post-checkout hook to notify breaking changes

post-checkout

#!/usr/bin/env node

var PREV_HEAD = process.argv[2];
var NEW_HEAD = process.argv[3];

var sys = require('sys'),
    exec = require('child_process').exec,
    FgRed = "\x1b[31m", FgGreen = "\x1b[32m", FgYellow = "\x1b[33m",
    FgBlue = "\x1b[34m", FgMagenta = "\x1b[35m", FgCyan = "\x1b[36m",
    FgWhite = "\x1b[37m",
    banner = '\n\n' +
             '   ########  ########  ########    ###    ##    ## #### ##    ##  ######    \n' +
             '   ##     ## ##     ## ##         ## ##   ##   ##   ##  ###   ## ##    ##   \n' +
             '   ##     ## ##     ## ##        ##   ##  ##  ##    ##  ####  ## ##         \n' +
             '   ########  ########  ######   ##     ## #####     ##  ## ## ## ##   ####  \n' +
             '   ##     ## ##   ##   ##       ######### ##  ##    ##  ##  #### ##    ##   \n' +
             '   ##     ## ##    ##  ##       ##     ## ##   ##   ##  ##   ### ##    ##   \n' +
             '   ########  ##     ## ######## ##     ## ##    ## #### ##    ##  ######    \n\n' +
             '    ######  ##     ##    ###    ##    ##  ######   ########  ######         \n' +
             '   ##    ## ##     ##   ## ##   ###   ## ##    ##  ##       ##    ##        \n' +
             '   ##       ##     ##  ##   ##  ####  ## ##        ##       ##              \n' +
             '   ##       ######### ##     ## ## ## ## ##   #### ######    ######         \n' +
             '   ##       ##     ## ######### ##  #### ##    ##  ##             ##        \n' +
             '   ##    ## ##     ## ##     ## ##   ### ##    ##  ##       ##    ##        \n' +
             '    ######  ##     ## ##     ## ##    ##  ######   ########  ######         \n';



var formatter = function(format) { return format.replace(/"/g, '^@^'); }
var format = formatter('\'{%n"hash":"%h",%n"subject":"%f",%n"author":"%an",%n"date":"%ad",%n"body":"%b"},\' ');

// http://git-scm.com/docs/git-log
exec('git log --no-merges --pretty=' + format + PREV_HEAD + '..' + NEW_HEAD, function(err, std) {
    // output to json
    var out = ("" + std).replace(/"/gm, '\\"').replace(/:\s*\^@\^([^]+?)\^@\^/gm, function(r) {
        return r.replace(/\r\n|\n/g, '\\n');
    }).replace(/\^@\^/gm, '"');
    var commits = JSON.parse('[' + out.slice(0, out.lastIndexOf(',')) + ']');

    // look for breaking changes and build output
    var match, breaking = '';
    for (var i = 0; i < commits.length; i++) {
        commit = commits[i];
        match = /\nbreaking\s+changes\n*([^]+)/ig.exec(commit.body);
        if (match && match[1]) {
            breaking += '\n\n' + FgYellow + commit.hash + FgWhite + ' · ' +
                        FgMagenta + commit.subject + ' · ' + FgWhite + commit.author + '\n' +
                        FgWhite + match[1] + '\n';
        }
    }
    // output
    breaking.length && sys.puts(FgRed + banner + breaking + '\n');
});