<?php
/**
 * HelpScout Proxy Client
 *
 * @package Aisentic\HelpScout
 */

namespace Aisentic\HelpScout;

// Exit if accessed directly.
defined( 'ABSPATH' ) || exit;

/**
 * Thin proxy client — routes all HelpScout calls through app.aisentic.com.
 * Authenticates using the existing llmProviders.aisentic.apiKey (ask_* key).
 */
class Api {

	/**
	 * Proxy base URL including the HelpScout path segment.
	 *
	 * @var string
	 */
	private string $proxy_base;

	/**
	 * Aisentic API key used to authenticate with the proxy.
	 *
	 * @var string
	 */
	private string $proxy_key;

	/**
	 * Constructor — reads endpoint and API key from plugin options.
	 *
	 * @throws \RuntimeException If the proxy key is not configured.
	 */
	public function __construct() {
		$base             = aisentic_get_option( 'llmProviders.aisentic.endpoint', AISENTIC_AI_PROVIDER );
		$this->proxy_base = rtrim( $base, '/' ) . '/api/v1/helpscout/';
		$this->proxy_key  = aisentic_get_option( 'llmProviders.aisentic.apiKey', '' );

		if ( empty( $this->proxy_key ) ) {
			throw new \RuntimeException( 'HelpScout proxy key is not configured. Please set proper api key for aisentic.' );
		}
	}

	/**
	 * Create a new HelpScout conversation via the proxy.
	 *
	 * @param string $subject        Conversation subject.
	 * @param string $customer_email Customer email address.
	 * @param string $first_name     Customer first name.
	 * @param string $body           Initial message body.
	 * @param array  $threads        Pre-built HelpScout thread array. If provided, this
	 *                               is used directly instead of the default single-thread
	 *                               created from $body.
	 *
	 * @throws \RuntimeException On proxy failure or missing conversation ID.
	 * @return int HelpScout conversation ID.
	 */
	public function create_conversation( string $subject, string $customer_email, string $first_name, string $body, array $threads = [] ): int {
		$first_name = trim( $first_name );
		if ( '' === $first_name ) {
			$user = wp_get_current_user();
			if ( isset( $user->first_name ) && '' !== $user->first_name ) {
				$first_name = $user->first_name;
			} elseif ( isset( $user->display_name ) && '' !== $user->display_name ) {
				$first_name = $user->display_name;
			} else {
				$first_name = 'Customer';
			}
		}

		$payload = [
			'subject'        => $subject,
			'customer_email' => $customer_email,
			'first_name'     => $first_name,
			'message'        => $body,
		];

		if ( ! empty( $threads ) ) {
			$payload['threads'] = $threads;
		}

		$response = $this->request(
			'POST',
			'conversations',
			$payload
		);

		$id = (int) ( $response['data']['conversation_id'] ?? 0 );

		if ( $id <= 0 ) {
			throw new \RuntimeException( __( 'Proxy did not return a valid conversation ID.', 'aisentic' ) ); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped
		}

		return $id;
	}

	/**
	 * Send a customer reply to an existing conversation via the proxy.
	 *
	 * @param int    $conversation_id HelpScout conversation ID.
	 * @param string $customer_email  Customer email address.
	 * @param string $body            Reply message body.
	 *
	 * @throws \RuntimeException On proxy failure.
	 * @return void
	 */
	public function add_reply( int $conversation_id, string $customer_email, string $body ): void {
		$this->request(
			'POST',
			"conversations/{$conversation_id}/reply",
			[
				'customer_email' => $customer_email,
				'message'        => $body,
			]
		);
	}

	/**
	 * Retrieve buffered agent messages for a conversation from the proxy.
	 * Messages are consumed cursor-style on the proxy side.
	 *
	 * @param int $conversation_id HelpScout conversation ID.
	 *
	 * @throws \RuntimeException On proxy failure.
	 * @return array<array{body: string, author: string, timestamp: string}>
	 */
	public function get_messages( int $conversation_id ): array {
		$response = $this->request( 'GET', "conversations/{$conversation_id}/messages" );
		return (array) ( $response['data']['messages'] ?? [] );
	}

	/**
	 * Make an authenticated request to the proxy.
	 *
	 * @param string $method HTTP method (GET, POST).
	 * @param string $path   Path relative to the proxy HelpScout base.
	 * @param array  $body   Request body — omitted for GET requests.
	 *
	 * @throws \RuntimeException On WP_Error, or non-2xx proxy response.
	 * @return array Parsed JSON response body.
	 */
	private function request( string $method, string $path, array $body = [] ): array {
		$args = [
			'method'  => strtoupper( $method ),
			'headers' => [
				'Authorization' => 'Bearer ' . $this->proxy_key,
				'Accept'        => 'application/json',
			],
			'timeout' => 20,
		];

		if ( ! empty( $body ) ) {
			$args['body']                    = wp_json_encode( $body );
			$args['headers']['Content-Type'] = 'application/json';
		}

		$response = wp_remote_request( $this->proxy_base . $path, $args );

		if ( is_wp_error( $response ) ) {
			throw new \RuntimeException( $response->get_error_message() ); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped
		}

		$status = (int) wp_remote_retrieve_response_code( $response );
		$parsed = json_decode( wp_remote_retrieve_body( $response ), true ) ?? [];

		if ( $status >= 400 ) {
			$message = $parsed['message'] ?? __( 'HelpScout proxy request failed.', 'aisentic' );
			throw new \RuntimeException( $message ); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped
		}

		return $parsed;
	}
}