<?php

declare(strict_types=1);

namespace Box\Mod\Mailgateway;

use FOSSBilling\InformationException;

class ImapConnectionTest
{
    public function __construct(private ?\Closure $factory = null) {}

    public function test(array $settings, bool $createFolders = false): array
    {
        if ($settings['password'] === '') {
            throw new InformationException('Save a mailbox password before testing the connection');
        }
        $client = null;
        $connected = false;
        $moveSupported = null;
        $folders = [];
        $errors = [];
        try {
            if ($this->factory === null) {
                if (!is_file(__DIR__ . '/vendor/autoload.php')) {
                    throw new InformationException('Install the Mail Gateway Composer dependencies first');
                }
                require_once __DIR__ . '/vendor/autoload.php';
            }
            $config = [
                'host' => $settings['host'], 'port' => (int) $settings['port'],
                'protocol' => 'imap', 'encryption' => $settings['encryption'],
                'validate_cert' => true, 'username' => $settings['username'],
                'password' => $settings['password'], 'authentication' => null,
                'timeout' => RuntimeConfig::get('imap_timeout_seconds'),
            ];
            $client = $this->factory !== null ? ($this->factory)($config)
                : (new \Webklex\PHPIMAP\ClientManager(['options' => ['debug' => false]]))->make($config);
            $client->connect();
            $connected = true;
            try {
                $capabilities = $client->getConnection()->getCapabilities()->validatedData();
                $moveSupported = in_array('MOVE', array_map('strtoupper', $capabilities), true);
                if (!$moveSupported) {
                    $errors[] = 'IMAP login succeeded, but the server does not support native MOVE. Importing requires MOVE to archive individual messages safely.';
                }
            } catch (\Throwable) {
                $errors[] = 'IMAP login succeeded, but checking server MOVE support failed. Check server access and try again.';
            }
            $paths = $this->paths($client);
            foreach (['inbox_folder', 'processed_folder', 'ignored_folder', 'failed_folder'] as $field) {
                $path = $settings[$field];
                $exists = $this->exists($path, $paths);
                $created = false;
                $error = null;
                if (!$exists && $field === 'inbox_folder') {
                    $error = 'The configured inbox does not exist. Correct its path or create it on the mail server.';
                } elseif (!$exists && $createFolders) {
                    try {
                        // Never expunge messages while creating a destination folder.
                        $client->createFolder($path, false);
                    } catch (\Throwable) {
                        $error = 'Folder creation failed. Check the folder path, parent folders, and mailbox permissions or quota.';
                    }
                    if ($error === null) {
                        try {
                            $paths = $this->paths($client);
                            $exists = $this->exists($path, $paths);
                            $created = $exists;
                            if (!$exists) {
                                $error = 'The server accepted folder creation, but the folder could not be found afterwards.';
                            }
                        } catch (\Throwable) {
                            $error = 'The folder creation request completed, but listing folders to verify it failed. Check server access and try again.';
                        }
                    }
                } elseif (!$exists) {
                    $error = 'The configured destination folder does not exist.';
                }
                $folders[] = ['path' => $path, 'exists' => $exists, 'created' => $created, 'error' => $error];
            }
        } catch (\Throwable) {
            // Never return IMAP exception messages or traces (may contain credentials).
            $errors[] = $connected
                ? 'IMAP login succeeded, but listing folders failed. Check mailbox permissions and server access.'
                : 'IMAP connection or login failed. Check the saved host, port, security, username, password, TLS certificate, and network access.';
        } finally {
            if ($client !== null) {
                try { $client->disconnect(); } catch (\Throwable) {}
            }
        }
        $success = $connected && $errors === [] && count($folders) === 4
            && array_filter($folders, fn ($folder) => !$folder['exists'] || $folder['error'] !== null) === [];
        return ['success' => $success, 'connected' => $connected, 'move_supported' => $moveSupported, 'folders' => $folders, 'errors' => $errors];
    }

    private function paths(object $client): array
    {
        $paths = [];
        foreach ($client->getFolders(false) as $folder) {
            $paths[] = $folder->path;
            $paths[] = $folder->full_name ?? $folder->path;
        }
        return $paths;
    }

    private function exists(string $path, array $paths): bool
    {
        return in_array($path, $paths, true)
            || (strcasecmp($path, 'INBOX') === 0 && in_array('INBOX', array_map('strtoupper', $paths), true));
    }
}