import {
  DESIGN_WIDTH, DESIGN_HEIGHT, CANVAS_WIDTH, CANVAS_HEIGHT,
  toCocosPosition, inferWidget, stretchWidget, isFullScreen, isOffscreen,
} from './coords.mjs';
import { frameFileName, padWidth } from './frames.mjs';
import { layerBucket, imageBuckets } from './buckets.mjs';

/** 中间描述组装。见 spec §1。 */

const OBJECT_TYPE_SPRITE = 2;
const OBJECT_TYPE_TEXT = 4;

/**
 * 帧号越界（旧数据里美术重导时帧数变少，但对象上的 FrameIndex 没跟着更新）。
 * 只拦这一种已知情况——预判而非 try/catch，免得连带吞掉 frameFileName 里真正的实现 bug。
 * 单帧图（frame_all<=1）的 FrameIndex 本就与渲染无关，不算越界。
 */
function isFrameIndexOutOfRange(obj, image) {
  const requested = obj.FrameIndex || 1;
  return image.frame_all > 1 && requested > image.frame_all;
}

function spriteBlock(obj, image, bucket, warnings) {
  const dir = `atlas-${bucket}`;
  const sliced = obj.L9 || obj.T9 || obj.R9 || obj.B9;
  const outOfRange = isFrameIndexOutOfRange(obj, image);
  const frameIndex = outOfRange ? 1 : (obj.FrameIndex || 1);

  if (outOfRange) {
    warnings.push({
      objectId: obj.ObjectID,
      layerId: obj.BelongLayerID,
      imageFileId: obj.ImageFileID,
      frameIndex: obj.FrameIndex,
      frameCount: image.frame_all,
      reason: `对象 ${obj.ObjectID}（${obj.ObjectName}）引用 ${image.bmp} 的帧 ${obj.FrameIndex}，`
        + `超出该图帧数 ${image.frame_all}（很可能是美术重导后 FrameIndex 未同步更新），已回退为帧 1`,
    });
  }

  const block = {
    frame: `${dir}/${frameFileName(image.bmp, frameIndex, image.frame_all)}`,
    type: sliced ? 'sliced' : 'simple',
  };
  if (image.frame_all > 1) {
    block.frameSet = {
      prefix: `${dir}/${image.bmp.replace(/\.png$/i, '')}`,
      count: image.frame_all,
      pad: padWidth(image.frame_all),
    };
  }
  if (sliced) {
    block.slice = { left: obj.L9, right: obj.R9, top: obj.T9, bottom: obj.B9 };
  }
  return { block, outOfRange };
}

function toNode(obj, source, imageBucketMap, warnings) {
  // 拉伸(四边置0)适用于全部满屏对象(spec §2.4: 实测 52 个)，不论是否层内首个。
  // backgroundNodeId(层内唯一)是另一件事：仅用于"首个+满屏"的背景判定，与此处解耦。
  const stretch = isFullScreen(obj.Width, obj.Height);
  const node = {
    id: obj.ObjectID,
    name: obj.ObjectName,
    kind: obj.ObjectType === OBJECT_TYPE_TEXT ? 'label' : 'sprite',
    position: toCocosPosition(obj.Left, obj.Top, obj.Width, obj.Height),
    size: { width: obj.Width, height: obj.Height },
    siblingIndex: obj.IndexOfLayer,
    widget: stretch ? stretchWidget() : inferWidget(obj.Left, obj.Width),
    flags: {
      stretch,
      offscreen: isOffscreen(obj.Left, obj.Top, obj.Width, obj.Height),
      animation: obj.FrameStyle === 1,
      frameIndexOutOfRange: false,
    },
    legacy: {
      objectId: obj.ObjectID,
      imageFileId: obj.ImageFileID ?? 0,
      frameIndex: obj.FrameIndex ?? 0,
      frameStyle: obj.FrameStyle ?? 0,
      groupId: obj.GroupID ?? 0,
      voiceFileId: obj.VoiceFileID ?? 0,
      timerInterval: obj.TimerInterval ?? 0,
      left: obj.Left,
      top: obj.Top,
      events: obj.events ?? [],
    },
  };

  if (node.kind === 'sprite' && obj.ImageFileID) {
    const image = source.images.get(obj.ImageFileID);
    if (!image) {
      throw new Error(
        `对象 ${obj.ObjectID}（${obj.ObjectName}）引用了不存在的图 ImageFileID=${obj.ImageFileID}`,
      );
    }
    const { block, outOfRange } = spriteBlock(
      obj, image, imageBucketMap.get(obj.ImageFileID) ?? 'unassigned', warnings,
    );
    node.sprite = block;
    node.flags.frameIndexOutOfRange = outOfRange;
  }
  return node;
}

export function convertLayer(source, layer, imageBucketMap) {
  const objs = layer.objectIds
    .map((id) => source.objects.get(id))
    .filter(Boolean);

  const first = objs[0];
  const backgroundNodeId =
    first && isFullScreen(first.Width, first.Height) ? first.ObjectID : null;

  const warnings = [];
  const nodes = objs
    .map((o) => toNode(o, source, imageBucketMap, warnings))
    .sort((a, b) => a.siblingIndex - b.siblingIndex);

  const nodeIdSet = new Set(nodes.map((n) => n.id));
  const groups = source.groups
    .map((g) => ({ groupId: g.groupId, nodeIds: g.objectIds.filter((id) => nodeIdSet.has(id)) }))
    .filter((g) => g.nodeIds.length > 0);

  return {
    layerId: layer.layerId,
    name: layer.name,
    bucket: layerBucket(layer.layerId, layer.name),
    backgroundNodeId,
    groups,
    nodes,
    warnings,
  };
}

export function convertAll(source) {
  const imageBucketMap = imageBuckets(source);
  const layers = source.layers.map((l) => convertLayer(source, l, imageBucketMap));

  const objectIndex = {};
  const warnings = [];
  for (const doc of layers) {
    for (const n of doc.nodes) objectIndex[String(n.id)] = { layerId: doc.layerId, nodeId: n.id };
    warnings.push(...doc.warnings);
  }

  const manifest = {
    generatedBy: 'scripts/convert-ui.mjs',
    // 内容区基准（旧数据事实），坐标/三区据此判定，不随设计分辨率改变。
    designWidth: DESIGN_WIDTH,
    designHeight: DESIGN_HEIGHT,
    // 设计分辨率画布（20:9），落地 Layer/Group 根节点尺寸据此设定。
    canvasWidth: CANVAS_WIDTH,
    canvasHeight: CANVAS_HEIGHT,
    layers: layers.map((d) => ({
      layerId: d.layerId,
      name: d.name,
      bucket: d.bucket,
      file: `${String(d.layerId).padStart(3, '0')}-${d.name}.json`,
      nodeCount: d.nodes.length,
    })),
    objectIndex,
  };
  return { layers, manifest, warnings };
}