using System.IO;
using System.Text;
using UnityEditor.Build;
using UnityEditor.Build.Reporting;
using UnityEngine;
using OnDeviceAgent.AgentCore;
namespace OnDeviceAgent.AgentCore.Editor
{

    // StreamingAssets directories can't be enumerated at runtime on Android/WebGL (compressed APK/bundle),
    // so FileStreamingAssetReader discovers skill folders from a per-"skills"-dir manifest (dir_manifest.txt)
    // instead. Regenerate those manifests before every build so on-device skill discovery always matches the
    // folders actually shipped, no hand-maintenance or drift.
    public sealed class SkillsManifestPreprocessor : IPreprocessBuildWithReport
    {
        public int callbackOrder => 0;

        public void OnPreprocessBuild(BuildReport report) => GenerateAll();

        static void GenerateAll()
        {
            var root = Application.streamingAssetsPath;
            if (!Directory.Exists(root))
                return;

            // StreamingAssets is copied to the player from disk as-is, so writing the manifest here (before
            // the copy step) is enough, no AssetDatabase.Refresh needed (and it's unsafe mid-build).
            foreach (var skillsDir in Directory.GetDirectories(root, "skills", SearchOption.AllDirectories))
                WriteManifest(skillsDir);
        }

        // Lists the immediate subdirectory names of one "skills" folder. Only rewrites on change so we don't
        // churn the build's StreamingAssets on every build.
        static void WriteManifest(string skillsDir)
        {
            var sb = new StringBuilder();
            sb.AppendLine("# auto-generated by SkillsManifestPreprocessor, one skill folder name per line.");
            sb.AppendLine("# Regenerated before each build; hand-edits are overwritten.");
            foreach (var sub in Directory.GetDirectories(skillsDir))
                sb.AppendLine(Path.GetFileName(sub));

            var manifestPath = Path.Combine(skillsDir, FileStreamingAssetReader.DirManifestFile);
            var next = sb.ToString();
            if (File.Exists(manifestPath) && File.ReadAllText(manifestPath) == next)
                return;

            File.WriteAllText(manifestPath, next);
            Debug.Log("[SkillsManifest] wrote " + manifestPath);
        }
    }
}