<?php

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

class AIEO_Workflow_AB {

	const MIN_REACH = 8; 

	public static function table() {
		global $wpdb;
		return $wpdb->prefix . 'aieo_workflow_ab';
	}

	public static function ensure_table() {
		global $wpdb;
		$t = self::table();
		if ( self::table_exists( $t ) ) {
			return true;
		}
		$charset = aieo_get_charset_collate();
		
		$wpdb->query( "CREATE TABLE IF NOT EXISTS `{$t}` (
			`id` bigint unsigned NOT NULL AUTO_INCREMENT,
			`workflow_id` bigint unsigned NOT NULL,
			`step_idx` int unsigned NOT NULL,
			`variant` int unsigned NOT NULL DEFAULT 0,
			`user_id` bigint unsigned NOT NULL DEFAULT 0,
			`recipient_email` varchar(190) NOT NULL DEFAULT '',
			`assigned_at` datetime DEFAULT NULL,
			PRIMARY KEY (`id`),
			UNIQUE KEY `uk_recipient` (`workflow_id`,`step_idx`,`user_id`,`recipient_email`),
			KEY `wf_step` (`workflow_id`,`step_idx`)
		) {$charset};" );
		return self::table_exists( $t );
	}

	
	public static function variants( $step ) {
		$base = array(
			'subject' => (string) ( $step['subject'] ?? '' ),
			'body'    => (string) ( $step['body'] ?? '' ),
		);
		$vs = trim( (string) ( $step['variant_subject'] ?? '' ) );
		$vb = trim( (string) ( $step['variant_body'] ?? '' ) );
		if ( '' === $vs && '' === $vb ) {
			return array( $base ); 
		}
		return array(
			$base,
			array(
				'subject' => '' !== $vs ? $vs : $base['subject'],
				'body'    => '' !== $vb ? $vb : $base['body'],
			),
		);
	}

	
	public static function choose( $workflow_id, $step_idx, $user_id, $email, $count ) {
		global $wpdb;
		$count = (int) $count;
		if ( $count <= 1 ) {
			return 0;
		}
		self::ensure_table();
		$t        = self::table();
		$user_id  = (int) $user_id;
		$email    = ( $user_id > 0 ) ? '' : strtolower( trim( (string) $email ) );
		$workflow_id = (int) $workflow_id;
		$step_idx = (int) $step_idx;

		
		$existing = $wpdb->get_var( $wpdb->prepare(
			"SELECT variant FROM `{$t}` WHERE workflow_id=%d AND step_idx=%d AND user_id=%d AND recipient_email=%s",
			$workflow_id, $step_idx, $user_id, $email
		) );
		if ( null !== $existing ) {
			return (int) $existing;
		}

		
		$epsilon = (float) apply_filters( 'aieo_ab_epsilon', 0.15 );
		$explore = ( $epsilon > 0 ) && ( mt_rand( 1, 1000 ) <= (int) round( $epsilon * 1000 ) );
		$variant = $explore ? mt_rand( 0, $count - 1 ) : self::best_variant( $workflow_id, $step_idx, $count );

		$wpdb->query( $wpdb->prepare(
			"INSERT IGNORE INTO `{$t}` (workflow_id, step_idx, variant, user_id, recipient_email, assigned_at)
			 VALUES (%d,%d,%d,%d,%s,%s)",
			$workflow_id, $step_idx, (int) $variant, $user_id, $email, gmdate( 'Y-m-d H:i:s' )
		) );
		
		$final = $wpdb->get_var( $wpdb->prepare(
			"SELECT variant FROM `{$t}` WHERE workflow_id=%d AND step_idx=%d AND user_id=%d AND recipient_email=%s",
			$workflow_id, $step_idx, $user_id, $email
		) );
		return ( null !== $final ) ? (int) $final : (int) $variant;
	}

	
	public static function best_variant( $workflow_id, $step_idx, $count ) {
		$perf = self::performance( $workflow_id, $step_idx );
		$rows = isset( $perf['variants'] ) ? $perf['variants'] : array();
		
		$reach = array_fill( 0, (int) $count, 0 );
		$reward = array_fill( 0, (int) $count, -1.0 );
		foreach ( $rows as $r ) {
			$i = (int) $r['variant'];
			if ( $i >= 0 && $i < $count ) {
				$reach[ $i ]  = (int) $r['reach'];
				$reward[ $i ] = (float) $r['reward'];
			}
		}
		foreach ( $reach as $i => $n ) {
			if ( $n < self::MIN_REACH ) {
				return $i; 
			}
		}
		$best = 0;
		$bestR = -1.0;
		foreach ( $reward as $i => $rw ) {
			if ( $rw > $bestR ) {
				$bestR = $rw;
				$best  = $i;
			}
		}
		return $best;
	}

	
	public static function performance( $workflow_id, $step_idx ) {
		global $wpdb;
		$workflow_id = (int) $workflow_id;
		$step_idx    = (int) $step_idx;
		$t    = self::table();
		$disp = $wpdb->prefix . 'aieo_push_dispatch';
		$out  = array( 'available' => false, 'variants' => array(), 'winner' => null );
		if ( ! self::table_exists( $t ) || ! self::table_exists( $disp ) ) {
			return $out;
		}
		$trigger = 'wf_' . $workflow_id;
		
		
		
		
		
		
		
		
		$rows = $wpdb->get_results( $wpdb->prepare(
			"SELECT x.variant AS variant, COUNT(*) AS reach,
			        SUM(x.opened) AS opens, SUM(x.clicked) AS clicks,
			        SUM(x.converted) AS conversions, SUM(x.revenue) AS revenue
			 FROM (
				SELECT ab.variant AS variant, ab.id AS abid,
				       MAX(d.opened_at IS NOT NULL) AS opened,
				       MAX(d.state = 'clicked') AS clicked,
				       MAX(CASE WHEN d.converted_order_id > 0 THEN 1 ELSE 0 END) AS converted,
				       COALESCE(SUM(d.revenue), 0) AS revenue
				FROM `{$t}` ab
				JOIN `{$disp}` d
				        ON d.trigger_id = %s
				       AND d.channel IN ('email','push')
				       AND d.state IN ('sent','clicked','converted','dismissed')
				       AND ( ( ab.user_id > 0 AND d.user_id = ab.user_id )
				             OR ( ab.user_id = 0 AND d.recipient_email = ab.recipient_email COLLATE utf8mb4_general_ci ) )
				WHERE ab.workflow_id = %d AND ab.step_idx = %d
				GROUP BY ab.id, ab.variant
			 ) x
			 GROUP BY x.variant
			 ORDER BY x.variant ASC",
			$trigger, $workflow_id, $step_idx
		), ARRAY_A );
		if ( empty( $rows ) ) {
			return $out;
		}
		$variants = array();
		$winner   = null;
		$best_rw  = -1.0;
		foreach ( $rows as $r ) {
			$reach  = (int) $r['reach'];
			$opens  = (int) $r['opens'];
			$clicks = (int) $r['clicks'];
			$conv   = (int) $r['conversions'];
			$reward = $reach > 0 ? ( ( $clicks + 0.25 * $opens ) / $reach ) : 0.0;
			$v = array(
				'variant'      => (int) $r['variant'],
				'reach'        => $reach,
				'opens'        => $opens,
				'open_rate'    => $reach > 0 ? round( 100 * $opens / $reach, 1 ) : 0.0,
				'clicks'       => $clicks,
				'ctr'          => $reach > 0 ? round( 100 * $clicks / $reach, 1 ) : 0.0,
				'conversions'  => $conv,
				'revenue'      => round( (float) $r['revenue'], 2 ),
				'reward'       => round( $reward, 4 ),
			);
			$variants[] = $v;
			if ( $reach >= self::MIN_REACH && $reward > $best_rw ) {
				$best_rw = $reward;
				$winner  = (int) $r['variant'];
			}
		}
		return array( 'available' => true, 'variants' => $variants, 'winner' => $winner );
	}

	private static function table_exists( $t ) {
		global $wpdb;
		return (string) $wpdb->get_var( $wpdb->prepare( 'SHOW TABLES LIKE %s', $t ) ) === $t;
	}
}