using Sdt.Config;
using Sdt.Runner;
using Spectre.Console;

namespace Sdt.Tui;

/// <summary>Thin wrapper used in Spectre.Console selection prompts.</summary>
internal sealed record MenuItem(string Display, string Value);

public enum AppExitReason { Quit, SwitchProject }
public sealed record AppResult(AppExitReason Reason, string? NewProjectRoot = null);

public sealed class App
{
    private DevToolConfig _config;
    private string _projectRoot;
    private readonly WorkspaceConfig? _workspace;
    private readonly string? _workspaceRoot;

    private IReadOnlyDictionary<string, BuildTarget> TargetMap =>
        _config.Targets.ToDictionary(t => t.Id, StringComparer.OrdinalIgnoreCase);

    public App(
        DevToolConfig config,
        string projectRoot,
        WorkspaceConfig? workspace = null,
        string? workspaceRoot = null)
    {
        _config = config;
        _projectRoot = projectRoot;
        _workspace = workspace;
        _workspaceRoot = workspaceRoot;
    }

    public async Task<AppResult> RunAsync()
    {
        while (true)
        {
            AnsiConsole.Clear();
            RenderBanner();

            var choice = ShowMainMenu();

            switch (choice)
            {
                case "__env__":
                    EditEnvironment();
                    break;

                case "__toolchains__":
                    await new ToolchainScreen(_config, _projectRoot).RunAsync();
                    break;

                case "__workspace__":
                    if (_workspace is not null && _workspaceRoot is not null)
                    {
                        var switcher = new WorkspaceScreen(_workspace, _workspaceRoot, _projectRoot);
                        var newRoot = switcher.SelectProject();
                        if (newRoot is not null)
                            return new AppResult(AppExitReason.SwitchProject, newRoot);
                    }
                    break;

                case "__quit__":
                    AnsiConsole.MarkupLine("\n" + Theme.Faint("Later.") + "\n");
                    return new AppResult(AppExitReason.Quit);

                default:
                    var targetMap = TargetMap;
                    if (targetMap.TryGetValue(choice, out var target))
                        await RunTargetAsync(target, targetMap);
                    break;
            }

            if (choice != "__quit__")
            {
                AnsiConsole.MarkupLine("\n" + Theme.Faint("Press any key to return to the menu..."));
                Console.ReadKey(intercept: true);
            }
        }
    }

    // ── Banner ────────────────────────────────────────────────────────────────

    private void RenderBanner()
    {
        // Phosphor green figlet
        AnsiConsole.Write(new FigletText("SDT").Color(Theme.GreenColor));

        // Project + workspace info line
        var wsInfo = _workspace is not null
            ? $" [{Theme.GreenDim}]∙ {Markup.Escape(_workspace.Name)}[/]"
            : string.Empty;

        AnsiConsole.Write(
            new Rule($"[bold {Theme.GreenBold}]{Markup.Escape(_config.Name)}[/]  [{Theme.GreenDim}]v{Markup.Escape(_config.Version)}[/]{wsInfo}")
                .RuleStyle(Theme.DimStyle));

        AnsiConsole.MarkupLine(Theme.Faint($"root: {_projectRoot}") + "\n");
    }

    // ── Main menu ─────────────────────────────────────────────────────────────

    private string ShowMainMenu()
    {
        var prompt = new SelectionPrompt<MenuItem>()
            .Title($"[{Theme.Green}]What would you like to do?[/]")
            .PageSize(28)
            .MoreChoicesText(Theme.Faint("(scroll to see more)"))
            .UseConverter(m => m.Display);

        // Targets, grouped
        var groups = _config.Targets
            .Where(t => !string.IsNullOrWhiteSpace(t.Label))
            .GroupBy(t => string.IsNullOrWhiteSpace(t.Group) ? "General" : t.Group);

        foreach (var group in groups)
        {
            var header = new MenuItem(
                $"[bold {Theme.Amber}]{Markup.Escape(group.Key.ToUpperInvariant())}[/]",
                "__group__");

            var items = group.Select(t => new MenuItem(
                $"[{Theme.Green}]{Markup.Escape(t.Label)}[/]  [{Theme.GreenDim}]{Markup.Escape(t.Description)}[/]",
                t.Id)).ToList();

            prompt.AddChoiceGroup(header, items);
        }

        // System actions
        var systemItems = new List<MenuItem>
        {
            new($"[{Theme.Green}]⚙  Edit environment variables[/]", "__env__"),
        };

        if (_config.Toolchains is not null)
            systemItems.Insert(0, new MenuItem(
                $"[{Theme.Green}]⬡  Toolchain management[/]  [{Theme.GreenDim}]python / node[/]",
                "__toolchains__"));

        if (_workspace is not null && (_workspace.Projects.Count > 1))
            systemItems.Insert(0, new MenuItem(
                $"[{Theme.Green}]⇄  Switch project[/]  [{Theme.GreenDim}]{Markup.Escape(_workspace.Name)}[/]",
                "__workspace__"));

        systemItems.Add(new MenuItem($"[{Theme.GreenDim}]✗  Quit[/]", "__quit__"));

        prompt.AddChoiceGroup(
            new MenuItem($"[bold {Theme.Amber}]SYSTEM[/]", "__group__"),
            systemItems);

        return AnsiConsole.Prompt(prompt).Value;
    }

    // ── Target execution ──────────────────────────────────────────────────────

    private async Task RunTargetAsync(BuildTarget target, IReadOnlyDictionary<string, BuildTarget> targetMap)
    {
        AnsiConsole.Clear();
        AnsiConsole.Write(Theme.SectionRule(target.Label));

        var plan = TargetRunner.ResolvePlan(target, targetMap);

        if (plan.Count == 0)
        {
            AnsiConsole.MarkupLine(Theme.Warn("This target has no executable steps."));
            return;
        }

        if (plan.Count > 1)
        {
            AnsiConsole.MarkupLine(Theme.Faint($"Execution plan — {plan.Count} steps:"));
            foreach (var step in plan)
                AnsiConsole.MarkupLine($"  [{Theme.GreenDim}]→[/] [{Theme.Green}]{Markup.Escape(step.Label)}[/]");
            AnsiConsole.WriteLine();
        }

        var allOk = true;
        var totalSw = System.Diagnostics.Stopwatch.StartNew();

        foreach (var step in plan)
        {
            AnsiConsole.Write(Theme.DimRule());

            var workingDir = Path.GetFullPath(Path.Combine(_projectRoot, step.WorkingDir));
            var cmdDisplay = $"{step.Command} {string.Join(" ", step.Args)}";

            AnsiConsole.MarkupLine($"[{Theme.GreenDim}]$ {Markup.Escape(cmdDisplay)}[/]");
            AnsiConsole.MarkupLine($"[{Theme.GreenDim}]  {Markup.Escape(workingDir)}[/]\n");

            RunResult result;
            try
            {
                result = await ProcessRunner.RunAsync(
                    step.Command!,
                    step.Args,
                    workingDir,
                    (line, isErr) =>
                    {
                        var escaped = Markup.Escape(line);
                        AnsiConsole.MarkupLine(isErr
                            ? $"[{Theme.Amber}]{escaped}[/]"
                            : $"[{Theme.Green}]{escaped}[/]");
                    });
            }
            catch (Exception ex)
            {
                AnsiConsole.MarkupLine("\n" + Theme.Fail($"Failed to launch: {ex.Message}"));
                allOk = false;
                break;
            }

            AnsiConsole.WriteLine();

            if (result.Success)
                AnsiConsole.MarkupLine(Theme.Ok($"{step.Label} ({result.Elapsed.TotalSeconds:F1}s)"));
            else
            {
                AnsiConsole.MarkupLine(Theme.Fail($"{step.Label} — exited {result.ExitCode} ({result.Elapsed.TotalSeconds:F1}s)"));
                allOk = false;
                break;
            }
        }

        totalSw.Stop();
        AnsiConsole.Write(Theme.SectionRule());
        AnsiConsole.MarkupLine(allOk
            ? "\n" + Theme.Ok($"Done!  Total: {totalSw.Elapsed.TotalSeconds:F1}s")
            : "\n" + Theme.Fail("Build failed. Check output above."));
    }

    // ── Environment editor ────────────────────────────────────────────────────

    private void EditEnvironment()
    {
        AnsiConsole.Clear();

        if (_config.Env.Count == 0)
        {
            AnsiConsole.MarkupLine(Theme.Warn("No environment variables defined in devtool.json."));
            AnsiConsole.MarkupLine("\n" + Theme.Faint("Press any key to go back..."));
            Console.ReadKey(intercept: true);
            return;
        }

        while (true)
        {
            AnsiConsole.Write(Theme.SectionRule("ENVIRONMENT"));

            var table = new Table()
                .Border(TableBorder.Rounded)
                .BorderStyle(Theme.DimStyle)
                .AddColumn(new TableColumn($"[{Theme.Amber}]Variable[/]"))
                .AddColumn(new TableColumn($"[{Theme.Amber}]Current Value[/]"))
                .AddColumn(new TableColumn($"[{Theme.Amber}]Description[/]"));

            foreach (var def in _config.Env)
            {
                var val = Environment.GetEnvironmentVariable(def.Key) ?? def.DefaultValue;
                table.AddRow(
                    Theme.Warn(def.Key),
                    Theme.Bold(val.Length > 0 ? val : "(not set)"),
                    Theme.Faint(def.Description));
            }

            AnsiConsole.Write(table);
            AnsiConsole.MarkupLine(Theme.Faint("Changes apply to this SDT session only.\n"));

            var choices = _config.Env
                .Select(e =>
                {
                    var curr = Environment.GetEnvironmentVariable(e.Key) ?? e.DefaultValue;
                    return new MenuItem(
                        $"[{Theme.Amber}]{Markup.Escape(e.Key)}[/]  [{Theme.GreenDim}]= {Markup.Escape(curr)}[/]",
                        e.Key);
                })
                .Append(new MenuItem(Theme.Faint("← Back"), "__back__"))
                .ToList();

            var selected = AnsiConsole.Prompt(
                new SelectionPrompt<MenuItem>()
                    .Title($"[{Theme.Green}]Select a variable to edit:[/]")
                    .UseConverter(m => m.Display)
                    .AddChoices(choices));

            if (selected.Value == "__back__") break;

            var envDef = _config.Env.First(e => e.Key == selected.Value);
            var current = Environment.GetEnvironmentVariable(envDef.Key) ?? envDef.DefaultValue;

            string newVal;
            if (envDef.Options.Count > 0)
            {
                newVal = AnsiConsole.Prompt(
                    new SelectionPrompt<string>()
                        .Title($"[{Theme.Amber}]{Markup.Escape(envDef.Key)}[/]  [{Theme.GreenDim}]current: {Markup.Escape(current)}[/]")
                        .AddChoices(envDef.Options));
            }
            else
            {
                newVal = AnsiConsole.Ask(
                    $"[{Theme.Amber}]{Markup.Escape(envDef.Key)}[/]", current);
            }

            Environment.SetEnvironmentVariable(envDef.Key, newVal);
            AnsiConsole.MarkupLine("\n" + Theme.Ok($"{envDef.Key} = {newVal}") + "\n");
            Thread.Sleep(500);
            AnsiConsole.Clear();
        }
    }
}