import * as IndexedDB from "$lib/indexedDB";
import { monotonicResolve } from "$lib/utils";
import { trpc, isTRPCClientError } from "$trpc/client";
import { FilesystemCache, decryptDirectoryMetadata, decryptFileMetadata } from "./internal.svelte";
import type { MaybeDirectoryInfo } from "./types";

const cache = new FilesystemCache<DirectoryId, MaybeDirectoryInfo>();

const fetchFromIndexedDB = async (id: DirectoryId) => {
  const [directory, subDirectories, files] = await Promise.all([
    id !== "root" ? IndexedDB.getDirectoryInfo(id) : undefined,
    IndexedDB.getDirectoryInfos(id),
    IndexedDB.getFileInfos(id),
  ]);

  if (id === "root") {
    return {
      id,
      exists: true as const,
      subDirectories,
      files,
    };
  } else if (directory) {
    return {
      id,
      exists: true as const,
      parentId: directory.parentId,
      name: directory.name,
      subDirectories,
      files,
    };
  }
};

const fetchFromServer = async (id: DirectoryId, masterKey: CryptoKey) => {
  try {
    const {
      metadata,
      subDirectories: subDirectoriesRaw,
      files: filesRaw,
    } = await trpc().directory.get.query({ id });

    void IndexedDB.deleteDanglingDirectoryInfos(id, new Set(subDirectoriesRaw.map(({ id }) => id)));
    void IndexedDB.deleteDanglingFileInfos(id, new Set(filesRaw.map(({ id }) => id)));

    const existingFiles = await IndexedDB.bulkGetFileInfos(filesRaw.map((file) => file.id));
    const [subDirectories, files, decryptedMetadata] = await Promise.all([
      Promise.all(
        subDirectoriesRaw.map(async (directory) => {
          const decrypted = await decryptDirectoryMetadata(directory, masterKey);
          await IndexedDB.storeDirectoryInfo({
            id: directory.id,
            parentId: id,
            name: decrypted.name,
          });
          return {
            id: directory.id,
            ...decrypted,
          };
        }),
      ),
      Promise.all(
        filesRaw.map(async (file, index) => {
          const decrypted = await decryptFileMetadata(file, masterKey);
          await IndexedDB.storeFileInfo({
            id: file.id,
            parentId: id,
            contentType: file.contentType,
            name: decrypted.name,
            createdAt: decrypted.createdAt,
            lastModifiedAt: decrypted.lastModifiedAt,
            categoryIds: existingFiles[index]?.categoryIds ?? [],
          });
          return {
            id: file.id,
            contentType: file.contentType,
            ...decrypted,
          };
        }),
      ),
      metadata ? decryptDirectoryMetadata(metadata, masterKey) : undefined,
    ]);

    if (id !== "root" && metadata && decryptedMetadata) {
      await IndexedDB.storeDirectoryInfo({
        id,
        parentId: metadata.parent,
        name: decryptedMetadata.name,
      });
    }

    if (id === "root") {
      return {
        id,
        exists: true as const,
        subDirectories,
        files,
      };
    } else {
      return {
        id,
        exists: true as const,
        parentId: metadata!.parent,
        subDirectories,
        files,
        ...decryptedMetadata!,
      };
    }
  } catch (e) {
    if (isTRPCClientError(e) && e.data?.code === "NOT_FOUND") {
      await IndexedDB.deleteDirectoryInfo(id as number);
      return { id, exists: false as const };
    }
    throw e;
  }
};

export const getDirectoryInfo = async (id: DirectoryId, masterKey: CryptoKey) => {
  return await cache.get(id, (isInitial, resolve) =>
    monotonicResolve(
      [isInitial && fetchFromIndexedDB(id), fetchFromServer(id, masterKey)],
      resolve,
    ),
  );
};