<?php
/**
 * @fs_premium_only
 *
 * Weekly email digest.
 *
 * A once-a-week WP-Cron job that emails the site owner a short summary: AI bot
 * visits, human referrals from AI assistants, top pages, the estimated token
 * saving and the current AI Readiness Score. No external services — it uses
 * wp_mail(), so it rides whatever mail transport the site already has.
 *
 * @package ADG_AI_Markdown
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

class ADG_AIM_Digest {

	/** Cron hook name. */
	const HOOK = 'adg_aim_weekly_digest';

	/**
	 * Register hooks (the cron callback).
	 */
	public function hooks() {
		add_action( self::HOOK, array( __CLASS__, 'send' ) );
		add_action( 'init', array( __CLASS__, 'ensure_schedule' ) );
	}

	/**
	 * Make the schedule match the setting: schedule when enabled, clear when not.
	 */
	public static function ensure_schedule() {
		$enabled   = (bool) ADG_AIM_Plugin::get_setting( 'weekly_digest', false );
		$scheduled = wp_next_scheduled( self::HOOK );

		if ( $enabled && ! $scheduled ) {
			// First run ~24h out, then weekly.
			wp_schedule_event( time() + DAY_IN_SECONDS, 'weekly', self::HOOK );
		} elseif ( ! $enabled && $scheduled ) {
			self::clear_schedule();
		}
	}

	/**
	 * Remove any scheduled digest events (deactivation / disable).
	 */
	public static function clear_schedule() {
		$ts = wp_next_scheduled( self::HOOK );
		while ( $ts ) {
			wp_unschedule_event( $ts, self::HOOK );
			$ts = wp_next_scheduled( self::HOOK );
		}
	}

	/**
	 * The recipient address.
	 *
	 * @return string
	 */
	public static function recipient() {
		$email = (string) ADG_AIM_Plugin::get_setting( 'digest_email', '' );
		$email = trim( $email );
		if ( '' === $email || ! is_email( $email ) ) {
			$email = get_option( 'admin_email' );
		}
		return (string) $email;
	}

	/**
	 * Build and send the digest email.
	 *
	 * @return bool Whether wp_mail() accepted the message.
	 */
	public static function send() {
		if ( ! (bool) ADG_AIM_Plugin::get_setting( 'weekly_digest', false ) ) {
			return false;
		}

		$to = self::recipient();
		if ( '' === $to ) {
			return false;
		}

		$site    = wp_specialchars_decode( get_bloginfo( 'name' ), ENT_QUOTES );
		$subject = sprintf(
			/* translators: %s: site name */
			__( '[%s] Weekly AI visibility digest', 'adg-markdown-for-ai-crawlers' ),
			$site
		);

		$body = self::build_body( $site );

		return (bool) wp_mail( $to, $subject, $body );
	}

	/**
	 * Compose the plain-text digest body.
	 *
	 * @param string $site Site name.
	 * @return string
	 */
	public static function build_body( $site ) {
		$stats     = ADG_AIM_Analytics::get();
		$refs      = ADG_AIM_Referrals::get();
		$readiness = ADG_AIM_Readiness::compute();
		$savings   = ADG_AIM_Token_Savings::get();

		$bot_week = (int) array_sum( ADG_AIM_Analytics::daily_series( $stats, 7 ) );
		$ref_week = ADG_AIM_Referrals::sum_last_days( $refs, 7 );

		$lines   = array();
		$lines[] = sprintf(
			/* translators: %s: site name */
			__( 'Weekly AI visibility digest for %s', 'adg-markdown-for-ai-crawlers' ),
			$site
		);
		$lines[] = str_repeat( '=', 48 );
		$lines[] = '';

		// Readiness.
		$lines[] = sprintf(
			/* translators: 1: score, 2: grade */
			__( 'AI Readiness Score: %1$d/100 (%2$s)', 'adg-markdown-for-ai-crawlers' ),
			(int) $readiness['score'],
			$readiness['grade']
		);
		$lines[] = '';

		// Bot activity.
		$lines[] = __( 'AI crawler visits (last 7 days): ', 'adg-markdown-for-ai-crawlers' ) . number_format_i18n( $bot_week );
		$lines[] = __( 'AI crawler visits (all time): ', 'adg-markdown-for-ai-crawlers' ) . number_format_i18n( ADG_AIM_Analytics::total( $stats ) );

		// Referrals.
		$lines[] = '';
		$lines[] = __( 'Human referrals from AI assistants (last 7 days): ', 'adg-markdown-for-ai-crawlers' ) . number_format_i18n( $ref_week );
		$by_source = ADG_AIM_Referrals::by_source( $refs );
		if ( ! empty( $by_source ) ) {
			foreach ( array_slice( $by_source, 0, 6 ) as $row ) {
				$lines[] = '  - ' . $row['label'] . ': ' . number_format_i18n( $row['count'] );
			}
		}

		// Token savings.
		$lines[] = '';
		if ( ! empty( $savings['posts'] ) ) {
			$lines[] = sprintf(
				/* translators: 1: percent, 2: token count, 3: sampled posts */
				__( 'Markdown saves ~%1$s%% vs HTML (~%2$s tokens across %3$d sampled pages).', 'adg-markdown-for-ai-crawlers' ),
				number_format_i18n( (float) $savings['pct'], 1 ),
				number_format_i18n( (int) $savings['tokens_saved'] ),
				(int) $savings['posts']
			);
		}

		// Top pages read by AI.
		$top = ADG_AIM_Analytics::top_pages( $stats, 5 );
		if ( ! empty( $top ) ) {
			$lines[] = '';
			$lines[] = __( 'Top pages read by AI crawlers:', 'adg-markdown-for-ai-crawlers' );
			foreach ( $top as $url => $count ) {
				$lines[] = '  - ' . $url . ' (' . number_format_i18n( $count ) . ')';
			}
		}

		$lines[] = '';
		$lines[] = str_repeat( '-', 48 );
		$lines[] = sprintf(
			/* translators: %s: settings URL */
			__( 'Manage: %s', 'adg-markdown-for-ai-crawlers' ),
			admin_url( 'options-general.php?page=' . ADG_AIM_Admin_Settings::PAGE_SLUG )
		);

		$text = implode( "\n", $lines ) . "\n";

		// Plain-text email: normalize the non-breaking spaces / HTML entities that
		// number_format_i18n() emits in some locales.
		$text = str_replace( array( "\xc2\xa0", '&nbsp;' ), ' ', $text );
		$text = html_entity_decode( $text, ENT_QUOTES, 'UTF-8' );

		return $text;
	}
}