<?php
/**
 * OpenAI Provider.
 *
 * @package AIIL
 */

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * OpenAI LLM Provider.
 */
class AIIL_OpenAI_Provider extends AIIL_LLM_Provider_Base {

	/**
	 * API endpoint.
	 *
	 * @var string
	 */
	private $api_url = 'https://api.openai.com/v1/chat/completions';

	/**
	 * Get provider name.
	 *
	 * @return string
	 */
	public function get_name() {
		return 'openai';
	}

	/**
	 * Get provider label.
	 *
	 * @return string
	 */
	public function get_label() {
		return __( 'OpenAI', 'ai-internal-links' );
	}

	/**
	 * Get available models.
	 *
	 * @return array
	 */
	public function get_models() {
		return array(
			'gpt-4o'      => 'GPT-4o',
			'gpt-4-turbo' => 'GPT-4 Turbo',
			'gpt-4'       => 'GPT-4',
			'gpt-3.5-turbo' => 'GPT-3.5 Turbo',
		);
	}

	/**
	 * Get required credential fields.
	 *
	 * @return array
	 */
	public function get_credential_fields() {
		return array(
			'api_key' => array(
				'label'       => __( 'API Key', 'ai-internal-links' ),
				'type'        => 'password',
				'description' => __( 'Enter your OpenAI API key. Get it from platform.openai.com', 'ai-internal-links' ),
				'required'    => true,
			),
		);
	}

	/**
	 * Validate API credentials.
	 *
	 * @param array $credentials API credentials.
	 * @return bool|WP_Error
	 */
	public function validate_credentials( $credentials ) {
		if ( empty( $credentials['api_key'] ) ) {
			return new WP_Error( 'missing_api_key', __( 'OpenAI API key is required.', 'ai-internal-links' ) );
		}

		// Test API key with a simple GET request to models endpoint.
		$response = wp_remote_get(
			'https://api.openai.com/v1/models',
			array(
				'headers' => array(
					'Authorization' => 'Bearer ' . $credentials['api_key'],
				),
				'timeout' => 10,
			)
		);

		if ( is_wp_error( $response ) ) {
			return $response;
		}

		$code = wp_remote_retrieve_response_code( $response );
		if ( 200 !== $code ) {
			$body = json_decode( wp_remote_retrieve_body( $response ), true );
			$message = isset( $body['error']['message'] ) ? $body['error']['message'] : __( 'Invalid API key.', 'ai-internal-links' );
			return new WP_Error( 'invalid_api_key', $message );
		}

		return true;
	}

	/**
	 * Generate internal link suggestions.
	 *
	 * @param string $content         Content to analyze.
	 * @param array  $available_links Available links for suggestions.
	 * @param array  $settings        Generation settings.
	 * @return array|WP_Error
	 */
	public function generate_suggestions( $content, $available_links, $settings ) {
		$api_key = isset( $settings['api_key'] ) ? $settings['api_key'] : '';
		$model   = isset( $settings['model'] ) ? $settings['model'] : 'gpt-4o-mini';
		$max_links = isset( $settings['max_links'] ) ? intval( $settings['max_links'] ) : 5;

		if ( empty( $api_key ) ) {
			return new WP_Error( 'missing_api_key', __( 'OpenAI API key is not configured.', 'ai-internal-links' ) );
		}

		// Prepare links list.
		$links_list = $this->format_links_list( $available_links );

		// Build prompts.
		$system_prompt = $this->build_system_prompt( $max_links );
		$user_prompt   = $this->build_user_prompt( $content, $links_list );

		// Make API request.
		$request_data = array(
			'model'    => $model,
			'messages' => array(
				array(
					'role'    => 'system',
					'content' => $system_prompt,
				),
				array(
					'role'    => 'user',
					'content' => $user_prompt,
				),
			),
			'temperature' => 0.3,
		);

		$response = wp_remote_post(
			$this->api_url,
			array(
				'headers' => array(
					'Authorization' => 'Bearer ' . $api_key,
					'Content-Type'  => 'application/json',
				),
				'body'    => wp_json_encode( $request_data ),
				'timeout' => 120,
			)
		);

		if ( is_wp_error( $response ) ) {
			return $response;
		}

		$code = wp_remote_retrieve_response_code( $response );
		$body = wp_remote_retrieve_body( $response );

		if ( 200 !== $code ) {
			$error_data = json_decode( $body, true );
			$message = isset( $error_data['error']['message'] ) ? $error_data['error']['message'] : __( 'OpenAI API request failed.', 'ai-internal-links' );
			return new WP_Error( 'openai_api_error', $message );
		}

		// Parse response.
		return $this->parse_response( $body );
	}

	/**
	 * Parse OpenAI response.
	 *
	 * @param string $response_body Response body.
	 * @return array|WP_Error
	 */
	private function parse_response( $response_body ) {
		$data = json_decode( $response_body, true );

		if ( ! isset( $data['choices'][0]['message']['content'] ) ) {
			return new WP_Error( 'invalid_response', __( 'Invalid response from OpenAI.', 'ai-internal-links' ) );
		}

		$content = trim( $data['choices'][0]['message']['content'] );

		// Remove markdown code blocks if present.
		$content = preg_replace( '/^```json\s*|\s*```$/m', '', $content );
		$content = trim( $content );

		$suggestions = json_decode( $content, true );

		if ( json_last_error() !== JSON_ERROR_NONE ) {
			return new WP_Error( 'json_parse_error', __( 'Failed to parse AI response.', 'ai-internal-links' ) );
		}

		if ( ! is_array( $suggestions ) ) {
			return new WP_Error( 'invalid_suggestions', __( 'Invalid suggestions format.', 'ai-internal-links' ) );
		}

		// Validate suggestions structure.
		$validated = array();
		foreach ( $suggestions as $suggestion ) {
			if ( isset( $suggestion['search'] ) && isset( $suggestion['replace'] ) ) {
				$validated[] = array(
					'search'  => $suggestion['search'],
					'replace' => $suggestion['replace'],
				);
			}
		}

		return $validated;
	}
}