using System;
using System.Threading.Tasks;
using AI.AgentIntegration;

namespace PcgDrawR.Services
{
    /// <summary>
    /// 负责导航、系统状态以及与界面相关的通用操作。
    /// </summary>
    public class NavigationService
    {
        private readonly IAppEnvironment env;

        public NavigationService(IAppEnvironment env)
        {
            this.env = env ?? throw new ArgumentNullException(nameof(env));
        }

        public Task<AppActionResult> DescribeStateAsync(AppAction action)
        {
            var state = env.State;
            string message = $"Current view: {state.Navigation.CurrentView}, " +
                             $"Active tab: {state.UI.ActiveTab ?? "None"}, " +
                             $"Unsaved changes: {state.File.HasUnsavedChanges}";

            return Task.FromResult(Success(message));
        }

        public Task<AppActionResult> SetBusyAsync(AppAction action)
        {
            if (action.Parameters.TryGetValue("isBusy", out var busyObj))
            {
                env.State.System.IsBusy = Convert.ToBoolean(busyObj);
            }
            return Task.FromResult(Success());
        }

        public Task<AppActionResult> NavigateAsync(AppAction action)
        {
            if (action.Parameters.TryGetValue("view", out var viewObj))
            {
                string view = viewObj.ToString();
                env.State.Navigation.NavigationStack.Add(env.State.Navigation.CurrentView);
                env.State.Navigation.CurrentView = view;
            }
            return Task.FromResult(Success());
        }

        public Task<AppActionResult> NavigateBackAsync(AppAction action)
        {
            var stack = env.State.Navigation.NavigationStack;
            if (stack.Count == 0)
            {
                return Task.FromResult(Fail("没有可以后退的历史记录"));
            }

            string prev = stack[stack.Count - 1];
            stack.RemoveAt(stack.Count - 1);
            env.State.Navigation.CurrentView = prev;
            return Task.FromResult(Success());
        }

        public Task<AppActionResult> NavigateForwardAsync(AppAction action)
        {
            // 前进导航需要维护一个前进栈，此处仍然保留桩实现
            return Task.FromResult(Success());
        }

        public Task<AppActionResult> GetOpenTabsAsync(AppAction action)
        {
            // 同步一次当前 UI 状态，避免依赖外部调用 GetCurrentState
            env.State.UI.OpenTabs = env.MainForm.OpenTabs;
            env.State.UI.ActiveTab = env.MainForm.ActivateTab;
            return Task.FromResult(Success(env.State.UI.OpenTabs));
        }

        public Task<AppActionResult> RefreshAsync(AppAction action)
        {
            env.MainForm.Invoke(() => env.MainForm.Refresh());
            return Task.FromResult(Success());
        }

        public Task<AppActionResult> ExitAsync(AppAction action)
        {
            env.MainForm.Invoke(() => env.MainForm.Close());
            return Task.FromResult(Success());
        }

        private AppActionResult Success(object data = null)
        {
            return new AppActionResult { Success = true, Data = data };
        }

        private AppActionResult Fail(string message)
        {
            return new AppActionResult { Success = false, Message = message };
        }
    }
}