using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using BeatLeader.Utils;
using Newtonsoft.Json;
using UnityEngine;
using UnityEngine.Networking;
using IPALogger = IPA.Logging.Logger;

namespace Setlist
{
    /// <summary>
    /// Parses BeatLeader sync URLs and checks ownership via GET /user/playlists.
    /// Reuses BeatLeader's sign-in by piggy-backing on Unity's process-wide
    /// <see cref="UnityWebRequest"/> cookie cache (the shipped 0.9.x BeatLeader
    /// signs in with <see cref="UnityWebRequest"/>; cookies are global per host).
    /// We block on BeatLeader's <c>Authentication._signedIn</c> via reflection so
    /// we don't fire the request before the cookie is in the cache.
    /// </summary>
    internal static class BeatLeaderPlaylistOwnership
    {
        private const string AuthenticationTypeName = "BeatLeader.API.Authentication";
        private const string SignedInFieldName = "_signedIn";
        private const float LoginWaitTimeoutSeconds = 90f;
        private const int RequestTimeoutSeconds = 30;

        private sealed class UserPlaylistSummary
        {
            [JsonProperty("guid")]
            public string Guid { get; set; }
        }

        internal static bool TryExtractBeatLeaderPlaylistGuid(string syncUrl, out string guid)
        {
            guid = string.Empty;
            if (string.IsNullOrWhiteSpace(syncUrl))
            {
                return false;
            }

            if (!Uri.TryCreate(syncUrl.Trim(), UriKind.Absolute, out var uri))
            {
                return false;
            }

            if (!string.Equals(uri.Host, "api.beatleader.com", StringComparison.OrdinalIgnoreCase))
            {
                return false;
            }

            var segments = uri.AbsolutePath.Split(new[] { '/' }, StringSplitOptions.RemoveEmptyEntries);
            if (segments.Length != 3)
            {
                return false;
            }

            if (!string.Equals(segments[0], "playlist", StringComparison.OrdinalIgnoreCase)
                || !string.Equals(segments[1], "guid", StringComparison.OrdinalIgnoreCase))
            {
                return false;
            }

            var id = segments[2];
            if (id.Length != 32 || !id.All(Uri.IsHexDigit))
            {
                return false;
            }

            guid = id;
            return true;
        }

        /// <summary>
        /// Spawns a hidden coroutine runner that waits for BeatLeader sign-in,
        /// fetches <c>/user/playlists</c>, then logs the per-playlist ownership.
        /// Must be called from the Unity main thread (BSIPA's <c>OnApplicationStart</c> is fine).
        /// </summary>
        internal static void ScheduleVerifyAndLog(
            List<(string Title, bool HasSyncUrl, string BeatLeaderGuid)> entries,
            IPALogger log)
        {
            var go = new GameObject("Setlist.OwnershipRunner");
            UnityEngine.Object.DontDestroyOnLoad(go);
            go.hideFlags = HideFlags.HideAndDontSave;
            var runner = go.AddComponent<OwnershipRunner>();
            runner.Initialize(entries, log);
        }

        /// <summary>
        /// Component that drives the verification coroutine; self-destroys when finished.
        /// </summary>
        private sealed class OwnershipRunner : MonoBehaviour
        {
            private List<(string Title, bool HasSyncUrl, string BeatLeaderGuid)> _entries;
            private IPALogger _log;

            public void Initialize(
                List<(string Title, bool HasSyncUrl, string BeatLeaderGuid)> entries,
                IPALogger log)
            {
                _entries = entries;
                _log = log;
                StartCoroutine(Run());
            }

            private IEnumerator Run()
            {
                HashSet<string> owned = null;
                string failure = null;

                FieldInfo signedInField;
                try
                {
                    signedInField = ResolveSignedInField(_log);
                }
                catch (Exception ex)
                {
                    signedInField = null;
                    failure = "reflecting BeatLeader Authentication failed: " + ex.Message;
                }

                if (signedInField != null)
                {
                    var waitedSeconds = 0f;
                    while (!IsSignedIn(signedInField))
                    {
                        if (waitedSeconds >= LoginWaitTimeoutSeconds)
                        {
                            failure = $"BeatLeader login did not complete within {LoginWaitTimeoutSeconds:F0}s; "
                                      + "is the BeatLeader mod actually signing in (check BeatLeader log lines)?";
                            break;
                        }
                        yield return new WaitForSeconds(1f);
                        waitedSeconds += 1f;
                    }

                    if (failure == null)
                    {
                        var fetchEnumerator = FetchOwnedGuids(result =>
                        {
                            owned = result.OwnedGuids;
                            failure = result.Failure;
                        });
                        yield return StartCoroutine(fetchEnumerator);
                    }
                }

                if (owned == null && failure != null)
                {
                    _log.Info("BeatLeader /user/playlists: " + failure);
                }

                foreach (var e in _entries)
                {
                    _log.Info(Plugin.FormatPlaylistLogLine(e.Title, e.HasSyncUrl, e.BeatLeaderGuid, owned));
                }

                Destroy(gameObject);
            }

            private struct FetchResult
            {
                public HashSet<string> OwnedGuids;
                public string Failure;
            }

            private IEnumerator FetchOwnedGuids(Action<FetchResult> onDone)
            {
                var url = BLConstants.BEATLEADER_API_URL + "/user/playlists";
                using (var request = UnityWebRequest.Get(url))
                {
                    request.timeout = RequestTimeoutSeconds;
                    request.SetRequestHeader("User-Agent", "Setlist/" + GetAssemblyVersion());

                    yield return request.SendWebRequest();

                    if (request.result == UnityWebRequest.Result.ConnectionError)
                    {
                        onDone(new FetchResult { Failure = "network error: " + request.error });
                        yield break;
                    }

                    if (request.result == UnityWebRequest.Result.ProtocolError)
                    {
                        onDone(new FetchResult
                        {
                            Failure = $"HTTP {request.responseCode} (cookie session not shared? "
                                      + "check BeatLeader login completed)",
                        });
                        yield break;
                    }

                    var body = request.downloadHandler != null ? request.downloadHandler.text : null;
                    if (string.IsNullOrEmpty(body))
                    {
                        onDone(new FetchResult { OwnedGuids = new HashSet<string>(StringComparer.OrdinalIgnoreCase) });
                        yield break;
                    }

                    HashSet<string> set;
                    try
                    {
                        var summaries = JsonConvert.DeserializeObject<List<UserPlaylistSummary>>(body);
                        set = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
                        if (summaries != null)
                        {
                            foreach (var s in summaries)
                            {
                                if (!string.IsNullOrEmpty(s?.Guid))
                                {
                                    set.Add(s.Guid);
                                }
                            }
                        }
                    }
                    catch (Exception ex)
                    {
                        onDone(new FetchResult { Failure = "JSON parse failed: " + ex.Message });
                        yield break;
                    }

                    onDone(new FetchResult { OwnedGuids = set });
                }
            }

            private static FieldInfo ResolveSignedInField(IPALogger log)
            {
                var beatLeaderAssembly = typeof(BLConstants).Assembly;
                var authType = beatLeaderAssembly.GetType(AuthenticationTypeName);
                if (authType == null)
                {
                    log.Info($"BeatLeader assembly has no {AuthenticationTypeName} type; cannot detect login state.");
                    return null;
                }

                var field = authType.GetField(SignedInFieldName, BindingFlags.NonPublic | BindingFlags.Static);
                if (field == null)
                {
                    log.Info($"{AuthenticationTypeName} has no static field '{SignedInFieldName}'; "
                             + "BeatLeader may have changed its API.");
                    return null;
                }

                return field;
            }

            private static bool IsSignedIn(FieldInfo signedInField)
            {
                var value = signedInField.GetValue(null);
                return value is bool b && b;
            }

            private static string GetAssemblyVersion()
            {
                var asm = typeof(BeatLeaderPlaylistOwnership).Assembly;
                return asm.GetName().Version?.ToString() ?? "0.0.0";
            }
        }
    }
}