import polyfill from "../polyfill";
import LanguageDetector from "i18next-browser-languagedetector";
import { useEffect, useMemo, useRef, useState } from "react";
import { trackEvent } from "../analytics";
import { getDefaultAppState } from "../appState";
import { ErrorDialog } from "../components/ErrorDialog";
import { TopErrorBoundary } from "../components/TopErrorBoundary";
import {
  APP_NAME,
  EVENT,
  THEME,
  TITLE_TIMEOUT,
  VERSION_TIMEOUT,
} from "../constants";
import { loadFromBlob } from "../data/blob";
import {
  ExcalidrawElement,
  FileId,
  NonDeletedExcalidrawElement,
  Theme,
} from "../element/types";
import { useCallbackRefState } from "../hooks/useCallbackRefState";
import { t } from "../i18n";
import {
  Excalidraw,
  defaultLang,
  Footer,
  MainMenu,
  WelcomeScreen,
} from "../packages/excalidraw/index";
import {
  AppState,
  LibraryItems,
  ExcalidrawImperativeAPI,
  BinaryFiles,
  ExcalidrawInitialDataState,
} from "../types";
import {
  debounce,
  getVersion,
  getFrame,
  isTestEnv,
  preventUnload,
  ResolvablePromise,
  resolvablePromise,
} from "../utils";
import {
  FIREBASE_STORAGE_PREFIXES,
  isExcalidrawPlusSignedUser,
  STORAGE_KEYS,
  SYNC_BROWSER_TABS_TIMEOUT,
} from "./app_constants";
import Collab, {
  CollabAPI,
  collabAPIAtom,
  collabDialogShownAtom,
  isCollaboratingAtom,
} from "./collab/Collab";
import {
  exportToBackend,
  getCollaborationLinkData,
  isCollaborationLink,
  loadScene,
} from "./data";
import {
  getLibraryItemsFromStorage,
  importFromLocalStorage,
  importUsernameFromLocalStorage,
} from "./data/localStorage";
import CustomStats from "./CustomStats";
import { restore, restoreAppState, RestoredDataState } from "../data/restore";

import "./index.scss";
import { ExportToExcalidrawPlus } from "./components/ExportToExcalidrawPlus";

import { updateStaleImageStatuses } from "./data/FileManager";
import { newElementWith } from "../element/mutateElement";
import { isInitializedImageElement } from "../element/typeChecks";
import { loadFilesFromFirebase } from "./data/firebase";
import { LocalData } from "./data/LocalData";
import { isBrowserStorageStateNewer } from "./data/tabSync";
import clsx from "clsx";
import { atom, Provider, useAtom } from "jotai";
import { jotaiStore, useAtomWithInitialValue } from "../jotai";
import { reconcileElements } from "./collab/reconciliation";
import { parseLibraryTokensFromUrl, useHandleLibrary } from "../data/library";
import { EncryptedIcon } from "./components/EncryptedIcon";
import { ExcalidrawPlusAppLink } from "./components/ExcalidrawPlusAppLink";
import { LanguageList } from "./components/LanguageList";
import { PlusPromoIcon, UsersIcon } from "../components/icons";

polyfill();

window.EXCALIDRAW_THROTTLE_RENDER = true;

const languageDetector = new LanguageDetector();
languageDetector.init({
  languageUtils: {},
});

const initializeScene = async (opts: {
  collabAPI: CollabAPI;
  excalidrawAPI: ExcalidrawImperativeAPI;
}): Promise<
  { scene: ExcalidrawInitialDataState | null } & (
    | { isExternalScene: true; id: string; key: string }
    | { isExternalScene: false; id?: null; key?: null }
  )
> => {
  const searchParams = new URLSearchParams(window.location.search);
  const id = searchParams.get("id");
  const jsonBackendMatch = window.location.hash.match(
    /^#json=([a-zA-Z0-9_-]+),([a-zA-Z0-9_-]+)$/,
  );
  const externalUrlMatch = window.location.hash.match(/^#url=(.*)$/);

  const localDataState = importFromLocalStorage();

  let scene: RestoredDataState & {
    scrollToContent?: boolean;
  } = await loadScene(null, null, localDataState);

  let roomLinkData = getCollaborationLinkData(window.location.href);
  const isExternalScene = !!(id || jsonBackendMatch || roomLinkData);
  if (isExternalScene) {
    if (
      // don't prompt if scene is empty
      !scene.elements.length ||
      // don't prompt for collab scenes because we don't override local storage
      roomLinkData ||
      // otherwise, prompt whether user wants to override current scene
      window.confirm(t("alerts.loadSceneOverridePrompt"))
    ) {
      if (jsonBackendMatch) {
        scene = await loadScene(
          jsonBackendMatch[1],
          jsonBackendMatch[2],
          localDataState,
        );
      }
      scene.scrollToContent = true;
      if (!roomLinkData) {
        window.history.replaceState({}, APP_NAME, window.location.origin);
      }
    } else {
      // https://github.com/excalidraw/excalidraw/issues/1919
      if (document.hidden) {
        return new Promise((resolve, reject) => {
          window.addEventListener(
            "focus",
            () => initializeScene(opts).then(resolve).catch(reject),
            {
              once: true,
            },
          );
        });
      }

      roomLinkData = null;
      window.history.replaceState({}, APP_NAME, window.location.origin);
    }
  } else if (externalUrlMatch) {
    window.history.replaceState({}, APP_NAME, window.location.origin);

    const url = externalUrlMatch[1];
    try {
      const request = await fetch(window.decodeURIComponent(url));
      const data = await loadFromBlob(await request.blob(), null, null);
      if (
        !scene.elements.length ||
        window.confirm(t("alerts.loadSceneOverridePrompt"))
      ) {
        return { scene: data, isExternalScene };
      }
    } catch (error: any) {
      return {
        scene: {
          appState: {
            errorMessage: t("alerts.invalidSceneUrl"),
          },
        },
        isExternalScene,
      };
    }
  }

  if (roomLinkData) {
    const { excalidrawAPI } = opts;

    const scene = await opts.collabAPI.startCollaboration(roomLinkData);

    return {
      // when collaborating, the state may have already been updated at this
      // point (we may have received updates from other clients), so reconcile
      // elements and appState with existing state
      scene: {
        ...scene,
        appState: {
          ...restoreAppState(
            {
              ...scene?.appState,
              theme: localDataState?.appState?.theme || scene?.appState?.theme,
            },
            excalidrawAPI.getAppState(),
          ),
          // necessary if we're invoking from a hashchange handler which doesn't
          // go through App.initializeScene() that resets this flag
          isLoading: false,
        },
        elements: reconcileElements(
          scene?.elements || [],
          excalidrawAPI.getSceneElementsIncludingDeleted(),
          excalidrawAPI.getAppState(),
        ),
      },
      isExternalScene: true,
      id: roomLinkData.roomId,
      key: roomLinkData.roomKey,
    };
  } else if (scene) {
    return isExternalScene && jsonBackendMatch
      ? {
          scene,
          isExternalScene,
          id: jsonBackendMatch[1],
          key: jsonBackendMatch[2],
        }
      : { scene, isExternalScene: false };
  }
  return { scene: null, isExternalScene: false };
};

const currentLangCode = languageDetector.detect() || defaultLang.code;

export const langCodeAtom = atom(
  Array.isArray(currentLangCode) ? currentLangCode[0] : currentLangCode,
);

const ExcalidrawWrapper = () => {
  const [errorMessage, setErrorMessage] = useState("");
  const [langCode, setLangCode] = useAtom(langCodeAtom);
  // initial state
  // ---------------------------------------------------------------------------

  const initialStatePromiseRef = useRef<{
    promise: ResolvablePromise<ExcalidrawInitialDataState | null>;
  }>({ promise: null! });
  if (!initialStatePromiseRef.current.promise) {
    initialStatePromiseRef.current.promise =
      resolvablePromise<ExcalidrawInitialDataState | null>();
  }

  useEffect(() => {
    trackEvent("load", "frame", getFrame());
    // Delayed so that the app has a time to load the latest SW
    setTimeout(() => {
      trackEvent("load", "version", getVersion());
    }, VERSION_TIMEOUT);
  }, []);

  const [excalidrawAPI, excalidrawRefCallback] =
    useCallbackRefState<ExcalidrawImperativeAPI>();

  const [collabAPI] = useAtom(collabAPIAtom);
  const [, setCollabDialogShown] = useAtom(collabDialogShownAtom);
  const [isCollaborating] = useAtomWithInitialValue(isCollaboratingAtom, () => {
    return isCollaborationLink(window.location.href);
  });

  useHandleLibrary({
    excalidrawAPI,
    getInitialLibraryItems: getLibraryItemsFromStorage,
  });

  useEffect(() => {
    if (!collabAPI || !excalidrawAPI) {
      return;
    }

    const loadImages = (
      data: ResolutionType<typeof initializeScene>,
      isInitialLoad = false,
    ) => {
      if (!data.scene) {
        return;
      }
      if (collabAPI.isCollaborating()) {
        if (data.scene.elements) {
          collabAPI
            .fetchImageFilesFromFirebase({
              elements: data.scene.elements,
              forceFetchFiles: true,
            })
            .then(({ loadedFiles, erroredFiles }) => {
              excalidrawAPI.addFiles(loadedFiles);
              updateStaleImageStatuses({
                excalidrawAPI,
                erroredFiles,
                elements: excalidrawAPI.getSceneElementsIncludingDeleted(),
              });
            });
        }
      } else {
        const fileIds =
          data.scene.elements?.reduce((acc, element) => {
            if (isInitializedImageElement(element)) {
              return acc.concat(element.fileId);
            }
            return acc;
          }, [] as FileId[]) || [];

        if (data.isExternalScene) {
          loadFilesFromFirebase(
            `${FIREBASE_STORAGE_PREFIXES.shareLinkFiles}/${data.id}`,
            data.key,
            fileIds,
          ).then(({ loadedFiles, erroredFiles }) => {
            excalidrawAPI.addFiles(loadedFiles);
            updateStaleImageStatuses({
              excalidrawAPI,
              erroredFiles,
              elements: excalidrawAPI.getSceneElementsIncludingDeleted(),
            });
          });
        } else if (isInitialLoad) {
          if (fileIds.length) {
            LocalData.fileStorage
              .getFiles(fileIds)
              .then(({ loadedFiles, erroredFiles }) => {
                if (loadedFiles.length) {
                  excalidrawAPI.addFiles(loadedFiles);
                }
                updateStaleImageStatuses({
                  excalidrawAPI,
                  erroredFiles,
                  elements: excalidrawAPI.getSceneElementsIncludingDeleted(),
                });
              });
          }
          // on fresh load, clear unused files from IDB (from previous
          // session)
          LocalData.fileStorage.clearObsoleteFiles({ currentFileIds: fileIds });
        }
      }
    };

    initializeScene({ collabAPI, excalidrawAPI }).then(async (data) => {
      loadImages(data, /* isInitialLoad */ true);
      initialStatePromiseRef.current.promise.resolve(data.scene);
    });

    const onHashChange = async (event: HashChangeEvent) => {
      event.preventDefault();
      const libraryUrlTokens = parseLibraryTokensFromUrl();
      if (!libraryUrlTokens) {
        if (
          collabAPI.isCollaborating() &&
          !isCollaborationLink(window.location.href)
        ) {
          collabAPI.stopCollaboration(false);
        }
        excalidrawAPI.updateScene({ appState: { isLoading: true } });

        initializeScene({ collabAPI, excalidrawAPI }).then((data) => {
          loadImages(data);
          if (data.scene) {
            excalidrawAPI.updateScene({
              ...data.scene,
              ...restore(data.scene, null, null),
              commitToHistory: true,
            });
          }
        });
      }
    };

    const titleTimeout = setTimeout(
      () => (document.title = APP_NAME),
      TITLE_TIMEOUT,
    );

    const syncData = debounce(() => {
      if (isTestEnv()) {
        return;
      }
      if (!document.hidden && !collabAPI.isCollaborating()) {
        // don't sync if local state is newer or identical to browser state
        if (isBrowserStorageStateNewer(STORAGE_KEYS.VERSION_DATA_STATE)) {
          const localDataState = importFromLocalStorage();
          const username = importUsernameFromLocalStorage();
          let langCode = languageDetector.detect() || defaultLang.code;
          if (Array.isArray(langCode)) {
            langCode = langCode[0];
          }
          setLangCode(langCode);
          excalidrawAPI.updateScene({
            ...localDataState,
          });
          excalidrawAPI.updateLibrary({
            libraryItems: getLibraryItemsFromStorage(),
          });
          collabAPI.setUsername(username || "");
        }

        if (isBrowserStorageStateNewer(STORAGE_KEYS.VERSION_FILES)) {
          const elements = excalidrawAPI.getSceneElementsIncludingDeleted();
          const currFiles = excalidrawAPI.getFiles();
          const fileIds =
            elements?.reduce((acc, element) => {
              if (
                isInitializedImageElement(element) &&
                // only load and update images that aren't already loaded
                !currFiles[element.fileId]
              ) {
                return acc.concat(element.fileId);
              }
              return acc;
            }, [] as FileId[]) || [];
          if (fileIds.length) {
            LocalData.fileStorage
              .getFiles(fileIds)
              .then(({ loadedFiles, erroredFiles }) => {
                if (loadedFiles.length) {
                  excalidrawAPI.addFiles(loadedFiles);
                }
                updateStaleImageStatuses({
                  excalidrawAPI,
                  erroredFiles,
                  elements: excalidrawAPI.getSceneElementsIncludingDeleted(),
                });
              });
          }
        }
      }
    }, SYNC_BROWSER_TABS_TIMEOUT);

    const onUnload = () => {
      LocalData.flushSave();
    };

    const visibilityChange = (event: FocusEvent | Event) => {
      if (event.type === EVENT.BLUR || document.hidden) {
        LocalData.flushSave();
      }
      if (
        event.type === EVENT.VISIBILITY_CHANGE ||
        event.type === EVENT.FOCUS
      ) {
        syncData();
      }
    };

    window.addEventListener(EVENT.HASHCHANGE, onHashChange, false);
    window.addEventListener(EVENT.UNLOAD, onUnload, false);
    window.addEventListener(EVENT.BLUR, visibilityChange, false);
    document.addEventListener(EVENT.VISIBILITY_CHANGE, visibilityChange, false);
    window.addEventListener(EVENT.FOCUS, visibilityChange, false);
    return () => {
      window.removeEventListener(EVENT.HASHCHANGE, onHashChange, false);
      window.removeEventListener(EVENT.UNLOAD, onUnload, false);
      window.removeEventListener(EVENT.BLUR, visibilityChange, false);
      window.removeEventListener(EVENT.FOCUS, visibilityChange, false);
      document.removeEventListener(
        EVENT.VISIBILITY_CHANGE,
        visibilityChange,
        false,
      );
      clearTimeout(titleTimeout);
    };
  }, [collabAPI, excalidrawAPI, setLangCode]);

  useEffect(() => {
    const unloadHandler = (event: BeforeUnloadEvent) => {
      LocalData.flushSave();

      if (
        excalidrawAPI &&
        LocalData.fileStorage.shouldPreventUnload(
          excalidrawAPI.getSceneElements(),
        )
      ) {
        preventUnload(event);
      }
    };
    window.addEventListener(EVENT.BEFORE_UNLOAD, unloadHandler);
    return () => {
      window.removeEventListener(EVENT.BEFORE_UNLOAD, unloadHandler);
    };
  }, [excalidrawAPI]);

  useEffect(() => {
    languageDetector.cacheUserLanguage(langCode);
  }, [langCode]);

  const [theme, setTheme] = useState<Theme>(
    () =>
      localStorage.getItem(STORAGE_KEYS.LOCAL_STORAGE_THEME) ||
      // FIXME migration from old LS scheme. Can be removed later. #5660
      importFromLocalStorage().appState?.theme ||
      THEME.LIGHT,
  );

  useEffect(() => {
    localStorage.setItem(STORAGE_KEYS.LOCAL_STORAGE_THEME, theme);
    // currently only used for body styling during init (see public/index.html),
    // but may change in the future
    document.documentElement.classList.toggle("dark", theme === THEME.DARK);
  }, [theme]);

  const onChange = (
    elements: readonly ExcalidrawElement[],
    appState: AppState,
    files: BinaryFiles,
  ) => {
    if (collabAPI?.isCollaborating()) {
      collabAPI.syncElements(elements);
    }

    setTheme(appState.theme);

    // this check is redundant, but since this is a hot path, it's best
    // not to evaludate the nested expression every time
    if (!LocalData.isSavePaused()) {
      LocalData.save(elements, appState, files, () => {
        if (excalidrawAPI) {
          let didChange = false;

          const elements = excalidrawAPI
            .getSceneElementsIncludingDeleted()
            .map((element) => {
              if (
                LocalData.fileStorage.shouldUpdateImageElementStatus(element)
              ) {
                const newElement = newElementWith(element, { status: "saved" });
                if (newElement !== element) {
                  didChange = true;
                }
                return newElement;
              }
              return element;
            });

          if (didChange) {
            excalidrawAPI.updateScene({
              elements,
            });
          }
        }
      });
    }
  };

  const onExportToBackend = async (
    exportedElements: readonly NonDeletedExcalidrawElement[],
    appState: AppState,
    files: BinaryFiles,
    canvas: HTMLCanvasElement | null,
  ) => {
    if (exportedElements.length === 0) {
      return window.alert(t("alerts.cannotExportEmptyCanvas"));
    }
    if (canvas) {
      try {
        await exportToBackend(
          exportedElements,
          {
            ...appState,
            viewBackgroundColor: appState.exportBackground
              ? appState.viewBackgroundColor
              : getDefaultAppState().viewBackgroundColor,
          },
          files,
        );
      } catch (error: any) {
        if (error.name !== "AbortError") {
          const { width, height } = canvas;
          console.error(error, { width, height });
          setErrorMessage(error.message);
        }
      }
    }
  };

  const renderCustomStats = (
    elements: readonly NonDeletedExcalidrawElement[],
    appState: AppState,
  ) => {
    return (
      <CustomStats
        setToast={(message) => excalidrawAPI!.setToast({ message })}
        appState={appState}
        elements={elements}
      />
    );
  };

  const onLibraryChange = async (items: LibraryItems) => {
    if (!items.length) {
      localStorage.removeItem(STORAGE_KEYS.LOCAL_STORAGE_LIBRARY);
      return;
    }
    const serializedItems = JSON.stringify(items);
    localStorage.setItem(STORAGE_KEYS.LOCAL_STORAGE_LIBRARY, serializedItems);
  };

  const renderMenu = () => {
    return (
      <MainMenu>
        <MainMenu.DefaultItems.LoadScene />
        <MainMenu.DefaultItems.SaveToActiveFile />
        <MainMenu.DefaultItems.Export />
        <MainMenu.DefaultItems.SaveAsImage />
        <MainMenu.DefaultItems.LiveCollaboration
          isCollaborating={isCollaborating}
          onSelect={() => setCollabDialogShown(true)}
        />

        <MainMenu.DefaultItems.Help />
        <MainMenu.DefaultItems.ClearCanvas />
        <MainMenu.Separator />
        <MainMenu.ItemLink
          icon={PlusPromoIcon}
          href="https://plus.excalidraw.com/plus?utm_source=excalidraw&utm_medium=app&utm_content=hamburger"
          className="ExcalidrawPlus"
        >
          Excalidraw+
        </MainMenu.ItemLink>
        <MainMenu.DefaultItems.Socials />
        <MainMenu.Separator />
        <MainMenu.DefaultItems.ToggleTheme />
        <MainMenu.ItemCustom>
          <LanguageList style={{ width: "100%" }} />
        </MainMenu.ItemCustom>
        <MainMenu.DefaultItems.ChangeCanvasBackground />
      </MainMenu>
    );
  };

  const welcomeScreenJSX = useMemo(() => {
    let headingContent;

    if (isExcalidrawPlusSignedUser) {
      headingContent = t("welcomeScreen.app.center_heading_plus")
        .split(/(Excalidraw\+)/)
        .map((bit, idx) => {
          if (bit === "Excalidraw+") {
            return (
              <a
                style={{ pointerEvents: "all" }}
                href={`${process.env.REACT_APP_PLUS_APP}?utm_source=excalidraw&utm_medium=app&utm_content=welcomeScreenSignedInUser`}
                key={idx}
              >
                Excalidraw+
              </a>
            );
          }
          return bit;
        });
    } else {
      headingContent = t("welcomeScreen.app.center_heading");
    }

    return (
      <WelcomeScreen>
        <WelcomeScreen.Hints.MenuHint>
          {t("welcomeScreen.app.menuHint")}
        </WelcomeScreen.Hints.MenuHint>
        <WelcomeScreen.Hints.ToolbarHint />
        <WelcomeScreen.Hints.HelpHint />
        <WelcomeScreen.Center>
          <WelcomeScreen.Center.Logo />
          <WelcomeScreen.Center.Heading>
            {headingContent}
          </WelcomeScreen.Center.Heading>
          <WelcomeScreen.Center.Menu>
            <WelcomeScreen.Center.MenuItemLoadScene />
            <WelcomeScreen.Center.MenuItemHelp />

            <WelcomeScreen.Center.MenuItem
              shortcut={null}
              onSelect={() => setCollabDialogShown(true)}
              icon={UsersIcon}
            >
              {t("labels.liveCollaboration")}
            </WelcomeScreen.Center.MenuItem>

            {!isExcalidrawPlusSignedUser && (
              <WelcomeScreen.Center.MenuItemLink
                href="https://plus.excalidraw.com/plus?utm_source=excalidraw&utm_medium=app&utm_content=welcomeScreenGuest"
                shortcut={null}
                icon={PlusPromoIcon}
              >
                Try Excalidraw Plus!
              </WelcomeScreen.Center.MenuItemLink>
            )}
          </WelcomeScreen.Center.Menu>
        </WelcomeScreen.Center>
      </WelcomeScreen>
    );
  }, [setCollabDialogShown]);

  return (
    <div
      style={{ height: "100%" }}
      className={clsx("excalidraw-app", {
        "is-collaborating": isCollaborating,
      })}
    >
      <Excalidraw
        ref={excalidrawRefCallback}
        onChange={onChange}
        initialData={initialStatePromiseRef.current.promise}
        onCollabButtonClick={() => setCollabDialogShown(true)}
        isCollaborating={isCollaborating}
        onPointerUpdate={collabAPI?.onPointerUpdate}
        UIOptions={{
          canvasActions: {
            toggleTheme: true,
            export: {
              onExportToBackend,
              renderCustomUI: (elements, appState, files) => {
                return (
                  <ExportToExcalidrawPlus
                    elements={elements}
                    appState={appState}
                    files={files}
                    onError={(error) => {
                      excalidrawAPI?.updateScene({
                        appState: {
                          errorMessage: error.message,
                        },
                      });
                    }}
                  />
                );
              },
            },
          },
        }}
        langCode={langCode}
        renderCustomStats={renderCustomStats}
        detectScroll={false}
        handleKeyboardGlobally={true}
        onLibraryChange={onLibraryChange}
        autoFocus={true}
        theme={theme}
      >
        {renderMenu()}
        <Footer>
          <div style={{ display: "flex", gap: ".5rem", alignItems: "center" }}>
            <ExcalidrawPlusAppLink />
            <EncryptedIcon />
          </div>
        </Footer>
        {welcomeScreenJSX}
      </Excalidraw>
      {excalidrawAPI && <Collab excalidrawAPI={excalidrawAPI} />}
      {errorMessage && (
        <ErrorDialog
          message={errorMessage}
          onClose={() => setErrorMessage("")}
        />
      )}
    </div>
  );
};

const ExcalidrawApp = () => {
  return (
    <TopErrorBoundary>
      <Provider unstable_createStore={() => jotaiStore}>
        <ExcalidrawWrapper />
      </Provider>
    </TopErrorBoundary>
  );
};

export default ExcalidrawApp;
