#nullable enable
using System;
using System.Collections.Generic;
using System.Linq;
using Cysharp.Threading.Tasks;
using ShrinkApp;

namespace ShrinkContext.AppAdapter
{
    /// <summary>
    /// 把现有 <see cref="IShrinkAppModuleInstaller"/> 包装为 ShrinkContext 组件：
    /// - inject 由 <c>DependsOn</c> 派生（模块依赖 → 模块键），依赖未就绪时安装器保持非活动等待，
    ///   而不是像拓扑排序那样直接抛错；
    /// - provide 发布模块键 <c>app.module.&lt;ModuleId&gt;</c>（安装器 Active 后对依赖者可见）；
    /// - apply 依次执行 RegisterServices + InitializeAsync，config 必须传入 <see cref="ShrinkAppServices"/>。
    ///
    /// 已知边界（后续阶段补齐）：ShrinkAppServices 尚无注销能力，
    /// 安装器卸载时不会移除已注册的服务；重新激活会重复执行 RegisterServices（同键覆盖）。
    /// </summary>
    public sealed class ShrinkAppInstallerComponent : IShrinkComponent
    {
        /// <summary>模块键前缀：依赖声明 <c>DependsOn = ["a"]</c> 映射为 <c>app.module.a</c>。</summary>
        public const string ModuleKeyPrefix = "app.module.";

        private readonly IShrinkAppModuleInstaller _installer;
        private readonly ShrinkAppSettings? _settings;
        private readonly string[] _inject;

        public ShrinkAppInstallerComponent(IShrinkAppModuleInstaller installer, ShrinkAppSettings? settings = null)
        {
            _installer = installer ?? throw new ArgumentNullException(nameof(installer));
            _settings = settings;
            _inject = (installer.DependsOn ?? Array.Empty<string>())
                .Where(id => !string.IsNullOrWhiteSpace(id))
                .Select(id => ModuleKeyPrefix + id.Trim())
                .ToArray();
        }

        public string Name => "app-installer:" + _installer.ModuleId;

        public IReadOnlyList<string> Inject => _inject;

        public IReadOnlyList<string> Provide => new[] { ModuleKeyPrefix + _installer.ModuleId };

        public IShrinkAppModuleInstaller Installer => _installer;

        public async UniTask ApplyAsync(ShrinkCtx ctx, object? config)
        {
            if (config is not ShrinkAppServices services)
                throw new InvalidOperationException(
                    $"ShrinkAppInstallerComponent '{_installer.ModuleId}' requires ShrinkAppServices as fiber config.");

            // 先发布模块键再执行安装：装载期绑定对依赖者不可见（提供者须 Active），
            // 供给冲突（重复 ModuleId）在安装器初始化之前即失败
            ctx.Set(Provide[0], _installer.ModuleId);

            var appContext = ShrinkAppContext.CreateStandalone(services, _settings);
            _installer.RegisterServices(appContext);
            await _installer.InitializeAsync(appContext);
        }
    }
}