<?php
/**
 * Attribution Tracker for AI-referred orders.
 *
 * @package AICommerce\Analytics
 */

declare(strict_types=1);

namespace AICommerce\Analytics;

/**
 * Tracks orders attributed to AI platform referrals.
 */
class AttributionTracker {

	/**
	 * Known AI platform domains.
	 *
	 * @var array<string, string[]>
	 */
	public const AI_PLATFORMS = [
		'Perplexity' => [ 'perplexity.ai' ],
		'ChatGPT'    => [ 'chatgpt.com', 'chat.openai.com' ],
		'Gemini'     => [ 'gemini.google.com', 'bard.google.com' ],
		'Copilot'    => [ 'copilot.microsoft.com' ],
		'Claude'     => [ 'claude.ai' ],
		'You.com'    => [ 'you.com' ],
		'Grok'       => [ 'grok.com' ],
	];

	/**
	 * Known AI UTM source values.
	 *
	 * @var string[]
	 */
	private const AI_UTM_SOURCES = [ 'chatgpt', 'perplexity', 'gemini', 'copilot', 'claude' ];

	/**
	 * WordPress database instance.
	 *
	 * @var \wpdb
	 */
	private \wpdb $wpdb;

	/**
	 * Constructor.
	 *
	 * @param \wpdb $wpdb WordPress database instance.
	 */
	public function __construct( \wpdb $wpdb ) {
		$this->wpdb = $wpdb;
	}

	/**
	 * Detect AI referral session from HTTP referer or UTM parameters.
	 *
	 * Hooked to `wp` on the front-end only.
	 *
	 * @return void
	 */
	public function detect_ai_session(): void {
		if ( is_admin() ) {
			return;
		}

		$platform = null;
		$referrer = '';

		// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.NonceVerification.Recommended
		$raw_referrer = isset( $_SERVER['HTTP_REFERER'] ) ? wp_unslash( $_SERVER['HTTP_REFERER'] ) : '';

		if ( ! empty( $raw_referrer ) ) {
			$referrer = esc_url_raw( $raw_referrer );
			$platform = $this->identify_platform( $referrer );
		}

		if ( null === $platform ) {
			// phpcs:ignore WordPress.Security.NonceVerification.Recommended
			$utm_source = isset( $_GET['utm_source'] ) ? sanitize_key( $_GET['utm_source'] ) : '';

			if ( ! empty( $utm_source ) ) {
				$platform = $this->identify_platform_by_utm( $utm_source );
			}
		}

		if ( null === $platform ) {
			return;
		}

		if ( headers_sent() ) {
			return;
		}

		$cookie_path   = defined( 'COOKIEPATH' ) ? COOKIEPATH : '/';
		$cookie_domain = defined( 'COOKIE_DOMAIN' ) ? COOKIE_DOMAIN : '';
		$secure        = is_ssl();
		$expiry        = time() + HOUR_IN_SECONDS;

		setcookie( 'aicommerce_ai_source', $platform, $expiry, $cookie_path, $cookie_domain, $secure, true );
		setcookie( 'aicommerce_ai_referrer', esc_url_raw( $referrer ), $expiry, $cookie_path, $cookie_domain, $secure, true );
	}

	/**
	 * Record an AI-attributed order at checkout.
	 *
	 * Hooked to `woocommerce_thankyou`.
	 *
	 * @param int $order_id WooCommerce order ID.
	 * @return void
	 */
	public function record_ai_order( int $order_id ): void {
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended
		$platform = isset( $_COOKIE['aicommerce_ai_source'] ) ? sanitize_text_field( wp_unslash( $_COOKIE['aicommerce_ai_source'] ) ) : '';

		if ( empty( $platform ) ) {
			return;
		}

		$order = wc_get_order( $order_id );

		if ( ! $order ) {
			return;
		}

		// phpcs:ignore WordPress.Security.NonceVerification.Recommended
		$referrer_url = isset( $_COOKIE['aicommerce_ai_referrer'] ) ? sanitize_url( wp_unslash( $_COOKIE['aicommerce_ai_referrer'] ) ) : '';

		// Safe: internal $wpdb->prefix table names; user values use placeholders.
		// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		$this->wpdb->insert(
			"{$this->wpdb->prefix}aicommerce_attribution",
			[
				'order_id'        => $order_id,
				'referrer_source' => sanitize_text_field( $platform ),
				'referrer_url'    => $referrer_url,
				'revenue'         => (float) $order->get_total(),
				'currency'        => $order->get_currency(),
				'attributed_at'   => current_time( 'mysql' ),
			],
			[ '%d', '%s', '%s', '%f', '%s', '%s' ]
		);
		// phpcs:enable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
	}

	/**
	 * Get attribution summary for a given number of days.
	 *
	 * @param int $days Number of days to look back (default 30).
	 * @return array{
	 *     total_revenue: float,
	 *     order_count: int,
	 *     by_platform: array<string, array{revenue: float, orders: int}>,
	 *     daily: array<int, array{date: string, revenue: float, orders: int}>,
	 *     vs_previous: array{revenue_change_pct: float, order_change_pct: float},
	 * }
	 */
	public function get_summary( int $days = 30 ): array {
		$table      = "{$this->wpdb->prefix}aicommerce_attribution";
		$date_start = gmdate( 'Y-m-d H:i:s', strtotime( "-{$days} days" ) );
		$prev_start = gmdate( 'Y-m-d H:i:s', strtotime( '-' . ( $days * 2 ) . ' days' ) );

		// 1. Total revenue and order count for the current period.
		// Safe: internal $wpdb->prefix table names; user values use placeholders.
		// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		$totals = $this->wpdb->get_row(
			$this->wpdb->prepare(
				"SELECT COALESCE(SUM(revenue), 0) AS total_revenue, COUNT(*) AS order_count FROM {$table} WHERE attributed_at >= %s",
				$date_start
			)
		);
		// phpcs:enable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter

		$total_revenue = null !== $totals ? (float) $totals->total_revenue : 0.0;
		$order_count   = null !== $totals ? (int) $totals->order_count : 0;

		// 2. Revenue and order count grouped by platform.
		// Safe: internal $wpdb->prefix table names; user values use placeholders.
		// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		$platform_rows = $this->wpdb->get_results(
			$this->wpdb->prepare(
				"SELECT referrer_source, COALESCE(SUM(revenue), 0) AS revenue, COUNT(*) AS orders FROM {$table} WHERE attributed_at >= %s GROUP BY referrer_source",
				$date_start
			)
		);
		// phpcs:enable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter

		$by_platform = [];
		if ( is_array( $platform_rows ) ) {
			foreach ( $platform_rows as $row ) {
				$by_platform[ $row->referrer_source ] = [
					'revenue' => (float) $row->revenue,
					'orders'  => (int) $row->orders,
				];
			}
		}

		// 3. Daily breakdown.
		// Safe: internal $wpdb->prefix table names; user values use placeholders.
		// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		$daily_rows = $this->wpdb->get_results(
			$this->wpdb->prepare(
				"SELECT DATE(attributed_at) AS date, COALESCE(SUM(revenue), 0) AS revenue, COUNT(*) AS orders FROM {$table} WHERE attributed_at >= %s GROUP BY DATE(attributed_at) ORDER BY date ASC",
				$date_start
			)
		);
		// phpcs:enable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter

		$daily = [];
		if ( is_array( $daily_rows ) ) {
			foreach ( $daily_rows as $row ) {
				$daily[] = [
					'date'    => $row->date,
					'revenue' => (float) $row->revenue,
					'orders'  => (int) $row->orders,
				];
			}
		}

		// 4. Previous period totals for comparison.
		// Safe: internal $wpdb->prefix table names; user values use placeholders.
		// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		$prev_totals = $this->wpdb->get_row(
			$this->wpdb->prepare(
				"SELECT COALESCE(SUM(revenue), 0) AS total_revenue, COUNT(*) AS order_count FROM {$table} WHERE attributed_at >= %s AND attributed_at < %s",
				$prev_start,
				$date_start
			)
		);
		// phpcs:enable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter

		$prev_revenue = null !== $prev_totals ? (float) $prev_totals->total_revenue : 0.0;
		$prev_orders  = null !== $prev_totals ? (int) $prev_totals->order_count : 0;

		$revenue_change_pct = 0.0 < $prev_revenue
			? round( ( ( $total_revenue - $prev_revenue ) / $prev_revenue ) * 100, 2 )
			: 0.0;

		$order_change_pct = 0 < $prev_orders
			? round( ( ( $order_count - $prev_orders ) / $prev_orders ) * 100, 2 )
			: 0.0;

		return [
			'total_revenue' => $total_revenue,
			'order_count'   => $order_count,
			'by_platform'   => $by_platform,
			'daily'         => $daily,
			'vs_previous'   => [
				'revenue_change_pct' => $revenue_change_pct,
				'order_change_pct'   => $order_change_pct,
			],
		];
	}

	/**
	 * Identify an AI platform from a referrer URL.
	 *
	 * @param string $referrer The HTTP referrer URL.
	 * @return string|null Platform name or null if not recognized.
	 */
	private function identify_platform( string $referrer ): ?string {
		$host = wp_parse_url( $referrer, PHP_URL_HOST );

		if ( empty( $host ) ) {
			return null;
		}

		$host = strtolower( $host );

		foreach ( self::AI_PLATFORMS as $platform => $domains ) {
			foreach ( $domains as $domain ) {
				if ( $host === $domain || str_ends_with( $host, '.' . $domain ) ) {
					return $platform;
				}
			}
		}

		return null;
	}

	/**
	 * Identify an AI platform from a UTM source parameter.
	 *
	 * @param string $utm_source The sanitized utm_source value.
	 * @return string|null Platform name or null if not recognized.
	 */
	private function identify_platform_by_utm( string $utm_source ): ?string {
		$utm_source = strtolower( $utm_source );

		if ( ! in_array( $utm_source, self::AI_UTM_SOURCES, true ) ) {
			return null;
		}

		$utm_to_platform = [
			'chatgpt'    => 'ChatGPT',
			'perplexity' => 'Perplexity',
			'gemini'     => 'Gemini',
			'copilot'    => 'Copilot',
			'claude'     => 'Claude',
		];

		return $utm_to_platform[ $utm_source ] ?? null;
	}
}