using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Timers;
using Playnite.SDK;
using Playnite.SDK.Data;
using Playnite.SDK.Events;
using Playnite.SDK.Models;
using Playnite.SDK.Plugins;

namespace PunktfunkSync
{
    /// <summary>
    /// Writes the Playnite library to <c>punktfunk-library.json</c> whenever it changes, to two
    /// places: this plugin's data directory (<c>…/Playnite/ExtensionsData/&lt;this-id&gt;/</c>) and —
    /// best-effort — the host's ingest inbox (<c>%ProgramData%\punktfunk\ingest\playnite\</c>). The
    /// second matters because the host's plugin runner is de-privileged (<c>NT AUTHORITY\LocalService</c>)
    /// and cannot read this user's <c>%APPDATA%</c>; <c>punktfunk-host plugins enable</c> makes the
    /// ingest inbox user-writable so we can drop the file where the runner can read it. This side
    /// stays a dumb, dependency-free exporter.
    /// </summary>
    public class PunktfunkSyncPlugin : GenericPlugin
    {
        private const int Schema = 1;
        private static readonly ILogger logger = LogManager.GetLogger();

        // Stable id → stable ExtensionsData folder. Never change it (it's the folder name the reader
        // finds), and keep it distinct from every other extension.
        public override Guid Id { get; } = Guid.Parse("d9f1b3a2-7c64-4e58-9a1b-6f2e3c4d5a6b");

        private readonly string exportPath;
        private readonly string ingestPath;
        private readonly Timer debounce;

        public PunktfunkSyncPlugin(IPlayniteAPI api) : base(api)
        {
            Properties = new GenericPluginProperties { HasSettings = false };
            exportPath = Path.Combine(GetPluginUserDataPath(), "punktfunk-library.json");
            // The host runner is de-privileged and can't read our %APPDATA%; drop a copy in the
            // host's user-writable ingest inbox too (see WriteAtomic). Keep this in lockstep with the
            // TS reader's `ingestDir()` (`<config_dir>/ingest/playnite`).
            ingestPath = Path.Combine(
                Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData),
                "punktfunk", "ingest", "playnite", "punktfunk-library.json");

            // Coalesce bursts of per-item events (a metadata download touches many games) into one write.
            debounce = new Timer(3000) { AutoReset = false };
            debounce.Elapsed += (s, e) => Export("changed");
        }

        public override void OnApplicationStarted(OnApplicationStartedEventArgs args)
        {
            // Initial export, then react to any subsequent library mutation.
            Export("app-started");
            PlayniteApi.Database.Games.ItemCollectionChanged += (s, e) => ScheduleExport();
            PlayniteApi.Database.Games.ItemUpdated += (s, e) => ScheduleExport();
        }

        public override void OnLibraryUpdated(OnLibraryUpdatedEventArgs args)
        {
            Export("library-updated");
        }

        public override IEnumerable<MainMenuItem> GetMainMenuItems(GetMainMenuItemsArgs args)
        {
            yield return new MainMenuItem
            {
                Description = "Export library to Punktfunk now",
                MenuSection = "@Punktfunk Sync",
                Action = a => Export("manual"),
            };
        }

        private void ScheduleExport()
        {
            debounce.Stop();
            debounce.Start();
        }

        /// <summary>Resolve a Playnite media reference to an absolute path (remote URLs pass through).</summary>
        private string ResolveArt(string reference)
        {
            if (string.IsNullOrEmpty(reference)) return null;
            if (reference.StartsWith("http", StringComparison.OrdinalIgnoreCase)) return reference;
            try
            {
                var full = PlayniteApi.Database.GetFullFilePath(reference);
                return File.Exists(full) ? full : null;
            }
            catch (Exception ex)
            {
                logger.Warn(ex, $"Punktfunk Sync: could not resolve art path '{reference}'");
                return null;
            }
        }

        private void Export(string reason)
        {
            try
            {
                var games = PlayniteApi.Database.Games.Select(g => new ExportedGame
                {
                    Id = g.Id.ToString("D"),
                    Name = g.Name ?? string.Empty,
                    Installed = g.IsInstalled,
                    Hidden = g.Hidden,
                    Source = g.Source?.Name,
                    Platforms = g.Platforms?.Select(p => p.Name).ToList() ?? new List<string>(),
                    Cover = ResolveArt(g.CoverImage),
                    Background = ResolveArt(g.BackgroundImage),
                    Icon = ResolveArt(g.Icon),
                }).ToList();

                var export = new LibraryExport
                {
                    Schema = Schema,
                    GeneratedAt = DateTime.UtcNow.ToString("yyyy-MM-ddTHH:mm:ssZ"),
                    Playnite = new PlayniteInfo
                    {
                        Version = PlayniteApi.ApplicationInfo.ApplicationVersion?.ToString(),
                        Mode = PlayniteApi.ApplicationInfo.Mode.ToString(),
                    },
                    Games = games,
                };

                WriteAtomic(Serialization.ToJson(export, true));
                logger.Info($"Punktfunk Sync: exported {games.Count} game(s) ({reason}) to {exportPath}");
            }
            catch (Exception ex)
            {
                logger.Error(ex, "Punktfunk Sync: export failed");
            }
        }

        /// <summary>
        /// Write the export to its ExtensionsData home (always) and to the host ingest inbox
        /// (best-effort — only when a punktfunk host is present on this box, so we never create a
        /// stray %ProgramData%\punktfunk on a machine that has no host).
        /// </summary>
        private void WriteAtomic(string json)
        {
            WriteAtomicTo(exportPath, json);
            try
            {
                var pfDir = Path.Combine(
                    Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData),
                    "punktfunk");
                if (Directory.Exists(pfDir)) WriteAtomicTo(ingestPath, json);
            }
            catch (Exception ex)
            {
                // The inbox only exists (and is writable) where `plugins enable` has run; a failure
                // here just means the de-privileged runner falls back to the ExtensionsData scan.
                logger.Info($"Punktfunk Sync: ingest drop skipped ({ex.Message})");
            }
        }

        /// <summary>Write via a temp file + move so a reader never sees a half-written export.</summary>
        private static void WriteAtomicTo(string path, string json)
        {
            Directory.CreateDirectory(Path.GetDirectoryName(path));
            var tmp = path + ".tmp";
            File.WriteAllText(tmp, json);
            if (File.Exists(path)) File.Delete(path);
            File.Move(tmp, path);
        }
    }
}