using System.Text.Json;
using System.Text.Json.Serialization;

namespace AcDream.App.Studio;

// ─────────────────────────────────────────────────────────────────────────────
// UiDumpModel — POCOs for docs/research/2026-06-25-retail-ui-layout-dump.json
//
// Schema (v1):
//   { "version":1, "panels":[ { "id":int, "slug":string, "title":string,
//       "bucket":string, "parent_slug":string|null,
//       "width":int, "height":int,
//       "nodes":[ { "traversal_index":int, "element_id":int,
//                   "layout_id":int, "parent_layout_id":int|null,
//                   "parent_traversal_index":int|null, "base_layout_id":int,
//                   "rect":{x,y,width,height},
//                   "widget_kind":"Group"|"Sprite"|"Button"|"Scrollbar"|"Slider",
//                   "state_set":{ "default_image":{image_id,alpha_image_id}|null,
//                                 "states":[{state_id,image:{...}}] }
//               } ] } ] }
//
// All ids in the dump are DECIMAL ints (e.g. element_id=268435925 = 0x100001D5,
// image_id=100693194 = 0x060074CA). Cast to uint before use in dat/GL APIs.
//
// Rect coordinates are ABSOLUTE (screen-space origin = panel's design position
// in retail layout, NOT relative to the parent). DumpLayout.Load converts them
// to parent-relative when building the UiElement tree.
// ─────────────────────────────────────────────────────────────────────────────

/// <summary>Top-level container for the retail UI layout dump.</summary>
public sealed class UiDump
{
    [JsonPropertyName("version")]
    public int Version { get; set; }

    [JsonPropertyName("panels")]
    public List<DumpPanel> Panels { get; set; } = new();
}

/// <summary>One panel (window) exported from the retail UI.</summary>
public sealed class DumpPanel
{
    [JsonPropertyName("id")]
    public long Id { get; set; }

    [JsonPropertyName("slug")]
    public string Slug { get; set; } = "";

    [JsonPropertyName("title")]
    public string Title { get; set; } = "";

    [JsonPropertyName("bucket")]
    public string Bucket { get; set; } = "";

    [JsonPropertyName("parent_slug")]
    public string? ParentSlug { get; set; }

    [JsonPropertyName("width")]
    public float Width { get; set; }

    [JsonPropertyName("height")]
    public float Height { get; set; }

    [JsonPropertyName("nodes")]
    public List<DumpNode> Nodes { get; set; } = new();
}

/// <summary>One element node within a panel's traversal list.</summary>
public sealed class DumpNode
{
    [JsonPropertyName("traversal_index")]
    public int TraversalIndex { get; set; }

    [JsonPropertyName("element_id")]
    public long ElementId { get; set; }

    [JsonPropertyName("layout_id")]
    public long LayoutId { get; set; }

    [JsonPropertyName("parent_layout_id")]
    public long? ParentLayoutId { get; set; }

    [JsonPropertyName("parent_traversal_index")]
    public int? ParentTraversalIndex { get; set; }

    [JsonPropertyName("base_layout_id")]
    public long BaseLayoutId { get; set; }

    [JsonPropertyName("rect")]
    public DumpRect Rect { get; set; } = new();

    [JsonPropertyName("widget_kind")]
    public string WidgetKind { get; set; } = "Group";

    [JsonPropertyName("state_set")]
    public DumpStateSet StateSet { get; set; } = new();
}

/// <summary>Absolute screen-space rect (see comment above — must subtract parent rect for UiElement).</summary>
public sealed class DumpRect
{
    [JsonPropertyName("x")]
    public float X { get; set; }

    [JsonPropertyName("y")]
    public float Y { get; set; }

    [JsonPropertyName("width")]
    public float Width { get; set; }

    [JsonPropertyName("height")]
    public float Height { get; set; }
}

/// <summary>State set for a node — default image plus per-state overrides.</summary>
public sealed class DumpStateSet
{
    [JsonPropertyName("default_image")]
    public DumpImage? DefaultImage { get; set; }

    [JsonPropertyName("states")]
    public List<DumpState> States { get; set; } = new();
}

/// <summary>Image reference (RenderSurface dat id + optional separate alpha surface).</summary>
public sealed class DumpImage
{
    [JsonPropertyName("image_id")]
    public long ImageId { get; set; }

    [JsonPropertyName("alpha_image_id")]
    public long? AlphaImageId { get; set; }
}

/// <summary>A named state override.</summary>
public sealed class DumpState
{
    [JsonPropertyName("state_id")]
    public int StateId { get; set; }

    [JsonPropertyName("image")]
    public DumpImage Image { get; set; } = new();
}

// ─────────────────────────────────────────────────────────────────────────────
// Helper statics
// ─────────────────────────────────────────────────────────────────────────────

/// <summary>
/// Parsing helpers for the retail UI dump JSON.
/// </summary>
public static class UiDumpModel
{
    private static readonly JsonSerializerOptions _opts = new()
    {
        PropertyNameCaseInsensitive = true,
        AllowTrailingCommas         = true,
        ReadCommentHandling         = JsonCommentHandling.Skip,
    };

    /// <summary>Parse the full dump from a file path. Returns null on failure.</summary>
    public static UiDump? Parse(string path)
    {
        try
        {
            using var stream = File.OpenRead(path);
            return JsonSerializer.Deserialize<UiDump>(stream, _opts);
        }
        catch
        {
            return null;
        }
    }

    /// <summary>
    /// Return the list of slugs in the dump (for smoke-testing every panel).
    /// Returns an empty list if the file cannot be parsed.
    /// </summary>
    public static IReadOnlyList<string> ListSlugs(string path)
    {
        var dump = Parse(path);
        if (dump is null) return Array.Empty<string>();
        return dump.Panels.Select(p => p.Slug).ToList();
    }

    /// <summary>
    /// Pick the sprite id to use for a node: prefer default_image.image_id;
    /// fall back to states[0].image.image_id; return 0 if neither exists.
    /// </summary>
    public static uint PickImageId(DumpNode node)
    {
        if (node.StateSet.DefaultImage is { ImageId: > 0 } di)
            return (uint)di.ImageId;
        if (node.StateSet.States.Count > 0 && node.StateSet.States[0].Image.ImageId > 0)
            return (uint)node.StateSet.States[0].Image.ImageId;
        return 0u;
    }
}