mp-helper.php; calculate all migration re-sequencing

gistfile1.txt

<?php

$fromBranch = 'master';
$toBranch = 'videoClips-integration';

// find common ancestor
$commonAncestor = commonAncestor($fromBranch, $toBranch);
print "Common ancestor of {$fromBranch}..{$toBranch} is {$commonAncestor}\n";

$sharedMigrations = migrationsForBranch($commonAncestor);
$lastSharedMigration = lastMigrationFromArray($sharedMigrations);
print "Most recent migration on both branches is {$lastSharedMigration}.\n";

$fromBranchMigrations = migrationsForBranch($fromBranch);
$lastFromMigration = lastMigrationFromArray($fromBranchMigrations);
print "Last migration on {$fromBranch} is {$lastFromMigration}.\n";

$resequenceBase = migrationNameAfterMigration($lastFromMigration);
$toBranchMigrations = migrationsForBranch($toBranch);

$onlyOnToBranch = array_diff($toBranchMigrations, $sharedMigrations);
$migrationToBeat = $lastFromMigration;
$githelpers = array();
foreach ($onlyOnToBranch as $migration) {
    if (compareMigrations($migration, $migrationToBeat) === -1)
    {
        // needs resequence
        $resequencedMigration = migrationNameAfterMigration($migrationToBeat);
        print "Need to reseqeunce {$migration} to {$resequencedMigration}\n";
        $migrationToBeat = $resequencedMigration;

        $githelpers[] = "git mv migrations/{$migration}.php migrations/{$resequencedMigration}.php && sed -i -e 's/{$migration}/{$resequencedMigration}/g' migrations/{$resequencedMigration}.php";
    }
    else
    {
        print "Migration {$migration} doesn't need re-sequencing.\n";
    }
}
print join("\n", $githelpers) . "\n";

function commonAncestor($a, $b)
{
    $cmd = "git merge-base {$a} {$b} 2>&1";
    $commonAncestor = `$cmd`;
    return trim($commonAncestor);
}
function migrationsForBranch($branch)
{
    $cmd = "git ls-tree {$branch} --name-only -r -- migrations | sed -n -e 's/migrations.\([0-9_]\+\).*/\\1/gp' 2>&1";
    $migrations = explode("\n", `$cmd`);            // split lines into array
    $migrations = array_map('trim', $migrations);   // trim whitespace
    $migrations = array_filter($migrations);        // remove empty lines
    return $migrations;
}
function lastMigrationFromArray($migrations)
{
    if (count($migrations) === 0) return NULL;
    $lastI = count($migrations) - 1; 
    return $migrations[$lastI];
}
function migrationNameAfterMigration($migration)
{
    $dts = strtotime(str_replace('_', ' ', $migration));
    if (!$dts) throw new Exception("couldn't parse $migration.");

    // is last migration from today? if so, bump dts by 1 s
    if (strtotime('today') < $dts)
    {
        $resequencedDts = $dts + 1;
    }
    // otherwise, use today_00000N
    else
    {
        $resequencedDts = strtotime('today') + 1;
    }
    return date('Ymd_His', $resequencedDts);
}

function compareMigrations($a, $b)
{
    // normalize & assert
    $tA = strtotime(str_replace('_', ' ', $a));
    $tB = strtotime(str_replace('_', ' ', $b));
    if (!$tA) throw new Exception("couldn't parse {$a}");
    if (!$tB) throw new Exception("couldn't parse {$b}");

    // compare
    if ($tA === $tB) return 0;
    return ($tA < $tB) ? -1 : 1;
}