prepare-commit-msg

#!/usr/bin/env -S node

// this can be used as a prepare-commit-msg
// Add it to your project source code in githooks/prepare-commit-msg
// `git config --local core.hooksPath githooks/`

const fs = require('fs');
const path = require('path');
const { execSync } = require('child_process');
const { argv, exit } = require('process');

const { currentGitActivity } = require('./helpers');

let branchName;

// Get the root directory of the git repository
const projectRootDir = execSync('git rev-parse --show-toplevel').toString().trim();

// Setup regex patterns for jira issue numbers specific to this project
const branchPattern = /^JEFF-\d+-[a-zA-Z-_]+$/;
const commitPattern = /^JEFF-\d+/;

const messageFilePath = argv[2];
const context = argv[3];

// Check if the hook is running in a message context
if (context !== 'message') {
    console.info(
        `Skipping prepare-commit-msg hook because hook running in non message (${context}) context`,
    );

    exit(0);
}

try {
    // Try to get branch name
    branchName = execSync('git symbolic-ref --short HEAD 2> /dev/null').toString().trim();

    if (!branchName) {
        console.info('Skipping prepare-commit-msg hook because branch name could not be determined');
        exit(0);
    }
} catch (err) {
    const activity = currentGitActivity();

    console.warn('Warning: Could not determine branch name');
    console.info(`Current git activity: ${activity}`);

    exit(0);
}

// Get path to git commit message file
const commitMessagePath = path.join(projectRootDir, messageFilePath);

let commitMessage = fs.readFileSync(commitMessagePath, 'utf8');

// Check if branch name is correctly formatted
if (!branchPattern.test(branchName)) {
    console.warn('Warning: Branch name is not correctly formatted. Please follow the pattern JEFF-\\d+-[a-zA-Z-_]+');
    console.warn('Leaving commit message as is. This should be corrected before pushing to remote.')
} else {
    const branchIssuePrefix = branchName.match(commitPattern)[0];
    const commitIssuePrefix = commitMessage.match(commitPattern) && commitMessage.match(commitPattern)[0];

    // Check if the commit message is correctly formatted
    if (!commitPattern.test(commitMessage)) {
        console.warn('Warning: Commit message missing issue number prefix (e.g., JEFF-\\d+).');
        console.info('Prefixing commit message with branch issue number.')
        commitMessage = `${branchIssuePrefix} ${commitMessage}`;
    } else if (branchIssuePrefix !== commitIssuePrefix) {
        console.warn('Warning: Commit message issue number does not match with the branch issue number. Prefixing with branch issue number.');
        console.info('Prefixing commit message with branch issue number.')
        commitMessage = `${branchIssuePrefix} ${commitMessage}`;
    }
}

// Write the (possibly modified) commit message back to the file
fs.writeFileSync(commitMessagePath, commitMessage);