<?php
/**
 * WordPress AI Client integration.
 *
 * @package Aivexa
 */

declare(strict_types=1);

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

use WordPress\AiClient\AiClient;
use WordPress\AiClient\Messages\DTO\Message;
use WordPress\AiClient\Messages\DTO\MessagePart;
use WordPress\AiClient\Messages\DTO\ModelMessage;
use WordPress\AiClient\Messages\DTO\UserMessage;
use WordPress\AiClient\Results\DTO\GenerativeAiResult;
use WordPress\AiClient\Tools\DTO\FunctionCall;

/**
 * Thin wrapper around WordPress core AI Client APIs.
 *
 * Does not call third-party AI provider hosts directly. Requests go through
 * `wp_ai_client_prompt()` / the WordPress AI Client and site Connectors.
 */
class Aivexa_Client {

	/**
	 * Whether the WordPress AI Client API is available.
	 */
	public static function is_available(): bool {
		return function_exists( 'wp_ai_client_prompt' )
			&& function_exists( 'wp_supports_ai' )
			&& class_exists( AiClient::class );
	}

	/**
	 * Whether at least one AI provider is configured via Connectors / AI Client.
	 */
	public static function is_provider_configured(): bool {
		if ( ! self::is_available() || ! wp_supports_ai() ) {
			return false;
		}

		try {
			$registry = AiClient::defaultRegistry();
			$ids      = $registry->getRegisteredProviderIds();
			if ( ! is_array( $ids ) || array() === $ids ) {
				return false;
			}

			foreach ( $ids as $id ) {
				if ( is_string( $id ) && '' !== $id && AiClient::isConfigured( $id ) ) {
					return true;
				}
			}
		} catch ( Throwable $exception ) {
			unset( $exception );
			return false;
		}

		return false;
	}

	/**
	 * Test connectivity with a short prompt.
	 *
	 * @return true|WP_Error
	 */
	public static function test_connection() {
		if ( ! self::is_available() ) {
			return new WP_Error(
				'aivexa_ai_unavailable',
				__( 'The WordPress AI Client is not available. Aivexa requires WordPress 7.0 or later.', 'aivexa' )
			);
		}

		if ( ! wp_supports_ai() ) {
			return new WP_Error(
				'aivexa_ai_disabled',
				__( 'AI features are disabled on this site.', 'aivexa' )
			);
		}

		if ( ! self::is_provider_configured() ) {
			return new WP_Error(
				'aivexa_no_provider',
				__( 'No AI provider is configured. Open Settings → Connectors, install an AI provider, and save an API key.', 'aivexa' )
			);
		}

		$builder = self::base_prompt( 'Reply with the single word: connected' );
		$result  = $builder->generate_text();

		if ( is_wp_error( $result ) ) {
			return self::friendly_error( $result );
		}

		return true;
	}

	/**
	 * Build a configured prompt builder.
	 *
	 * @param string|Message|null $prompt Prompt.
	 * @return WP_AI_Client_Prompt_Builder|WP_Error
	 */
	public static function base_prompt( $prompt = null ) {
		if ( ! self::is_available() ) {
			return new WP_Error(
				'aivexa_ai_unavailable',
				__( 'The WordPress AI Client is not available.', 'aivexa' )
			);
		}

		$settings = Aivexa_Settings::get_all();
		$builder  = wp_ai_client_prompt( $prompt );

		$builder = $builder
			->using_system_instruction( (string) $settings['system_instructions'] )
			->using_max_tokens( max( 16, (int) $settings['max_output_tokens'] ) )
			->using_temperature( (float) $settings['temperature'] );

		$model = trim( (string) $settings['model'] );
		if ( '' !== $model && method_exists( $builder, 'using_model_preference' ) ) {
			$builder = $builder->using_model_preference( $model );
		}

		return $builder;
	}

	/**
	 * Convert stored conversation rows into AI Client Message objects.
	 *
	 * @param array<int, array<string, mixed>> $rows Messages.
	 * @return Message[]
	 */
	public static function messages_from_history( array $rows ): array {
		$messages = array();

		foreach ( $rows as $row ) {
			$role    = isset( $row['role'] ) ? (string) $row['role'] : 'user';
			$content = isset( $row['content'] ) ? (string) $row['content'] : '';
			if ( '' === trim( $content ) ) {
				continue;
			}

			$part = new MessagePart( $content );
			if ( 'assistant' === $role || 'model' === $role ) {
				$messages[] = new ModelMessage( array( $part ) );
			} else {
				$messages[] = new UserMessage( array( $part ) );
			}
		}

		return $messages;
	}

	/**
	 * Extract function calls from a generative result message.
	 *
	 * @param Message $message Message.
	 * @return FunctionCall[]
	 */
	public static function extract_function_calls( Message $message ): array {
		$calls = array();

		foreach ( $message->getParts() as $part ) {
			if ( $part->getType()->isFunctionCall() ) {
				$call = $part->getFunctionCall();
				if ( $call instanceof FunctionCall ) {
					$calls[] = $call;
				}
			}
		}

		return $calls;
	}

	/**
	 * Extract assistant text from a result.
	 *
	 * @param GenerativeAiResult $result Result.
	 */
	public static function extract_text( GenerativeAiResult $result ): string {
		try {
			$text = $result->toText();
			return is_string( $text ) ? trim( $text ) : '';
		} catch ( Throwable $exception ) {
			unset( $exception );
			return '';
		}
	}

	/**
	 * Map AI Client / WP_Error into a visitor-safe error.
	 *
	 * @param WP_Error $error Error.
	 */
	public static function friendly_error( WP_Error $error ): WP_Error {
		$code    = $error->get_error_code();
		$message = Aivexa_Security::redact_sensitive( $error->get_error_message() );

		if ( str_contains( strtolower( $message ), 'api key' ) || str_contains( strtolower( $message ), 'unauthorized' ) || str_contains( (string) $code, 'auth' ) ) {
			return new WP_Error(
				'aivexa_ai_auth',
				__( 'AI authentication failed. Check Settings → Connectors and your provider API key.', 'aivexa' ),
				array( 'status' => 502 )
			);
		}

		if ( str_contains( strtolower( $message ), 'rate' ) || str_contains( (string) $code, 'rate' ) ) {
			return new WP_Error(
				'aivexa_ai_rate_limited',
				__( 'The AI service is temporarily busy. Please try again later.', 'aivexa' ),
				array( 'status' => 429 )
			);
		}

		return new WP_Error(
			'aivexa_ai_error',
			__( 'Sorry, the AI assistant is temporarily unavailable. Please try again later.', 'aivexa' ),
			array( 'status' => 502 )
		);
	}
}