using System;
using System.Collections.Generic;
using Newtonsoft.Json.Linq;
using UnityEditor;
using UnityEngine;
using UnityEngine.Networking;

namespace Chameleon.Editor.PolyHaven
{
    /// <summary>One downloadable file variant (a specific map/resolution/format).</summary>
    public readonly struct PolyHavenFile
    {
        public readonly string Url;
        public readonly string Format; // "jpg" / "png" / "exr"
        public readonly long Size;

        public PolyHavenFile(string url, string format, long size)
        {
            Url = url;
            Format = format;
            Size = size;
        }

        public bool IsValid => !string.IsNullOrEmpty(Url);
    }

    /// <summary>Asset metadata from /info/{slug}.</summary>
    public sealed class PolyHavenInfo
    {
        public string Slug;
        public string Name;
        public int Type;            // 0=HDRI, 1=Texture, 2=Model
        public string ThumbnailUrl;
        public string[] Categories = Array.Empty<string>();
    }

    /// <summary>One catalog entry from /assets (lightweight, for the browser grid).</summary>
    public sealed class PolyHavenAsset
    {
        public string Slug;
        public string Name;
        public string ThumbnailUrl;
        public string[] Categories = Array.Empty<string>();
        public string[] Tags = Array.Empty<string>();
        public string Search; // pre-lowered "name slug categories tags" haystack
    }

    /// <summary>Parsed /files/{slug}: MapType -> resolution("2k") -> best file.</summary>
    public sealed class PolyHavenFiles
    {
        public readonly Dictionary<PolyHavenMapType, Dictionary<string, PolyHavenFile>> Maps =
            new Dictionary<PolyHavenMapType, Dictionary<string, PolyHavenFile>>();

        // Every resolution string seen across all maps (e.g. "1k","2k","4k"), sorted low->high.
        public List<string> Resolutions = new List<string>();

        public bool Has(PolyHavenMapType type) => Maps.ContainsKey(type);

        public bool TryGet(PolyHavenMapType type, string res, out PolyHavenFile file)
        {
            file = default;
            return Maps.TryGetValue(type, out var byRes) && byRes.TryGetValue(res, out file);
        }

        /// <summary>Best available file at res, else next-lower resolution of the same map.</summary>
        public bool TryGetWithFallback(PolyHavenMapType type, string res, out PolyHavenFile file, out string usedRes)
        {
            file = default;
            usedRes = null;
            if (!Maps.TryGetValue(type, out var byRes))
                return false;
            if (byRes.TryGetValue(res, out file)) { usedRes = res; return true; }

            int target = ResolutionRank(res);
            int bestRank = -1;
            foreach (var kv in byRes)
            {
                int rank = ResolutionRank(kv.Key);
                if (rank <= target && rank > bestRank)
                {
                    bestRank = rank;
                    file = kv.Value;
                    usedRes = kv.Key;
                }
            }
            if (usedRes == null) // nothing at-or-below target: take the lowest available
            {
                foreach (var kv in byRes)
                {
                    int rank = ResolutionRank(kv.Key);
                    if (bestRank == -1 || rank < bestRank)
                    {
                        bestRank = rank;
                        file = kv.Value;
                        usedRes = kv.Key;
                    }
                }
            }
            return usedRes != null;
        }

        public static int ResolutionRank(string res)
        {
            if (string.IsNullOrEmpty(res)) return int.MaxValue;
            var digits = res.TrimEnd('k', 'K');
            return int.TryParse(digits, out var n) ? n : int.MaxValue;
        }
    }

    /// <summary>
    /// Async client for the public Poly Haven API (same endpoints the Blender/UE5 plugins use).
    /// All requests poll on EditorApplication.update — never blocks the editor.
    /// </summary>
    public static class PolyHavenApi
    {
        private const string ApiBase = "https://api.polyhaven.com";
        private const string UserAgent = "Chameleon-Unity-PolyHavenImporter/1.0";

        // Best format preference per map: lossless where it matters, jpg otherwise.
        private static readonly string[] LosslessPref = { "png", "exr", "jpg" };
        private static readonly string[] LossyPref = { "jpg", "png", "exr" };

        public static string ExtractSlug(string urlOrSlug)
        {
            if (string.IsNullOrWhiteSpace(urlOrSlug)) return null;
            var s = urlOrSlug.Trim();

            // Full URL like https://polyhaven.com/a/broken_brick_wall
            int a = s.IndexOf("/a/", StringComparison.OrdinalIgnoreCase);
            if (a >= 0)
                s = s.Substring(a + 3);

            // Strip any trailing path/query/fragment.
            foreach (var sep in new[] { '?', '#', '/' })
            {
                int i = s.IndexOf(sep);
                if (i >= 0) s = s.Substring(0, i);
            }
            s = s.Trim();
            return s.Length == 0 ? null : s;
        }

        public static string ThumbnailUrl(string slug) =>
            $"https://cdn.polyhaven.com/asset_img/thumbs/{slug}.png?width=256&height=256";

        // ---- Requests ----------------------------------------------------------

        public static void FetchInfo(string slug, Action<PolyHavenInfo> onDone, Action<string> onError)
        {
            var req = UnityWebRequest.Get($"{ApiBase}/info/{slug}");
            req.SetRequestHeader("User-Agent", UserAgent);
            Send(req, () =>
            {
                try
                {
                    var o = JObject.Parse(req.downloadHandler.text);
                    var info = new PolyHavenInfo
                    {
                        Slug = slug,
                        Name = (string)o["name"] ?? slug,
                        Type = o["type"] != null ? (int)o["type"] : -1,
                        ThumbnailUrl = (string)o["thumbnail_url"] ?? ThumbnailUrl(slug),
                    };
                    if (o["categories"] is JArray cats)
                    {
                        var list = new List<string>();
                        foreach (var c in cats) list.Add((string)c);
                        info.Categories = list.ToArray();
                    }
                    onDone?.Invoke(info);
                }
                catch (Exception e) { onError?.Invoke($"Info parse failed: {e.Message}"); }
            }, onError);
        }

        /// <summary>Loads the full texture catalog (keyed by slug) for the browser grid.</summary>
        public static void FetchAssets(string type, Action<List<PolyHavenAsset>> onDone, Action<string> onError)
        {
            var req = UnityWebRequest.Get($"{ApiBase}/assets?t={type}");
            req.SetRequestHeader("User-Agent", UserAgent);
            Send(req, () =>
            {
                try
                {
                    var root = JObject.Parse(req.downloadHandler.text);
                    var list = new List<PolyHavenAsset>(root.Count);
                    foreach (var prop in root)
                    {
                        if (prop.Value is not JObject o) continue;
                        var a = new PolyHavenAsset
                        {
                            Slug = prop.Key,
                            Name = (string)o["name"] ?? prop.Key,
                            ThumbnailUrl = (string)o["thumbnail_url"] ?? ThumbnailUrl(prop.Key),
                            Categories = ToStringArray(o["categories"]),
                            Tags = ToStringArray(o["tags"]),
                        };
                        a.Search = (a.Name + " " + a.Slug + " " +
                                    string.Join(" ", a.Categories) + " " +
                                    string.Join(" ", a.Tags)).ToLowerInvariant();
                        list.Add(a);
                    }
                    list.Sort((x, y) => string.Compare(x.Name, y.Name, StringComparison.OrdinalIgnoreCase));
                    onDone?.Invoke(list);
                }
                catch (Exception e) { onError?.Invoke($"Assets parse failed: {e.Message}"); }
            }, onError);
        }

        public static void FetchFiles(string slug, Action<PolyHavenFiles> onDone, Action<string> onError)
        {
            var req = UnityWebRequest.Get($"{ApiBase}/files/{slug}");
            req.SetRequestHeader("User-Agent", UserAgent);
            Send(req, () =>
            {
                try { onDone?.Invoke(ParseFiles(req.downloadHandler.text)); }
                catch (Exception e) { onError?.Invoke($"Files parse failed: {e.Message}"); }
            }, onError);
        }

        public static void FetchThumbnail(string url, Action<Texture2D> onDone, Action<string> onError)
        {
            var req = UnityWebRequestTexture.GetTexture(url);
            req.SetRequestHeader("User-Agent", UserAgent);
            Send(req, () =>
            {
                var tex = DownloadHandlerTexture.GetContent(req);
                // Survive play-mode enter/exit cleanup — otherwise Unity destroys these
                // loose runtime textures and the browser previews go blank.
                if (tex)
                    tex.hideFlags = HideFlags.HideAndDontSave;
                onDone?.Invoke(tex);
            }, onError);
        }

        /// <summary>Streams a file straight to disk (no RAM peak on big EXR/8K files).</summary>
        public static void DownloadFile(PolyHavenFile file, string destPath, Action onDone,
            Action<string> onError, Action<float> onProgress = null)
        {
            var req = new UnityWebRequest(file.Url, UnityWebRequest.kHttpVerbGET);
            req.downloadHandler = new DownloadHandlerFile(destPath) { removeFileOnAbort = true };
            req.SetRequestHeader("User-Agent", UserAgent);
            Send(req, () => onDone?.Invoke(), onError, onProgress);
        }

        // ---- Parsing -----------------------------------------------------------

        private static string[] ToStringArray(JToken token)
        {
            if (token is not JArray arr) return Array.Empty<string>();
            var list = new List<string>(arr.Count);
            foreach (var t in arr)
            {
                var s = (string)t;
                if (!string.IsNullOrEmpty(s)) list.Add(s);
            }
            return list.ToArray();
        }

        private static PolyHavenFiles ParseFiles(string json)
        {
            var root = JObject.Parse(json);
            var result = new PolyHavenFiles();
            var resSet = new HashSet<string>();

            foreach (var meta in PolyHavenMapInfo.All)
            {
                if (root[meta.ApiKey] is not JObject byRes)
                    continue;

                var pref = (meta.IsNormal || meta.Type == PolyHavenMapType.Displacement)
                    ? LosslessPref
                    : LossyPref;

                var perRes = new Dictionary<string, PolyHavenFile>();
                foreach (var resProp in byRes)
                {
                    string res = resProp.Key;
                    if (resProp.Value is not JObject formats)
                        continue;

                    PolyHavenFile picked = default;
                    foreach (var fmt in pref)
                    {
                        if (formats[fmt] is JObject fo && fo["url"] != null)
                        {
                            picked = new PolyHavenFile(
                                (string)fo["url"], fmt,
                                fo["size"] != null ? (long)fo["size"] : 0);
                            break;
                        }
                    }
                    if (picked.IsValid)
                    {
                        perRes[res] = picked;
                        resSet.Add(res);
                    }
                }

                if (perRes.Count > 0)
                    result.Maps[meta.Type] = perRes;
            }

            var resList = new List<string>(resSet);
            resList.Sort((x, y) => PolyHavenFiles.ResolutionRank(x).CompareTo(PolyHavenFiles.ResolutionRank(y)));
            result.Resolutions = resList;
            return result;
        }

        // ---- Non-blocking transport -------------------------------------------

        private static void Send(UnityWebRequest req, Action onSuccess, Action<string> onError,
            Action<float> onProgress = null)
        {
            var op = req.SendWebRequest();
            void Tick()
            {
                if (onProgress != null && !op.isDone)
                    onProgress(req.downloadProgress);

                if (!op.isDone)
                    return;

                EditorApplication.update -= Tick;
                try
                {
                    if (req.result != UnityWebRequest.Result.Success)
                    {
                        onError?.Invoke($"{req.error} ({req.url})");
                    }
                    else
                    {
                        onProgress?.Invoke(1f);
                        onSuccess?.Invoke();
                    }
                }
                finally
                {
                    req.Dispose();
                }
            }
            EditorApplication.update += Tick;
        }
    }
}