using System.Text.Json;
using dbsync.Config;
using Npgsql;
using Serilog;

namespace TvSyncApp.Services;

public class TvSyncService
{
    private readonly string _connectionString;

    public TvSyncService(string connectionString)
    {
        _connectionString = connectionString;
    }

    // -----------------------------------------
    // 1. Download Updates
    // -----------------------------------------
    public async Task<Dictionary<int, long>> DownloadTvMazeUpdatesAsync(
        string updatesUrl,
        string tempDir)
    {
        using var http = new HttpClient();

        var json = await http.GetStringAsync(updatesUrl);

        // Deserialize first to validate and normalize
        var parsed = JsonSerializer.Deserialize<Dictionary<string, long>>(json)
                     ?? new Dictionary<string, long>();

        // Convert to int-key dictionary (what your app uses)
        var result = parsed
            .Where(k => int.TryParse(k.Key, out _))
            .ToDictionary(k => int.Parse(k.Key), v => v.Value);

        // Pretty-print JSON before saving
        var options = new JsonSerializerOptions
        {
            WriteIndented = true
        };

        var formattedJson = JsonSerializer.Serialize(result, options);

        var filePath = Path.Combine(tempDir, "tvmaze_updates.json");
        await File.WriteAllTextAsync(filePath, formattedJson);

        return result;
    }


    // -----------------------------------------
    // 2. Update DB
    // -----------------------------------------
    public void UpdateTvUpdatesTable(Dictionary<int, long> updates)
    {
        using var conn = new NpgsqlConnection(_connectionString);
        conn.Open();

        using var transaction = conn.BeginTransaction();

        using var batch = new NpgsqlBatch(conn, transaction);

        foreach (var kvp in updates)
        {
            var cmd = new NpgsqlBatchCommand(@"
            INSERT INTO updates.tvupdates (seriesid, timestamp)
            VALUES (@id, @ts)
            ON CONFLICT (seriesid)
            DO UPDATE SET timestamp = EXCLUDED.timestamp;");

            cmd.Parameters.AddWithValue("id", kvp.Key);
            cmd.Parameters.AddWithValue("ts", kvp.Value);

            batch.BatchCommands.Add(cmd);
        }

        batch.ExecuteNonQuery();

        transaction.Commit();

        Log.Information("Batch updated tvupdates table with {Count} entries.", updates.Count);
    }


    // -----------------------------------------
    // 3. Determine Files Needed
    // -----------------------------------------
    public List<(string Directory, string FileName)> DetermineFilesNeeded(
        Dictionary<int, long> downloadedUpdates,
        Dictionary<int, long> previousUpdates,
        Dictionary<string, string> directories)
    {
        var filesNeeded = new List<(string, string)>();
        var directoryList = directories.Values.ToList();

        foreach (var kvp in downloadedUpdates)
        {
            var seriesId = kvp.Key;
            var newTs = kvp.Value;

            if (previousUpdates.TryGetValue(seriesId, out var oldTs))
            {
                if (newTs > oldTs)
                    foreach (var dir in directoryList)
                        filesNeeded.Add((dir, $"{seriesId}.json"));
            }
            else
            {
                foreach (var dir in directoryList)
                    filesNeeded.Add((dir, $"{seriesId}.json"));
            }
        }

        return filesNeeded;
    }

    // -----------------------------------------
    // 4. Download Files
    // -----------------------------------------
    public async Task DownloadSeriesFilesAsync(
        List<(string Directory, string FileName)> filesNeeded,
        Dictionary<string, string> skipIds,
        Settings settings)
    {
        using var http = new HttpClient();

        foreach (var item in filesNeeded)
        {
            var seriesId = item.FileName.Replace(".json", "");
            var url = settings.Json!.SeriesApi!
                .Replace("<seriesid>", seriesId);

            if (skipIds.ContainsKey(seriesId))
            {
                Log.Information("Skipping series {SeriesId}", seriesId);
                continue;
            }

            try
            {
                var json = await http.GetStringAsync(url);
                var savePath = Path.Combine(item.Directory, item.FileName);
                await File.WriteAllTextAsync(savePath, json);
            }
            catch (Exception ex)
            {
                Log.Error(ex, "Failed downloading {SeriesId}", seriesId);
            }
        }
    }
}