<?php
/**
 * Optional transactional reward emails with durable attempt deduplication.
 *
 * @package DevoynxRewards
 */

namespace Devoynx\Rewards\Programs;

use Devoynx\Rewards\Database\ProgramStore;

defined( 'ABSPATH' ) || exit;

/** Queue alongside ledger writes; never invoke a mail transport inside that transaction. */
final class BasicEmails {

	const OPTION = 'devoynx_rewards_email_settings';
	const HOOK   = 'devoynx_rewards_basic_emails';

	/** Register economic observers, scheduler and scoped views. */
	public function register() {
		add_action( 'devoynx_rewards_points_awarded', array( $this, 'awarded' ), 70, 4 );
		add_action( 'devoynx_rewards_points_redeemed', array( $this, 'redeemed' ), 70, 4 );
		add_action( 'init', array( $this, 'schedule' ), 20 );
		add_action( self::HOOK, array( $this, 'process' ) );
		add_filter( 'devoynx_rewards_admin_tabs', array( $this, 'tabs' ) );
		add_action( 'devoynx_rewards_admin_tab', array( $this, 'render_admin' ) );
		add_action( 'admin_post_devoynx_rewards_basic_emails', array( $this, 'save' ) );
		add_action( 'admin_post_devoynx_rewards_email_preference', array( $this, 'save_preference' ) );
		add_action( 'devoynx_rewards_wallet_after_activity', array( $this, 'render_preference' ), 45 );
	}

	/**
	 * Localized defaults; mail is disabled until the merchant opts in.
	 *
	 * @return array
	 */
	public function defaults() {
		return array(
			'enabled'   => 0,
			'templates' => array(
				'earned'   => array(
					'enabled' => 1,
					'subject' => __( 'You earned {points} reward points', 'devoynx-rewards' ),
					'body'    => __( 'Hi {customer_name}, you earned {points} points at {site_name}. View your wallet: {wallet_url}', 'devoynx-rewards' ),
				),
				'redeemed' => array(
					'enabled' => 1,
					'subject' => __( 'You used {points} reward points', 'devoynx-rewards' ),
					'body'    => __( 'Hi {customer_name}, you used {points} points at {site_name}. View your wallet: {wallet_url}', 'devoynx-rewards' ),
				),
				'referral' => array(
					'enabled' => 1,
					'subject' => __( 'Your referral earned {points} points', 'devoynx-rewards' ),
					'body'    => __( 'Hi {customer_name}, your referral earned {points} points at {site_name}. View your wallet: {wallet_url}', 'devoynx-rewards' ),
				),
			),
		);
	}

	/**
	 * Validate fixed email categories and bounded plain-text templates.
	 *
	 * @param mixed $input Submitted settings.
	 * @return array|\WP_Error
	 */
	public function sanitize( $input ) {
		$result = $this->defaults();
		if ( ! is_array( $input ) || ( isset( $input['templates'] ) && ! is_array( $input['templates'] ) ) ) {
			return new \WP_Error( 'invalid_email_settings' );
		}
		$result['enabled'] = empty( $input['enabled'] ) ? 0 : 1;
		foreach ( $result['templates'] as $kind => $default ) {
			$row = $input['templates'][ $kind ] ?? $default;
			if ( ! is_array( $row ) || ! is_scalar( $row['subject'] ?? null ) || ! is_scalar( $row['body'] ?? null ) ) {
				return new \WP_Error( 'invalid_email_template' );
			}
			$subject = sanitize_text_field( (string) $row['subject'] );
			$body    = sanitize_textarea_field( (string) $row['body'] );
			if ( '' === $subject || '' === $body || mb_strlen( $subject ) > 160 || mb_strlen( $body ) > 2000 ) {
				return new \WP_Error( 'invalid_email_template' );
			}
			$result['templates'][ $kind ] = array(
				'enabled' => empty( $row['enabled'] ) ? 0 : 1,
				'subject' => $subject,
				'body'    => $body,
			);
		}
		return $result;
	}

	/**
	 * Read validated configuration.
	 *
	 * @return array
	 */
	public function settings() {
		$result = $this->sanitize( get_option( self::OPTION, array() ) );
		return is_wp_error( $result ) ? $this->defaults() : $result;
	}

	/**
	 * Queue either earned or referral mail, never both for the same award.
	 *
	 * @param int   $user_id Recipient.
	 * @param int   $points Awarded points.
	 * @param int   $entry_id Immutable ledger entry.
	 * @param array $context Ledger event context.
	 */
	public function awarded( $user_id, $points, $entry_id, $context ) {
		$kind = in_array( $context['event_type'] ?? '', array( 'referral_award', 'referral_friend_award' ), true ) ? 'referral' : 'earned';
		$this->queue( $kind, $user_id, $points, $entry_id );
	}

	/**
	 * Queue a redemption receipt, not a reservation or released selection.
	 *
	 * @param int   $user_id Recipient.
	 * @param int   $points Redeemed points.
	 * @param int   $entry_id Immutable ledger entry.
	 * @param array $context Ledger context.
	 */
	public function redeemed( $user_id, $points, $entry_id, $context ) {
		unset( $context );
		$this->queue( 'redeemed', $user_id, $points, $entry_id );
	}

	/**
	 * Append the outbox record inside an existing ledger transaction when present.
	 *
	 * @param string $kind Template category.
	 * @param int    $user_id Recipient.
	 * @param int    $points Event points.
	 * @param int    $entry_id Ledger entry.
	 */
	private function queue( $kind, $user_id, $points, $entry_id ) {
		$settings = $this->settings();
		$event    = 'redeemed' === $kind ? 'points_redeemed' : 'points_awarded';
		if ( ! $settings['enabled'] || ! $settings['templates'][ $kind ]['enabled'] || ! $user_id || ! $entry_id || ! $this->email_allowed( $user_id ) || false === apply_filters(
			'devoynx_rewards_notification_allowed',
			true,
			$event,
			$user_id,
			array(
				'points'   => $points,
				'entry_id' => $entry_id,
			)
		) ) {
			return;
		}
		try {
			$store = new ProgramStore();
			$store->locked(
				'email:' . $kind . ':' . absint( $entry_id ),
				'basic_email',
				static function ( $row ) use ( $store, $kind, $user_id, $points, $entry_id ) {
					return 'new' === $row['status'] ? $store->save(
						$row,
						array(
							'category' => $kind,
							'points'   => absint( $points ),
							'entry_id' => absint( $entry_id ),
						),
						'queued',
						array( 'user_id' => $user_id )
					) : $row;
				}
			);
		} catch ( \Throwable $error ) {
			// Notification infrastructure must not turn a committed payment into a failed checkout.
			wc_get_logger()->error( 'A reward email could not be queued safely.', array( 'source' => 'devoynx-rewards' ) );
		}
	}

	/**
	 * Respect the existing shared Free/Pro customer communication preference.
	 *
	 * @param int $user_id Recipient.
	 * @return bool
	 */
	private function email_allowed( $user_id ) {
		$preferences = get_user_meta( $user_id, '_devoynx_rewards_notification_preferences', true );
		return ! is_array( $preferences ) || ! array_key_exists( 'email', $preferences ) || ! empty( $preferences['email'] );
	}

	/** Schedule only after Action Scheduler initialization; no external service is used. */
	public function schedule() {
		if ( ! $this->settings()['enabled'] && ! ( new ProgramStore() )->pending( 'basic_email', 'queued', 1 ) ) {
			return;
		}
		if ( function_exists( 'as_has_scheduled_action' ) ) {
			if ( ! as_has_scheduled_action( self::HOOK, array(), 'devoynx-rewards' ) ) {
				as_schedule_recurring_action( time() + MINUTE_IN_SECONDS, 5 * MINUTE_IN_SECONDS, self::HOOK, array(), 'devoynx-rewards', true );
			}
		} elseif ( ! wp_next_scheduled( self::HOOK ) ) {
			wp_schedule_event( time() + HOUR_IN_SECONDS, 'hourly', self::HOOK );
		}
	}

	/** Process at most ten pending receipts per invocation. */
	public function process() {
		foreach ( ( new ProgramStore() )->pending( 'basic_email', 'queued', 10 ) as $row ) {
			$this->deliver( $row['event_key'] );
		}
	}

	/**
	 * Commit an attempt marker before calling mail; concurrent workers cannot resend.
	 *
	 * A crash after marking may lose delivery. Never automatically retry an uncertain
	 * transport attempt: WordPress mail acceptance cannot prove inbox delivery.
	 *
	 * @param string $key Outbox key.
	 * @return bool Whether the transport accepted this attempt.
	 */
	public function deliver( $key ) {
		$store    = new ProgramStore();
		$existing = $store->find( $key );
		if ( ! $existing || 'basic_email' !== $existing['kind'] ) {
			return false;
		}
		$row = $store->locked(
			$key,
			'basic_email',
			static function ( $locked ) use ( $store ) {
				if ( 'queued' !== $locked['status'] ) {
					return null;
				}
				return $store->save( $locked, json_decode( $locked['payload'], true ), 'attempted' );
			}
		);
		if ( ! $row ) {
			return false;
		}
		$status   = 'cancelled';
		$accepted = false;
		$switched = switch_to_user_locale( $row['user_id'] );
		try {
			$data     = json_decode( $row['payload'], true );
			$settings = $this->settings();
			$template = $settings['templates'][ $data['category'] ] ?? null;
			$user     = get_userdata( $row['user_id'] );
			if ( $settings['enabled'] && $template && $template['enabled'] && $user && is_email( $user->user_email ) && $this->email_allowed( $user->ID ) ) {
				$tokens   = array(
					'{points}'        => number_format_i18n( $data['points'] ),
					'{customer_name}' => sanitize_text_field( $user->display_name ),
					'{site_name}'     => sanitize_text_field( wp_specialchars_decode( get_bloginfo( 'name' ), ENT_QUOTES ) ),
					'{wallet_url}'    => wc_get_account_endpoint_url( 'rewards' ),
				);
				$subject  = sanitize_text_field( strtr( $template['subject'], $tokens ) );
				$body     = strtr( $template['body'], $tokens );
				$status   = 'failed';
				$accepted = (bool) wp_mail( $user->user_email, $subject, $body, array( 'Content-Type: text/plain; charset=UTF-8' ) );
				$status   = $accepted ? 'accepted' : 'failed';
			}
		} catch ( \Throwable $error ) {
			$status = 'failed';
		} finally {
			if ( $switched ) {
				restore_previous_locale();
			}
		}
		$store->locked(
			$key,
			'basic_email',
			static function ( $locked ) use ( $store, $status ) {
				return 'attempted' === $locked['status'] ? $store->save( $locked, json_decode( $locked['payload'], true ), $status ) : $locked;
			}
		);
		return $accepted;
	}

	/**
	 * Add the email configuration tab.
	 *
	 * @param array $tabs Existing tabs.
	 * @return array
	 */
	public function tabs( $tabs ) {
		$tabs['emails'] = __( 'Emails', 'devoynx-rewards' );
		return $tabs;
	}

	/** Save merchant-only plain-text template configuration. */
	public function save() {
		if ( 'POST' !== sanitize_text_field( wp_unslash( $_SERVER['REQUEST_METHOD'] ?? '' ) ) || ! current_user_can( 'manage_devoynx_rewards' ) ) {
			wp_die( esc_html__( 'Permission denied.', 'devoynx-rewards' ), 403 );
		}
		check_admin_referer( 'devoynx_rewards_basic_emails' );
		$settings = $this->sanitize( isset( $_POST['emails'] ) ? wp_unslash( $_POST['emails'] ) : array() ); // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- Every field is strictly validated and sanitized before persistence.
		if ( ! is_wp_error( $settings ) ) {
			update_option( self::OPTION, $settings, false );
		}
		wp_safe_redirect(
			add_query_arg(
				array(
					'page'         => 'devoynx-rewards',
					'tab'          => 'emails',
					'email_result' => is_wp_error( $settings ) ? 'invalid' : 'saved',
				),
				admin_url( 'admin.php' )
			)
		);
		exit;
	}

	/** Save only the current customer's shared email preference. */
	public function save_preference() {
		if ( 'POST' !== sanitize_text_field( wp_unslash( $_SERVER['REQUEST_METHOD'] ?? '' ) ) || ! get_current_user_id() ) {
			wp_die( esc_html__( 'Permission denied.', 'devoynx-rewards' ), 403 );
		}
		check_admin_referer( 'devoynx_rewards_email_preference' );
		$preferences          = get_user_meta( get_current_user_id(), '_devoynx_rewards_notification_preferences', true );
		$preferences          = is_array( $preferences ) ? $preferences : array();
		$preferences['email'] = ! empty( $_POST['email_enabled'] );
		update_user_meta( get_current_user_id(), '_devoynx_rewards_notification_preferences', $preferences );
		wp_safe_redirect( add_query_arg( 'email_preference_saved', '1', wc_get_account_endpoint_url( 'rewards' ) ) );
		exit;
	}

	/**
	 * Show the owner the Free email preference independently of add-ons.
	 *
	 * @param int $user_id Wallet owner.
	 */
	public function render_preference( $user_id ) {
		if ( ! $user_id || get_current_user_id() !== (int) $user_id || ! $this->settings()['enabled'] ) {
			return;
		}
		?>
		<section class="devoynx-email-preferences"><h3><?php esc_html_e( 'Reward email preferences', 'devoynx-rewards' ); ?></h3>
		<?php // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Read-only feedback on the owner's wallet.
		if ( isset( $_GET['email_preference_saved'] ) ) :
			?>
		<p role="status"><?php esc_html_e( 'Your email preference was saved.', 'devoynx-rewards' ); ?></p><?php endif; ?>
		<form method="post" action="<?php echo esc_url( admin_url( 'admin-post.php' ) ); ?>"><input type="hidden" name="action" value="devoynx_rewards_email_preference" /><?php wp_nonce_field( 'devoynx_rewards_email_preference' ); ?>
		<label><input type="checkbox" name="email_enabled" value="1" <?php checked( $this->email_allowed( $user_id ) ); ?> /> <?php esc_html_e( 'Email me when I earn, redeem or receive referral points', 'devoynx-rewards' ); ?></label>
		<button type="submit"><?php esc_html_e( 'Save email preference', 'devoynx-rewards' ); ?></button></form></section>
		<?php
	}

	/**
	 * Render actual queue counts and configurable templates.
	 *
	 * @param string $tab Selected merchant tab.
	 */
	public function render_admin( $tab ) {
		if ( 'emails' !== $tab || ! current_user_can( 'manage_devoynx_rewards' ) ) {
			return;
		}
		global $wpdb;
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery -- Merchant-only actual counts from the indexed custom outbox.
		$counts   = $wpdb->get_results( $wpdb->prepare( "SELECT status,COUNT(*) total FROM %i WHERE kind = 'basic_email' GROUP BY status", $wpdb->prefix . 'devoynx_rewards_program_records' ), ARRAY_A );
		$settings = $this->settings();
		$labels   = array(
			'earned'   => __( 'Earned points', 'devoynx-rewards' ),
			'redeemed' => __( 'Redeemed points', 'devoynx-rewards' ),
			'referral' => __( 'Referral points', 'devoynx-rewards' ),
		);
		$statuses = array(
			'queued'    => __( 'Queued', 'devoynx-rewards' ),
			'attempted' => __( 'Attempt started (outcome unknown)', 'devoynx-rewards' ),
			'accepted'  => __( 'Accepted by WordPress', 'devoynx-rewards' ),
			'failed'    => __( 'Failed', 'devoynx-rewards' ),
			'cancelled' => __( 'Cancelled', 'devoynx-rewards' ),
		);
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Read-only result notice on an authorized screen.
		$result = isset( $_GET['email_result'] ) ? sanitize_key( wp_unslash( $_GET['email_result'] ) ) : '';
		?>
		<section class="devoynx-panel"><h2><?php esc_html_e( 'Useful reward receipts', 'devoynx-rewards' ); ?></h2>
		<p><?php esc_html_e( 'Optional plain-text emails use your WordPress mail transport. Only one Free email category is queued per ledger event, and historical backfill emails are suppressed.', 'devoynx-rewards' ); ?></p>
		<p><?php esc_html_e( 'Attempts are marked before transport to prevent concurrent or repeated sends. Accepted means WordPress accepted the message, not that it reached an inbox. Failed or interrupted attempts are not automatically retried; inspect your mail logs. Sending depends on your background scheduler and can be delayed.', 'devoynx-rewards' ); ?></p>
		<?php
		if ( 'invalid' === $result ) :
			?>
			<p role="alert" class="devoynx-status--bad"><?php esc_html_e( 'Nothing was saved. Each template needs a nonempty plain-text subject and body within the displayed limits.', 'devoynx-rewards' ); ?></p>
			<?php
elseif ( 'saved' === $result ) :
	?>
			<p role="status" class="devoynx-status--ok"><?php esc_html_e( 'Email settings saved.', 'devoynx-rewards' ); ?></p><?php endif; ?>
		<dl class="devoynx-diagnostics">
		<?php
		foreach ( $counts as $count ) :
			?>
			<dt><?php echo esc_html( $statuses[ $count['status'] ] ?? __( 'Unknown', 'devoynx-rewards' ) ); ?></dt><dd><?php echo esc_html( number_format_i18n( $count['total'] ) ); ?></dd><?php endforeach; ?>
		</dl>
		<?php
		if ( ! $counts ) :
			?>
			<p><?php esc_html_e( 'No reward emails have been queued.', 'devoynx-rewards' ); ?></p><?php endif; ?>
		<form method="post" action="<?php echo esc_url( admin_url( 'admin-post.php' ) ); ?>"><input type="hidden" name="action" value="devoynx_rewards_basic_emails" /><?php wp_nonce_field( 'devoynx_rewards_basic_emails' ); ?>
		<label class="devoynx-form__check"><input type="checkbox" name="emails[enabled]" value="1" <?php checked( $settings['enabled'], 1 ); ?> /><?php esc_html_e( 'Enable Free reward emails', 'devoynx-rewards' ); ?></label>
		<p><?php esc_html_e( 'Supported placeholders: {points}, {customer_name}, {site_name}, {wallet_url}. Customer email preferences are honored again when queued messages are sent.', 'devoynx-rewards' ); ?></p>
		<?php foreach ( $labels as $kind => $label ) : ?>
			<fieldset class="devoynx-definition"><legend><?php echo esc_html( $label ); ?></legend>
			<?php
			$template = $settings['templates'][ $kind ];
			$prefix   = 'emails[templates][' . $kind . ']';
			?>
			<label><input type="checkbox" name="<?php echo esc_attr( $prefix . '[enabled]' ); ?>" value="1" <?php checked( $template['enabled'], 1 ); ?> /><?php esc_html_e( 'Send this receipt type', 'devoynx-rewards' ); ?></label>
			<label><?php esc_html_e( 'Subject (up to 160 characters)', 'devoynx-rewards' ); ?><input required maxlength="160" name="<?php echo esc_attr( $prefix . '[subject]' ); ?>" value="<?php echo esc_attr( $template['subject'] ); ?>" /></label>
			<label><?php esc_html_e( 'Plain-text body (up to 2,000 characters)', 'devoynx-rewards' ); ?><textarea required maxlength="2000" rows="4" name="<?php echo esc_attr( $prefix . '[body]' ); ?>"><?php echo esc_textarea( $template['body'] ); ?></textarea></label></fieldset>
		<?php endforeach; ?>
		<?php submit_button( __( 'Save email settings', 'devoynx-rewards' ) ); ?></form></section>
		<?php
	}
}