using System.Text.Json;
using MAF1.PluginContract;

namespace MAF1.Plugins;

/// <summary>
/// 扫描 exe 旁边的 plugins/*/plugin.json。源码目录 Plugins/ 不会被运行时直接读到，要先 build 复制到输出目录。
/// </summary>
public sealed class PluginScanner(PluginOptions options)
{
    public PluginScanResult Scan()
    {
        string root = options.ResolveRoot();
        Directory.CreateDirectory(root);

        List<LoadedPlugin> plugins = [];
        List<CatalogIssue> issues = [];
        HashSet<string> ids = new(StringComparer.OrdinalIgnoreCase);

        foreach (string folder in Directory.GetDirectories(root))
        {
            string folderName = Path.GetFileName(folder);
            if (folderName.StartsWith('_') || folderName.StartsWith('.'))
            {
                continue;
            }

            string manifestPath = Path.Combine(folder, "plugin.json");
            if (!File.Exists(manifestPath))
            {
                issues.Add(new CatalogIssue
                {
                    Level = "warning",
                    Source = folderName,
                    Message = "目录里没有 plugin.json，已跳过。",
                });
                continue;
            }

            PluginManifest? manifest;
            try
            {
                string json = File.ReadAllText(manifestPath);
                manifest = JsonSerializer.Deserialize<PluginManifest>(json, PluginJson.Options);
            }
            catch (Exception ex)
            {
                issues.Add(new CatalogIssue
                {
                    Level = "error",
                    Source = folderName,
                    Message = $"plugin.json 无法解析：{ex.Message}",
                });
                continue;
            }

            if (manifest is null || string.IsNullOrWhiteSpace(manifest.Id))
            {
                issues.Add(new CatalogIssue
                {
                    Level = "error",
                    Source = folderName,
                    Message = "plugin.json 缺少 id。",
                });
                continue;
            }

            if (string.IsNullOrWhiteSpace(manifest.Launch.Command))
            {
                issues.Add(new CatalogIssue
                {
                    Level = "error",
                    Source = manifest.Id,
                    Message = "plugin.json 缺少 launch.command，宿主不会替插件拼命令。",
                });
                continue;
            }

            if (!ids.Add(manifest.Id))
            {
                issues.Add(new CatalogIssue
                {
                    Level = "error",
                    Source = manifest.Id,
                    Message = $"插件 id `{manifest.Id}` 重复，已忽略目录 {folderName}。",
                });
                continue;
            }

            if (DuplicatePortNames(manifest.Inputs))
            {
                issues.Add(new CatalogIssue { Level = "error", Source = manifest.Id, Message = "inputs 字段名重复。" });
                continue;
            }

            if (DuplicatePortNames(manifest.Outputs))
            {
                issues.Add(new CatalogIssue { Level = "error", Source = manifest.Id, Message = "outputs 字段名重复。" });
                continue;
            }

            plugins.Add(new LoadedPlugin
            {
                FolderName = folderName,
                FolderPath = folder,
                Manifest = manifest,
            });
        }

        return new PluginScanResult(root, plugins, issues);
    }

    private static bool DuplicatePortNames(List<PluginPort> ports)
        => ports.GroupBy(p => p.Name, StringComparer.OrdinalIgnoreCase).Any(g => g.Count() > 1);
}

public sealed record PluginScanResult(
    string Root,
    IReadOnlyList<LoadedPlugin> Plugins,
    IReadOnlyList<CatalogIssue> Issues);