<?php
/** Aggregate individual retained requests instead of conversation rows. */
namespace AISupportAssistant\Chat;
if ( ! defined( 'ABSPATH' ) ) { exit; }

class Statistics {
	public static function summarize(): array {
		global $wpdb;
		$result = array( 'total' => 0, 'today' => 0, 'completed' => 0, 'fallback' => 0, 'failed' => 0, 'unknown' => 0, 'openai' => 0, 'gemini' => 0, 'native' => 0, 'days' => array() );
		$today = new \DateTimeImmutable( 'today', wp_timezone() );
		for ( $i = 6; $i >= 0; --$i ) {
			$result['days'][ $today->modify( '-' . $i . ' days' )->format( 'Y-m-d' ) ] = 0;
		}
		$last_id = 0;
		do {
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- No core API reads these custom conversation records; bounded pages keep admin metrics current after writes and retention cleanup.
			$rows = $wpdb->get_results( $wpdb->prepare( 'SELECT id, messages, question, answer, provider, status, created_at, updated_at FROM %i WHERE id > %d ORDER BY id LIMIT 100', \AISupportAssistant\Database\DatabaseManager::get_chat_history_table(), $last_id ), ARRAY_A );
			foreach ( $rows as $row ) {
				$last_id = (int) $row['id'];
				foreach ( self::turns( $row ) as $turn ) {
					++$result['total'];
					$outcome = $turn['outcome'];
					++$result[ $outcome ];
					$day = substr( $turn['time'], 0, 10 );
					if ( $day === current_time( 'Y-m-d' ) ) { ++$result['today']; }
					if ( isset( $result['days'][ $day ] ) ) { ++$result['days'][ $day ]; }
					// Do not attribute documentation-only fallback replies to a chat API.
					if ( 'fallback' === $outcome ) { continue; }
					$provider = $turn['provider'];
					$key = 'wp_native_ai' === $provider ? 'native' : ( false !== strpos( $provider, 'openai' ) ? 'openai' : ( preg_match( '/gemini|google/', $provider ) ? 'gemini' : '' ) );
					if ( $key ) { ++$result[ $key ]; }
				}
			}
		} while ( count( $rows ) === 100 );
		return $result;
	}

	/** Legacy replies have unknown outcomes; do not invent historical resolution rates. */
	public static function turns( array $row ): array {
		$messages = json_decode( $row['messages'] ?? '', true );
		if ( ! is_array( $messages ) || ! $messages ) {
			$messages = array( array( 'role' => 'assistant', 'time' => $row['updated_at'] ?: $row['created_at'], 'outcome' => 'failed' === $row['status'] ? 'failed' : 'unknown', 'provider' => $row['provider'] ) );
		}
		$turns = array();
		foreach ( $messages as $message ) {
			if ( 'assistant' !== ( $message['role'] ?? '' ) && 'failed' !== ( $message['outcome'] ?? '' ) ) { continue; }
			$outcome = $message['outcome'] ?? 'unknown';
			$turns[] = array( 'outcome' => in_array( $outcome, array( 'completed', 'fallback', 'failed' ), true ) ? $outcome : 'unknown', 'time' => $message['time'] ?? $row['created_at'], 'provider' => $message['provider'] ?? $row['provider'] );
		}
		// Old failed records have an unanswered user message without outcome metadata.
		$last = end( $messages );
		if ( 'failed' === $row['status'] && 'user' === ( $last['role'] ?? '' ) && ! isset( $last['outcome'] ) ) {
			$turns[] = array( 'outcome' => 'failed', 'time' => $last['time'] ?? $row['updated_at'], 'provider' => $row['provider'] );
		}
		return $turns;
	}
}