update

#!/usr/bin/env node

// clns/node-commit-msg
// http://git-scm.com/docs/githooks#update

var path = require('path');
var spawn = require('child_process').spawn;
var exec = require('child_process').exec;
var util = require('util');
var CommitMessage = require('..');

// Vars
var refname = process.argv[2];
var oldrev  = process.argv[3];
var newrev  = process.argv[4];

// Safety check
if (!process.env.GIT_DIR) {
    console.error('Don\'t run this script from the command line.\n' +
        ' (if you want, you could supply GIT_DIR then run\n' +
        '  %s <ref> <oldrev> <newrev>)',
        process.argv[1]);
    process.exit(1);
}

if (!refname || !oldrev || !newrev) {
    console.error('usage: %s <ref> <oldrev> <newrev>', process.argv[1]);
    process.exit(1);
}

// Configurations
var defaultConfig = CommitMessage.Config(config);
config = CommitMessage.Config(
    CommitMessage.resolveConfigSync(process.env.GIT_DIR),
    defaultConfig
);
var showFirst = config.updateHook.showFirst; // show first X commits with errors
var config = { // validator default config (can be overwritten by package.json)
    subjectPreferredMaxLineLength: false,
    bodyMaxLineLength: false,
    squashFixup: {allow: false}
};

// Process a commit
var processing = false;
var hashes = [];
var errors = []; // contains all short hashes that failed validation
var hash, shortHash, subject, idx, idx2;
var firstFew = []; // contains output lines for the first 'showFirst' commits with errors
var processCommit = function() {
    if (processing) return;

    hash = hashes.shift();
    if (!hash) {
        processing = false;
        return;
    }

    exec(util.format('git show -s --format=%s %s', '%h%n%s%n%B', hash), {
        cwd: process.env.GIT_DIR
    }, function(err, stdout) {
        if (err) {
            console.error(err);
            process.exit(1);
        }

        idx = stdout.indexOf('\n');
        idx2 = stdout.indexOf('\n', idx+1);
        shortHash = stdout.substring(0, idx+1).slice(0, -1);
        subject = stdout.substring(idx+1, idx2+1).slice(0, -1);
        stdout = stdout.slice(idx2+1);

        CommitMessage.parse(stdout, config, function(err, validator) {
            if (err) {
                console.error(err);
                process.exit(1);
            }
            stdout = null;
            if (validator.hasErrors()) {
                errors.push(shortHash);
            }
            if (errors.length <= showFirst && (validator.hasErrors() || validator.hasWarnings())) {
                firstFew.push(util.format(
                    '%s: %s\n' +
                    '%s',
                    shortHash, subject,
                    validator.formattedMessages
                ));
            }
            validator = null;
            processing = false;
            processCommit(); // continue
        });
    });
}

// Process commits in the range <oldrev>..<newrev> or just <newrev>
var range = util.format('%s%s', parseInt(oldrev)?(oldrev+'..'):'', newrev);
var proc = spawn('git', ['rev-list', range], {
    cwd: process.env.GIT_DIR
});

proc.stdout.on('data', function(data) {
    data.toString('utf8').split('\n').forEach(function(c) {
        hashes.push(c);
    });
    processCommit();
});

proc.stderr.on('data', function(data) {
    console.error(data.toString('utf8'));
});

proc.on('close', function(code) {
    code === 0 || process.exit(code);
});

process.on('beforeExit', function() {
    if (errors.length) {
        var msg = errors.length == 1 ? '1 commit' :
            util.format('%d commits', errors.length);
        console.log(
            '%s failed on %s due to invalid commit message%s',
            msg,
            refname,
            firstFew.length && firstFew.length!=errors.length ?
                util.format('; showing the last %s ...', (firstFew.length==1?'one':firstFew.length)) :
                ''
        );
        firstFew.length && console.log(firstFew.join('\n'));
        console.log('You can run this command in your project root to see all the error messages:');
        console.log('  $ echo "%s" | node node_modules/commit-msg/bin/validate stdin',
            errors.join(' '));
        // https://nodejs.org/api/process.html#process_exit_codes
        process.exit(1); // Uncaught Fatal Exception
    }
});