<?php

use App\DB;

const DRY_RUN = false;

require __DIR__ . '/../vendor/autoload.php';
require __DIR__ . '/../include/mailer.php';

function verify_signature($requestBody) {
    if (isset($_SERVER['HTTP_X_HUB_SIGNATURE'])){
        $sig = 'sha1=' . hash_hmac('sha1', $requestBody, getenv('GITHUB_SECRET'));
        return $sig === $_SERVER['HTTP_X_HUB_SIGNATURE'];
    }
    return false;
}

function is_pr($issue) {
    return strpos($issue->html_url, '/pull/') !== false;
}

function prep_title(object $issue, string $repoName): string {
    $issueNumber = $issue->number;
    $title = $issue->title;
    $type = is_pr($issue) ? 'PR' : 'Issue';

    return sprintf('[%s] %s #%s: %s', $repoName, $type, $issueNumber, $title);
}

function send_mail($to, $subject, $message, MailAddress $from, array $replyTos = []) {
    printf("Sending mail...\nTo: %s\nFrom: %s <%s>\nSubject: %s\nMessage:\n%s",
        $to, $from->name, $from->email, $subject, $message);

    if (!DRY_RUN) {
        mailer($to, $subject, $message, $from, $replyTos);
    }
}

function get_first_line($message) {
    $newLinePos = strpos($message, "\n");
    return $newLinePos !== false ? substr($message, 0, $newLinePos) : $message;
}

function handle_bug_close($commit) {
    $message = $commit->message;
    $author = $commit->author->username;
    $committer = $commit->committer->username;
    $url = $commit->url;

    if (!preg_match_all('/^Fix(?:ed)? (?:bug )?\#([0-9]+)/mi', $message, $matches)) {
        return;
    }
    $bugIds = $matches[1];

    if ($author === $committer) {
        $blame = $author;
    } else {
        $blame = "$author (author) and $committer (committer)";
    }

    $firstLine = get_first_line($message);

    $comment = <<<MSG
Automatic comment on behalf of $blame
Revision: $url
Log: $firstLine
MSG;

    foreach ($bugIds as $bugId) {
        $postData = [
            'user' => 'git',
            'id' => (int) $bugId,
            'ncomment' => $comment,
            'status' => 'Closed',
            'MAGIC_COOKIE' => getenv('BUGS_MAGIC_COOKIE'),
        ];
        $postData = http_build_query($postData, '', '&');

        echo "Closing bug #$bugId\n";
        if (!DRY_RUN) {
            $context = stream_context_create(['http' => [
                'method' => 'POST',
                'header' => 'Content-Type: application/x-www-form-urlencoded',
                'content' => $postData,
                'timeout' => 5,
            ]]);
            $result = file_get_contents('https://bugs.php.net/rpc.php', false, $context);
            echo "Response: $result\n";
        }
    }
}

function get_commit_mailing_list($repoName) {
    if ($repoName === 'playground') {
        return 'nikic@php.net';
    } else if ($repoName === 'php-src' || $repoName === 'karma') {
        return 'php-cvs@lists.php.net';
    } else if ($repoName === 'php-langspec') {
        return 'standards-vcs@lists.php.net';
    } else if ($repoName === 'phpruntests' || $repoName === 'pftt2' || $repoName === 'web-qa') {
        return 'php-qa@lists.php.net';
    } else if ($repoName === 'systems') {
        return 'systems@php.net';
    } else if ($repoName === 'php-gtk-src') {
        return 'php-gtk-cvs@lists.php.net';
    } else if ($repoName === 'presentations' || $repoName === 'web-pres2') {
        return 'pres@lists.php.net';
    } else if ($repoName === 'doc-base' || $repoName === 'doc-en'
        || $repoName === 'phd' || $repoName === 'web-doc-editor') {
        return 'doc-cvs@lists.php.net';
    } else if ($repoName === 'web-doc') {
        return 'doc-web@lists.php.net';
    } else if ($repoName === 'web-pecl') {
        return 'pecl-cvs@lists.php.net';
    } else if (strpos($repoName, 'web-') === 0) {
        return 'php-webmaster@lists.php.net';
    } else if (strpos($repoName, 'pecl-') === 0) {
        return 'pecl-cvs@lists.php.net';
    } else if (strpos($repoName, 'doc-') === 0 && $repoName !== 'doc-gtk') {
        return str_replace('-', '_', $repoName) . '@lists.php.net';
    } else {
        return null;
    }
}

function get_issue_mailing_list(string $repoName, bool $isPR) {
    if ($repoName === 'playground') {
        return 'nikic@php.net';
    } else if ($repoName === 'php-src') {
        if ($isPR) {
            return 'git-pulls@lists.php.net';
        } else {
            return 'php-bugs@lists.php.net';
        }
    } else if (strpos($repoName, 'web-') === 0) {
        return 'php-webmaster@lists.php.net';
    } else if (strpos($repoName, 'pecl-') === 0) {
        return 'pecl-dev@lists.php.net';
    } else {
        return null;
    }
}

function parse_ref($ref) {
    if (!preg_match('(^refs/([^/]+)/(.+)$)', $ref, $matches)) {
        return null;
    }

    return [$matches[1], $matches[2]];
}

function handle_ref_change_mail($mailingList, $payload) {
    $repoName = $payload->repository->name;
    $ref = $payload->ref;
    $before = $payload->before;
    $after = $payload->after;
    $compare = $payload->compare;
    $pusherName = $payload->pusher->name;

    if (!$parsedRef = parse_ref($ref)) {
        echo "Unexpected ref format: $ref";
        return;
    }

    list($refKind, $refName) = $parsedRef;
    if ($refKind === 'heads') {
        $what = "branch $refName";
    } else if ($refKind === 'tags') {
        $what = "tag $refName";
    } else {
        $what = "unknown ref $ref";
    }

    if ($payload->created) {
        $action = "created";
    } else if ($payload->deleted) {
        $action = "deleted";
    } else if ($payload->forced) {
        $action = "force pushed";
    } else {
        $action = "performed unknown action on";
    }

    $subject = "[$repoName] $action $what";

    $message = ucfirst($action) . " $what in repository $repoName.\n\n";
    $message .= "Pusher: $pusherName\n";
    if ($action !== 'created') {
        $message .= "Before: https://github.com/php/$repoName/commit/$before\n";
    }
    if ($action !== 'deleted') {
        $message .= "After: https://github.com/php/$repoName/commit/$after\n";
    }
    $message .= "Compare: $compare\n";
    $message .= "Tree: https://github.com/php/$repoName/tree/$refName\n";
    if ($refKind === 'tags') {
        $message .= "Tag: https://github.com/php/$repoName/releases/tag/$refName\n";
    }

    if ($payload->forced) {
        $message .= "\nCommit mails will not be sent for force-pushed commits!\n";
    }

    send_mail($mailingList, $subject, $message, MailAddress::noReply($pusherName));
}

function handle_commit_mail(PDO $dbh, $mailingList, $repoName, $ref, $pusherUser, $commit) {
    $query = $dbh->prepare('INSERT INTO commits (repo, hash) VALUES (?, ?)');
    try {
        $query->execute([$repoName, $commit->id]);
    } catch (PDOException $e) {
        if ($e->errorInfo[1] === 1062) {
            // We don't want to send a mail when an existing commit gets merged into a new branch.
            // In that case, only a mail for the merge commit should be sent (or a mail for the
            // new branch). Unfortunately, the "distinct" flag that GitHub provides for this purpose
            // is buggy: If multiple branches are pushed at the same time, then the commits will
            // have distict=false for all pushes, rather than having the first push with
            // distinct=true and the rest with distinct=false. For this reason, we store all the
            // commit hashes we saw in the database and only send a mail for new commits.
            return;
        }

        throw $e;
    }

    $authorUser = $commit->author->username ?? null;
    $authorName = $commit->author->name;
    $committerUser = $commit->committer->username ?? null;
    $committerName = $commit->committer->name;
    $message = $commit->message;
    $timestamp = $commit->timestamp;
    $url = $commit->url;
    $diffUrl = $url . '.diff';
    $firstLine = get_first_line($message);

    if (!$parsedRef = parse_ref($ref)) {
        echo "Unexpected ref format: $ref";
        return;
    }

    list(, $refName) = $parsedRef;

    $from = $authorName === $committerName ? $authorName : "$authorName via $committerName";
    $replyTos = [new MailAddress($commit->author->email, $authorName)];
    if ($commit->committer->email !== 'noreply@github.com') {
        $replyTos[] = new MailAddress($commit->committer->email, $committerName);
    }

    $subject = "[$repoName] $refName: $firstLine";
    $body = "Author: $authorName" . ($authorUser ? " ($authorUser)" : "") . "\n";
    if ($authorName !== $committerName) {
        $body .= "Committer: $committerName" . ($committerUser ? " ($committerUser)" : "") . "\n";
    }
    if ($committerUser !== $pusherUser) {
        $body .= "Pusher: $pusherUser\n";
    }
    $body .= "Date: $timestamp\n\n";

    $body .= "Commit: $url\n";
    $body .= "Raw diff: $diffUrl\n\n";
    $body .= "$message\n\n";

    $body .= "Changed paths:\n";
    foreach ($commit->added as $file) {
        $body .= "  A  $file\n";
    }
    foreach ($commit->removed as $file) {
        $body .= "  D  $file\n";
    }
    foreach ($commit->modified as $file) {
        $body .= "  M  $file\n";
    }
    $body .= "\n\n";

    $diff = file_get_contents($diffUrl);
    if (strlen($diff) > 128 * 1024) {
        $body .= "Diff exceeded maximum size.";
    } else {
        $body .= "Diff:\n\n$diff";
    }

    send_mail($mailingList, $subject, $body, MailAddress::noReply($from), $replyTos);
}

function handle_push_mail($payload) {
    $repoName = $payload->repository->name;
    $ref = $payload->ref;
    $mailingList = get_commit_mailing_list($repoName);
    if ($mailingList === null) {
        echo "Not sending mail for $repoName (no mailing list)";
        return;
    }

    if ($payload->created || $payload->deleted || $payload->forced) {
        handle_ref_change_mail($mailingList, $payload);
    }

    if ($payload->forced) {
        // Do not send commit mails for force-pushed branches. These are generally rebases
        // of existing commits and cause a lot of noise.
        return;
    }

    $dbh = DB::connect();

    $pusherName = $payload->pusher->name;
    foreach ($payload->commits as $commit) {
        handle_commit_mail($dbh, $mailingList, $repoName, $ref, $pusherName, $commit);
    }
}

if (DRY_RUN) {
    $body = file_get_contents("php://stdin");
    $event = $argv[1];
} else {
    $body = file_get_contents("php://input");
    $event = $_SERVER['HTTP_X_GITHUB_EVENT'];

    if (!verify_signature($body)) {
        header('HTTP/1.1 403 Forbidden');
        exit;
    }
}

$payload = json_decode($body);
if ($payload === null) {
    header("HTTP/1.1 400 Bad Request");
    echo "Failed to decode payload: ", json_last_error_msg(), "\n";
    echo "Body:\n", $body, "\n";
    exit;
}

$repoName = $payload->repository->name;
switch ($event) {
    case 'ping':
        break;
    case 'pull_request':
    case 'issues':
        $action = $payload->action;
        $issue = $event == 'issues' ? $payload->issue : $payload->pull_request;
        $htmlUrl = $issue->html_url;

        $description = $issue->body;
        $username = $payload->sender->login;

        $isPR = is_pr($issue);
        $to = get_issue_mailing_list($repoName, $isPR);
        if ($to === null) {
            echo "Not sending mail for $repoName (no mailing list)";
            return;
        }

        $subject = prep_title($issue, $repoName);
        $type = $isPR ? 'Pull Request' : 'Issue';

        $message = sprintf("%s: %s\r\n", $type, $htmlUrl);
        switch ($action) {
            case 'opened':
                $message .= sprintf(
                    "Author: %s\r\n\r\n%s", $username, $description);
                break;
            case 'closed':
                $message .= "\r\nClosed by $username.";
                break;
            case 'reopened':
                $message .= "\r\nReopened by $username.";
                break;
            case 'transferred':
                $new_url = $payload->changes->new_issue->html_url;
                $message .= "\r\nTransferred to $new_url by $username.";
                break;
            case 'assigned':
            case 'unassigned':
            case 'labeled':
            case 'unlabeled':
            case 'edited':
            case 'synchronize':
            case 'converted_to_draft':
            case 'locked':
            case 'unlocked':
            case 'enqueued':
            case 'dequeued':
            case 'milestoned':
            case 'demilestoned':
            case 'ready_for_review':
            case 'review_requested':
            case 'review_request_removed':
            case 'auto_merge_enabled':
            case 'auto_merge_disabled':
            // Undocumented as of yet
            case 'typed':
            case 'untyped':
                // Ignore these actions
                break 2;
            default:
                $message .= "\r\nUnknown action: $action";
                break;
        }

        send_mail($to, $subject, $message, MailAddress::noReply($username));
        break;

    case 'push':
        if ($payload->ref === 'refs/heads/master') {
            // Only close bugs for pushes to master.
            foreach ($payload->commits as $commit) {
                handle_bug_close($commit);
            }
        }

        handle_push_mail($payload);
        break;

    default:
        header('HTTP/1.1 501 Not Implemented');
}