using Dapper;
using Npgsql;
using PlanTempusAdmin.Models;

namespace PlanTempusAdmin.Services;

public class BackupService
{
    private readonly string _connectionString;
    private readonly ILogger<BackupService> _logger;

    static BackupService()
    {
        DefaultTypeMap.MatchNamesWithUnderscores = true;
    }

    public BackupService(IConfiguration configuration, ILogger<BackupService> logger)
    {
        _connectionString = configuration.GetConnectionString("BackupDb")
            ?? throw new InvalidOperationException("BackupDb connection string not configured");
        _logger = logger;
    }

    public async Task<List<BackupLog>> GetLogsAsync(int limit = 100)
    {
        try
        {
            await using var connection = new NpgsqlConnection(_connectionString);
            var logs = await connection.QueryAsync<BackupLog>(@"
                SELECT id, started_at, completed_at, duration_ms, backup_type, source_name, source_path,
                       destination, remote_path, status, size_bytes, file_count, error_message, error_code,
                       retry_count, hostname, script_version, checksum, created_at
                FROM backup_logs
                ORDER BY started_at DESC
                LIMIT @limit", new { limit });
            return logs.ToList();
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error fetching backup logs");
            return new List<BackupLog>();
        }
    }

    public async Task<BackupSummary> GetSummaryAsync()
    {
        try
        {
            await using var connection = new NpgsqlConnection(_connectionString);
            var summary = await connection.QuerySingleOrDefaultAsync<BackupSummary>(@"
                SELECT
                    COUNT(*)::int as total_backups,
                    COUNT(*) FILTER (WHERE status = 'success')::int as successful_backups,
                    COUNT(*) FILTER (WHERE status = 'failed')::int as failed_backups,
                    MAX(started_at) as last_backup,
                    MAX(started_at) FILTER (WHERE status = 'success') as last_successful_backup,
                    COALESCE(SUM(size_bytes) FILTER (WHERE status = 'success'), 0) as total_size_bytes
                FROM backup_logs");
            return summary ?? new BackupSummary();
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error fetching backup summary");
            return new BackupSummary();
        }
    }

    public async Task<List<RepositorySummary>> GetRepositorySummariesAsync()
    {
        try
        {
            await using var connection = new NpgsqlConnection(_connectionString);
            var summaries = await connection.QueryAsync<RepositorySummary>(@"
                WITH ranked_backups AS (
                    SELECT
                        source_name,
                        backup_type,
                        size_bytes,
                        started_at,
                        status,
                        ROW_NUMBER() OVER (PARTITION BY source_name ORDER BY started_at DESC) as rn
                    FROM backup_logs
                    WHERE status = 'success'
                )
                SELECT
                    bl.source_name,
                    bl.backup_type,
                    COUNT(*)::int as total_backups,
                    COUNT(*) FILTER (WHERE bl.status = 'success')::int as successful_backups,
                    COUNT(*) FILTER (WHERE bl.status = 'failed')::int as failed_backups,
                    MAX(bl.started_at) as last_backup,
                    MAX(bl.started_at) FILTER (WHERE bl.status = 'success') as last_successful_backup,
                    COALESCE(SUM(bl.size_bytes) FILTER (WHERE bl.status = 'success'), 0) as total_size_bytes,
                    (SELECT rb.size_bytes FROM ranked_backups rb WHERE rb.source_name = bl.source_name AND rb.rn = 1) as last_backup_size_bytes,
                    (SELECT rb.size_bytes FROM ranked_backups rb WHERE rb.source_name = bl.source_name AND rb.rn = 2) as previous_backup_size_bytes
                FROM backup_logs bl
                GROUP BY bl.source_name, bl.backup_type
                ORDER BY last_backup DESC NULLS LAST");
            return summaries.ToList();
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error fetching repository summaries");
            return new List<RepositorySummary>();
        }
    }

    public async Task<BackupDashboard> GetDashboardAsync()
    {
        var dashboard = new BackupDashboard();

        try
        {
            await using var connection = new NpgsqlConnection(_connectionString);

            // Overall stats
            var stats = await connection.QuerySingleOrDefaultAsync<dynamic>(@"
                SELECT
                    COUNT(*)::int as total_backups,
                    COUNT(*) FILTER (WHERE status = 'success')::int as successful_backups,
                    COUNT(*) FILTER (WHERE status = 'failed')::int as failed_backups,
                    COUNT(*) FILTER (WHERE status = 'running')::int as running_backups,
                    COALESCE(SUM(size_bytes) FILTER (WHERE status = 'success'), 0) as total_size_bytes,
                    MAX(started_at) as last_backup,
                    MAX(started_at) FILTER (WHERE status = 'success') as last_successful_backup,
                    COUNT(*) FILTER (WHERE started_at > NOW() - INTERVAL '24 hours')::int as backups_last_24_hours,
                    COUNT(*) FILTER (WHERE started_at > NOW() - INTERVAL '7 days')::int as backups_last_7_days,
                    COALESCE(SUM(size_bytes) FILTER (WHERE status = 'success' AND started_at > NOW() - INTERVAL '24 hours'), 0) as size_last_24_hours,
                    COALESCE(SUM(size_bytes) FILTER (WHERE status = 'success' AND started_at > NOW() - INTERVAL '7 days'), 0) as size_last_7_days
                FROM backup_logs");

            if (stats != null)
            {
                dashboard.TotalBackups = (int)stats.total_backups;
                dashboard.SuccessfulBackups = (int)stats.successful_backups;
                dashboard.FailedBackups = (int)stats.failed_backups;
                dashboard.RunningBackups = (int)stats.running_backups;
                dashboard.TotalSizeBytes = (long)stats.total_size_bytes;
                dashboard.LastBackup = stats.last_backup;
                dashboard.LastSuccessfulBackup = stats.last_successful_backup;
                dashboard.BackupsLast24Hours = (int)stats.backups_last_24_hours;
                dashboard.BackupsLast7Days = (int)stats.backups_last_7_days;
                dashboard.SizeLast24Hours = (long)stats.size_last_24_hours;
                dashboard.SizeLast7Days = (long)stats.size_last_7_days;
            }

            // By backup type
            dashboard.ByType = (await connection.QueryAsync<BackupTypeStat>(@"
                SELECT
                    backup_type,
                    COUNT(*)::int as total,
                    COUNT(*) FILTER (WHERE status = 'success')::int as successful,
                    COUNT(*) FILTER (WHERE status = 'failed')::int as failed,
                    COUNT(*) FILTER (WHERE status = 'running')::int as running,
                    COALESCE(SUM(size_bytes) FILTER (WHERE status = 'success'), 0) as total_size,
                    MAX(started_at) as last_backup
                FROM backup_logs
                GROUP BY backup_type
                ORDER BY total DESC")).ToList();

            // By destination
            dashboard.ByDestination = (await connection.QueryAsync<DestinationStat>(@"
                SELECT
                    destination,
                    COUNT(*)::int as total,
                    COUNT(*) FILTER (WHERE status = 'success')::int as successful,
                    COUNT(*) FILTER (WHERE status = 'failed')::int as failed,
                    COALESCE(SUM(size_bytes) FILTER (WHERE status = 'success'), 0) as total_size,
                    MAX(started_at) as last_backup
                FROM backup_logs
                GROUP BY destination
                ORDER BY total DESC")).ToList();

            // By host
            dashboard.ByHost = (await connection.QueryAsync<HostStat>(@"
                SELECT
                    COALESCE(hostname, 'unknown') as hostname,
                    COUNT(*)::int as total,
                    COUNT(*) FILTER (WHERE status = 'success')::int as successful,
                    COUNT(*) FILTER (WHERE status = 'failed')::int as failed,
                    COUNT(*) FILTER (WHERE status = 'running')::int as running,
                    MAX(started_at) as last_backup,
                    (SELECT script_version FROM backup_logs b2
                     WHERE COALESCE(b2.hostname, 'unknown') = COALESCE(backup_logs.hostname, 'unknown')
                     ORDER BY started_at DESC LIMIT 1) as script_version
                FROM backup_logs
                GROUP BY COALESCE(hostname, 'unknown')
                ORDER BY total DESC")).ToList();

            // Top errors
            dashboard.TopErrors = (await connection.QueryAsync<ErrorStat>(@"
                SELECT
                    COALESCE(error_code, 'UNKNOWN') as error_code,
                    COUNT(*)::int as count,
                    MAX(started_at) as last_occurrence,
                    (SELECT error_message FROM backup_logs b2
                     WHERE COALESCE(b2.error_code, 'UNKNOWN') = COALESCE(backup_logs.error_code, 'UNKNOWN')
                     AND b2.status = 'failed'
                     ORDER BY started_at DESC LIMIT 1) as last_message
                FROM backup_logs
                WHERE status = 'failed'
                GROUP BY COALESCE(error_code, 'UNKNOWN')
                ORDER BY count DESC
                LIMIT 5")).ToList();

            // Daily stats (last 14 days)
            dashboard.DailyStats = (await connection.QueryAsync<DailyStat>(@"
                SELECT
                    DATE(started_at) as date,
                    COUNT(*)::int as total,
                    COUNT(*) FILTER (WHERE status = 'success')::int as successful,
                    COUNT(*) FILTER (WHERE status = 'failed')::int as failed,
                    COALESCE(SUM(size_bytes) FILTER (WHERE status = 'success'), 0) as total_size
                FROM backup_logs
                WHERE started_at > NOW() - INTERVAL '14 days'
                GROUP BY DATE(started_at)
                ORDER BY date DESC")).ToList();

            // Running now
            dashboard.RunningNow = (await connection.QueryAsync<BackupLog>(@"
                SELECT * FROM backup_logs
                WHERE status = 'running'
                ORDER BY started_at DESC")).ToList();

            // Recent successes
            dashboard.RecentSuccesses = (await connection.QueryAsync<BackupLog>(@"
                SELECT * FROM backup_logs
                WHERE status = 'success'
                ORDER BY started_at DESC
                LIMIT 5")).ToList();

            // Recent failures
            dashboard.RecentFailures = (await connection.QueryAsync<BackupLog>(@"
                SELECT * FROM backup_logs
                WHERE status = 'failed'
                ORDER BY started_at DESC
                LIMIT 5")).ToList();
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error fetching backup dashboard");
        }

        return dashboard;
    }

    public async Task<bool> TestConnectionAsync()
    {
        try
        {
            await using var connection = new NpgsqlConnection(_connectionString);
            await connection.OpenAsync();
            return true;
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Could not connect to backup database");
            return false;
        }
    }
}