using System.ComponentModel;
using System.Diagnostics;
using System.IO;
using PersonalToolbox.Models;

namespace PersonalToolbox.Services;

public sealed class ToolLaunchService
{
    public async Task<LaunchResult> LaunchAsync(
        ToolItem tool,
        IReadOnlyCollection<ToolItem> allTools,
        Action<LogMessage> log,
        CancellationToken cancellationToken = default)
    {
        if (tool.IsDeleted)
        {
            var result = LaunchResult.Fail(tool, LaunchResultKind.Skipped, "工具已删除。");
            log(CreateLog(LogLevel.Warning, $"跳过已删除工具：{tool.Name}"));
            return result;
        }

        if (tool.Type == ToolType.Combination)
        {
            return await LaunchCombinationAsync(tool, allTools, log, cancellationToken);
        }

        return LaunchSingleTool(tool, log);
    }

    private async Task<LaunchResult> LaunchCombinationAsync(
        ToolItem combination,
        IReadOnlyCollection<ToolItem> allTools,
        Action<LogMessage> log,
        CancellationToken cancellationToken)
    {
        var validation = ValidateCombination(combination, allTools);
        if (!validation.Success)
        {
            log(CreateLog(LogLevel.Error, $"组合校验失败：{combination.Name}，{validation.ErrorMessage}"));
            return validation;
        }

        log(CreateLog(LogLevel.Info, $"启动组合：{combination.Name}"));
        var successCount = 0;
        var failedCount = 0;
        var members = combination.Combination?.Members
            .Where(member => member.Enabled)
            .OrderBy(member => member.SortOrder)
            .ToList() ?? [];

        foreach (var member in members)
        {
            cancellationToken.ThrowIfCancellationRequested();

            var memberTool = allTools.FirstOrDefault(tool => tool.Id == member.ToolId && !tool.IsDeleted);
            if (memberTool is null)
            {
                failedCount++;
                log(CreateLog(LogLevel.Error, $"组合成员不存在：{member.ToolId}"));
                if (combination.Combination?.FailurePolicy == FailurePolicy.Stop)
                {
                    break;
                }

                continue;
            }

            var result = await LaunchAsync(memberTool, allTools, log, cancellationToken);
            if (result.Success)
            {
                successCount++;
            }
            else
            {
                failedCount++;
                if (combination.Combination?.FailurePolicy == FailurePolicy.Stop)
                {
                    log(CreateLog(LogLevel.Warning, $"组合已停止：{combination.Name}"));
                    break;
                }
            }

            if (member.IntervalAfterMs > 0)
            {
                await Task.Delay(member.IntervalAfterMs, cancellationToken);
            }
        }

        log(CreateLog(LogLevel.Info, $"组合执行完成：{combination.Name}，成功 {successCount} 项，失败 {failedCount} 项"));
        return failedCount == 0
            ? LaunchResult.Ok(combination)
            : LaunchResult.Fail(combination, LaunchResultKind.UnknownError, $"组合执行完成，但有 {failedCount} 项失败。");
    }

    public LaunchResult ValidateCombination(ToolItem combination, IReadOnlyCollection<ToolItem> allTools)
    {
        if (combination.Type != ToolType.Combination)
        {
            return LaunchResult.Ok(combination);
        }

        var stack = new Stack<string>();
        var finalToolIds = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
        var toolMap = allTools.Where(tool => !tool.IsDeleted).ToDictionary(tool => tool.Id, StringComparer.OrdinalIgnoreCase);

        LaunchResult? failure = null;

        void Visit(ToolItem current)
        {
            if (failure is not null)
            {
                return;
            }

            if (current.Type != ToolType.Combination)
            {
                if (!finalToolIds.Add(current.Id))
                {
                    failure = LaunchResult.Fail(combination, LaunchResultKind.DuplicateTool, $"展开后存在重复工具：{current.Name}");
                }

                return;
            }

            if (stack.Contains(current.Id, StringComparer.OrdinalIgnoreCase))
            {
                var path = string.Join(" -> ", stack.Reverse().Concat([current.Id]).Select(id => toolMap.TryGetValue(id, out var tool) ? tool.Name : id));
                failure = LaunchResult.Fail(combination, LaunchResultKind.CircularReference, $"存在循环引用：{path}");
                return;
            }

            stack.Push(current.Id);
            var members = current.Combination?.Members
                .Where(member => member.Enabled)
                .OrderBy(member => member.SortOrder)
                ?? Enumerable.Empty<CombinationMember>();
            foreach (var member in members)
            {
                if (!toolMap.TryGetValue(member.ToolId, out var memberTool))
                {
                    failure = LaunchResult.Fail(combination, LaunchResultKind.MissingReference, $"成员引用不存在：{member.ToolId}");
                    break;
                }

                Visit(memberTool);
            }

            stack.Pop();
        }

        Visit(combination);
        return failure ?? LaunchResult.Ok(combination);
    }

    private LaunchResult LaunchSingleTool(ToolItem tool, Action<LogMessage> log)
    {
        try
        {
            var startInfo = CreateStartInfo(tool, out var validationFailure);
            if (validationFailure is not null)
            {
                log(CreateLog(LogLevel.Error, $"启动失败：{tool.Name}，{validationFailure.ErrorMessage}"));
                return validationFailure;
            }

            log(CreateLog(LogLevel.Info, $"开始启动工具：{tool.Name}"));
            Process.Start(startInfo!);
            log(CreateLog(LogLevel.Success, $"启动成功：{tool.Name}"));
            return LaunchResult.Ok(tool);
        }
        catch (Win32Exception ex) when (ex.NativeErrorCode == 1223)
        {
            log(CreateLog(LogLevel.Warning, $"用户取消管理员权限：{tool.Name}"));
            return LaunchResult.Fail(tool, LaunchResultKind.UserCancelledElevation, "用户取消管理员权限。");
        }
        catch (UnauthorizedAccessException ex)
        {
            log(CreateLog(LogLevel.Error, $"访问被拒绝：{tool.Name}，{ex.Message}"));
            return LaunchResult.Fail(tool, LaunchResultKind.AccessDenied, ex.Message);
        }
        catch (Exception ex)
        {
            log(CreateLog(LogLevel.Error, $"启动失败：{tool.Name}，{ex.Message}"));
            return LaunchResult.Fail(tool, LaunchResultKind.ProcessStartFailed, ex.Message);
        }
    }

    private static ProcessStartInfo? CreateStartInfo(ToolItem tool, out LaunchResult? validationFailure)
    {
        validationFailure = null;

        if (tool.Type == ToolType.Url)
        {
            if (!PathValidationService.IsValidUrl(tool.Url, out var normalizedUrl))
            {
                validationFailure = LaunchResult.Fail(tool, LaunchResultKind.InvalidUrl, "网址格式无效。");
                return null;
            }

            return new ProcessStartInfo
            {
                FileName = normalizedUrl,
                UseShellExecute = true
            };
        }

        var target = tool.LaunchTarget;
        if (string.IsNullOrWhiteSpace(target))
        {
            validationFailure = LaunchResult.Fail(tool, LaunchResultKind.PathMissing, "启动目标为空。");
            return null;
        }

        if (tool.Type == ToolType.Local && !File.Exists(target) && !Directory.Exists(target))
        {
            validationFailure = LaunchResult.Fail(tool, LaunchResultKind.PathMissing, "路径不存在。");
            return null;
        }

        if (!string.IsNullOrWhiteSpace(tool.WorkingDirectory) && !Directory.Exists(tool.WorkingDirectory))
        {
            validationFailure = LaunchResult.Fail(tool, LaunchResultKind.PathMissing, "工作目录不存在。");
            return null;
        }

        var startInfo = new ProcessStartInfo
        {
            FileName = target,
            Arguments = tool.Arguments ?? "",
            WorkingDirectory = tool.WorkingDirectory ?? "",
            UseShellExecute = true
        };

        if (tool.RunAsAdmin)
        {
            startInfo.Verb = "runas";
        }

        return startInfo;
    }

    private static LogMessage CreateLog(LogLevel level, string message)
    {
        return new LogMessage
        {
            Level = level,
            Message = message
        };
    }
}