//! Configuration management for CalDAV synchronizer

use serde::{Deserialize, Serialize};
use std::path::Path;
use anyhow::Result;

/// Main configuration structure
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Config {
    /// Server configuration
    pub server: ServerConfig,
    /// Calendar configuration
    pub calendar: CalendarConfig,
    /// Filter configuration
    pub filters: Option<FilterConfig>,
    /// Sync configuration
    pub sync: SyncConfig,
}

/// Server connection configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ServerConfig {
    /// CalDAV server URL
    pub url: String,
    /// Username for authentication
    pub username: String,
    /// Password for authentication
    pub password: String,
    /// Whether to use HTTPS
    pub use_https: bool,
    /// Timeout in seconds
    pub timeout: u64,
    /// Custom headers to send with requests
    pub headers: Option<std::collections::HashMap<String, String>>,
}

/// Calendar-specific configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CalendarConfig {
    /// Calendar name/path
    pub name: String,
    /// Calendar display name
    pub display_name: Option<String>,
    /// Calendar color
    pub color: Option<String>,
    /// Calendar timezone
    pub timezone: String,
    /// Whether to sync this calendar
    pub enabled: bool,
}

/// Filter configuration for events
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FilterConfig {
    /// Start date filter (ISO 8601)
    pub start_date: Option<String>,
    /// End date filter (ISO 8601)
    pub end_date: Option<String>,
    /// Event types to include
    pub event_types: Option<Vec<String>>,
    /// Keywords to filter by
    pub keywords: Option<Vec<String>>,
    /// Exclude keywords
    pub exclude_keywords: Option<Vec<String>>,
}

/// Synchronization configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SyncConfig {
    /// Sync interval in seconds
    pub interval: u64,
    /// Whether to sync on startup
    pub sync_on_startup: bool,
    /// Maximum number of retries
    pub max_retries: u32,
    /// Retry delay in seconds
    pub retry_delay: u64,
    /// Whether to delete events not found on server
    pub delete_missing: bool,
    /// Date range configuration
    pub date_range: DateRangeConfig,
}

/// Date range configuration for event synchronization
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DateRangeConfig {
    /// Number of days ahead to sync
    pub days_ahead: i64,
    /// Number of days in the past to sync
    pub days_back: i64,
    /// Whether to sync all events regardless of date
    pub sync_all_events: bool,
}

impl Default for Config {
    fn default() -> Self {
        Self {
            server: ServerConfig::default(),
            calendar: CalendarConfig::default(),
            filters: None,
            sync: SyncConfig::default(),
        }
    }
}

impl Default for ServerConfig {
    fn default() -> Self {
        Self {
            url: "https://caldav.example.com".to_string(),
            username: String::new(),
            password: String::new(),
            use_https: true,
            timeout: 30,
            headers: None,
        }
    }
}

impl Default for CalendarConfig {
    fn default() -> Self {
        Self {
            name: "calendar".to_string(),
            display_name: None,
            color: None,
            timezone: "UTC".to_string(),
            enabled: true,
        }
    }
}

impl Default for SyncConfig {
    fn default() -> Self {
        Self {
            interval: 300, // 5 minutes
            sync_on_startup: true,
            max_retries: 3,
            retry_delay: 5,
            delete_missing: false,
            date_range: DateRangeConfig::default(),
        }
    }
}

impl Default for DateRangeConfig {
    fn default() -> Self {
        Self {
            days_ahead: 7, // Next week
            days_back: 0,  // Today only
            sync_all_events: false,
        }
    }
}

impl Config {
    /// Load configuration from a TOML file
    pub fn from_file<P: AsRef<Path>>(path: P) -> Result<Self> {
        let content = std::fs::read_to_string(path)?;
        let config: Config = toml::from_str(&content)?;
        Ok(config)
    }

    /// Save configuration to a TOML file
    pub fn to_file<P: AsRef<Path>>(&self, path: P) -> Result<()> {
        let content = toml::to_string_pretty(self)?;
        std::fs::write(path, content)?;
        Ok(())
    }

    /// Load configuration from environment variables
    pub fn from_env() -> Result<Self> {
        let mut config = Config::default();

        if let Ok(url) = std::env::var("CALDAV_URL") {
            config.server.url = url;
        }
        if let Ok(username) = std::env::var("CALDAV_USERNAME") {
            config.server.username = username;
        }
        if let Ok(password) = std::env::var("CALDAV_PASSWORD") {
            config.server.password = password;
        }
        if let Ok(calendar) = std::env::var("CALDAV_CALENDAR") {
            config.calendar.name = calendar;
        }

        Ok(config)
    }

    /// Validate configuration
    pub fn validate(&self) -> Result<()> {
        if self.server.url.is_empty() {
            anyhow::bail!("Server URL cannot be empty");
        }
        if self.server.username.is_empty() {
            anyhow::bail!("Username cannot be empty");
        }
        if self.server.password.is_empty() {
            anyhow::bail!("Password cannot be empty");
        }
        if self.calendar.name.is_empty() {
            anyhow::bail!("Calendar name cannot be empty");
        }
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_default_config() {
        let config = Config::default();
        assert_eq!(config.server.url, "https://caldav.example.com");
        assert_eq!(config.calendar.name, "calendar");
        assert_eq!(config.sync.interval, 300);
    }

    #[test]
    fn test_config_validation() {
        let mut config = Config::default();
        assert!(config.validate().is_err()); // Empty username/password

        config.server.username = "test".to_string();
        config.server.password = "test".to_string();
        assert!(config.validate().is_ok());
    }
}