<?php

/**
 * Per-service email alias manager backed by the PostfixAdmin `alias` table.
 *
 * Config (see config.inc.php.dist):
 *  - postfixadmin_db_dsn   DSN of the PostfixAdmin database
 *  - alias_email_domain    domain the aliases are created in
 *  - alias_email_hash_len  length of the random suffix (default 7)
 *  - alias_max_per_user    maximum number of aliases per user (default 100, 0 = unlimited)
 */
class aliasmanager extends rcube_plugin {

	const LABEL_MAX_LEN = 40;

	public $task = 'settings';

	private $rcmail;

	private $db;

	public function init() {
		$this->rcmail = rcube::get_instance();
		$this->load_config();
		$this->add_texts('localization/');

		$this->include_stylesheet('assets/styles/app.css');

		$this->add_hook('settings_actions', [$this, 'hookSettingsActions']);

		$this->register_action('plugin.aliasmanager', [$this, 'onShowSettingsPage']);
		$this->register_action('plugin.aliasmanager-get-alias-list', [$this, 'onGetAliasList']);
		$this->register_action('plugin.aliasmanager-add-alias', [$this, 'onAddAlias']);
		$this->register_action('plugin.aliasmanager-toggle-alias', [$this, 'onToggleAlias']);
		$this->register_action('plugin.aliasmanager-delete-alias', [$this, 'onDeleteAlias']);
	}

	public function hookSettingsActions($arg): array {
		$arg['actions'][] = [
			'action' => 'plugin.aliasmanager',
			'class'  => 'aliasmanager',
			'label'  => 'settings_menu_label',
			'title'  => 'settings_menu_label',
			'domain' => 'aliasmanager',
		];

		return $arg;
	}

	public function onShowSettingsPage() {
		$this->include_script('assets/scripts/app.js');

		$labels = [];
		foreach (['add_failed', 'toggle_failed', 'delete_failed', 'list_failed', 'name_required', 'confirm_delete', 'copied', 'copy', 'delete', 'empty', 'no_matches'] as $key) {
			$labels[$key] = $this->gettext($key);
		}
		$this->rcmail->output->set_env('aliasmanager_labels', $labels);

		$this->register_handler('plugin.body', [$this, 'settingsPageHandler']);
		$this->rcmail->output->set_pagetitle($this->gettext('settings_menu_label'));
		$this->rcmail->output->send('plugin');
	}

	public function settingsPageHandler() {
		$html = file_get_contents(__DIR__.'/skins/elastic/templates/settings.html');

		return preg_replace_callback('/\[\+([a-z_]+)\+\]/', function ($m) {
			return rcube::Q($this->gettext($m[1]));
		}, $html);
	}

	public function onGetAliasList() {
		if (!$this->guard()) {
			return;
		}

		$result = $this->db()->query(
			'SELECT address, active, created FROM alias WHERE address != goto AND goto = ? AND domain = ? ORDER BY created DESC, address',
			$this->username(),
			$this->aliasDomain()
		);
		if ($this->db()->is_error($result)) {
			$this->fail('list_failed');
		}

		$list = [];
		while ($row = $this->db()->fetch_assoc($result)) {
			$list[] = [
				'email'   => $row['address'],
				'active'  => (int)$row['active'] === 1,
				'created' => substr($row['created'], 0, 10),
			];
		}

		$this->respond(['alias_list' => $list]);
	}

	public function onAddAlias() {
		if (!$this->guard()) {
			return;
		}

		$label = $this->normalizeLabel((string)rcube_utils::get_input_value('email', rcube_utils::INPUT_POST));
		if ($label === '') {
			$this->fail('name_required');
		}

		$domain = $this->aliasDomain();

		$max = (int)$this->rcmail->config->get('alias_max_per_user', 100);
		if ($max > 0 && $this->countAliases() >= $max) {
			$this->fail('limit_reached');
		}

		$hash_len = max(4, (int)$this->rcmail->config->get('alias_email_hash_len', 7));

		// retry on the (unlikely) address collision
		for ($attempt = 0; $attempt < 5; $attempt++) {
			$email = $label.'-'.$this->randomHash($hash_len).'@'.$domain;

			$exists = $this->db()->query('SELECT 1 FROM alias WHERE address = ?', $email);
			if ($this->db()->fetch_array($exists)) {
				continue;
			}

			$result = $this->db()->query(
				'INSERT INTO alias (address, goto, domain, created, modified, active) VALUES (?, ?, ?, NOW(), NOW(), 1)',
				$email,
				$this->username(),
				$domain
			);
			if ($this->db()->affected_rows($result) < 1) {
				$this->fail('add_failed');
			}

			$this->respond(['email' => $email]);
		}

		$this->fail('add_failed');
	}

	public function onToggleAlias() {
		if (!$this->guard()) {
			return;
		}

		$email = trim((string)rcube_utils::get_input_value('email', rcube_utils::INPUT_POST));
		$state = rcube_utils::get_input_value('state', rcube_utils::INPUT_POST) === 'true' ? 1 : 0;

		$result = $this->db()->query(
			'UPDATE alias SET active = ?, modified = NOW() WHERE address = ? AND goto = ? AND domain = ? AND address != goto',
			$state,
			$email,
			$this->username(),
			$this->aliasDomain()
		);
		if ($this->db()->is_error($result)) {
			$this->fail('toggle_failed');
		}

		$this->respond([]);
	}

	public function onDeleteAlias() {
		if (!$this->guard()) {
			return;
		}

		$email = trim((string)rcube_utils::get_input_value('email', rcube_utils::INPUT_POST));

		$result = $this->db()->query(
			'DELETE FROM alias WHERE address = ? AND goto = ? AND domain = ? AND address != goto',
			$email,
			$this->username(),
			$this->aliasDomain()
		);
		if ($this->db()->is_error($result) || $this->db()->affected_rows($result) < 1) {
			$this->fail('delete_failed');
		}

		$this->respond([]);
	}

	/**
	 * Rejects requests without a valid CSRF token and with a broken configuration.
	 */
	private function guard(): bool {
		if (!$this->rcmail->check_request(rcube_utils::INPUT_POST)) {
			$this->fail('request_invalid');
		}
		if ($this->aliasDomain() === '' || !$this->db()) {
			$this->fail('not_configured');
		}

		return true;
	}

	private function db() {
		if ($this->db === null) {
			$dsn = $this->rcmail->config->get('postfixadmin_db_dsn');
			$this->db = $dsn ? rcube_db::factory($dsn, '', false) : false;
		}

		return $this->db;
	}

	private function username(): string {
		return $this->rcmail->user->get_username();
	}

	private function aliasDomain(): string {
		return (string)$this->rcmail->config->get('alias_email_domain', '');
	}

	private function countAliases(): int {
		$result = $this->db()->query('SELECT COUNT(*) FROM alias WHERE address != goto AND goto = ? AND domain = ?', $this->username(), $this->aliasDomain());
		$row = $this->db()->fetch_array($result);

		return (int)($row[0] ?? 0);
	}

	/**
	 * Reduces user input to a safe email local part: [a-z0-9._-], at most LABEL_MAX_LEN chars.
	 */
	private function normalizeLabel(string $input): string {
		$label = strtolower(trim($input));
		$label = preg_replace('/[^a-z0-9._-]+/', '-', $label);
		$label = preg_replace('/([._-])\1+/', '$1', $label);
		$label = substr($label, 0, self::LABEL_MAX_LEN);

		return trim($label, '._-');
	}

	private function randomHash(int $length): string {
		$characters = '0123456789abcdefghijklmnopqrstuvwxyz';
		$max = strlen($characters) - 1;
		$hash = '';
		for ($i = 0; $i < $length; $i++) {
			$hash .= $characters[random_int(0, $max)];
		}

		return $hash;
	}

	private function respond(array $data) {
		$this->send(['success' => true, 'data' => $data]);
	}

	private function fail(string $label) {
		$this->send(['success' => false, 'message' => $this->gettext($label)]);
	}

	private function send(array $payload) {
		if (ob_get_length()) {
			@ob_end_clean();
		}

		header('Content-Type: application/json; charset=UTF-8');
		exit(json_encode($payload));
	}
}