using System;
using System.IO;
using UnityEngine;

namespace OnDeviceAgent.Inference
{
    // Resolves a "Model/<X>/..." relative path to a concrete file path. In a player build it resolves under
    // Application.streamingAssetsPath; in the Editor the weights live only in the com.sky.sentis.* packages
    // (Models~), so the path is redirected there and nothing is duplicated into Assets/StreamingAssets. The
    // build step copies the package payloads into StreamingAssets so the player ships them.
    public static class ModelPathResolver
    {
        public static string GetModelFilePath(string relativePath)
        {
            var rel = (relativePath ?? string.Empty).Replace('\\', '/').TrimStart('/');
#if UNITY_EDITOR
            var packagePath = TryResolveInPackage(rel);
            if (packagePath != null)
                return packagePath;
#endif
            return Path.Combine(Application.streamingAssetsPath, rel.Replace('/', Path.DirectorySeparatorChar));
        }

#if UNITY_EDITOR
        // StreamingAssets subfolder -> owning package.
        public static readonly (string streamingAssetsSubdir, string packageName)[] PackageMap =
        {
            ("Model/E5", "com.sky.sentis.e5"),
            ("Model/OpenWakeWord", "com.sky.sentis.openwakeword"),
            ("Model/SileroVad", "com.sky.sentis.silero-vad"),
            ("Model/Supertonic", "com.sky.sentis.supertonic"),
            ("Model/Whisper", "com.sky.sentis.whisper"),
            ("Model/YOLO", "com.sky.sentis.yolox"),
        };

        // Physical root of a package. Embedded packages live at <project>/Packages/<name>, but git and
        // registry dependencies resolve into Library/PackageCache/<name>@<hash>, so the location is
        // queried from the Package Manager and only falls back to the project-relative path.
        static string ResolvePackageRoot(string pkg)
        {
            var info = UnityEditor.PackageManager.PackageInfo.FindForAssetPath("Packages/" + pkg);
            if (info != null && !string.IsNullOrEmpty(info.resolvedPath))
                return info.resolvedPath;
            return Path.GetFullPath(Path.Combine("Packages", pkg));
        }

        static string TryResolveInPackage(string rel)
        {
            foreach (var (sub, pkg) in PackageMap)
            {
                if (rel != sub && !rel.StartsWith(sub + "/", StringComparison.Ordinal))
                    continue;

                var tail = rel.Substring(sub.Length).TrimStart('/');
                var full = Path.Combine(ResolvePackageRoot(pkg), "Models~", tail.Replace('/', Path.DirectorySeparatorChar));
                if (File.Exists(full) || Directory.Exists(full))
                    return full;
                return null; // package is known but the file is missing; fall back to StreamingAssets
            }
            return null;
        }

        // Copies every package's Models~ payload into Assets/StreamingAssets/<subdir> so a player build
        // ships the weights. Called by the build pre-process step.
        public static void ProvisionToStreamingAssets()
        {
            foreach (var (sub, pkg) in PackageMap)
            {
                var src = Path.Combine(ResolvePackageRoot(pkg), "Models~");
                if (!Directory.Exists(src))
                    continue;
                var dst = Path.Combine(Application.streamingAssetsPath, sub.Replace('/', Path.DirectorySeparatorChar));
                CopyDir(src, dst);
                WriteFilesManifest(dst);
            }
        }

        // Lists every copied file under dst (relative, forward slashes), so the Android runtime can stage the
        // tree out of the APK without directory enumeration. Excludes .meta and the manifest itself.
        const string FilesManifestFile = "files_manifest.txt";

        static void WriteFilesManifest(string dst)
        {
            if (!Directory.Exists(dst))
                return;

            var entries = new System.Collections.Generic.List<string>();
            foreach (var file in Directory.GetFiles(dst, "*", SearchOption.AllDirectories))
            {
                if (file.EndsWith(".meta", StringComparison.Ordinal))
                    continue;
                var rel = file.Substring(dst.Length).TrimStart(Path.DirectorySeparatorChar, '/').Replace('\\', '/');
                if (rel == FilesManifestFile)
                    continue;
                entries.Add(rel);
            }
            entries.Sort(StringComparer.Ordinal);
            File.WriteAllText(Path.Combine(dst, FilesManifestFile), string.Join("\n", entries) + "\n");
        }

        // Deletes Assets/StreamingAssets/Model so the weights never linger in the project tree.
        public static void RemoveFromStreamingAssets()
        {
            var modelRoot = Path.Combine(Application.streamingAssetsPath, "Model");
            if (Directory.Exists(modelRoot))
                Directory.Delete(modelRoot, true);
            var meta = modelRoot + ".meta";
            if (File.Exists(meta))
                File.Delete(meta);
        }

        static void CopyDir(string src, string dst)
        {
            Directory.CreateDirectory(dst);
            foreach (var file in Directory.GetFiles(src))
            {
                if (file.EndsWith(".meta", StringComparison.Ordinal))
                    continue;
                File.Copy(file, Path.Combine(dst, Path.GetFileName(file)), true);
            }
            foreach (var dir in Directory.GetDirectories(src))
                CopyDir(dir, Path.Combine(dst, Path.GetFileName(dir)));
        }
#endif
    }
}