import { get, writable, type Writable } from "svelte/store";
import { callGetApi } from "$lib/hooks";
import {
  getDirectoryInfos as getDirectoryInfosFromIndexedDB,
  getDirectoryInfo as getDirectoryInfoFromIndexedDB,
  storeDirectoryInfo,
  deleteDirectoryInfo,
  getFileInfos as getFileInfosFromIndexedDB,
  getFileInfo as getFileInfoFromIndexedDB,
  storeFileInfo,
  deleteFileInfo,
  getCategoryInfos as getCategoryInfosFromIndexedDB,
  getCategoryInfo as getCategoryInfoFromIndexedDB,
  storeCategoryInfo,
  updateCategoryInfo as updateCategoryInfoInIndexedDB,
  deleteCategoryInfo,
  type DirectoryId,
  type CategoryId,
} from "$lib/indexedDB";
import { unwrapDataKey, decryptString } from "$lib/modules/crypto";
import type {
  CategoryInfoResponse,
  CategoryFileListResponse,
  DirectoryInfoResponse,
  FileInfoResponse,
} from "$lib/server/schemas";

export type DirectoryInfo =
  | {
      id: "root";
      dataKey?: undefined;
      dataKeyVersion?: undefined;
      name?: undefined;
      subDirectoryIds: number[];
      fileIds: number[];
    }
  | {
      id: number;
      dataKey?: CryptoKey;
      dataKeyVersion?: Date;
      name: string;
      subDirectoryIds: number[];
      fileIds: number[];
    };

export interface FileInfo {
  id: number;
  dataKey?: CryptoKey;
  dataKeyVersion?: Date;
  contentType: string;
  contentIv?: string;
  name: string;
  createdAt?: Date;
  lastModifiedAt: Date;
  categoryIds: number[];
}

export type CategoryInfo =
  | {
      id: "root";
      dataKey?: undefined;
      dataKeyVersion?: undefined;
      name?: undefined;
      subCategoryIds: number[];
      files?: undefined;
      isFileRecursive?: undefined;
    }
  | {
      id: number;
      dataKey?: CryptoKey;
      dataKeyVersion?: Date;
      name: string;
      subCategoryIds: number[];
      files: { id: number; isRecursive: boolean }[];
      isFileRecursive: boolean;
    };

const directoryInfoStore = new Map<DirectoryId, Writable<DirectoryInfo | null>>();
const fileInfoStore = new Map<number, Writable<FileInfo | null>>();
const categoryInfoStore = new Map<CategoryId, Writable<CategoryInfo | null>>();

const fetchDirectoryInfoFromIndexedDB = async (
  id: DirectoryId,
  info: Writable<DirectoryInfo | null>,
) => {
  if (get(info)) return;

  const [directory, subDirectories, files] = await Promise.all([
    id !== "root" ? getDirectoryInfoFromIndexedDB(id) : undefined,
    getDirectoryInfosFromIndexedDB(id),
    getFileInfosFromIndexedDB(id),
  ]);
  const subDirectoryIds = subDirectories.map(({ id }) => id);
  const fileIds = files.map(({ id }) => id);

  if (id === "root") {
    info.set({ id, subDirectoryIds, fileIds });
  } else {
    if (!directory) return;
    info.set({ id, name: directory.name, subDirectoryIds, fileIds });
  }
};

const fetchDirectoryInfoFromServer = async (
  id: DirectoryId,
  info: Writable<DirectoryInfo | null>,
  masterKey: CryptoKey,
) => {
  const res = await callGetApi(`/api/directory/${id}`);
  if (res.status === 404) {
    info.set(null);
    await deleteDirectoryInfo(id as number);
    return;
  } else if (!res.ok) {
    throw new Error("Failed to fetch directory information");
  }

  const {
    metadata,
    subDirectories: subDirectoryIds,
    files: fileIds,
  }: DirectoryInfoResponse = await res.json();

  if (id === "root") {
    info.set({ id, subDirectoryIds, fileIds });
  } else {
    const { dataKey } = await unwrapDataKey(metadata!.dek, masterKey);
    const name = await decryptString(metadata!.name, metadata!.nameIv, dataKey);

    info.set({
      id,
      dataKey,
      dataKeyVersion: new Date(metadata!.dekVersion),
      name,
      subDirectoryIds,
      fileIds,
    });
    await storeDirectoryInfo({ id, parentId: metadata!.parent, name });
  }
};

const fetchDirectoryInfo = async (
  id: DirectoryId,
  info: Writable<DirectoryInfo | null>,
  masterKey: CryptoKey,
) => {
  await fetchDirectoryInfoFromIndexedDB(id, info);
  await fetchDirectoryInfoFromServer(id, info, masterKey);
};

export const getDirectoryInfo = (id: DirectoryId, masterKey: CryptoKey) => {
  // TODO: MEK rotation

  let info = directoryInfoStore.get(id);
  if (!info) {
    info = writable(null);
    directoryInfoStore.set(id, info);
  }

  fetchDirectoryInfo(id, info, masterKey); // Intended
  return info;
};

const fetchFileInfoFromIndexedDB = async (id: number, info: Writable<FileInfo | null>) => {
  if (get(info)) return;

  const file = await getFileInfoFromIndexedDB(id);
  if (!file) return;

  info.set(file);
};

const decryptDate = async (ciphertext: string, iv: string, dataKey: CryptoKey) => {
  return new Date(parseInt(await decryptString(ciphertext, iv, dataKey), 10));
};

const fetchFileInfoFromServer = async (
  id: number,
  info: Writable<FileInfo | null>,
  masterKey: CryptoKey,
) => {
  const res = await callGetApi(`/api/file/${id}`);
  if (res.status === 404) {
    info.set(null);
    await deleteFileInfo(id);
    return;
  } else if (!res.ok) {
    throw new Error("Failed to fetch file information");
  }

  const metadata: FileInfoResponse = await res.json();
  const { dataKey } = await unwrapDataKey(metadata.dek, masterKey);

  const name = await decryptString(metadata.name, metadata.nameIv, dataKey);
  const createdAt =
    metadata.createdAt && metadata.createdAtIv
      ? await decryptDate(metadata.createdAt, metadata.createdAtIv, dataKey)
      : undefined;
  const lastModifiedAt = await decryptDate(
    metadata.lastModifiedAt,
    metadata.lastModifiedAtIv,
    dataKey,
  );

  info.set({
    id,
    dataKey,
    dataKeyVersion: new Date(metadata.dekVersion),
    contentType: metadata.contentType,
    contentIv: metadata.contentIv,
    name,
    createdAt,
    lastModifiedAt,
    categoryIds: metadata.categories,
  });
  await storeFileInfo({
    id,
    parentId: metadata.parent,
    name,
    contentType: metadata.contentType,
    createdAt,
    lastModifiedAt,
    categoryIds: metadata.categories,
  });
};

const fetchFileInfo = async (id: number, info: Writable<FileInfo | null>, masterKey: CryptoKey) => {
  await fetchFileInfoFromIndexedDB(id, info);
  await fetchFileInfoFromServer(id, info, masterKey);
};

export const getFileInfo = (fileId: number, masterKey: CryptoKey) => {
  // TODO: MEK rotation

  let info = fileInfoStore.get(fileId);
  if (!info) {
    info = writable(null);
    fileInfoStore.set(fileId, info);
  }

  fetchFileInfo(fileId, info, masterKey); // Intended
  return info;
};

const fetchCategoryInfoFromIndexedDB = async (
  id: CategoryId,
  info: Writable<CategoryInfo | null>,
) => {
  if (get(info)) return;

  const [category, subCategories] = await Promise.all([
    id !== "root" ? getCategoryInfoFromIndexedDB(id) : undefined,
    getCategoryInfosFromIndexedDB(id),
  ]);
  const subCategoryIds = subCategories.map(({ id }) => id);

  if (id === "root") {
    info.set({ id, subCategoryIds });
  } else {
    if (!category) return;
    info.set({
      id,
      name: category.name,
      subCategoryIds,
      files: category.files,
      isFileRecursive: category.isFileRecursive,
    });
  }
};

const fetchCategoryInfoFromServer = async (
  id: CategoryId,
  info: Writable<CategoryInfo | null>,
  masterKey: CryptoKey,
) => {
  let res = await callGetApi(`/api/category/${id}`);
  if (res.status === 404) {
    info.set(null);
    await deleteCategoryInfo(id as number);
    return;
  } else if (!res.ok) {
    throw new Error("Failed to fetch category information");
  }

  const { metadata, subCategories }: CategoryInfoResponse = await res.json();

  if (id === "root") {
    info.set({ id, subCategoryIds: subCategories });
  } else {
    const { dataKey } = await unwrapDataKey(metadata!.dek, masterKey);
    const name = await decryptString(metadata!.name, metadata!.nameIv, dataKey);

    res = await callGetApi(`/api/category/${id}/file/list?recurse=true`);
    if (!res.ok) {
      throw new Error("Failed to fetch category files");
    }

    const { files }: CategoryFileListResponse = await res.json();
    const filesMapped = files.map(({ file, isRecursive }) => ({ id: file, isRecursive }));
    let isFileRecursive: boolean | undefined = undefined;

    info.update((value) => {
      const newValue = {
        isFileRecursive: false,
        ...value,
        id,
        dataKey,
        dataKeyVersion: new Date(metadata!.dekVersion),
        name,
        subCategoryIds: subCategories,
        files: filesMapped,
      };
      isFileRecursive = newValue.isFileRecursive;
      return newValue;
    });
    await storeCategoryInfo({
      id,
      parentId: metadata!.parent,
      name,
      files: filesMapped,
      isFileRecursive: isFileRecursive!,
    });
  }
};

const fetchCategoryInfo = async (
  id: CategoryId,
  info: Writable<CategoryInfo | null>,
  masterKey: CryptoKey,
) => {
  await fetchCategoryInfoFromIndexedDB(id, info);
  await fetchCategoryInfoFromServer(id, info, masterKey);
};

export const getCategoryInfo = (categoryId: CategoryId, masterKey: CryptoKey) => {
  // TODO: MEK rotation

  let info = categoryInfoStore.get(categoryId);
  if (!info) {
    info = writable(null);
    categoryInfoStore.set(categoryId, info);
  }

  fetchCategoryInfo(categoryId, info, masterKey); // Intended
  return info;
};

export const updateCategoryInfo = async (
  categoryId: number,
  changes: { isFileRecursive?: boolean },
) => {
  await updateCategoryInfoInIndexedDB(categoryId, changes);
  categoryInfoStore.get(categoryId)?.update((value) => {
    if (!value) return value;
    if (changes.isFileRecursive !== undefined) {
      value.isFileRecursive = changes.isFileRecursive;
    }
    return value;
  });
};