namespace AcDream.App.Studio;

/// <summary>
/// Parsed options for the acdream UI Studio standalone tool.
/// Constructed by <see cref="Parse"/> from the command-line tokens that follow
/// the <c>ui-studio</c> dispatch token.
/// </summary>
public sealed record StudioOptions(
    string DatDir,
    uint? LayoutId,
    string? MarkupPath,
    string? DumpSlug       = null,
    string? DumpFile       = null,
    string? ScreenshotPath = null)
{
    /// <summary>
    /// Parse studio options from the args that come AFTER the <c>ui-studio</c> token.
    ///
    /// <para>Positional (first non-flag arg): dat directory. Falls back to
    /// <c>ACDREAM_DAT_DIR</c> when omitted.</para>
    /// <para><c>--layout 0xNNNN</c>: hex LayoutDesc dat id to preview.</para>
    /// <para><c>--markup &lt;path&gt;</c>: path to a KSML markup file (Task 6, unsupported for now).</para>
    /// <para><c>--dump &lt;slug&gt;</c>: load a panel from the retail UI dump JSON by slug
    /// (e.g. <c>inventory</c>, <c>radar</c>, <c>toolbar</c>). Static mockup — no controllers.</para>
    /// <para><c>--dump-file &lt;path&gt;</c>: override the default dump file path
    /// (<c>docs/research/2026-06-25-retail-ui-layout-dump.json</c> from the solution root).
    /// Only meaningful when <c>--dump</c> is also given.</para>
    /// <para><c>--screenshot &lt;path&gt;</c>: headless mode — render the loaded panel to a PNG
    /// at <paramref name="path"/> and exit without showing an interactive window.
    /// Combines with <c>--dump</c> or <c>--layout</c>.</para>
    /// <para>When neither <c>--layout</c>, <c>--markup</c>, nor <c>--dump</c> is given the
    /// default layout <c>0x2100006C</c> (vitals) is used.</para>
    /// </summary>
    public static StudioOptions Parse(string[] args)
    {
        string? datDir         = null;
        uint?   layoutId       = null;
        string? markupPath     = null;
        string? dumpSlug       = null;
        string? dumpFile       = null;
        string? screenshotPath = null;

        for (int i = 0; i < args.Length; i++)
        {
            if (args[i] == "--layout" && i + 1 < args.Length)
            {
                var raw = args[++i];
                // Accept 0xNNNN or plain hex.
                if (raw.StartsWith("0x", StringComparison.OrdinalIgnoreCase))
                    raw = raw[2..];
                if (uint.TryParse(raw, System.Globalization.NumberStyles.HexNumber, null, out var id))
                    layoutId = id;
            }
            else if (args[i] == "--markup" && i + 1 < args.Length)
            {
                markupPath = args[++i];
            }
            else if (args[i] == "--dump" && i + 1 < args.Length)
            {
                dumpSlug = args[++i];
            }
            else if (args[i] == "--dump-file" && i + 1 < args.Length)
            {
                dumpFile = args[++i];
            }
            else if (args[i] == "--screenshot" && i + 1 < args.Length)
            {
                screenshotPath = args[++i];
            }
            else if (!args[i].StartsWith('-'))
            {
                datDir ??= args[i];
            }
        }

        // Fall back to ACDREAM_DAT_DIR when no positional dat dir was given.
        datDir ??= Environment.GetEnvironmentVariable("ACDREAM_DAT_DIR");

        if (string.IsNullOrWhiteSpace(datDir))
            throw new InvalidOperationException(
                "ui-studio: dat directory required — pass as first arg or set ACDREAM_DAT_DIR.");

        // Default layout: vitals (0x2100006C), unless a dump slug or markup is requested.
        if (layoutId is null && markupPath is null && dumpSlug is null)
            layoutId = 0x2100006Cu;

        return new StudioOptions(datDir, layoutId, markupPath, dumpSlug, dumpFile, screenshotPath);
    }

    /// <summary>
    /// Resolve the dump file path for this session:
    /// <list type="bullet">
    ///   <item><see cref="DumpFile"/> if explicitly set.</item>
    ///   <item>Otherwise <c>&lt;solutionRoot&gt;/docs/research/2026-06-25-retail-ui-layout-dump.json</c>.</item>
    /// </list>
    /// Returns null when neither the override nor the default file exists.
    /// </summary>
    public string? ResolveDumpFile()
    {
        if (!string.IsNullOrEmpty(DumpFile))
            return DumpFile;

        // Walk up from the App binary to the solution root (same approach as
        // ConformanceDats.SolutionRoot in the test project).
        var dir = AppContext.BaseDirectory;
        while (!string.IsNullOrEmpty(dir))
        {
            var candidate = Path.Combine(dir, "docs", "research",
                "2026-06-25-retail-ui-layout-dump.json");
            if (File.Exists(candidate))
                return candidate;
            dir = Path.GetDirectoryName(dir);
        }
        return null;
    }
}