Add some classes to handle file events

src/events/handler.ts

@@ -0,0 +1,97 @@
+import { Vault, TAbstractFile } from "obsidian";
+import { Event } from "./types";
+import MetadataStore from "../metadata-store";
+import EventsQueue from "./queue";
+
+/**
+ * Tracks changes to local sync directory and updates files metadata.
+ */
+export default class EventsHandler {
+  private eventsQueue: EventsQueue = new EventsQueue();
+
+  constructor(
+    private vault: Vault,
+    private metadataStore: MetadataStore,
+    private localContentDir: string,
+    private repoContentDir: string,
+  ) {
+    this.vault.on("create", this.onCreate.bind(this));
+    this.vault.on("delete", this.onDelete.bind(this));
+    this.vault.on("modify", this.onModify.bind(this));
+    this.vault.on("rename", this.onRename.bind(this));
+  }
+
+  private async onCreate(file: TAbstractFile) {
+    if (!file.path.startsWith(this.localContentDir)) {
+      // The file has not been created in directory that we're syncing with GitHub
+      return;
+    }
+    this.metadataStore.data[file.path] = {
+      localPath: file.path,
+      remotePath: file.path.replace(this.localContentDir, this.repoContentDir),
+      sha: null,
+      dirty: true,
+    };
+    await this.metadataStore.save();
+    this.eventsQueue.enqueue({
+      type: "create",
+      filePath: file.path,
+    });
+  }
+
+  private async onDelete(file: TAbstractFile) {
+    if (!file.path.startsWith(this.localContentDir)) {
+      // The file was not in directory that we're syncing with GitHub
+      return;
+    }
+    delete this.metadataStore.data[file.path];
+    await this.metadataStore.save();
+    this.eventsQueue.enqueue({
+      type: "delete",
+      filePath: file.path,
+    });
+  }
+
+  private async onModify(file: TAbstractFile) {
+    if (!file.path.startsWith(this.localContentDir)) {
+      // The file has not been create in directory that we're syncing with GitHub
+      return;
+    }
+    this.metadataStore.data[file.path].dirty = true;
+    await this.metadataStore.save();
+    this.eventsQueue.enqueue({
+      type: "modify",
+      filePath: file.path,
+    });
+  }
+
+  private async onRename(file: TAbstractFile, oldPath: string) {
+    if (
+      !file.path.startsWith(this.localContentDir) &&
+      !oldPath.startsWith(this.localContentDir)
+    ) {
+      // Both are not in directory that we're syncing with GitHub
+      return;
+    }
+
+    if (
+      file.path.startsWith(this.localContentDir) &&
+      oldPath.startsWith(this.localContentDir)
+    ) {
+      // Both files are in the synced directory
+      // First create the new one
+      await this.onCreate(file);
+      // Then delete the old one
+      await this.onDelete(file);
+      return;
+    } else if (file.path.startsWith(this.localContentDir)) {
+      // Only the new file is in the local directory
+      await this.onCreate(file);
+      return;
+    } else if (oldPath.startsWith(this.localContentDir)) {
+      // Only the old file was in the local directory
+      await this.onDelete(file);
+      return;
+    }
+  }
+}

src/events/queue.ts

@@ -0,0 +1,47 @@
+import { Event } from "./types";
+
+/**
+ * A custom queue to better handle events.
+ */
+export default class EventsQueue {
+  private eventsQueue: Map<string, Event> = new Map();
+
+  /**
+   * Enqueues an event in the queue.
+   * Handles special cases when the previous event and the new one
+   * would cancel themselves out.
+   */
+  enqueue(event: Event) {
+    if (!this.eventsQueue.has(event.filePath)) {
+      // No other event exist for this file, just enqueue it
+      this.eventsQueue.set(event.filePath, event);
+      return;
+    }
+
+    if (
+      this.eventsQueue.get(event.filePath)?.type === "create" &&
+      event.type === "delete"
+    ) {
+      // The previous event was a create and the new one is a delete.
+      // Just delete the previous one as they would amount to the same outcome.
+      this.eventsQueue.delete(event.filePath);
+    } else if (
+      this.eventsQueue.get(event.filePath)?.type === "delete" &&
+      event.type === "create"
+    ) {
+      // The old event was a delete and the new one is a create.
+      // Delete the old one and enqueue a modify event as it likely
+      // that the content changed.
+      this.eventsQueue.delete(event.filePath);
+      this.eventsQueue.set(event.filePath, {
+        type: "modify",
+        filePath: event.filePath,
+      });
+    } else {
+      // Delete and enqueue the event in all other cases.
+      // We first delete the event to change the order of the queue
+      this.eventsQueue.delete(event.filePath);
+      this.eventsQueue.set(event.filePath, event);
+    }
+  }
+}

src/events/types.ts

@@ -0,0 +1,4 @@
+export type Event = {
+  type: "create" | "delete" | "modify";
+  filePath: string;
+};