#!/usr/local/bin/perl
# vim:sts=4 sw=4 et
# perltidy -bext=/ -se -i=4 -it=2 -ci=2 -xci -l=132 -pt=2 -ce -cti=1 -cab=4 -cb -cbo=0 -wbb="% + - * / x != == >= <= =~ !~ < > | &" -enc=utf8 -wn -sot -sct -asc -tqw -sbq=0 -csc -csct=30

use strict;
use warnings;
use 5.024;

use Git;

################################################################
# Helper functions
################################################################

my $git = Git->repository;

my $branch_main    = 'refs/heads/main';
my $re_quarterlies = qr{^refs/heads/20\d\dQ\d\z}oms;

{    # sub context to avoid leaking @push_options
    my @push_options;
    for (my $i = 0 ; $i < $ENV{GIT_PUSH_OPTION_COUNT} ; ++$i) {
        push @push_options, $ENV{"GIT_PUSH_OPTION_${i}"};
    }

    sub has_option {
        my ($opt) = @_;
        for (@push_options) {
            return 1 if $opt eq $_;
        }
        return 0;
    } ## end sub has_option
}

my @quarterlies;

for ($git->command('show-ref', '--heads')) {
    my ($hash, $ref) = split / /;
    next if $ref !~ m{refs/heads/\d\d\d\dQ\d\z}oms;
    push @quarterlies, $ref;
}

@quarterlies = sort @quarterlies;

my $latest_quarterly = $quarterlies[-1];

sub do_die {
    die "\n================================================================\n"
      . join("\n", @_)
      . "\n================================================================\n\n";
}

sub short_ref {
    my ($ref) = @_;
    $ref =~ s{refs/heads/}{}oms;
    return $ref;
}

################################################################
# Here starts actual hooks

################################################################
# Some filenames are forbidden in the repo.
sub deny_filenames {
    my ($rev, @changed) = @_;

    for my $line (@changed) {
        if (
            $line    =~ m{\A(?:CVS|[.](?:svn|git))\z}oms    # cvs/svn/git
            || $line =~ m{[.](?:rej|orig)\z}oms             # patch
            || $line =~ m{[.]core\z}oms                     # core file
           )
        {
            do_die
              'This file in your commit look suspiciously like core file,',
              'patch leftover, CVS, Subversion or git directory:',
              $line,
              'Please double-check your commit and try committing again.';
        } ## end if ($line =~ m{\A(?:CVS|[.](?:svn|git))\z}oms...)

        if ($line =~ m{(?:\A|/)Makefile.local\z}oms) {
            do_die
              'Makefile.local is a user file and MUST NOT be committed:',
              $line;
        }
    } ## end for my $line (@changed)
} ## end sub deny_filenames

################################################################
# Empty files forbidden
sub empty {
    my ($rev, @changed) = @_;

    for my $file (@changed) {
        my $content = $git->command('show', "$rev:$file");

        next if length($content) > 0;

        do_die
          "Some files in your commit are empty: $file",
          "Please fix this and try committing again.";
    } ## end for my $file (@changed)
} ## end sub empty

################################################################
# vulm.xml has to be committed alone, as it is never merged back to the
# quarterly branches.
sub vuxml_unique {
    my ($ref, $rev, @changed) = @_;

    my ($seen, $other) = (0, 0);

    for my $line (@changed) {
        if ($line =~ m{\Asecurity/vuxml/vuln(?:-\d{4})?.xml\z}oms) {
            $seen = 1;
        } else {
            $other = 1;
        }
    } ## end for my $line (@changed)

    if ($seen && $branch_main ne $ref) {
        do_die "Commits to security/vuxml/vuln.xml are only allowed on main";

    }
    if ($seen && $other) {
        do_die "Commit to security/vuxml/vuln.xml first, and then other files";
    }
} ## end sub vuxml_unique

################################################################
# Check git cherry-pick ran with `-x`
sub cherry_pick {
    my ($ref, $log) = @_;

    # Only do this on quarterlies
    return if $ref !~ $re_quarterlies;

    # Gave the magic push option
    return if has_option('direct-quarterly-commit');

    # Found the actual magic words
    return if $log =~ m{
                        ^                                  # Start of line
                        [(]                                # A litteral opening parenthesis
                        cherry[ ]picked[ ]from[ ]commit    # The magic words
                        [0-9a-fA-F]{30,}                   # A commit hash
                        [)]                                # A litteral closing parenthesis
                        $                                  # End of line
                       }omsx;

    do_die                                                                              # Comments
      "$ENV{GL_USER}, you are pushing a commit to ${\(short_ref($ref))} which does",    # to get this
      'not seems to be a cherry-pick.',                                                 # indented
      '',                                                                               # properly
      'If you did a cherry-pick, you probably forgot to add `-x`,',                     # by
      'make sure you do run `git cherry-pick -x <hash>`.',                              # perltidy
      '',                                                                               #
      'If you did a direct commit, make sure it was approved first, and then run:',     #
      "\tgit push --push-option=direct-quarterly-commit";
} ## end sub cherry_pick

################################################################
# Check that commits only go to the latest quarterly branch
sub unsupported_quarterly {
    my ($ref) = @_;

    # Only applies to quarterlies
    return if $ref !~ $re_quarterlies;

    # Gave the magic push option
    return if has_option('direct-quarterly-commit');

    do_die                                                                                 # Comments
      "$ENV{GL_USER}, you are pushing a commit to ${\(short_ref($ref))} which is not",     # for
      "the latest quarterly branch. The latest is ${\(short_ref($latest_quarterly))}.",    # indentation
      '',                                                                                  #
      'Please check that you really mean to do this, and got approval, use:',              #
      "\tgit push --push-option=unsupported-quarterly";
} ## end sub unsupported_quarterly

################################################################
# Check log does not contains stuff generated by phabricator
sub stomp_bad_formatting {
    my ($log) = @_;

    if ($log =~ m|\n\nReviewers:[\t ]+|oms) {
        do_die "Non-standard/badly formatted template - found 'Reviewers:' instead of 'Reviewed by:'.";
    }

    if ($log =~ m|\n\nSubscribers:[\t ]+|oms) {
        do_die "Non-standard/badly formatted template - found 'Subscribers:'.";
    }
} ## end sub stomp_bad_formatting

################################################################
# Main loop, everything called in here.
for (<STDIN>) {
    chomp;
    my ($old, $new, $ref) = split / /;

    unsupported_quarterly($ref);

    for my $rev ($git->command('log', '--format=%H', $new, '--not', '--all')) {
        my @changed = $git->command('diff', '--name-only', "$rev~1..$rev");
        my $log     = $git->command('show', '-s', '--format=%B', $rev);
        deny_filenames($rev, @changed);
        vuxml_unique($ref, $rev, @changed);
        cherry_pick($ref, $log);
        stomp_bad_formatting($log);
        empty($rev, @changed);
    } ## end for my $rev ($git->command('log',...))
} ## end for (<STDIN>)

exit 1;