在 VS Code 扩展中检测 Git HEAD 变更以响应终端操作

npm install chokidar
# 或者
yarn add chokidar

import * as vscode from 'vscode';
import * as path from 'path';
import * as chokidar from 'chokidar';

function getGitHeadPath(): string | undefined {
    const workspaceFolders = vscode.workspace.workspaceFolders;
    if (!workspaceFolders || workspaceFolders.length === 0) {
        return undefined;
    }

    // 假设我们只关心第一个工作区根目录下的 Git 仓库
    const rootPath = workspaceFolders[0].uri.fsPath;
    const gitHeadPath = path.join(rootPath, '.git', 'HEAD');

    // 可以在这里添加检查，确保 .git 目录和 HEAD 文件确实存在
    // 例如：const fs = require('fs'); if (!fs.existsSync(gitHeadPath)) return undefined;

    return gitHeadPath;
}

import * as vscode from 'vscode';
import * as path from 'path';
import * as chokidar from 'chokidar';
import * as fs from 'fs'; // 用于读取文件内容

let gitHeadWatcher: chokidar.FSWatcher | undefined;
let currentBranch: string | undefined;

// 读取 .git/HEAD 文件内容并解析当前分支
function readCurrentBranch(headPath: string): string | undefined {
    try {
        const content = fs.readFileSync(headPath, 'utf-8').trim();
        if (content.startsWith('ref: refs/heads/')) {
            return content.substring('ref: refs/heads/'.length);
        } else {
            // 分离头指针状态，直接返回 SHA 或其他标识
            return content;
        }
    } catch (error) {
        console.error(`Failed to read .git/HEAD: ${error}`);
        return undefined;
    }
}

export function activate(context: vscode.ExtensionContext) {
    console.log('您的扩展 "my-git-watcher" 已激活！');

    const gitHeadPath = getGitHeadPath();

    if (gitHeadPath) {
        // 初始化当前分支状态
        currentBranch = readCurrentBranch(gitHeadPath);
        console.log(`初始分支: ${currentBranch || '未知'}`);

        gitHeadWatcher = chokidar.watch(gitHeadPath, {
            persistent: true, // 保持观察器活动
            ignoreInitial: true, // 忽略文件首次被发现时的事件
            awaitWriteFinish: { // 等待文件写入完成，避免读取部分写入的文件
                stabilityThreshold: 50,
                pollInterval: 10
            }
        });

        gitHeadWatcher.on('change', () => {
            console.log('.git/HEAD 文件发生变化！');
            const newBranch = readCurrentBranch(gitHeadPath);

            if (newBranch && newBranch !== currentBranch) {
                console.log(`分支已从 "${currentBranch || '未知'}" 切换到 "${newBranch}"`);
                // 在这里执行您的自定义逻辑
                vscode.window.showInformationMessage(`Git 分支已切换到: ${newBranch}`);
                currentBranch = newBranch; // 更新当前分支状态
            } else if (newBranch === currentBranch) {
                console.log('HEAD 变化，但分支名称未变 (例如，提交操作)');
                // 可以在这里处理提交等操作，如果需要的话
            } else {
                console.log('无法读取新分支信息。');
            }
        });

        gitHeadWatcher.on('error', error => console.error(`Watcher error: ${error}`));
    } else {
        vscode.window.showWarningMessage('未找到 Git 仓库的 .git/HEAD 文件，Git 监听功能将不工作。');
    }

    // 注册一个命令，以便在扩展被禁用时清理资源
    context.subscriptions.push(
        vscode.commands.registerCommand('my-git-watcher.disposeWatcher', () => {
            if (gitHeadWatcher) {
                gitHeadWatcher.close();
                console.log('Git HEAD 观察器已关闭。');
            }
        })
    );
}

export function deactivate() {
    if (gitHeadWatcher) {
        gitHeadWatcher.close();
        console.log('扩展停用，Git HEAD 观察器已关闭。');
    }
}