<?php
/**
 * Email digest builder, scheduler, and sender.
 *
 * @package ContentCortex
 */

defined( 'ABSPATH' ) || exit;

/**
 * Class OCAP_Email
 */
class OCAP_Email {

	/**
	 * Hook name for cron.
	 */
	const CRON_HOOK = 'ocap_send_digest';

	/**
	 * Plain text content holder for phpmailer_init.
	 *
	 * @var string
	 */
	protected $current_alt_body = '';

	/**
	 * Initialize hooks.
	 */
	public function init() {
		add_action( self::CRON_HOOK, array( $this, 'cron_send_digest' ) );
		add_action( 'sct_send_digest', array( $this, 'cron_send_digest' ) );
		add_action( 'wp_ajax_ocap_send_test_email', array( $this, 'ajax_send_test_email' ) );
		add_action( 'wp_ajax_sct_send_test_email', array( $this, 'ajax_send_test_email' ) );
		add_action( 'wp_ajax_ocap_email_preview', array( $this, 'ajax_preview_email' ) );
		add_action( 'wp_ajax_sct_email_preview', array( $this, 'ajax_preview_email' ) );
	}

	/**
	 * Cron callback to send scheduled digest and queue the next one.
	 */
	public function cron_send_digest() {
		$settings  = ocap_get_settings();
		$email_cfg = isset( $settings['email'] ) ? $settings['email'] : array();

		if ( empty( $email_cfg['enabled'] ) ) {
			return;
		}

		$this->send_digest();

		// Schedule next event.
		$this->schedule_next_event();
	}

	/**
	 * Calculate the next send timestamp in UTC based on settings.
	 *
	 * @param array|null             $email_cfg Optional email config override.
	 * @param DateTimeImmutable|null $from_dt   Optional reference datetime.
	 * @return int Unix timestamp.
	 */
	public function calculate_next_timestamp( $email_cfg = null, $from_dt = null ) {
		if ( null === $email_cfg ) {
			$settings  = ocap_get_settings();
			$email_cfg = isset( $settings['email'] ) ? $settings['email'] : array();
		}

		$tz = wp_timezone();

		if ( null === $from_dt ) {
			$now = new DateTimeImmutable( 'now', $tz );
		} else {
			$now = $from_dt->setTimezone( $tz );
		}

		$frequency = isset( $email_cfg['frequency'] ) ? $email_cfg['frequency'] : 'quarterly';
		$send_day  = isset( $email_cfg['send_day'] ) ? (int) $email_cfg['send_day'] : 1;
		$send_time = ! empty( $email_cfg['send_time'] ) ? $email_cfg['send_time'] : '09:00';

		$time_parts = explode( ':', $send_time );
		$hour       = isset( $time_parts[0] ) ? (int) $time_parts[0] : 9;
		$minute     = isset( $time_parts[1] ) ? (int) $time_parts[1] : 0;

		if ( 'weekly' === $frequency ) {
			// Day of week: 1 for Monday through 7 for Sunday.
			$send_day = max( 1, min( 7, $send_day ) );
			$cur_w    = (int) $now->format( 'N' ); // 1 (Mon) to 7 (Sun).

			$candidate = $now->setTime( $hour, $minute, 0 );

			if ( $cur_w === $send_day && $candidate > $now ) {
				// Today at send_time.
				$next_dt = $candidate;
			} else {
				$days_ahead = ( $send_day - $cur_w + 7 ) % 7;
				if ( 0 === $days_ahead ) {
					$days_ahead = 7;
				}
				$next_dt = $now->modify( "+{$days_ahead} days" )->setTime( $hour, $minute, 0 );
			}
		} elseif ( 'monthly' === $frequency ) {
			// send_day: 1 to 28.
			$send_day  = max( 1, min( 28, $send_day ) );
			$candidate = $now->setDate( (int) $now->format( 'Y' ), (int) $now->format( 'm' ), $send_day )->setTime( $hour, $minute, 0 );

			if ( $candidate > $now ) {
				$next_dt = $candidate;
			} else {
				$next_dt = $candidate->modify( '+1 month' );
			}
		} else {
			// Quarterly: every 3 months.
			$send_day  = max( 1, min( 28, $send_day ) );
			$candidate = $now->setDate( (int) $now->format( 'Y' ), (int) $now->format( 'm' ), $send_day )->setTime( $hour, $minute, 0 );

			if ( $candidate > $now ) {
				$next_dt = $candidate;
			} else {
				$next_dt = $candidate->modify( '+3 months' );
			}
		}

		return $next_dt->getTimestamp();
	}

	/**
	 * Schedule the next digest run.
	 */
	public function schedule_next_event() {
		$this->clear_scheduled_event();

		$settings  = ocap_get_settings();
		$email_cfg = isset( $settings['email'] ) ? $settings['email'] : array();

		if ( empty( $email_cfg['enabled'] ) ) {
			return;
		}

		$next_ts = $this->calculate_next_timestamp( $email_cfg );
		wp_schedule_single_event( $next_ts, self::CRON_HOOK );
	}

	/**
	 * Clear scheduled cron event.
	 */
	public function clear_scheduled_event() {
		wp_clear_scheduled_hook( self::CRON_HOOK );
		wp_clear_scheduled_hook( 'sct_send_digest' );
	}

	/**
	 * Get formatted string of next scheduled send date.
	 *
	 * @return string Formatted date or 'Not scheduled'.
	 */
	public function get_next_scheduled_date() {
		$next_ts = wp_next_scheduled( self::CRON_HOOK );
		if ( ! $next_ts ) {
			$next_ts = wp_next_scheduled( 'sct_send_digest' );
		}

		if ( ! $next_ts ) {
			return __( 'Not scheduled (digest is disabled or not set up)', 'contentcortex' );
		}

		$tz      = wp_timezone();
		$dt      = new DateTimeImmutable( '@' . $next_ts );
		$dt_site = $dt->setTimezone( $tz );

		$date_format = get_option( 'date_format' ) . ' ' . get_option( 'time_format' );
		return $dt_site->format( $date_format ) . ' (' . $tz->getName() . ')';
	}

	/**
	 * Build template data array.
	 *
	 * @param array|null $custom_settings Optional settings override (e.g. from test form).
	 * @return array
	 */
	public function build_template_data( $custom_settings = null ) {
		$settings  = ocap_get_settings();
		$email_cfg = isset( $settings['email'] ) ? $settings['email'] : array();

		if ( is_array( $custom_settings ) ) {
			$email_cfg = array_merge( $email_cfg, $custom_settings );
		}

		$max_items = isset( $email_cfg['max_items'] ) ? max( 1, (int) $email_cfg['max_items'] ) : 25;

		// Query stale items.
		$query = new OCAP_Query(
			array(
				'view'     => 'stale',
				'per_page' => $max_items,
				'paged'    => 1,
				'orderby'  => 'days',
				'order'    => 'DESC',
			)
		);

		$items       = $query->get_results();
		$total_count = $query->get_total_items();
		$by_type_raw = $query->get_counts_by_type();

		// Convert by_type to human labels.
		$by_type = array();
		foreach ( $by_type_raw as $pt => $cnt ) {
			$pt_obj            = get_post_type_object( $pt );
			$label             = $pt_obj ? $pt_obj->labels->name : ucfirst( $pt );
			$by_type[ $label ] = $cnt;
		}

		// Calculate quarter e.g. "Q4 2026".
		$tz      = wp_timezone();
		$now     = new DateTimeImmutable( 'now', $tz );
		$month   = (int) $now->format( 'n' );
		$q_num   = (int) ceil( $month / 3 );
		$quarter = sprintf( 'Q%d %s', $q_num, $now->format( 'Y' ) );

		$site_name   = get_bloginfo( 'name' );
		$site_url    = home_url();
		$report_url  = ocap_get_report_url();
		$date_format = get_option( 'date_format' );
		$send_date   = $now->format( $date_format );

		$placeholders = array(
			'{site_name}'   => esc_html( $site_name ),
			'{site_url}'    => esc_url( $site_url ),
			'{stale_count}' => number_format_i18n( $total_count ),
			'{report_url}'  => esc_url( $report_url ),
			'{date}'        => esc_html( $send_date ),
			'{quarter}'     => esc_html( $quarter ),
		);

		// Subject placeholders (plain text).
		$subject_placeholders = array(
			'{site_name}'   => $site_name,
			'{site_url}'    => $site_url,
			'{stale_count}' => (string) $total_count,
			'{report_url}'  => $report_url,
			'{date}'        => $send_date,
			'{quarter}'     => $quarter,
		);

		$raw_heading = ! empty( $email_cfg['heading'] ) ? $email_cfg['heading'] : __( 'Content that needs your attention', 'contentcortex' );
		$raw_intro   = ! empty( $email_cfg['intro'] ) ? $email_cfg['intro'] : __( 'These items have not been updated within their review window.', 'contentcortex' );
		$raw_footer  = ! empty( $email_cfg['footer'] ) ? $email_cfg['footer'] : __( 'Sent by ContentCortex from {site_name}.', 'contentcortex' );
		$raw_subject = ! empty( $email_cfg['subject'] ) ? $email_cfg['subject'] : __( 'Content refresh report: {stale_count} outdated items on {site_name}', 'contentcortex' );

		$heading = strtr( esc_html( $raw_heading ), $placeholders );
		$intro   = wp_kses_post( strtr( $raw_intro, $placeholders ) );
		$footer  = wp_kses_post( strtr( $raw_footer, $placeholders ) );
		$subject = strtr( sanitize_text_field( $raw_subject ), $subject_placeholders );

		$logo_id  = isset( $email_cfg['logo_id'] ) ? absint( $email_cfg['logo_id'] ) : 0;
		$logo_url = '';
		if ( $logo_id > 0 ) {
			$logo_src = wp_get_attachment_image_src( $logo_id, 'medium' );
			if ( $logo_src ) {
				$logo_url = $logo_src[0];
			}
		}

		$brand_color = ! empty( $email_cfg['brand_color'] ) ? sanitize_hex_color( $email_cfg['brand_color'] ) : '#2563eb';
		if ( empty( $brand_color ) ) {
			$brand_color = '#2563eb';
		}

		$button_text = ! empty( $email_cfg['button_text'] ) ? sanitize_text_field( $email_cfg['button_text'] ) : __( 'Open full report', 'contentcortex' );
		$columns     = isset( $email_cfg['show_columns'] ) && is_array( $email_cfg['show_columns'] ) ? $email_cfg['show_columns'] : array( 'type', 'days', 'author' );

		$formatted_items = array();
		foreach ( $items as $item ) {
			$formatted_items[] = array(
				'title'    => $item['title'],
				'edit_url' => $item['edit_url'],
				'view_url' => $item['view_url'],
				'type'     => $item['post_type_label'],
				'days'     => $item['days_since_update'],
				'limit'    => $item['day_limit'],
				'author'   => $item['author_name'],
				'severity' => $item['severity'],
			);
		}

		$data = array(
			'site_name'   => $site_name,
			'heading'     => $heading,
			'intro'       => $intro,
			'footer'      => $footer,
			'subject'     => $subject,
			'logo_url'    => $logo_url,
			'brand_color' => $brand_color,
			'button_text' => $button_text,
			'report_url'  => $report_url,
			'total'       => $total_count,
			'shown'       => count( $formatted_items ),
			'columns'     => $columns,
			'items'       => $formatted_items,
			'by_type'     => $by_type,
		);

		return apply_filters( 'ocap_email_data', $data );
	}

	/**
	 * Locate template file, checking theme override first.
	 *
	 * @param string $template_name Relative template file name.
	 * @return string File path.
	 */
	public function locate_template( $template_name ) {
		// Check child theme then parent theme: {theme}/contentcortex/email/{template_name}.
		$theme_file = locate_template(
			array(
				'contentcortex/email/' . $template_name,
				'contentcortex/' . $template_name,
				'stale-content-tracker/email/' . $template_name,
				'stale-content-tracker/' . $template_name,
			)
		);

		if ( $theme_file ) {
			return $theme_file;
		}

		return OCAP_PLUGIN_DIR . 'templates/email/' . $template_name;
	}

	/**
	 * Render HTML digest email.
	 *
	 * @param array $data Template data.
	 * @return string Rendered HTML.
	 */
	public function render_html( $data ) {
		$template_path = $this->locate_template( 'digest.php' );

		ob_start();
		if ( file_exists( $template_path ) ) {
			include $template_path;
		}
		$html = ob_get_clean();

		return apply_filters( 'ocap_email_html', $html, $data );
	}

	/**
	 * Render plain text digest email fallback.
	 *
	 * @param array $data Template data.
	 * @return string Rendered plain text.
	 */
	public function render_plain( $data ) {
		$template_path = $this->locate_template( 'digest-plain.php' );

		ob_start();
		if ( file_exists( $template_path ) ) {
			include $template_path;
		}
		$plain = ob_get_clean();

		return apply_filters( 'ocap_email_plain', $plain, $data );
	}

	/**
	 * Hook callback to set text/html content type.
	 *
	 * @return string
	 */
	public function set_html_content_type() {
		return 'text/html';
	}

	/**
	 * Hook callback to configure PHPMailer AltBody for multipart email.
	 *
	 * @param \PHPMailer\PHPMailer\PHPMailer $phpmailer PHPMailer instance.
	 */
	public function set_phpmailer_alt_body( $phpmailer ) {
		if ( ! empty( $this->current_alt_body ) ) {
			// phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- External library PHPMailer property.
			$phpmailer->AltBody = $this->current_alt_body;
		}
	}

	/**
	 * Send the digest email.
	 *
	 * @param array|null $recipients_override Optional recipients list.
	 * @param array|null $settings_override   Optional settings override.
	 * @return bool True if sent, false otherwise.
	 */
	public function send_digest( $recipients_override = null, $settings_override = null ) {
		$settings  = ocap_get_settings();
		$email_cfg = isset( $settings['email'] ) ? $settings['email'] : array();

		if ( is_array( $settings_override ) ) {
			$email_cfg = array_merge( $email_cfg, $settings_override );
		}

		$data = $this->build_template_data( $settings_override );

		// Check only_if_stale flag.
		if ( ! empty( $email_cfg['only_if_stale'] ) && 0 === $data['total'] && null === $recipients_override ) {
			// Skip sending if no stale items (except for explicit test sends).
			return false;
		}

		// Determine recipients.
		if ( ! empty( $recipients_override ) ) {
			$recipients = (array) $recipients_override;
		} else {
			$recipients = isset( $email_cfg['recipients'] ) ? (array) $email_cfg['recipients'] : array();
		}

		$recipients = array_filter( array_map( 'sanitize_email', $recipients ) );
		$recipients = apply_filters( 'ocap_email_recipients', $recipients );

		if ( empty( $recipients ) ) {
			return false;
		}

		$subject = apply_filters( 'ocap_email_subject', $data['subject'], $data );
		$html    = $this->render_html( $data );
		$plain   = $this->render_plain( $data );

		$this->current_alt_body = $plain;

		// Attach hooks.
		add_filter( 'wp_mail_content_type', array( $this, 'set_html_content_type' ) );
		add_action( 'phpmailer_init', array( $this, 'set_phpmailer_alt_body' ) );

		$sent = wp_mail( $recipients, $subject, $html );

		// Clean up hooks.
		remove_filter( 'wp_mail_content_type', array( $this, 'set_html_content_type' ) );
		remove_action( 'phpmailer_init', array( $this, 'set_phpmailer_alt_body' ) );
		$this->current_alt_body = '';

		return (bool) $sent;
	}

	/**
	 * AJAX endpoint to render live HTML preview.
	 */
	public function ajax_preview_email() {
		if ( ! check_ajax_referer( 'ocap_preview_nonce', 'security', false ) && ! check_ajax_referer( 'sct_preview_nonce', 'security', false ) ) {
			wp_die( -1 );
		}

		if ( ! current_user_can( 'manage_options' ) ) {
			wp_die( -1 );
		}

		// Optional overrides passed from form.
		$overrides = array();
		if ( isset( $_POST['heading'] ) ) {
			$overrides['heading'] = sanitize_text_field( wp_unslash( $_POST['heading'] ) );
		}
		if ( isset( $_POST['intro'] ) ) {
			$overrides['intro'] = wp_kses_post( wp_unslash( $_POST['intro'] ) );
		}
		if ( isset( $_POST['footer'] ) ) {
			$overrides['footer'] = wp_kses_post( wp_unslash( $_POST['footer'] ) );
		}
		if ( isset( $_POST['button_text'] ) ) {
			$overrides['button_text'] = sanitize_text_field( wp_unslash( $_POST['button_text'] ) );
		}
		if ( isset( $_POST['brand_color'] ) ) {
			$overrides['brand_color'] = sanitize_hex_color( wp_unslash( $_POST['brand_color'] ) );
		}
		if ( isset( $_POST['logo_id'] ) ) {
			$overrides['logo_id'] = absint( $_POST['logo_id'] );
		}
		if ( isset( $_POST['show_columns'] ) && is_array( $_POST['show_columns'] ) ) {
			$overrides['show_columns'] = array_map( 'sanitize_key', $_POST['show_columns'] );
		}

		$data = $this->build_template_data( $overrides );
		$html = $this->render_html( $data );

		header( 'Content-Type: text/html; charset=utf-8' );
		echo $html; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
		exit;
	}

	/**
	 * AJAX endpoint to send a test email to the current user.
	 */
	public function ajax_send_test_email() {
		if ( ! check_ajax_referer( 'ocap_test_email_nonce', 'security', false ) && ! check_ajax_referer( 'sct_test_email_nonce', 'security', false ) ) {
			wp_send_json_error( array( 'message' => __( 'Security check failed.', 'contentcortex' ) ) );
		}

		if ( ! current_user_can( 'manage_options' ) ) {
			wp_send_json_error( array( 'message' => __( 'Permission denied.', 'contentcortex' ) ) );
		}

		$current_user = wp_get_current_user();
		if ( ! $current_user || ! is_email( $current_user->user_email ) ) {
			wp_send_json_error( array( 'message' => __( 'Could not find current user email.', 'contentcortex' ) ) );
		}

		// Optional overrides passed from form.
		$overrides = array();
		if ( isset( $_POST['heading'] ) ) {
			$overrides['heading'] = sanitize_text_field( wp_unslash( $_POST['heading'] ) );
		}
		if ( isset( $_POST['intro'] ) ) {
			$overrides['intro'] = wp_kses_post( wp_unslash( $_POST['intro'] ) );
		}
		if ( isset( $_POST['footer'] ) ) {
			$overrides['footer'] = wp_kses_post( wp_unslash( $_POST['footer'] ) );
		}
		if ( isset( $_POST['button_text'] ) ) {
			$overrides['button_text'] = sanitize_text_field( wp_unslash( $_POST['button_text'] ) );
		}
		if ( isset( $_POST['brand_color'] ) ) {
			$overrides['brand_color'] = sanitize_hex_color( wp_unslash( $_POST['brand_color'] ) );
		}
		if ( isset( $_POST['logo_id'] ) ) {
			$overrides['logo_id'] = absint( $_POST['logo_id'] );
		}
		if ( isset( $_POST['show_columns'] ) && is_array( $_POST['show_columns'] ) ) {
			$overrides['show_columns'] = array_map( 'sanitize_key', $_POST['show_columns'] );
		}

		$sent = $this->send_digest( array( $current_user->user_email ), $overrides );

		if ( $sent ) {
			wp_send_json_success(
				array(
					'message' => sprintf(
						/* translators: %s: recipient email address */
						__( 'Test email successfully sent to %s!', 'contentcortex' ),
						esc_html( $current_user->user_email )
					),
				)
			);
		} else {
			wp_send_json_error(
				array(
					'message' => sprintf(
						/* translators: %s: recipient email address */
						__( 'Failed to send test email to %s. Please check your WordPress mail configuration.', 'contentcortex' ),
						esc_html( $current_user->user_email )
					),
				)
			);
		}
	}
}