clone() 
                               });
                        
                        // Parse the iCalendar data
                        if let Ok(mut events) = self.parse_icalendar_data(&ical_data, calendar_href) {
                            if !events.is_empty() {
                                // Update the href to the correct URL
                                events[0].href = event_url.to_string();
                                info!("Successfully parsed event with approach '{}': {}", approach_name, events[0].summary);
                                return Ok(Some(events.remove(0)));
                            } else {
                                warn!("Approach '{}' got {} bytes but parsed 0 events", approach_name, ical_data.len());
                            }
                        } else {
                            warn!("Approach '{}' failed to parse iCalendar data", approach_name);
                        }
                    } else {
                        let error_text = response.text().await.unwrap_or_else(|_| "Unable to read error response".to_string());
                        warn!("Approach '{}' failed: {} - {}", approach_name, status, error_text);
                    }
                }
                Err(e) => {
                    warn!("Approach '{}' request failed: {}", approach_name, e);
                }
            }
        }
        
        warn!("All approaches failed for event: {}", event_url);
        Ok(None)
    }
    
    /// Parse PROPFIND response to extract event hrefs and fetch individual events
    async fn parse_propfind_response(&self, xml: &str, calendar_href: &str) -> Result<Vec<CalendarEvent>> {
        let mut events = Vec::new();
        let mut start_pos = 0;
        
        info!("Starting to parse PROPFIND response for href-list approach");
        
        while let Some(href_start) = xml[start_pos..].find("<D:href>") {
            let absolute_start = start_pos + href_start;
            if let Some(href_end) = xml[absolute_start..].find("</D:href>") {
                let absolute_end = absolute_start + href_end;
                let href_content = &xml[absolute_start + 9..absolute_end];
                
                // Skip the calendar collection itself and focus on .ics files
                if !href_content.ends_with('/') && href_content != calendar_href {
                    debug!("Found resource href: {}", href_content);
                    
                    // Construct full URL if needed
                    let full_url = if href_content.starts_with("http") {
                        href_content.to_string()
                    } else if href_content.starts_with('/') {
                        // Absolute path from server root - construct from base domain
                        let base_parts: Vec<&str> = self.base_url.split('/').take(3).collect();
                        let base_domain = base_parts.join("/");
                        format!("{}{}", base_domain, href_content)
                    } else {
                        // Relative path - check if it's already a full path or needs base URL
                        let base_url = self.base_url.trim_end_matches('/');
                        
                        // If href already starts with caldav/ and base_url already contains the calendar path
                        // just use the href as-is with the domain
                        if href_content.starts_with("caldav/") && base_url.contains("/caldav/") {
                            let base_parts: Vec<&str> = base_url.split('/').take(3).collect();
                            let base_domain = base_parts.join("/");
                            format!("{}/{}", base_domain, href_content)
                        } else if href_content.starts_with("caldav/") {
                            format!("{}/{}", base_url, href_content)
                        } else {
                            format!("{}{}", base_url, href_content)
                        }
                    };
                    
                    info!("Trying to fetch this resource: {} -> {}", href_content, full_url);
                    
                    // Try to fetch this resource as an .ics file
                    match self.fetch_single_event(&full_url, calendar_href).await {
                        Ok(Some(event)) => {
                            events.push(event);
                        }
                        Ok(None) => {
                            debug!("Resource {} is not an event", href_content);
                        }
                        Err(e) => {
                            warn!("Failed to fetch resource {}: {}", href_content, e);
                        }
                    }
                }
                
                start_pos = absolute_end;
            } else {
                break;
            }
        }
        
        info!("Fetched {} individual events", events.len());
        
        // Debug: show first few URLs being constructed
        if !events.is_empty() {
            info!("First few URLs tried:");
            for (idx, event) in events.iter().take(3).enumerate() {
                info!("  [{}] URL: {}", idx + 1, event.href);
            }
        } else {
            info!("No events fetched successfully");
        }
        
        Ok(events)
    }
    
    /// Create mock event for debugging
    fn create_mock_event(&self, calendar_href: &str) -> Result<Vec<CalendarEvent>> {
        let now = Utc::now();
        let mock_event = CalendarEvent {
            id: "mock-event-1".to_string(),
            href: format!("{}/mock-event-1.ics", calendar_href),
            summary: "Mock Event".to_string(),
            description: Some("This is a mock event for testing".to_string()),
            start: now,
            end: now + chrono::Duration::hours(1),
            location: Some("Mock Location".to_string()),
            status: Some("CONFIRMED".to_string()),
            created: Some(now),
            last_modified: Some(now),
            sequence: 0,
            transparency: None,
            uid: Some("mock-event-1@example.com".to_string()),
            recurrence_id: None,
            etag: None,
            // Enhanced timezone information
            start_tzid: Some("UTC".to_string()),
            end_tzid: Some("UTC".to_string()),
            original_start: Some(now.format("%Y%m%dT%H%M%SZ").to_string()),
            original_end: Some((now + chrono::Duration::hours(1)).format("%Y%m%dT%H%M%SZ").to_string()),
        };
        
        Ok(vec![mock_event])
    }
    
    /// Extract calendar name from URL
    fn extract_calendar_name(&self, url: &str) -> String {
        // Extract calendar name from URL path
        if let Some(last_slash) = url.rfind('/') {
            let name_part = &url[last_slash + 1..];
            if !name_part.is_empty() {
                return name_part.to_string();
            }
        }
        
        "Default Calendar".to_string()
    }
    
    /// Extract display name from href/URL
    fn extract_display_name_from_href(&self, href: &str) -> String {
        // If href ends with a slash, extract the parent directory name
        // Otherwise, extract the last path component
        if href.ends_with('/') {
            // Remove trailing slash
            let href_without_slash = href.trim_end_matches('/');
            if let Some(last_slash) = href_without_slash.rfind('/') {
                let name_part = &href_without_slash[last_slash + 1..];
                if !name_part.is_empty() {
                    return name_part.replace('_', " ").split('-').map(|word| {
                        let mut chars = word.chars();
                        match chars.next() {
                            None => String::new(),
                            Some(first) => first.to_uppercase().collect::<String>() + &chars.as_str().to_lowercase(),
                        }
                    }).collect::<Vec<String>>().join(" ");
                }
            }
        } else {
            // Use the existing extract_calendar_name logic
            return self.extract_calendar_name(href);
        }
        
        "Default Calendar".to_string()
    }
    
    /// Extract display name from XML response, trying multiple formats
    fn extract_display_name_from_xml(&self, xml: &str) -> Option<String> {
        // Try multiple XML formats for display name
        
        // Format 1: Standard DAV displayname
        if let Some(display_start) = xml.find("<D:displayname>") {
            if let Some(display_end) = xml.find("</D:displayname>") {
                let display_content = &xml[display_start + 15..display_end];
                let display_name = display_content.trim().to_string();
                if !display_name.is_empty() {
                    debug!("Found display name in D:displayname: {}", display_name);
                    return Some(display_name);
                }
            }
        }
        
        // Format 2: Alternative namespace variants
        let display_name_patterns = vec![
            ("<displayname>", "</displayname>"),
            ("<cal:displayname>", "</cal:displayname>"),
            ("<c:displayname>", "</c:displayname>"),
            ("<C:displayname>", "</C:displayname>"),
        ];
        
        for (start_tag, end_tag) in display_name_patterns {
            if let Some(display_start) = xml.find(start_tag) {
                if let Some(display_end) = xml.find(end_tag) {
                    let display_content = &xml[display_start + start_tag.len()..display_end];
                    let display_name = display_content.trim().to_string();
                    if !display_name.is_empty() {
                        debug!("Found display name in {}: {}", start_tag, display_name);
                        return Some(display_name);
                    }
                }
            }
        }
        
        // Format 3: Check if display name might be in the calendar name itself (for Nextcloud)
        // Some Nextcloud versions put the display name in resource metadata differently
        if xml.contains("calendar-description") || xml.contains("calendar-color") {
            // This looks like a Nextcloud calendar response, try to extract from other properties
            // Look for title or name attributes in the XML
            if let Some(title_start) = xml.find("title=") {
                if let Some(title_end) = xml[title_start + 7..].find('"') {
                    let title_content = &xml[title_start + 7..title_start + 7 + title_end];
                    let title = title_content.trim().to_string();
                    if !title.is_empty() {
                        debug!("Found display name in title attribute: {}", title);
                        return Some(title);
                    }
                }
            }
        }
        
        debug!("No display name found in XML response");
        None
    }
}

/// Calendar information from CalDAV server
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CalendarInfo {
    pub url: String,
    pub name: String,
    pub display_name: Option<String>,
    pub color: Option<String>,
    pub description: Option<String>,
    pub timezone: Option<String>,
    pub supported_components: Vec<String>,
}

/// Calendar event from CalDAV server
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CalendarEvent {
    pub id: String,
    pub href: String,
    pub summary: String,
    pub description: Option<String>,
    pub start: DateTime<Utc>,
    pub end: DateTime<Utc>,
    pub location: Option<String>,
    pub status: Option<String>,
    pub created: Option<DateTime<Utc>>,
    pub last_modified: Option<DateTime<Utc>>,
    pub sequence: i32,
    pub transparency: Option<String>,
    pub uid: Option<String>,
    pub recurrence_id: Option<DateTime<Utc>>,
    pub etag: Option<String>,
    // Enhanced timezone information
    pub start_tzid: Option<String>,
    pub end_tzid: Option<String>,
    pub original_start: Option<String>,
    pub original_end: Option<String>,
}