import type {
  CompletionContext,
  CompletionResult,
} from "@codemirror/autocomplete";
import type { Compartment } from "@codemirror/state";
import { EditorView } from "@codemirror/view";
import { syntaxTree } from "@codemirror/language";
import { compile as gitIgnoreCompiler } from "gitignore-parser";
import type { SyntaxNode } from "@lezer/common";
import { Space } from "../common/space.ts";
import type { FilterOption } from "@silverbulletmd/silverbullet/type/client";
import { EventHook } from "../common/hooks/event.ts";
import type { AppCommand } from "$lib/command.ts";
import {
  type PageState,
  parsePageRefFromURI,
  PathPageNavigator,
} from "./navigator.ts";

import type { AppViewState } from "./type.ts";

import type {
  AppEvent,
  CompleteEvent,
  SlashCompletions,
} from "../plug-api/types.ts";
import type { StyleObject } from "../plugs/index/style.ts";
import { throttle } from "$lib/async.ts";
import { PlugSpacePrimitives } from "$common/spaces/plug_space_primitives.ts";
import { EventedSpacePrimitives } from "$common/spaces/evented_space_primitives.ts";
import {
  type ISyncService,
  NoSyncSyncService,
  pageSyncInterval,
  SyncService,
} from "./sync_service.ts";
import { simpleHash } from "$lib/crypto.ts";
import type { SyncStatus } from "$common/spaces/sync.ts";
import { HttpSpacePrimitives } from "$common/spaces/http_space_primitives.ts";
import { FallbackSpacePrimitives } from "$common/spaces/fallback_space_primitives.ts";
import { FilteredSpacePrimitives } from "$common/spaces/filtered_space_primitives.ts";
import {
  encodePageRef,
  encodePageURI,
  validatePageName,
} from "@silverbulletmd/silverbullet/lib/page_ref";
import { ClientSystem } from "./client_system.ts";
import { createEditorState } from "./editor_state.ts";
import { MainUI } from "./editor_ui.tsx";
import { cleanPageRef } from "@silverbulletmd/silverbullet/lib/resolve";
import type { SpacePrimitives } from "$common/spaces/space_primitives.ts";
import type {
  CodeWidgetButton,
  FileMeta,
  PageMeta,
} from "../plug-api/types.ts";
import { DataStore } from "$lib/data/datastore.ts";
import { IndexedDBKvPrimitives } from "$lib/data/indexeddb_kv_primitives.ts";
import { DataStoreMQ } from "$lib/data/mq.datastore.ts";
import { DataStoreSpacePrimitives } from "$common/spaces/datastore_space_primitives.ts";

import { ensureSpaceIndex } from "$common/space_index.ts";
import { renderTheTemplate } from "$common/syscalls/template.ts";
import type { PageRef } from "../plug-api/lib/page_ref.ts";
import { ReadOnlySpacePrimitives } from "$common/spaces/ro_space_primitives.ts";
import type { KvPrimitives } from "$lib/data/kv_primitives.ts";
import { builtinFunctions } from "$lib/builtin_query_functions.ts";
import {
  ensureAndLoadSettingsAndIndex,
  updateObjectDecorators,
} from "../common/config.ts";
import { LimitedMap } from "$lib/limited_map.ts";
import { plugPrefix } from "$common/spaces/constants.ts";
import { lezerToParseTree } from "$common/markdown_parser/parse_tree.ts";
import { findNodeMatching } from "@silverbulletmd/silverbullet/lib/tree";
import type { AspiringPageObject } from "../plugs/index/page_links.ts";
import type { Config, ConfigContainer } from "../type/config.ts";
import { editor } from "@silverbulletmd/silverbullet/syscalls";

const frontMatterRegex = /^---\n(([^\n]|\n)*?)---\n/;

const autoSaveInterval = 1000;

declare global {
  // deno-lint-ignore no-var
  var silverBulletConfig: {
    spaceFolderPath: string;
    syncOnly: boolean;
    readOnly: boolean;
    enableSpaceScript: boolean;
  };
  // deno-lint-ignore no-var
  var client: Client;
}

type WidgetCacheItem = {
  height: number;
  html: string;
  buttons?: CodeWidgetButton[];
  banner?: string;
};

export class Client implements ConfigContainer {
  // Event bus used to communicate between components
  eventHook = new EventHook();

  space!: Space;
  config!: Config;

  clientSystem!: ClientSystem;
  plugSpaceRemotePrimitives!: PlugSpacePrimitives;
  httpSpacePrimitives!: HttpSpacePrimitives;

  ui!: MainUI;
  stateDataStore!: DataStore;
  spaceKV?: KvPrimitives;
  mq!: DataStoreMQ;

  // CodeMirror editor
  editorView!: EditorView;
  keyHandlerCompartment?: Compartment;

  private pageNavigator!: PathPageNavigator;

  private dbPrefix: string;

  saveTimeout?: number;
  debouncedUpdateEvent = throttle(() => {
    this.eventHook
      .dispatchEvent("editor:updated")
      .catch((e) => console.error("Error dispatching editor:updated event", e));
  }, 1000);

  // Sync related stuff
  // Track if plugs have been updated since sync cycle
  fullSyncCompleted = false;
  syncService!: ISyncService;

  private onLoadPageRef: PageRef;

  constructor(
    private parent: Element,
    public syncMode: boolean,
    private readOnlyMode: boolean,
  ) {
    if (!syncMode) {
      this.fullSyncCompleted = true;
    }
    // Generate a semi-unique prefix for the database so not to reuse databases for different space paths
    this.dbPrefix = "" + simpleHash(window.silverBulletConfig.spaceFolderPath);
    this.onLoadPageRef = parsePageRefFromURI();
  }

  /**
   * Initialize the client
   * This is a separated from the constructor to allow for async initialization
   */
  async init() {
    // Setup the state data store
    const stateKvPrimitives = new IndexedDBKvPrimitives(
      `${this.dbPrefix}_state`,
    );
    await stateKvPrimitives.init();
    this.stateDataStore = new DataStore(stateKvPrimitives);

    // Setup message queue
    this.mq = new DataStoreMQ(this.stateDataStore);

    // Instantiate a PlugOS system
    this.clientSystem = new ClientSystem(
      this,
      this.mq,
      this.stateDataStore,
      this.eventHook,
      this.readOnlyMode,
    );

    const localSpacePrimitives = await this.initSpace();

    this.syncService = this.syncMode
      ? new SyncService(
        localSpacePrimitives,
        this.plugSpaceRemotePrimitives,
        this.stateDataStore,
        this.eventHook,
        (path) => { // isSyncCandidate
          // Exclude all plug space primitives paths
          return !this.plugSpaceRemotePrimitives.isLikelyHandled(path) ||
            // Except federated ones
            path.startsWith("!");
        },
      )
      : new NoSyncSyncService(this.space);

    this.ui = new MainUI(this);
    this.ui.render(this.parent);

    this.editorView = new EditorView({
      state: createEditorState(this, "", "", false),
      parent: document.getElementById("sb-editor")!,
    });

    this.focus();

    this.clientSystem.init();

    await this.loadCaches();

    // Let's ping the remote space to ensure we're authenticated properly, if not will result in a redirect to auth page
    try {
      await this.httpSpacePrimitives.ping();
    } catch (e: any) {
      if (e.message === "Not authenticated") {
        console.warn("Not authenticated, redirecting to auth page");
        return;
      }
      if (e.message.includes("Offline") && !this.syncMode) {
        // Offline and not in sync mode, this is not going to fly.
        this.flashNotification(
          "Could not reach remote server, going to reload in a few seconds",
          "error",
        );
        setTimeout(() => {
          location.reload();
        }, 5000);
        throw e;
      }
      console.warn(
        "Could not reach remote server, we're offline or the server is down",
        e,
      );
    }

    // Load plugs
    await this.loadPlugs();

    // Load config (after the plugs, specifically the 'index' plug is loaded)
    await this.loadConfig();

    await this.clientSystem.loadSpaceScripts();

    await this.initNavigator();
    await this.initSync();

    // We can load custom styles async
    this.loadCustomStyles().catch(console.error);

    await this.dispatchAppEvent("editor:init");

    // Regularly sync the currently open file
    setInterval(() => {
      try {
        this.syncService.syncFile(`${this.currentPage}.md`).catch((e: any) => {
          console.error("Interval sync error", e);
        });
      } catch (e: any) {
        console.error("Interval sync error", e);
      }
    }, pageSyncInterval);

    // Let's update the local page list cache asynchronously
    this.updatePageListCache().catch(console.error);
  }

  async loadConfig() {
    this.config = await ensureAndLoadSettingsAndIndex(
      this.space.spacePrimitives,
      this.clientSystem.system,
    );
    updateObjectDecorators(this.config, this.stateDataStore);
    this.ui.viewDispatch({
      type: "config-loaded",
      config: this.config,
    });
    this.clientSystem.slashCommandHook.buildAllCommands(
      this.clientSystem.system,
    );
    this.eventHook.dispatchEvent("config:loaded", this.config);
  }

  private async initSync() {
    this.syncService.start();

    // We're still booting, if a initial sync has already been completed we know this is the initial sync
    let initialSync = !await this.syncService.hasInitialSyncCompleted();

    this.eventHook.addLocalListener("sync:success", async (operations) => {
      if (operations > 0) {
        // Update the page list
        await this.space.updatePageList();
      }
      if (operations !== undefined) {
        // "sync:success" is called with a number of operations only from syncSpace(), not from syncing individual pages
        this.fullSyncCompleted = true;

        console.log("Full sync completed");

        // A full sync just completed
        if (!initialSync) {
          // If this was NOT the initial sync let's check if we need to perform a space reindex
          ensureSpaceIndex(this.stateDataStore, this.clientSystem.system).catch(
            console.error,
          );
        } else { // initialSync
          // Let's load space scripts again, which probably weren't loaded before
          await this.clientSystem.loadSpaceScripts();
          console.log(
            "Initial sync completed, now need to do a full space index to ensure all pages are indexed using any custom space script indexers",
          );
          ensureSpaceIndex(this.stateDataStore, this.clientSystem.system).catch(
            console.error,
          );
          initialSync = false;
        }
      }
      if (operations) {
        // Likely initial sync so let's show visually that we're synced now
        this.showProgress(100);
      }

      this.ui.viewDispatch({ type: "sync-change", syncSuccess: true });
    });

    this.eventHook.addLocalListener("sync:error", (_name) => {
      this.ui.viewDispatch({ type: "sync-change", syncSuccess: false });
    });

    this.eventHook.addLocalListener("sync:conflict", (name) => {
      this.flashNotification(
        `Sync: conflict detected for ${name} - conflict copy created`,
        "error",
      );
    });

    this.eventHook.addLocalListener("sync:progress", (status: SyncStatus) => {
      this.showProgress(
        Math.round(status.filesProcessed / status.totalFiles * 100),
      );
    });

    this.eventHook.addLocalListener(
      "file:synced",
      (meta: FileMeta, direction: string) => {
        if (meta.name.endsWith(".md") && direction === "secondary->primary") {
          // We likely polled the currently open page which trigggered a local update, let's update the editor accordingly
          this.space.getPageMeta(meta.name.slice(0, -3));
        }
      },
    );
  }

  private navigateWithinPage(pageState: PageState) {
    // Did we end up doing anything in terms of internal navigation?
    let adjustedPosition = false;

    // Was a particular scroll position persisted?
    if (
      pageState.scrollTop !== undefined &&
      !(pageState.scrollTop === 0 &&
        (pageState.pos !== undefined || pageState.anchor !== undefined ||
          pageState.header !== undefined))
    ) {
      setTimeout(() => {
        this.editorView.scrollDOM.scrollTop = pageState.scrollTop!;
      });
      adjustedPosition = true;
    }

    // Was a particular cursor/selection set?
    if (
      pageState.selection?.anchor && !pageState.pos && !pageState.anchor &&
      !pageState.header
    ) { // Only do this if we got a specific cursor position
      console.log("Changing cursor position to", pageState.selection);
      this.editorView.dispatch({
        selection: pageState.selection,
      });
      adjustedPosition = true;
    }

    // Was there a pos or anchor set?
    let pos: number | { line: number; column: number } | undefined =
      pageState.pos;
    if (pageState.anchor) {
      console.log("Navigating to anchor", pageState.anchor);
      const pageText = this.editorView.state.sliceDoc();

      const sTree = syntaxTree(this.editorView.state);
      const tree = lezerToParseTree(pageText, sTree.topNode);

      const foundNode = findNodeMatching(tree, (node) => {
        if (
          node.type === "NamedAnchor" &&
          node.children![0].text === `$${pageState.anchor}`
        ) {
          return true;
        }
        return false;
      });

      if (!foundNode) {
        return this.flashNotification(
          `Could not find anchor $${pageState.anchor}`,
          "error",
        );
      } else {
        pos = foundNode.from;
      }

      adjustedPosition = true;
    }
    if (pageState.header) {
      console.log("Navigating to header", pageState.header);
      const pageText = this.editorView.state.sliceDoc();

      // This is somewhat of a simplistic way to find the header, but it works for now
      pos = pageText.indexOf(`# ${pageState.header}\n`) + 2;

      if (pos === -1) {
        return this.flashNotification(
          `Could not find header "${pageState.header}"`,
          "error",
        );
      }

      adjustedPosition = true;
    }
    if (pos !== undefined) {
      // Translate line and column number to position in text
      if (pos instanceof Object) {
        // CodeMirror already keeps information about lines
        const cmLine = this.editorView.state.doc.line(pos.line);
        // How much to move inside the line, column number starts from 1
        const offset = Math.max(0, Math.min(cmLine.length, pos.column - 1));
        pos = cmLine.from + offset;
      }

      this.editorView.dispatch({
        selection: { anchor: pos! },
        effects: EditorView.scrollIntoView(pos!, {
          y: "start",
          yMargin: 5,
        }),
      });
      adjustedPosition = true;
    }

    // If not: just put the cursor at the top of the page, right after the frontmatter
    if (!adjustedPosition) {
      // Somewhat ad-hoc way to determine if the document contains frontmatter and if so, putting the cursor _after it_.
      const pageText = this.editorView.state.sliceDoc();

      // Default the cursor to be at position 0
      let initialCursorPos = 0;
      const match = frontMatterRegex.exec(pageText);
      if (match) {
        // Frontmatter found, put cursor after it
        initialCursorPos = match[0].length;
      }
      // By default scroll to the top
      this.editorView.scrollDOM.scrollTop = 0;
      this.editorView.dispatch({
        selection: { anchor: initialCursorPos },
        // And then scroll down if required
        scrollIntoView: true,
      });
    }
  }

  private async initNavigator() {
    this.pageNavigator = new PathPageNavigator(this);

    await this.pageNavigator.init();

    this.pageNavigator.subscribe(async (pageState) => {
      console.log("Now navigating to", pageState);

      await this.loadPage(pageState.page);

      // Setup scroll position, cursor position, etc
      this.navigateWithinPage(pageState);

      // Persist this page as the last opened page, we'll use this for cold start PWA loads
      await this.stateDataStore.set(
        ["client", "lastOpenedPage"],
        pageState.page,
      );
    });

    if (location.hash === "#boot" && this.config.pwaOpenLastPage !== false) {
      // Cold start PWA load
      const lastPage = await this.stateDataStore.get([
        "client",
        "lastOpenedPage",
      ]);
      if (lastPage) {
        console.log("Navigating to last opened page", lastPage);
        await this.navigate({ page: lastPage });
      }
    }
  }

  async initSpace(): Promise<SpacePrimitives> {
    this.httpSpacePrimitives = new HttpSpacePrimitives(
      location.origin,
      window.silverBulletConfig.spaceFolderPath,
    );

    let remoteSpacePrimitives: SpacePrimitives = this.httpSpacePrimitives;

    if (this.readOnlyMode) {
      remoteSpacePrimitives = new ReadOnlySpacePrimitives(
        remoteSpacePrimitives,
      );
    }

    this.plugSpaceRemotePrimitives = new PlugSpacePrimitives(
      remoteSpacePrimitives,
      this.clientSystem.namespaceHook,
      this.syncMode ? undefined : "client",
    );

    let fileFilterFn: (s: string) => boolean = () => true;

    let localSpacePrimitives: SpacePrimitives | undefined;

    if (this.syncMode) {
      // We'll store the space files in a separate data store
      const spaceKvPrimitives = new IndexedDBKvPrimitives(
        `${this.dbPrefix}_synced_space`,
      );
      await spaceKvPrimitives.init();

      this.spaceKV = spaceKvPrimitives;

      localSpacePrimitives = new FilteredSpacePrimitives(
        new EventedSpacePrimitives(
          // Using fallback space primitives here to allow (by default) local reads to "fall through" to HTTP when files aren't synced yet
          new FallbackSpacePrimitives(
            new DataStoreSpacePrimitives(
              new DataStore(
                spaceKvPrimitives,
                {},
              ),
            ),
            this.plugSpaceRemotePrimitives,
          ),
          this.eventHook,
        ),
        (meta) => fileFilterFn(meta.name),
        // Run when a list of files has been retrieved
        async () => {
          if (!this.config) {
            await this.loadConfig();
          }

          if (typeof this.config?.spaceIgnore === "string") {
            fileFilterFn = gitIgnoreCompiler(this.config.spaceIgnore).accepts;
          } else {
            fileFilterFn = () => true;
          }
        },
      );
    } else {
      localSpacePrimitives = new EventedSpacePrimitives(
        this.plugSpaceRemotePrimitives,
        this.eventHook,
      );
    }

    this.space = new Space(
      localSpacePrimitives,
      this.eventHook,
    );

    let lastSaveTimestamp: number | undefined;

    this.eventHook.addLocalListener("editor:pageSaving", () => {
      lastSaveTimestamp = Date.now();
    });

    this.eventHook.addLocalListener(
      "file:changed",
      (
        path: string,
        _localChange: boolean,
        oldHash: number,
        newHash: number,
      ) => {
        // Only reload when watching the current page (to avoid reloading when switching pages)
        if (
          this.space.watchInterval && `${this.currentPage}.md` === path &&
          // Avoid reloading if the page was just saved (5s window)
          (!lastSaveTimestamp || (lastSaveTimestamp < Date.now() - 5000))
        ) {
          console.log(
            "Page changed elsewhere, reloading. Old hash",
            oldHash,
            "new hash",
            newHash,
          );
          console.log(
            "Last save timestamp",
            lastSaveTimestamp,
            "now",
            Date.now(),
          );
          this.flashNotification("Page changed elsewhere, reloading");
          this.reloadPage();
        }
      },
    );

    // Caching a list of known files for the wiki_link highlighter (that checks if a file exists)
    // And keeping it up to date as we go
    this.eventHook.addLocalListener("file:changed", (fileName: string) => {
      // Make sure this file is in the list of known pages
      this.clientSystem.allKnownFiles.add(fileName);
    });
    this.eventHook.addLocalListener("file:deleted", (fileName: string) => {
      this.clientSystem.allKnownFiles.delete(fileName);
    });
    this.eventHook.addLocalListener(
      "file:listed",
      (allFiles: FileMeta[]) => {
        // Update list of known pages
        this.clientSystem.allKnownFiles.clear();
        allFiles.forEach((f) => {
          if (!f.name.startsWith(plugPrefix)) {
            this.clientSystem.allKnownFiles.add(f.name);
          }
        });
      },
    );

    this.space.watch();

    return localSpacePrimitives;
  }

  get currentPage(): string {
    return this.ui.viewState.currentPage !== undefined
      ? this.ui.viewState.currentPage
      : this.onLoadPageRef.page; // best effort
  }

  dispatchAppEvent(name: AppEvent, ...args: any[]): Promise<any[]> {
    return this.eventHook.dispatchEvent(name, ...args);
  }

  // Save the current page
  save(immediate = false): Promise<void> {
    return new Promise((resolve, reject) => {
      if (this.saveTimeout) {
        clearTimeout(this.saveTimeout);
      }
      this.saveTimeout = setTimeout(
        () => {
          if (this.currentPage) {
            if (
              !this.ui.viewState.unsavedChanges ||
              this.ui.viewState.uiOptions.forcedROMode
            ) {
              // No unsaved changes, or read-only mode, not gonna save
              return resolve();
            }
            console.log("Saving page", this.currentPage);
            this.dispatchAppEvent(
              "editor:pageSaving",
              this.currentPage,
            );
            this.space
              .writePage(
                this.currentPage,
                this.editorView.state.sliceDoc(0),
                true,
              )
              .then(async (meta) => {
                this.ui.viewDispatch({ type: "page-saved" });
                await this.dispatchAppEvent(
                  "editor:pageSaved",
                  this.currentPage,
                  meta,
                );

                // At this all the essential stuff is done, let's proceed
                resolve();

                // In the background we'll fetch any enriched meta data, if any
                const enrichedMeta = await this.clientSystem.getObjectByRef<
                  PageMeta
                >(
                  this.currentPage,
                  "page",
                  this.currentPage,
                );
                if (enrichedMeta) {
                  this.ui.viewDispatch({
                    type: "update-current-page-meta",
                    meta: enrichedMeta,
                  });
                }
              })
              .catch((e) => {
                this.flashNotification(
                  "Could not save page, retrying again in 10 seconds",
                  "error",
                );
                this.saveTimeout = setTimeout(this.save.bind(this), 10000);
                reject(e);
              });
          } else {
            resolve();
          }
        },
        immediate ? 0 : autoSaveInterval,
      );
    });
  }

  flashNotification(message: string, type: "info" | "error" = "info") {
    const id = Math.floor(Math.random() * 1000000);
    this.ui.viewDispatch({
      type: "show-notification",
      notification: {
        id,
        type,
        message,
        date: new Date(),
      },
    });
    setTimeout(
      () => {
        this.ui.viewDispatch({
          type: "dismiss-notification",
          id: id,
        });
      },
      type === "info" ? 4000 : 5000,
    );
  }

  startPageNavigate(mode: "page" | "meta" | "all") {
    // Then show the page navigator
    this.ui.viewDispatch({ type: "start-navigate", mode });
    // And update the page list cache asynchronously
    this.updatePageListCache().catch(console.error);
  }

  async updatePageListCache() {
    console.log("Updating page list cache");
    if (!this.clientSystem.system.loadedPlugs.has("index")) {
      console.warn("Index plug not loaded, cannot update page list cache");
      return;
    }
    const allPages = await this.clientSystem.queryObjects<PageMeta>("page", {});
    const allAspiringPages = (await this.clientSystem.queryObjects<
      AspiringPageObject
    >("aspiring-page", {
      select: [{ name: "name" }],
    })).map((aspiringPage): PageMeta => ({
      ref: aspiringPage.name,
      tag: "page",
      _isAspiring: true,
      name: aspiringPage.name,
      created: "",
      lastModified: "",
      perm: "rw",
    }));

    this.ui.viewDispatch({
      type: "update-page-list",
      allPages: allPages.concat(allAspiringPages),
    });
  }

  // Progress circle handling
  private progressTimeout?: number;

  showProgress(progressPerc: number) {
    this.ui.viewDispatch({
      type: "set-progress",
      progressPerc,
    });
    if (this.progressTimeout) {
      clearTimeout(this.progressTimeout);
    }
    this.progressTimeout = setTimeout(
      () => {
        this.ui.viewDispatch({
          type: "set-progress",
        });
      },
      10000,
    );
  }

  // Various UI elements
  filterBox(
    label: string,
    options: FilterOption[],
    helpText = "",
    placeHolder = "",
  ): Promise<FilterOption | undefined> {
    return new Promise((resolve) => {
      this.ui.viewDispatch({
        type: "show-filterbox",
        label,
        options,
        placeHolder,
        helpText,
        onSelect: (option: any) => {
          this.ui.viewDispatch({ type: "hide-filterbox" });
          this.focus();
          resolve(option);
        },
      });
    });
  }

  prompt(
    message: string,
    defaultValue = "",
  ): Promise<string | undefined> {
    return new Promise((resolve) => {
      this.ui.viewDispatch({
        type: "show-prompt",
        message,
        defaultValue,
        callback: (value: string | undefined) => {
          this.ui.viewDispatch({ type: "hide-prompt" });
          this.focus();
          resolve(value);
        },
      });
    });
  }

  confirm(
    message: string,
  ): Promise<boolean> {
    return new Promise((resolve) => {
      this.ui.viewDispatch({
        type: "show-confirm",
        message,
        callback: (value: boolean) => {
          this.ui.viewDispatch({ type: "hide-confirm" });
          this.focus();
          resolve(value);
        },
      });
    });
  }

  async loadPlugs() {
    await this.clientSystem.reloadPlugsFromSpace(this.space);
    await this.eventHook.dispatchEvent("system:ready");
    await this.dispatchAppEvent("plugs:loaded");
  }

  rebuildEditorState() {
    const editorView = this.editorView;
    console.log("Rebuilding editor state");

    if (this.currentPage) {
      editorView.setState(
        createEditorState(
          this,
          this.currentPage,
          editorView.state.sliceDoc(),
          this.ui.viewState.currentPageMeta?.perm === "ro",
        ),
      );
      if (editorView.contentDOM) {
        this.tweakEditorDOM(
          editorView.contentDOM,
        );
      }
    }
  }

  // Code completion support
  async completeWithEvent(
    context: CompletionContext,
    eventName: AppEvent,
  ): Promise<CompletionResult | SlashCompletions | null> {
    const editorState = context.state;
    const selection = editorState.selection.main;
    const line = editorState.doc.lineAt(selection.from);
    const linePrefix = line.text.slice(0, selection.from - line.from);

    // Build up list of parent nodes, some completions need this
    const parentNodes: string[] = [];
    const sTree = syntaxTree(editorState);
    const currentNode = sTree.resolveInner(selection.from);
    if (currentNode) {
      let node: SyntaxNode | null = currentNode;
      do {
        if (node.name === "FencedCode" || node.name === "FrontMatter") {
          const body = editorState.sliceDoc(node.from + 3, node.to - 3);
          parentNodes.push(`${node.name}:${body}`);
        } else {
          parentNodes.push(node.name);
        }
        node = node.parent;
      } while (node);
    }

    // Dispatch the event
    const results = await this.dispatchAppEvent(eventName, {
      pageName: this.currentPage,
      linePrefix,
      pos: selection.from,
      parentNodes,
    } as CompleteEvent);

    // Merge results
    let currentResult: CompletionResult | null = null;
    for (const result of results) {
      if (!result) {
        continue;
      }
      if (currentResult) {
        // Let's see if we can merge results
        if (currentResult.from !== result.from) {
          console.error(
            "Got completion results from multiple sources with different `from` locators, cannot deal with that",
          );
          console.error(
            "Previously had",
            currentResult,
            "now also got",
            result,
          );
          return null;
        } else {
          // Merge
          currentResult = {
            from: result.from,
            options: [...currentResult.options, ...result.options],
          };
        }
      } else {
        currentResult = result;
      }
    }
    return currentResult;
  }

  editorComplete(
    context: CompletionContext,
  ): Promise<CompletionResult | null> {
    return this.completeWithEvent(context, "editor:complete") as Promise<
      CompletionResult | null
    >;
  }

  miniEditorComplete(
    context: CompletionContext,
  ): Promise<CompletionResult | null> {
    return this.completeWithEvent(context, "minieditor:complete") as Promise<
      CompletionResult | null
    >;
  }

  async reloadPage() {
    console.log("Reloading page");
    clearTimeout(this.saveTimeout);
    await this.loadPage(this.currentPage);
  }

  // Focus the editor
  focus() {
    const viewState = this.ui.viewState;
    if (
      [
        viewState.showCommandPalette,
        viewState.showPageNavigator,
        viewState.showFilterBox,
        viewState.showConfirm,
        viewState.showPrompt,
      ].some(Boolean)
    ) {
      // console.log("not focusing");
      // Some other modal UI element is visible, don't focus editor now
      return;
    }
    this.editorView.focus();
  }

  async navigate(
    pageRef: PageRef,
    replaceState = false,
    newWindow = false,
  ) {
    if (!pageRef.page) {
      pageRef.page = cleanPageRef(
        await renderTheTemplate(
          this.config.indexPage,
          {},
          {},
          builtinFunctions,
        ),
      );
    }

    try {
      validatePageName(pageRef.page);
    } catch (e: any) {
      return this.flashNotification(e.message, "error");
    }

    if (newWindow) {
      console.log(
        "Navigating to new page in new window",
        `${location.origin}/${encodePageURI(encodePageRef(pageRef))}`,
      );
      const win = globalThis.open(
        `${location.origin}/${encodePageURI(encodePageRef(pageRef))}`,
        "_blank",
      );
      if (win) {
        win.focus();
      }
      return;
    }

    await this.pageNavigator!.navigate(
      pageRef,
      replaceState,
    );
    this.focus();
  }

  async loadPage(pageName: string) {
    const loadingDifferentPage = pageName !== this.currentPage;
    const editorView = this.editorView;
    const previousPage = this.currentPage;

    // Persist current page state and nicely close page
    if (previousPage) {
      // this.openPages.saveState(previousPage);
      this.space.unwatchPage(previousPage);
      if (previousPage !== pageName) {
        await this.save(true);
      }
    }

    this.ui.viewDispatch({
      type: "page-loading",
      name: pageName,
    });

    // Fetch next page to open
    let doc;
    try {
      doc = await this.space.readPage(pageName);
    } catch (e: any) {
      if (e.message.includes("Not found")) {
        // Not found, new page
        console.log("Page doesn't exist, creating new page:", pageName);
        // Initialize page
        doc = {
          text: "",
          meta: {
            ref: pageName,
            tags: ["page"],
            name: pageName,
            lastModified: "",
            created: "",
            perm: "rw",
          } as PageMeta,
        };
        // Create new page based on a template
        this.clientSystem.system.invokeFunction("template.newPage", [pageName])
          .then(
            () => {
              this.focus();
            },
          ).catch(
            console.error,
          );
      } else {
        this.flashNotification(
          `Could not load page ${pageName}: ${e.message}`,
          "error",
        );
        if (previousPage) {
          this.ui.viewDispatch({
            type: "page-loading",
            name: previousPage,
          });
        }

        return false;
      }
    }

    this.ui.viewDispatch({
      type: "page-loaded",
      meta: doc.meta,
    });

    // Fetch (possibly) enriched meta data asynchronously
    this.clientSystem.getObjectByRef<
      PageMeta
    >(
      this.currentPage,
      "page",
      this.currentPage,
    ).then((enrichedMeta) => {
      if (!enrichedMeta) {
        // Nothing in the store, revert to default
        enrichedMeta = doc.meta;
      }

      const bodyEl = this.parent.parentElement;
      if (bodyEl) {
        bodyEl.removeAttribute("class");
        if (enrichedMeta.pageDecoration?.cssClasses) {
          bodyEl.className = enrichedMeta.pageDecoration.cssClasses.join(" ")
            .replaceAll(/[^a-zA-Z0-9-_ ]/g, "");
        }
      }
      this.ui.viewDispatch({
        type: "update-current-page-meta",
        meta: enrichedMeta,
      });
    }).catch(console.error);

    // When loading a different page OR if the page is read-only (in which case we don't want to apply local patches, because there's no point)
    if (loadingDifferentPage || doc.meta.perm === "ro") {
      const editorState = createEditorState(
        this,
        pageName,
        doc.text,
        doc.meta.perm === "ro",
      );
      editorView.setState(editorState);
      if (editorView.contentDOM) {
        this.tweakEditorDOM(editorView.contentDOM);
      }
      this.space.watchPage(pageName);
    } else {
      // Just apply minimal patches so that the cursor is preserved
      await editor.setText(doc.text);
    }

    // Note: these events are dispatched asynchronously deliberately (not waiting for results)
    if (loadingDifferentPage) {
      this.eventHook.dispatchEvent("editor:pageLoaded", pageName, previousPage)
        .catch(
          console.error,
        );
    } else {
      this.eventHook.dispatchEvent("editor:pageReloaded", pageName).catch(
        console.error,
      );
    }
  }

  tweakEditorDOM(contentDOM: HTMLElement) {
    contentDOM.spellcheck = true;
    contentDOM.setAttribute("autocorrect", "on");
    contentDOM.setAttribute("autocapitalize", "on");
  }

  async loadCustomStyles() {
    const spaceStyles = await this.clientSystem.queryObjects<StyleObject>(
      "space-style",
      {},
    );
    if (!spaceStyles) {
      return;
    }

    // Sort stylesheets (last declared styles take precedence)
    // Order is 1: Imported styles, 2: Other styles, 3: customStyles from Settings
    const sortOrder = ["library", "user", "config"];
    spaceStyles.sort((a, b) =>
      sortOrder.indexOf(a.origin) - sortOrder.indexOf(b.origin)
    );

    const accumulatedCSS: string[] = [];
    for (const s of spaceStyles) {
      accumulatedCSS.push(s.style);
    }
    const customStylesContent = accumulatedCSS.join("\n\n");
    this.ui.viewDispatch({
      type: "set-ui-option",
      key: "customStyles",
      value: customStylesContent,
    });
    document.getElementById("custom-styles")!.innerHTML = customStylesContent;
  }

  async runCommandByName(name: string, args?: any[]) {
    const cmd = this.ui.viewState.commands.get(name);
    if (cmd) {
      if (args) {
        await cmd.run(args);
      } else {
        await cmd.run();
      }
    } else {
      throw new Error(`Command ${name} not found`);
    }
  }

  getCommandsByContext(
    state: AppViewState,
  ): Map<string, AppCommand> {
    const commands = new Map(state.commands);
    for (const [k, v] of state.commands.entries()) {
      if (
        v.command.contexts &&
        (!state.showCommandPaletteContext ||
          !v.command.contexts.includes(state.showCommandPaletteContext))
      ) {
        commands.delete(k);
      }
    }

    return commands;
  }

  getContext(): string | undefined {
    const state = this.editorView.state;
    const selection = state.selection.main;
    if (selection.empty) {
      return syntaxTree(state).resolveInner(selection.from).type.name;
    }
    return;
  }

  // Widget and image height caching
  private widgetCache = new LimitedMap<WidgetCacheItem>(100); // bodyText -> WidgetCacheItem
  private widgetHeightCache = new LimitedMap<number>(100); // bodytext -> height

  async loadCaches() {
    const [widgetHeightCache, widgetCache] = await this
      .stateDataStore.batchGet([[
        "cache",
        "widgetHeight",
      ], ["cache", "widgets"]]);
    this.widgetHeightCache = new LimitedMap(100, widgetHeightCache || {});
    this.widgetCache = new LimitedMap(100, widgetCache || {});
  }

  debouncedWidgetHeightCacheFlush = throttle(() => {
    this.stateDataStore.set(
      ["cache", "widgetHeight"],
      this.widgetHeightCache.toJSON(),
    )
      .catch(
        console.error,
      );
    // console.log("Flushed widget height cache to store");
  }, 2000);

  setCachedWidgetHeight(bodyText: string, height: number) {
    this.widgetHeightCache.set(bodyText, height);
    this.debouncedWidgetHeightCacheFlush();
  }
  getCachedWidgetHeight(bodyText: string): number {
    return this.widgetHeightCache.get(bodyText) ?? -1;
  }

  debouncedWidgetCacheFlush = throttle(() => {
    this.stateDataStore.set(["cache", "widgets"], this.widgetCache.toJSON())
      .catch(
        console.error,
      );
    console.log("Flushed widget cache to store");
  }, 2000);

  setWidgetCache(key: string, cacheItem: WidgetCacheItem) {
    this.widgetCache.set(key, cacheItem);
    this.debouncedWidgetCacheFlush();
  }

  getWidgetCache(key: string): WidgetCacheItem | undefined {
    return this.widgetCache.get(key);
  }
}