use async_trait::async_trait;
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use serde_json::json;
use std::process::Stdio;
use std::time::Duration;
use tokio::process::Command;
use tokio::time::timeout;
use tokio::fs;

use super::{AgentType, Collector, CollectorError, CollectorOutput};

#[derive(Debug, Clone)]
pub struct BackupCollector {
    pub enabled: bool,
    pub interval: Duration,
    pub restic_repo: Option<String>,
    pub backup_service: String,
    pub timeout_ms: u64,
}

impl BackupCollector {
    pub fn new(
        enabled: bool,
        interval_ms: u64,
        restic_repo: Option<String>,
        backup_service: String,
    ) -> Self {
        Self {
            enabled,
            interval: Duration::from_millis(interval_ms),
            restic_repo,
            backup_service,
            timeout_ms: 30000, // 30 second timeout for backup operations
        }
    }

    async fn get_borgbackup_metrics(&self) -> Result<BorgbackupMetrics, CollectorError> {
        // Read metrics from the borgbackup JSON file
        let metrics_path = "/var/lib/backup/backup-metrics.json";
        
        let content = fs::read_to_string(metrics_path)
            .await
            .map_err(|e| CollectorError::IoError {
                message: format!("Failed to read backup metrics file: {}", e),
            })?;
        
        let metrics: BorgbackupMetrics = serde_json::from_str(&content)
            .map_err(|e| CollectorError::ParseError {
                message: format!("Failed to parse backup metrics JSON: {}", e),
            })?;
        
        Ok(metrics)
    }
    
    async fn get_restic_snapshots(&self) -> Result<ResticStats, CollectorError> {
        let repo = self
            .restic_repo
            .as_ref()
            .ok_or_else(|| CollectorError::ConfigError {
                message: "No restic repository configured".to_string(),
            })?;

        let timeout_duration = Duration::from_millis(self.timeout_ms);

        // Get restic snapshots
        let output = timeout(
            timeout_duration,
            Command::new("restic")
                .args(["-r", repo, "snapshots", "--json"])
                .stdout(Stdio::piped())
                .stderr(Stdio::piped())
                .output(),
        )
        .await
        .map_err(|_| CollectorError::Timeout {
            duration_ms: self.timeout_ms,
        })?
        .map_err(|e| CollectorError::CommandFailed {
            command: format!("restic -r {} snapshots --json", repo),
            message: e.to_string(),
        })?;

        if !output.status.success() {
            let stderr = String::from_utf8_lossy(&output.stderr);
            return Err(CollectorError::CommandFailed {
                command: format!("restic -r {} snapshots --json", repo),
                message: stderr.to_string(),
            });
        }

        let stdout = String::from_utf8_lossy(&output.stdout);
        let snapshots: Vec<ResticSnapshot> =
            serde_json::from_str(&stdout).map_err(|e| CollectorError::ParseError {
                message: format!("Failed to parse restic snapshots: {}", e),
            })?;

        // Get repository stats
        let stats_output = timeout(
            timeout_duration,
            Command::new("restic")
                .args(["-r", repo, "stats", "--json"])
                .stdout(Stdio::piped())
                .stderr(Stdio::piped())
                .output(),
        )
        .await
        .map_err(|_| CollectorError::Timeout {
            duration_ms: self.timeout_ms,
        })?
        .map_err(|e| CollectorError::CommandFailed {
            command: format!("restic -r {} stats --json", repo),
            message: e.to_string(),
        })?;

        let repo_size_gb = if stats_output.status.success() {
            let stats_stdout = String::from_utf8_lossy(&stats_output.stdout);
            let stats: Result<ResticStats, _> = serde_json::from_str(&stats_stdout);
            stats
                .ok()
                .map(|s| s.total_size as f32 / (1024.0 * 1024.0 * 1024.0))
                .unwrap_or(0.0)
        } else {
            0.0
        };

        // Find most recent snapshot
        let last_success = snapshots.iter().map(|s| s.time).max();

        Ok(ResticStats {
            total_size: (repo_size_gb * 1024.0 * 1024.0 * 1024.0) as u64,
            snapshot_count: snapshots.len() as u32,
            last_success,
        })
    }

    async fn get_backup_service_status(&self) -> Result<BackupServiceData, CollectorError> {
        let timeout_duration = Duration::from_millis(self.timeout_ms);

        // Get systemctl status for backup service
        let status_output = timeout(
            timeout_duration,
            Command::new("systemctl")
                .args([
                    "show",
                    &self.backup_service,
                    "--property=ActiveState,SubState,MainPID",
                ])
                .stdout(Stdio::piped())
                .stderr(Stdio::piped())
                .output(),
        )
        .await
        .map_err(|_| CollectorError::Timeout {
            duration_ms: self.timeout_ms,
        })?
        .map_err(|e| CollectorError::CommandFailed {
            command: format!("systemctl show {}", self.backup_service),
            message: e.to_string(),
        })?;

        let enabled = if status_output.status.success() {
            let status_stdout = String::from_utf8_lossy(&status_output.stdout);
            status_stdout.contains("ActiveState=active")
                || status_stdout.contains("SubState=running")
        } else {
            false
        };

        // Check for backup timer or service logs for last message
        let last_message = self.get_last_backup_log_message().await.ok();

        // Check for pending backup jobs (simplified - could check systemd timers)
        let pending_jobs = 0; // TODO: Implement proper pending job detection

        Ok(BackupServiceData {
            enabled,
            pending_jobs,
            last_message,
        })
    }

    async fn get_last_backup_log_message(&self) -> Result<String, CollectorError> {
        let output = Command::new("journalctl")
            .args([
                "-u",
                &self.backup_service,
                "--lines=1",
                "--no-pager",
                "--output=cat",
            ])
            .stdout(Stdio::piped())
            .stderr(Stdio::piped())
            .output()
            .await
            .map_err(|e| CollectorError::CommandFailed {
                command: format!("journalctl -u {} --lines=1", self.backup_service),
                message: e.to_string(),
            })?;

        if output.status.success() {
            let stdout = String::from_utf8_lossy(&output.stdout);
            let message = stdout.trim().to_string();
            if !message.is_empty() {
                return Ok(message);
            }
        }

        Err(CollectorError::ParseError {
            message: "No log messages found".to_string(),
        })
    }

    async fn get_backup_logs_for_failures(&self) -> Result<Option<DateTime<Utc>>, CollectorError> {
        let output = Command::new("journalctl")
            .args([
                "-u",
                &self.backup_service,
                "--since",
                "1 week ago",
                "--grep=failed\\|error\\|ERROR",
                "--output=json",
                "--lines=1",
            ])
            .stdout(Stdio::piped())
            .stderr(Stdio::piped())
            .output()
            .await
            .map_err(|e| CollectorError::CommandFailed {
                command: format!(
                    "journalctl -u {} --since='1 week ago' --grep=failed",
                    self.backup_service
                ),
                message: e.to_string(),
            })?;

        if output.status.success() {
            let stdout = String::from_utf8_lossy(&output.stdout);
            if let Ok(log_entry) = serde_json::from_str::<JournalEntry>(&stdout) {
                if let Ok(timestamp) = log_entry.realtime_timestamp.parse::<i64>() {
                    let dt =
                        DateTime::from_timestamp_micros(timestamp).unwrap_or_else(|| Utc::now());
                    return Ok(Some(dt));
                }
            }
        }

        Ok(None)
    }

    fn determine_backup_status(
        &self,
        restic_stats: &Result<ResticStats, CollectorError>,
        service_data: &BackupServiceData,
        last_failure: Option<DateTime<Utc>>,
    ) -> BackupStatus {
        match restic_stats {
            Ok(stats) => {
                if let Some(last_success) = stats.last_success {
                    let hours_since_backup =
                        Utc::now().signed_duration_since(last_success).num_hours();

                    if hours_since_backup > 48 {
                        BackupStatus::Warning // More than 2 days since last backup
                    } else if let Some(failure) = last_failure {
                        if failure > last_success {
                            BackupStatus::Failed // Failure after last success
                        } else {
                            BackupStatus::Healthy
                        }
                    } else {
                        BackupStatus::Healthy
                    }
                } else {
                    BackupStatus::Warning // No successful backups found
                }
            }
            Err(_) => {
                if service_data.enabled {
                    BackupStatus::Failed // Service enabled but can't access repo
                } else {
                    BackupStatus::Unknown // Service disabled
                }
            }
        }
    }
}

#[async_trait]
impl Collector for BackupCollector {
    fn name(&self) -> &str {
        "backup"
    }

    fn agent_type(&self) -> AgentType {
        AgentType::Backup
    }

    fn collect_interval(&self) -> Duration {
        self.interval
    }

    fn is_enabled(&self) -> bool {
        self.enabled
    }

    fn requires_root(&self) -> bool {
        false // Depends on restic repo permissions
    }

    async fn collect(&self) -> Result<CollectorOutput, CollectorError> {
        // Try to get borgbackup metrics first, fall back to restic if not available
        let borgbackup_result = self.get_borgbackup_metrics().await;
        
        let (backup_info, overall_status) = match &borgbackup_result {
            Ok(borg_metrics) => {
                // Parse borgbackup timestamp to DateTime
                let last_success = chrono::DateTime::from_timestamp(borg_metrics.timestamp, 0);
                
                // Determine status from borgbackup data
                let status = match borg_metrics.status.as_str() {
                    "success" => BackupStatus::Healthy,
                    "warning" => BackupStatus::Warning,
                    "failed" => BackupStatus::Failed,
                    _ => BackupStatus::Unknown,
                };
                
                let backup_info = BackupInfo {
                    last_success,
                    last_failure: None, // borgbackup metrics don't include failure info
                    size_gb: borg_metrics.repository.total_repository_size_bytes as f32 / (1024.0 * 1024.0 * 1024.0),
                    latest_archive_size_gb: Some(borg_metrics.repository.latest_archive_size_bytes as f32 / (1024.0 * 1024.0 * 1024.0)),
                    snapshot_count: borg_metrics.repository.total_archives as u32,
                };
                
                (backup_info, status)
            },
            Err(_) => {
                // Fall back to restic if borgbackup metrics not available
                let restic_stats = self.get_restic_snapshots().await;
                let last_failure = self.get_backup_logs_for_failures().await.unwrap_or(None);
                
                // Get backup service status for fallback determination
                let service_data = self
                    .get_backup_service_status()
                    .await
                    .unwrap_or(BackupServiceData {
                        enabled: false,
                        pending_jobs: 0,
                        last_message: None,
                    });
                
                let overall_status = self.determine_backup_status(&restic_stats, &service_data, last_failure);
                
                let backup_info = match &restic_stats {
                    Ok(stats) => BackupInfo {
                        last_success: stats.last_success,
                        last_failure,
                        size_gb: stats.total_size as f32 / (1024.0 * 1024.0 * 1024.0),
                        latest_archive_size_gb: None, // Restic doesn't provide this easily
                        snapshot_count: stats.snapshot_count,
                    },
                    Err(_) => BackupInfo {
                        last_success: None,
                        last_failure,
                        size_gb: 0.0,
                        latest_archive_size_gb: None,
                        snapshot_count: 0,
                    },
                };
                
                (backup_info, overall_status)
            }
        };

        // Get backup service status
        let service_data = self
            .get_backup_service_status()
            .await
            .unwrap_or(BackupServiceData {
                enabled: false,
                pending_jobs: 0,
                last_message: None,
            });

        // Add disk information if available from borgbackup metrics
        let mut backup_json = json!({
            "overall_status": overall_status,
            "backup": backup_info,
            "service": service_data,
            "timestamp": Utc::now()
        });
        
        // If we got borgbackup metrics, include disk information
        if let Ok(borg_metrics) = &borgbackup_result {
            backup_json["disk"] = json!({
                "device": borg_metrics.backup_disk.device,
                "health": borg_metrics.backup_disk.health,
                "total_gb": borg_metrics.backup_disk.total_bytes as f32 / (1024.0 * 1024.0 * 1024.0),
                "used_gb": borg_metrics.backup_disk.used_bytes as f32 / (1024.0 * 1024.0 * 1024.0),
                "usage_percent": borg_metrics.backup_disk.usage_percent
            });
        }

        let backup_metrics = backup_json;

        Ok(CollectorOutput {
            agent_type: AgentType::Backup,
            data: backup_metrics,
            timestamp: Utc::now(),
        })
    }
}

#[derive(Debug, Deserialize)]
struct ResticSnapshot {
    time: DateTime<Utc>,
}

#[derive(Debug, Deserialize)]
struct ResticStats {
    total_size: u64,
    snapshot_count: u32,
    last_success: Option<DateTime<Utc>>,
}

#[derive(Debug, Serialize)]
struct BackupServiceData {
    enabled: bool,
    pending_jobs: u32,
    last_message: Option<String>,
}

#[derive(Debug, Serialize)]
struct BackupInfo {
    last_success: Option<DateTime<Utc>>,
    last_failure: Option<DateTime<Utc>>,
    size_gb: f32,
    latest_archive_size_gb: Option<f32>,
    snapshot_count: u32,
}

#[derive(Debug, Serialize)]
enum BackupStatus {
    Healthy,
    Warning,
    Failed,
    Unknown,
}

#[derive(Debug, Deserialize)]
struct JournalEntry {
    #[serde(rename = "__REALTIME_TIMESTAMP")]
    realtime_timestamp: String,
}

// Borgbackup metrics structure from backup script
#[derive(Debug, Deserialize)]
struct BorgbackupMetrics {
    backup_name: String,
    start_time: String,
    end_time: String,
    duration_seconds: i64,
    status: String,
    exit_codes: ExitCodes,
    repository: Repository,
    backup_disk: BackupDisk,
    timestamp: i64,
}

#[derive(Debug, Deserialize)]
struct ExitCodes {
    global: i32,
    backup: i32,
    prune: i32,
    compact: i32,
}

#[derive(Debug, Deserialize)]
struct Repository {
    total_archives: i32,
    latest_archive_size_bytes: i64,
    total_repository_size_bytes: i64,
    path: String,
}

#[derive(Debug, Deserialize)]
struct BackupDisk {
    device: String,
    health: String,
    total_bytes: i64,
    used_bytes: i64,
    available_bytes: i64,
    usage_percent: f32,
}