import path from "node:path";
import { escapeRegExp } from "es-toolkit/compat";
import type { ZipFile } from "yazl";
import type { NavigationNode } from "@shared/types";
import { FileOperationFormat } from "@shared/types";
import Logger from "@server/logging/Logger";
import type { Collection } from "@server/models";
import Attachment from "@server/models/Attachment";
import Document from "@server/models/Document";
import { DocumentHelper } from "@server/models/helpers/DocumentHelper";
import { ProsemirrorHelper } from "@server/models/helpers/ProsemirrorHelper";
import ZipHelper from "@server/utils/ZipHelper";
import { serializeFilename } from "@server/utils/fs";
import ExportTask from "./ExportTask";

export default abstract class ExportDocumentTreeTask extends ExportTask {
  /**
   * Exports the document tree to the given zip instance.
   *
   * @param zip The yazl ZipFile to add files to
   * @param documentId The document ID to export
   * @param pathInZip The path in the zip to add the document to
   * @param format The format to export in
   */
  protected async processDocument({
    zip,
    pathInZip,
    documentId,
    format,
    includeAttachments,
    pathMap,
  }: {
    zip: ZipFile;
    pathInZip: string;
    documentId: string;
    format: FileOperationFormat;
    includeAttachments: boolean;
    pathMap: Map<string, string>;
  }) {
    Logger.debug("task", `Adding document to archive`, { documentId });
    const document = await Document.findByPk(documentId);
    if (!document) {
      return;
    }

    let text =
      format === FileOperationFormat.HTMLZip
        ? await DocumentHelper.toHTML(document, { centered: true })
        : await DocumentHelper.toMarkdown(document);

    const attachmentIds = includeAttachments
      ? ProsemirrorHelper.parseAttachmentIds(
          DocumentHelper.toProsemirror(document)
        )
      : [];
    const attachments = attachmentIds.length
      ? await Attachment.findAll({
          where: {
            teamId: document.teamId,
            id: attachmentIds,
          },
        })
      : [];

    // Add any referenced attachments to the zip file and replace the
    // reference in the document with the path to the attachment in the zip
    for (const attachment of attachments) {
      Logger.debug("task", `Adding attachment to archive`, {
        documentId,
        key: attachment.key,
      });

      // Skip attachments with a malformed key that has no filename component,
      // as yazl rejects entries whose path ends with a slash.
      if (!attachment.key || attachment.key.endsWith("/")) {
        Logger.warn(`Skipping attachment with invalid key`, {
          attachmentId: attachment.id,
          teamId: attachment.teamId,
          key: attachment.key,
        });
        continue;
      }

      const dir = path.dirname(pathInZip);
      let buffer: Buffer;
      try {
        buffer = await attachment.buffer;
      } catch (err) {
        Logger.warn(`Failed to read attachment from storage`, {
          attachmentId: attachment.id,
          teamId: attachment.teamId,
          error: err.message,
        });
        buffer = Buffer.from("");
      }
      zip.addBuffer(buffer, path.join(dir, attachment.key), {
        mtime: attachment.updatedAt,
      });

      text = text.replace(
        new RegExp(escapeRegExp(attachment.redirectUrl), "g"),
        encodeURI(attachment.key)
      );
    }

    // Replace any internal links with relative paths to the document in the zip
    const internalLinks = [
      ...text.matchAll(/\/doc\/(?:[0-9a-zA-Z-_~]*-)?([a-zA-Z0-9]{10,15})/g),
    ];
    internalLinks.forEach((match) => {
      const matchedLink = match[0];
      const matchedDocPath = pathMap.get(matchedLink);

      if (matchedDocPath) {
        const relativePath = path.relative(pathInZip, matchedDocPath);
        if (relativePath.startsWith(".")) {
          text = text.replace(
            matchedLink,
            encodeURI(relativePath.substring(1))
          );
        }
      }
    });

    // Finally, add the document to the zip file
    zip.addBuffer(Buffer.from(text), pathInZip, {
      mtime: document.updatedAt,
      fileComment: JSON.stringify({
        createdAt: document.createdAt,
        updatedAt: document.updatedAt,
      }),
    });
  }

  /**
   * Exports the documents and attachments in the given collections to a zip file
   * and returns the path to the zip file in tmp.
   *
   * @param zip The yazl ZipFile to add files to
   * @param collections The collections to export
   * @param format The format to export in
   * @param includeAttachments Whether to include attachments in the export
   *
   * @returns The path to the zip file in tmp.
   */
  protected async addCollectionsToArchive(
    zip: ZipFile,
    collections: Collection[],
    format: FileOperationFormat,
    includeAttachments = true
  ) {
    const pathMap = this.createPathMap(collections, format);
    Logger.debug(
      "task",
      `Start adding ${Object.values(pathMap).length} documents to archive`
    );

    for (const path of pathMap) {
      const documentId = path[0].replace("/doc/", "");
      const pathInZip = path[1];

      await this.processDocument({
        zip,
        pathInZip,
        documentId,
        includeAttachments,
        format,
        pathMap,
      });
    }

    Logger.debug("task", "Completed adding documents to archive");

    return await ZipHelper.toTmpFile(zip);
  }

  protected async addDocumentToArchive({
    document,
    format,
    documentStructure,
    zip,
  }: {
    document: Document;
    format: FileOperationFormat;
    documentStructure: NavigationNode[];
    zip: ZipFile;
  }) {
    const pathMap = new Map<string, string>();

    const extension = format === FileOperationFormat.HTMLZip ? "html" : "md";
    const rootFolderName = serializeFilename(document.titleWithDefault);

    // entry for root document
    pathMap.set(document.path, `${rootFolderName}.${extension}`);

    this.addDocumentTreeToPathMap(
      pathMap,
      documentStructure,
      serializeFilename(document.titleWithDefault),
      format
    );

    Logger.debug(
      "task",
      `Start adding ${Object.values(pathMap).length} documents to archive`
    );

    for (const entry of pathMap) {
      const documentId = entry[0].replace("/doc/", "");
      const pathInZip = entry[1];

      await this.processDocument({
        zip,
        pathInZip,
        documentId,
        includeAttachments: true,
        format,
        pathMap,
      });
    }

    Logger.debug("task", "Completed adding documents to archive");

    return await ZipHelper.toTmpFile(zip);
  }

  /**
   * Generates a map of document urls to their path in the zip file.
   *
   * @param collections The collections to generate the path map for.
   * @param format The format of the exported documents.
   */
  private createPathMap(
    collections: Collection[],
    format: FileOperationFormat
  ) {
    const map = new Map<string, string>();
    const usedRoots = new Set<string>();

    for (const collection of collections) {
      if (collection.documentStructure) {
        let root = serializeFilename(collection.name);
        let i = 0;
        while (usedRoots.has(root)) {
          root = `${serializeFilename(collection.name)} (${++i})`;
        }
        usedRoots.add(root);

        this.addDocumentTreeToPathMap(
          map,
          collection.documentStructure,
          root,
          format
        );
      }
    }

    return map;
  }

  private addDocumentTreeToPathMap(
    map: Map<string, string>,
    nodes: NavigationNode[],
    root: string,
    format: FileOperationFormat
  ) {
    for (const node of nodes) {
      const title = serializeFilename(node.title) || "Untitled";
      const extension = format === FileOperationFormat.HTMLZip ? "html" : "md";

      // Ensure the document is given a unique path in zip, even if it has
      // the same title as another document in the same collection.
      let i = 0;
      let filePath = path.join(root, `${title}.${extension}`);
      while (Array.from(map.values()).includes(filePath)) {
        filePath = path.join(root, `${title} (${++i}).${extension}`);
      }

      map.set(node.url, filePath);

      // If this is an imported document, the references to this doc are in the 'doc/{docId}' format.
      // Set this format to replace them with relative URLs in the zip.
      map.set(`/doc/${node.id}`, filePath);

      if (node.children?.length) {
        this.addDocumentTreeToPathMap(
          map,
          node.children,
          path.join(root, title),
          format
        );
      }
    }
  }
}