import JSZip from 'jszip';
import { useCallback, useRef, useState } from 'react';

import { hasReadableAssetSource } from '../../services/assetReadUrlService';
import type {
  CanvasAssetExportImage,
  CanvasAssetExportMetadata,
  CanvasLayer,
} from './ImageCanvasEditorTypes';
import {
  blobToUint8Array,
  buildAnimatedGifPreviewBytes,
  buildLayerExportMetadata,
  buildLayerVisibleExportMetadata,
  buildSpineImageSequenceJson,
  buildSpineImageSequenceReadme,
  type ExportedImageSequenceFrame,
  formatExportDate,
  getImageSequenceFrameFileName,
  getLayerAssetExtensionFromTypeOrSrc,
  getLayerExportKey,
  getLayerImageSequenceFrames,
  readLayerAssetBlob,
  readLayerImageSequenceFrameBlob,
  sanitizeExportFilePart,
} from './ImageCanvasExportModel';

export type AssetExportStatus = {
  tone: 'info' | 'success' | 'error';
  message: string;
};

export type ImageSequenceExportMode = 'spine-json' | 'sequence-with-preview';

type UseImageCanvasAssetExportWorkflowOptions = {
  layers: CanvasLayer[];
  projectId: string | null;
  projectTitle: string;
};

const GIF_PREVIEW_MAX_EDGE = 320;
const ASSET_EXPORT_READ_CONCURRENCY = 4;

function hasReadableLayerExportSource(layer: CanvasLayer) {
  if (layer.mediaType === 'image-sequence') {
    return getLayerImageSequenceFrames(layer).some((frame) =>
      hasReadableAssetSource(frame.imageSrc, frame.objectKey),
    );
  }
  return hasReadableAssetSource(layer.src, layer.objectKey);
}

type AssetExportPlan = {
  key: string;
  layer: CanvasLayer;
  indexedFileName: string;
};

type PreparedSequenceFrame = {
  fileName: string;
  bytes: Uint8Array;
  exportedFrame: ExportedImageSequenceFrame;
};

type PreparedAssetExport =
  | {
      status: 'asset';
      plan: AssetExportPlan;
      blob: Blob;
      bytes: Uint8Array;
      folderName: 'images' | 'media';
      fileName: string;
    }
  | {
      status: 'sequence';
      plan: AssetExportPlan;
      sequenceFolderName: string;
      frames: PreparedSequenceFrame[];
      failedFrames: Array<{ frameIndex: number; error: string }>;
      frameCount: number;
    }
  | {
      status: 'error';
      plan: AssetExportPlan;
      file: string;
      error: string;
    };

function createBoundedTaskRunner(concurrency: number) {
  const maximumConcurrency = Math.max(1, Math.floor(concurrency));
  const pendingTasks: Array<() => void> = [];
  let activeTaskCount = 0;

  return function runBoundedTask<T>(task: () => Promise<T>): Promise<T> {
    return new Promise<T>((resolve, reject) => {
      const startTask = () => {
        activeTaskCount += 1;
        void task()
          .then(resolve, reject)
          .finally(() => {
            activeTaskCount -= 1;
            pendingTasks.shift()?.();
          });
      };

      if (activeTaskCount < maximumConcurrency) {
        startTask();
        return;
      }
      pendingTasks.push(startTask);
    });
  };
}

function triggerBrowserDownload(blob: Blob, downloadName: string) {
  if (
    typeof URL.createObjectURL !== 'function' ||
    typeof URL.revokeObjectURL !== 'function'
  ) {
    return false;
  }
  const downloadUrl = URL.createObjectURL(blob);
  const link = document.createElement('a');
  link.href = downloadUrl;
  link.download = downloadName;
  document.body.appendChild(link);
  link.click();
  link.remove();
  URL.revokeObjectURL(downloadUrl);
  return true;
}

function createFallbackPreviewBlob(frameBlob: Blob) {
  return frameBlob.size
    ? new Blob([frameBlob], { type: 'image/gif' })
    : new Blob([], { type: 'image/gif' });
}

function resolveGifPreviewSize(width: number, height: number) {
  const safeWidth = Math.max(1, Math.round(width));
  const safeHeight = Math.max(1, Math.round(height));
  const scale = Math.min(
    1,
    GIF_PREVIEW_MAX_EDGE / Math.max(safeWidth, safeHeight),
  );
  return {
    width: Math.max(1, Math.round(safeWidth * scale)),
    height: Math.max(1, Math.round(safeHeight * scale)),
  };
}

async function buildAnimatedSequencePreview(
  frameBlobs: Blob[],
  size: { width: number; height: number },
  durationSeconds: number | null | undefined,
) {
  const firstFrameBlob = frameBlobs[0];
  if (!firstFrameBlob?.size) {
    return createFallbackPreviewBlob(firstFrameBlob ?? new Blob());
  }

  try {
    if (typeof createImageBitmap === 'undefined') {
      return createFallbackPreviewBlob(firstFrameBlob);
    }
    const firstFrameImage = await createImageBitmap(firstFrameBlob);
    const canvas = document.createElement('canvas');
    canvas.width = size.width || firstFrameImage.width;
    canvas.height = size.height || firstFrameImage.height;
    const context = canvas.getContext('2d');
    if (!context) {
      return createFallbackPreviewBlob(firstFrameBlob);
    }

    const { width, height } = resolveGifPreviewSize(
      size.width || firstFrameImage.width,
      size.height || firstFrameImage.height,
    );
    canvas.width = width;
    canvas.height = height;

    const previewFrames = [];
    for (const frameBlob of frameBlobs) {
      const frameImage =
        frameBlob === firstFrameBlob
          ? firstFrameImage
          : await createImageBitmap(frameBlob);
      context.clearRect(0, 0, width, height);
      context.drawImage(frameImage, 0, 0, width, height);
      previewFrames.push({
        width,
        height,
        rgba: context.getImageData(0, 0, width, height).data,
      });
    }

    const duration =
      typeof durationSeconds === 'number' && durationSeconds > 0
        ? durationSeconds
        : frameBlobs.length;
    const delayCentiseconds = (duration / Math.max(1, frameBlobs.length)) * 100;
    return new Blob(
      [
        buildAnimatedGifPreviewBytes({
          width,
          height,
          frames: previewFrames,
          frameDelayCentiseconds: delayCentiseconds,
        }),
      ],
      {
        type: 'image/gif',
      },
    );
  } catch {
    return createFallbackPreviewBlob(firstFrameBlob);
  }
}

async function buildImageSequenceZip(
  layer: CanvasLayer,
  mode: ImageSequenceExportMode,
) {
  const frames = getLayerImageSequenceFrames(layer);
  if (!frames.length) {
    throw new Error('序列帧为空');
  }
  const durationSeconds = layer.imageSequenceDurationMs
    ? layer.imageSequenceDurationMs / 1_000
    : undefined;
  const zip = new JSZip();
  const framesFolder = zip.folder('frames') ?? zip;
  const failedFrames: Array<{
    frameIndex: number;
    error: string;
  }> = [];
  const exportedFrames: ExportedImageSequenceFrame[] = [];
  let successCount = 0;
  const frameBlobs: Blob[] = [];

  for (const [index, frame] of frames.entries()) {
    try {
      const blob = await readLayerImageSequenceFrameBlob(layer, frame);
      frameBlobs.push(blob);
      const fileName = getImageSequenceFrameFileName(frame, index, blob.type);
      framesFolder.file(fileName, await blobToUint8Array(blob));
      exportedFrames.push({
        fileName,
        width: frame.width,
        height: frame.height,
      });
      successCount += 1;
    } catch (error) {
      failedFrames.push({
        frameIndex: index + 1,
        error: error instanceof Error ? error.message : '序列帧读取失败',
      });
    }
  }

  if (successCount === 0) {
    throw new Error('序列帧读取失败');
  }

  const sequenceManifestLines = [
    `素材：${layer.title}`,
    `类型：${mode === 'spine-json' ? 'Spine JSON' : '序列帧'}`,
    `帧数：${successCount}/${frames.length}`,
    `时长：${durationSeconds ? `${durationSeconds}s` : '0s'}`,
    failedFrames.length ? `失败帧数：${failedFrames.length}` : null,
  ].filter(Boolean);

  if (mode === 'sequence-with-preview') {
    if (frameBlobs.length) {
      const previewBlob = await buildAnimatedSequencePreview(
        frameBlobs,
        {
          width: layer.width,
          height: layer.height,
        },
        durationSeconds,
      );
      zip.file('preview.gif', await blobToUint8Array(previewBlob));
    }

    zip.file(
      'metadata.json',
      JSON.stringify(
        {
          title: layer.title,
          visible: buildLayerVisibleExportMetadata(layer),
          frameCount: frames.length,
          exportedFrameCount: successCount,
          failedFrames,
        },
        null,
        2,
      ),
    );
    zip.file('manifest.txt', sequenceManifestLines.join('\n'));
    return zip.generateAsync({ type: 'blob' });
  }

  zip.file(
    'metadata.json',
    JSON.stringify(
      {
        title: layer.title,
        visible: buildLayerVisibleExportMetadata(layer),
        frameCount: frames.length,
        exportedFrameCount: successCount,
        failedFrames,
      },
      null,
      2,
    ),
  );
  zip.file(
    'skeleton.json',
    JSON.stringify(
      buildSpineImageSequenceJson({ layer, frames: exportedFrames }),
      null,
      2,
    ),
  );
  zip.file('README.md', buildSpineImageSequenceReadme(layer));
  zip.file(
    'manifest.txt',
    [
      `素材：${layer.title}`,
      `类型：序列帧`,
      `帧数：${successCount}/${frames.length}`,
      'Spine JSON：skeleton.json',
      durationSeconds ? `时长：${durationSeconds}s` : null,
      failedFrames.length ? `失败帧数：${failedFrames.length}` : null,
    ]
      .filter(Boolean)
      .join('\n'),
  );

  return zip.generateAsync({ type: 'blob' });
}

export function useImageCanvasAssetExportWorkflow({
  layers,
  projectTitle,
}: UseImageCanvasAssetExportWorkflowOptions) {
  const [assetExportStatus, setAssetExportStatus] =
    useState<AssetExportStatus | null>(null);
  const [isExportingAssets, setIsExportingAssets] = useState(false);
  const isExportingAssetsRef = useRef(false);

  const exportLayerImageUnlocked = useCallback(
    async (
      layer: CanvasLayer | null,
      options: { mode?: ImageSequenceExportMode } = {},
    ) => {
      const exportMode = options.mode ?? 'spine-json';
      if (!layer) {
        return false;
      }
      if (layer.mediaType === 'image-sequence') {
        try {
          const zipBlob = await buildImageSequenceZip(layer, exportMode);
          const modeName =
            exportMode === 'spine-json' ? 'SpineJSON' : 'Sequence';
          const exportStamp = formatExportDate(new Date());
          const downloaded = triggerBrowserDownload(
            zipBlob,
            `${sanitizeExportFilePart(layer.title, '角色动作')}-${modeName}-${exportStamp}.zip`,
          );
          if (!downloaded) {
            setAssetExportStatus({
              tone: 'error',
              message: '当前浏览器不支持素材下载',
            });
          }
          return downloaded;
        } catch {
          const hasFrameSource = (layer.imageSequenceFrames?.length ?? 0) > 0;
          setAssetExportStatus({
            tone: 'error',
            message: hasFrameSource
              ? '序列帧导出失败'
              : `角色动作素材“${layer.title}”不完整：缺少可用序列帧。`,
          });
          return false;
        }
      }

      try {
        const blob = await readLayerAssetBlob(layer);
        const extension = getLayerAssetExtensionFromTypeOrSrc(
          layer.mediaType ?? 'image',
          blob.type,
          layer.objectKey ?? layer.src,
        );
        const downloaded = triggerBrowserDownload(
          blob,
          `${sanitizeExportFilePart(layer.title, 'canvas-layer')}-${formatExportDate(new Date())}.${extension}`,
        );
        if (!downloaded) {
          setAssetExportStatus({
            tone: 'error',
            message: '当前浏览器不支持素材下载',
          });
        }
        return downloaded;
      } catch {
        setAssetExportStatus({
          tone: 'error',
          message: '素材导出失败',
        });
        return false;
      }
    },
    [],
  );

  const exportLayerImage = useCallback(
    async (
      layer: CanvasLayer | null,
      options: { mode?: ImageSequenceExportMode } = {},
    ) => {
      if (!layer || isExportingAssetsRef.current) {
        return false;
      }
      isExportingAssetsRef.current = true;
      setIsExportingAssets(true);
      setAssetExportStatus(null);
      try {
        return await exportLayerImageUnlocked(layer, options);
      } finally {
        isExportingAssetsRef.current = false;
        setIsExportingAssets(false);
      }
    },
    [exportLayerImageUnlocked],
  );

  const exportAssetCollection = useCallback(
    async ({
      targetLayers,
      archiveLabel,
      emptyMessage,
      successMessage,
    }: {
      targetLayers: CanvasLayer[];
      archiveLabel: string;
      emptyMessage: string;
      successMessage: string;
    }) => {
      if (isExportingAssetsRef.current) {
        return;
      }
      const exportableLayers = targetLayers
        .filter(hasReadableLayerExportSource)
        .sort((left, right) => left.zIndex - right.zIndex);
      if (!exportableLayers.length) {
        setAssetExportStatus({
          tone: 'info',
          message: emptyMessage,
        });
        return;
      }

      isExportingAssetsRef.current = true;
      setIsExportingAssets(true);
      setAssetExportStatus(null);

      try {
        const exportedAt = new Date();
        const projectName = sanitizeExportFilePart(projectTitle, '未命名画布');
        const rootFolderName = `${projectName}-${archiveLabel}`;
        const zip = new JSZip();
        const rootFolder = zip.folder(rootFolderName) ?? zip;
        const imagesFolder = rootFolder.folder('images') ?? rootFolder;
        const mediaFolder = rootFolder.folder('media') ?? rootFolder;
        const imageByKey = new Map<string, CanvasAssetExportImage>();
        const usedFileNames = new Map<string, number>();
        const plannedKeys = new Set<string>();
        const exportPlans: AssetExportPlan[] = [];

        for (const layer of exportableLayers) {
          const key = getLayerExportKey(layer);
          if (plannedKeys.has(key)) {
            continue;
          }
          plannedKeys.add(key);
          const index = exportPlans.length + 1;
          const safeTitle = sanitizeExportFilePart(layer.title, '画布素材');
          const baseFileName = `${String(index).padStart(3, '0')}-${safeTitle}`;
          const duplicateCount = usedFileNames.get(baseFileName) ?? 0;
          usedFileNames.set(baseFileName, duplicateCount + 1);
          const indexedFileName =
            duplicateCount > 0
              ? `${baseFileName}-${duplicateCount + 1}`
              : baseFileName;
          exportPlans.push({ key, layer, indexedFileName });
        }

        const runBoundedRead = createBoundedTaskRunner(
          ASSET_EXPORT_READ_CONCURRENCY,
        );
        const preparedExports = await Promise.all(
          exportPlans.map(async (plan): Promise<PreparedAssetExport> => {
            const { layer, indexedFileName } = plan;
            try {
              // TODO image sequence (action) logic should be refactored together with its backend data structure impl.
              if (layer.mediaType === 'image-sequence') {
                const frames = getLayerImageSequenceFrames(layer);
                if (!frames.length) {
                  throw new Error('序列帧为空');
                }
                const sequenceFolderName = `sequences/${indexedFileName}`;
                const preparedFrames = await Promise.all(
                  frames.map((frame, frameArrayIndex) =>
                    runBoundedRead(async () => {
                      try {
                        const frameBlob = await readLayerImageSequenceFrameBlob(
                          layer,
                          frame,
                        );
                        const fileName = getImageSequenceFrameFileName(
                          frame,
                          frameArrayIndex,
                          frameBlob.type,
                        );
                        return {
                          status: 'success' as const,
                          frame: {
                            fileName,
                            bytes: await blobToUint8Array(frameBlob),
                            exportedFrame: {
                              fileName,
                              width: frame.width,
                              height: frame.height,
                            },
                          },
                        };
                      } catch (error) {
                        return {
                          status: 'error' as const,
                          failure: {
                            frameIndex: frameArrayIndex + 1,
                            error:
                              error instanceof Error
                                ? error.message
                                : '序列帧读取失败',
                          },
                        };
                      }
                    }),
                  ),
                );
                // TODO(master 既有行为待讨论): 当前至少一帧成功即导出；需先明确部分失败的顶层状态和原时间点保留契约，再决定整体失败或部分导出。
                const successfulFrames = preparedFrames
                  .filter((result) => result.status === 'success')
                  .map((result) => result.frame);
                if (successfulFrames.length === 0) {
                  throw new Error('序列帧读取失败');
                }
                return {
                  status: 'sequence',
                  plan,
                  sequenceFolderName,
                  frames: successfulFrames,
                  failedFrames: preparedFrames
                    .filter((result) => result.status === 'error')
                    .map((result) => result.failure),
                  frameCount: frames.length,
                };
              }

              const { blob, bytes } = await runBoundedRead(async () => {
                const nextBlob = await readLayerAssetBlob(layer);
                return {
                  blob: nextBlob,
                  bytes: await blobToUint8Array(nextBlob),
                };
              });
              const mediaType = layer.mediaType ?? 'image';
              const extension = getLayerAssetExtensionFromTypeOrSrc(
                mediaType,
                blob.type,
                layer.objectKey ?? layer.src,
              );
              const folderName = mediaType === 'image' ? 'images' : 'media';
              return {
                status: 'asset',
                plan,
                blob,
                bytes,
                folderName,
                fileName: `${indexedFileName}.${extension}`,
              };
            } catch (error) {
              const mediaType = layer.mediaType ?? 'image';
              const extension = getLayerAssetExtensionFromTypeOrSrc(
                mediaType,
                '',
                layer.objectKey ?? layer.src,
              );
              const folderName = mediaType === 'image' ? 'images' : 'media';
              return {
                status: 'error',
                plan,
                file: `${folderName}/${indexedFileName}.${extension}`,
                error: error instanceof Error ? error.message : '素材读取失败',
              };
            }
          }),
        );

        for (const preparedExport of preparedExports) {
          const { key, layer } = preparedExport.plan;
          if (preparedExport.status === 'error') {
            imageByKey.set(key, {
              key,
              file: preparedExport.file,
              layer,
              error: preparedExport.error,
            });
            continue;
          }
          if (preparedExport.status === 'asset') {
            const targetFolder =
              preparedExport.folderName === 'images'
                ? imagesFolder
                : mediaFolder;
            targetFolder.file(preparedExport.fileName, preparedExport.bytes);
            imageByKey.set(key, {
              key,
              file: `${preparedExport.folderName}/${preparedExport.fileName}`,
              layer,
              blob: preparedExport.blob,
            });
            continue;
          }

          const sequenceFolder =
            rootFolder.folder(preparedExport.sequenceFolderName) ?? rootFolder;
          const framesFolder =
            sequenceFolder.folder('frames') ?? sequenceFolder;
          preparedExport.frames.forEach((frame) => {
            framesFolder.file(frame.fileName, frame.bytes);
          });
          const exportedFrames = preparedExport.frames.map(
            (frame) => frame.exportedFrame,
          );
          sequenceFolder.file(
            'metadata.json',
            JSON.stringify(
              {
                title: layer.title,
                visible: buildLayerVisibleExportMetadata(layer),
                frameCount: preparedExport.frameCount,
                exportedFrameCount: exportedFrames.length,
                failedFrames: preparedExport.failedFrames,
              },
              null,
              2,
            ),
          );
          sequenceFolder.file(
            'skeleton.json',
            JSON.stringify(
              buildSpineImageSequenceJson({ layer, frames: exportedFrames }),
              null,
              2,
            ),
          );
          sequenceFolder.file(
            'README.md',
            buildSpineImageSequenceReadme(layer),
          );
          sequenceFolder.file(
            'manifest.txt',
            [
              `素材：${layer.title}`,
              `类型：序列帧`,
              `帧数：${exportedFrames.length}/${preparedExport.frameCount}`,
              'Spine JSON：skeleton.json',
              layer.imageSequenceDurationMs
                ? `时长：${layer.imageSequenceDurationMs / 1_000}s`
                : null,
              preparedExport.failedFrames.length
                ? `失败帧数：${preparedExport.failedFrames.length}`
                : null,
            ]
              .filter(Boolean)
              .join('\n'),
          );
          imageByKey.set(key, {
            key,
            file: `${preparedExport.sequenceFolderName}/manifest.txt`,
            layer,
            blob: new Blob([], { type: 'application/zip' }),
          });
        }

        const failedImages = [...imageByKey.values()].filter(
          (image) => image.error,
        );
        const successfulImages = [...imageByKey.values()].filter(
          (image) => image.blob,
        );
        if (!successfulImages.length) {
          setAssetExportStatus({
            tone: 'error',
            message: '素材导出失败',
          });
          return;
        }

        const metadata: CanvasAssetExportMetadata = {
          projectTitle,
          exportedAt: exportedAt.toISOString(),
          layers: exportableLayers.map((layer) => {
            const image = imageByKey.get(getLayerExportKey(layer));
            return buildLayerExportMetadata(
              layer,
              image?.blob ? image.file : null,
              image?.error,
            );
          }),
          failedImages: failedImages.map((image) => ({
            title: image.layer.title,
            error: image.error ?? '素材读取失败',
          })),
        };
        const manifest = [
          `项目：${projectTitle}`,
          `导出时间：${metadata.exportedAt}`,
          `素材数量：${successfulImages.length}`,
          `图层数量：${exportableLayers.length}`,
          failedImages.length ? `失败素材数量：${failedImages.length}` : null,
        ]
          .filter(Boolean)
          .join('\n');

        rootFolder.file('metadata.json', JSON.stringify(metadata, null, 2));
        rootFolder.file('manifest.txt', manifest);

        const zipBlob = await zip.generateAsync({ type: 'blob' });
        if (
          typeof URL.createObjectURL !== 'function' ||
          typeof URL.revokeObjectURL !== 'function'
        ) {
          setAssetExportStatus({
            tone: 'error',
            message: '当前浏览器不支持素材下载',
          });
          return;
        }

        const downloadUrl = URL.createObjectURL(zipBlob);
        const link = document.createElement('a');
        link.href = downloadUrl;
        link.download = `${rootFolderName}-${formatExportDate(exportedAt)}.zip`;
        document.body.appendChild(link);
        link.click();
        link.remove();
        URL.revokeObjectURL(downloadUrl);
        setAssetExportStatus({
          tone: failedImages.length ? 'error' : 'success',
          message: failedImages.length ? '部分素材未能导出' : successMessage,
        });
      } catch {
        setAssetExportStatus({
          tone: 'error',
          message: '素材导出失败',
        });
      } finally {
        isExportingAssetsRef.current = false;
        setIsExportingAssets(false);
      }
    },
    [projectTitle],
  );

  const exportCanvasAssets = useCallback(
    () =>
      exportAssetCollection({
        targetLayers: layers,
        archiveLabel: '画布素材',
        emptyMessage: '当前画布没有可导出的素材',
        successMessage: '画布素材已导出',
      }),
    [exportAssetCollection, layers],
  );

  const exportSelectedAssets = useCallback(
    async (selectedLayers: CanvasLayer[]) => {
      if (isExportingAssetsRef.current) {
        return;
      }
      const exportableLayers = selectedLayers.filter(
        hasReadableLayerExportSource,
      );
      if (!exportableLayers.length) {
        setAssetExportStatus({
          tone: 'info',
          message: '请先选择可下载的素材',
        });
        return;
      }
      if (exportableLayers.length === 1) {
        const downloaded = await exportLayerImage(exportableLayers[0] ?? null);
        if (downloaded) {
          setAssetExportStatus({
            tone: 'success',
            message: '选中素材已导出',
          });
        }
        return;
      }
      await exportAssetCollection({
        targetLayers: exportableLayers,
        archiveLabel: '选中素材',
        emptyMessage: '请先选择可下载的素材',
        successMessage: '选中素材已导出',
      });
    },
    [exportAssetCollection, exportLayerImage],
  );

  const reportAssetError = useCallback((message: string) => {
    setAssetExportStatus({ tone: 'error', message });
  }, []);

  return {
    assetExportStatus,
    isExportingAssets,
    exportCanvasAssets,
    exportSelectedAssets,
    exportLayerImage,
    reportAssetError,
  };
}