//! Agent configuration handling
//!
//! Configuration is loaded from a TOML file (default: agent.toml).
//! The config file defines server connection, metrics collection,
//! and watchdog settings.

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

/// Root configuration structure
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AgentConfig {
    /// Server connection settings
    pub server: ServerConfig,

    /// Metrics collection settings
    #[serde(default)]
    pub metrics: MetricsConfig,

    /// Watchdog settings for monitoring services/processes
    #[serde(default)]
    pub watchdog: WatchdogConfig,
}

/// Server connection configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ServerConfig {
    /// WebSocket URL for the GuruRMM server (e.g., wss://rmm.example.com/ws)
    pub url: String,

    /// API key for authentication (obtained from server during registration)
    pub api_key: String,

    /// Optional custom hostname to report (defaults to system hostname)
    pub hostname_override: Option<String>,
}

/// Metrics collection configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MetricsConfig {
    /// Interval in seconds between metrics collection (default: 60)
    #[serde(default = "default_metrics_interval")]
    pub interval_seconds: u64,

    /// Whether to collect CPU metrics
    #[serde(default = "default_true")]
    pub collect_cpu: bool,

    /// Whether to collect memory metrics
    #[serde(default = "default_true")]
    pub collect_memory: bool,

    /// Whether to collect disk metrics
    #[serde(default = "default_true")]
    pub collect_disk: bool,

    /// Whether to collect network metrics
    #[serde(default = "default_true")]
    pub collect_network: bool,
}

impl Default for MetricsConfig {
    fn default() -> Self {
        Self {
            interval_seconds: 60,
            collect_cpu: true,
            collect_memory: true,
            collect_disk: true,
            collect_network: true,
        }
    }
}

/// Watchdog configuration for service/process monitoring
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct WatchdogConfig {
    /// Enable/disable watchdog functionality
    #[serde(default)]
    pub enabled: bool,

    /// Interval in seconds between watchdog checks (default: 30)
    #[serde(default = "default_watchdog_interval")]
    pub check_interval_seconds: u64,

    /// List of Windows/systemd services to monitor
    #[serde(default)]
    pub services: Vec<ServiceWatch>,

    /// List of processes to monitor
    #[serde(default)]
    pub processes: Vec<ProcessWatch>,
}

impl Default for WatchdogConfig {
    fn default() -> Self {
        Self {
            enabled: false,
            check_interval_seconds: 30,
            services: Vec::new(),
            processes: Vec::new(),
        }
    }
}

/// Configuration for monitoring a service
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ServiceWatch {
    /// Service name (e.g., "CagService" for Datto RMM, "Syncro" for Syncro)
    pub name: String,

    /// Action to take when service is stopped
    #[serde(default)]
    pub action: WatchAction,

    /// Maximum number of restart attempts before alerting (default: 3)
    #[serde(default = "default_max_restarts")]
    pub max_restarts: u32,

    /// Cooldown period in seconds between restart attempts
    #[serde(default = "default_restart_cooldown")]
    pub restart_cooldown_seconds: u64,
}

/// Configuration for monitoring a process
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ProcessWatch {
    /// Process name (e.g., "AEM.exe")
    pub name: String,

    /// Action to take when process is not found
    #[serde(default)]
    pub action: WatchAction,

    /// Optional path to executable to start if process is not running
    pub start_command: Option<String>,
}

/// Action to take when a watched service/process is down
#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq)]
#[serde(rename_all = "lowercase")]
pub enum WatchAction {
    /// Only send an alert to the server
    #[default]
    Alert,

    /// Attempt to restart the service/process
    Restart,

    /// Ignore (for temporary disable without removing config)
    Ignore,
}

// Default value functions for serde
fn default_metrics_interval() -> u64 {
    60
}

fn default_watchdog_interval() -> u64 {
    30
}

fn default_max_restarts() -> u32 {
    3
}

fn default_restart_cooldown() -> u64 {
    60
}

fn default_true() -> bool {
    true
}

impl AgentConfig {
    /// Load configuration from a TOML file
    pub fn load(path: &Path) -> Result<Self> {
        let content = std::fs::read_to_string(path)
            .with_context(|| format!("Failed to read config file: {:?}", path))?;

        let config: Self = toml::from_str(&content)
            .with_context(|| format!("Failed to parse config file: {:?}", path))?;

        config.validate()?;
        Ok(config)
    }

    /// Validate the configuration
    fn validate(&self) -> Result<()> {
        // Validate server URL
        if self.server.url.is_empty() {
            anyhow::bail!("Server URL cannot be empty");
        }

        if !self.server.url.starts_with("ws://") && !self.server.url.starts_with("wss://") {
            anyhow::bail!("Server URL must start with ws:// or wss://");
        }

        // Validate API key
        if self.server.api_key.is_empty() {
            anyhow::bail!("API key cannot be empty");
        }

        // Validate intervals
        if self.metrics.interval_seconds < 10 {
            anyhow::bail!("Metrics interval must be at least 10 seconds");
        }

        if self.watchdog.check_interval_seconds < 5 {
            anyhow::bail!("Watchdog check interval must be at least 5 seconds");
        }

        Ok(())
    }

    /// Generate a sample configuration
    pub fn sample() -> Self {
        Self {
            server: ServerConfig {
                url: "wss://rmm-api.azcomputerguru.com/ws".to_string(),
                api_key: "your-api-key-here".to_string(),
                hostname_override: None,
            },
            metrics: MetricsConfig::default(),
            watchdog: WatchdogConfig {
                enabled: true,
                check_interval_seconds: 30,
                services: vec![
                    ServiceWatch {
                        name: "CagService".to_string(), // Datto RMM
                        action: WatchAction::Restart,
                        max_restarts: 3,
                        restart_cooldown_seconds: 60,
                    },
                    ServiceWatch {
                        name: "Syncro".to_string(),
                        action: WatchAction::Restart,
                        max_restarts: 3,
                        restart_cooldown_seconds: 60,
                    },
                ],
                processes: vec![ProcessWatch {
                    name: "AEM.exe".to_string(), // Datto AEM
                    action: WatchAction::Alert,
                    start_command: None,
                }],
            },
        }
    }

    /// Get the hostname to report to the server
    pub fn get_hostname(&self) -> String {
        self.server
            .hostname_override
            .clone()
            .unwrap_or_else(|| hostname::get().map(|h| h.to_string_lossy().to_string()).unwrap_or_else(|_| "unknown".to_string()))
    }
}

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

    #[test]
    fn test_sample_config_is_valid_structure() {
        let sample = AgentConfig::sample();
        // Sample uses placeholder values, so it won't pass full validation
        // but the structure should be correct
        assert!(!sample.server.url.is_empty());
        assert!(!sample.server.api_key.is_empty());
        assert!(sample.watchdog.enabled);
        assert!(!sample.watchdog.services.is_empty());
    }

    #[test]
    fn test_default_metrics_config() {
        let config = MetricsConfig::default();
        assert_eq!(config.interval_seconds, 60);
        assert!(config.collect_cpu);
        assert!(config.collect_memory);
        assert!(config.collect_disk);
        assert!(config.collect_network);
    }

    #[test]
    fn test_watch_action_default() {
        let action = WatchAction::default();
        assert_eq!(action, WatchAction::Alert);
    }
}