<?php
/**
 * Business Central API Client
 *
 * @package WooBusinessCentral
 */

// Prevent direct access
if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

/**
 * Class WBC_API_Client
 *
 * HTTP client for Business Central API using native cURL.
 */
class WBC_API_Client {

    /**
     * Base API URL template
     */
    const BASE_URL = 'https://api.businesscentral.dynamics.com/v2.0/%s/api/v2.0';

    /**
     * OData V4 URL template: tenant_id, environment, company_name
     */
    const ODATA_URL = 'https://api.businesscentral.dynamics.com/v2.0/%s/%s/ODataV4/Company(\'%s\')';

    /**
     * Maximum retry attempts
     */
    const MAX_RETRIES = 3;

    /**
     * Retry delay in seconds
     */
    const RETRY_DELAY = 2;

    /**
     * Request timeout in seconds
     */
    const TIMEOUT = 30;

    /**
     * Get the base API URL
     *
     * @return string
     */
    private static function get_base_url() {
        $environment = WBC_OAuth::get_environment();
        return sprintf( self::BASE_URL, $environment );
    }

    /**
     * Get company ID for URL
     *
     * @return string
     */
    private static function get_company_id() {
        return WBC_OAuth::get_company_id();
    }

    /**
     * Build full endpoint URL
     *
     * @param string $endpoint The API endpoint.
     * @param bool   $include_company Whether to include company ID in URL.
     * @return string Full URL.
     */
    private static function build_url( $endpoint, $include_company = true ) {
        $base_url = self::get_base_url();

        if ( $include_company ) {
            $company_id = self::get_company_id();
            return $base_url . '/companies(' . $company_id . ')' . $endpoint;
        }

        return $base_url . $endpoint;
    }

    /**
     * Make an HTTP request to the Business Central API
     *
     * @param string $method      HTTP method (GET, POST, PATCH, DELETE).
     * @param string $endpoint    API endpoint.
     * @param array  $params      Query parameters (for GET) or body data (for POST/PATCH).
     * @param bool   $include_company Whether to include company ID in URL.
     * @param int    $retry_count Current retry attempt.
     * @return array|WP_Error Response data or error.
     */
    private static function request( $method, $endpoint, $params = array(), $include_company = true, $retry_count = 0 ) {
        // Get access token
        $token = WBC_OAuth::get_access_token();

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

        // Build URL
        $url = self::build_url( $endpoint, $include_company );

        // Add query parameters for GET requests
        if ( $method === 'GET' && ! empty( $params ) ) {
            $url .= '?' . http_build_query( $params );
        }

        WBC_Logger::debug( 'API', "Making $method request", array(
            'url'    => $url,
            'method' => $method,
        ) );

        // Initialize cURL
        $ch = curl_init();

        // Set base options
        $curl_options = array(
            CURLOPT_URL            => $url,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT        => self::TIMEOUT,
            CURLOPT_HTTPHEADER     => array(
                'Authorization: Bearer ' . $token,
                'Content-Type: application/json',
                'Accept: application/json',
            ),
        );

        // Set method-specific options
        switch ( $method ) {
            case 'POST':
                $curl_options[ CURLOPT_POST ] = true;
                if ( ! empty( $params ) ) {
                    $curl_options[ CURLOPT_POSTFIELDS ] = wp_json_encode( $params );
                }
                break;

            case 'PATCH':
                $curl_options[ CURLOPT_CUSTOMREQUEST ] = 'PATCH';
                if ( ! empty( $params ) ) {
                    $curl_options[ CURLOPT_POSTFIELDS ] = wp_json_encode( $params );
                }
                // Add If-Match header for PATCH requests
                $curl_options[ CURLOPT_HTTPHEADER ][] = 'If-Match: *';
                break;

            case 'DELETE':
                $curl_options[ CURLOPT_CUSTOMREQUEST ] = 'DELETE';
                break;

            default: // GET
                $curl_options[ CURLOPT_HTTPGET ] = true;
                break;
        }

        curl_setopt_array( $ch, $curl_options );

        // Execute request
        $response = curl_exec( $ch );
        $http_code = curl_getinfo( $ch, CURLINFO_HTTP_CODE );
        $curl_error = curl_error( $ch );

        curl_close( $ch );

        // Handle cURL errors
        if ( $response === false ) {
            WBC_Logger::error( 'API', 'cURL error', array(
                'error' => $curl_error,
                'url'   => $url,
            ) );
            return new WP_Error( 'wbc_curl_error', $curl_error );
        }

        // Parse response
        $data = json_decode( $response, true );

        // Handle 401 (unauthorized) - token might be expired
        if ( $http_code === 401 && $retry_count < self::MAX_RETRIES ) {
            WBC_Logger::warning( 'API', 'Received 401, refreshing token and retrying', array(
                'retry_count' => $retry_count + 1,
            ) );

            // Clear token cache and retry
            WBC_OAuth::clear_token_cache();
            sleep( self::RETRY_DELAY );

            return self::request( $method, $endpoint, $params, $include_company, $retry_count + 1 );
        }

        // Handle rate limiting (429)
        if ( $http_code === 429 && $retry_count < self::MAX_RETRIES ) {
            $retry_after = isset( $data['error']['retryAfterSeconds'] ) ? (int) $data['error']['retryAfterSeconds'] : self::RETRY_DELAY * ( $retry_count + 1 );

            WBC_Logger::warning( 'API', 'Rate limited, retrying after delay', array(
                'retry_after'  => $retry_after,
                'retry_count'  => $retry_count + 1,
            ) );

            sleep( $retry_after );

            return self::request( $method, $endpoint, $params, $include_company, $retry_count + 1 );
        }

        // Handle server errors (5xx)
        if ( $http_code >= 500 && $retry_count < self::MAX_RETRIES ) {
            WBC_Logger::warning( 'API', 'Server error, retrying', array(
                'http_code'   => $http_code,
                'retry_count' => $retry_count + 1,
            ) );

            sleep( self::RETRY_DELAY * ( $retry_count + 1 ) );

            return self::request( $method, $endpoint, $params, $include_company, $retry_count + 1 );
        }

        // Handle other errors
        if ( $http_code >= 400 ) {
            $error_message = isset( $data['error']['message'] ) ? $data['error']['message'] : __( 'API request failed', 'woo-business-central' );

            WBC_Logger::error( 'API', 'Request failed', array(
                'http_code' => $http_code,
                'error'     => $data['error'] ?? null,
                'url'       => $url,
            ) );

            return new WP_Error( 'wbc_api_error', $error_message, array(
                'status' => $http_code,
                'error'  => $data['error'] ?? null,
            ) );
        }

        WBC_Logger::debug( 'API', 'Request successful', array(
            'http_code' => $http_code,
            'url'       => $url,
        ) );

        return $data;
    }

    /**
     * GET request
     *
     * @param string $endpoint API endpoint.
     * @param array  $params   Query parameters.
     * @param bool   $include_company Whether to include company ID.
     * @return array|WP_Error Response data or error.
     */
    public static function get( $endpoint, $params = array(), $include_company = true ) {
        return self::request( 'GET', $endpoint, $params, $include_company );
    }

    /**
     * POST request
     *
     * @param string $endpoint API endpoint.
     * @param array  $data     Request body data.
     * @param bool   $include_company Whether to include company ID.
     * @return array|WP_Error Response data or error.
     */
    public static function post( $endpoint, $data = array(), $include_company = true ) {
        return self::request( 'POST', $endpoint, $data, $include_company );
    }

    /**
     * PATCH request
     *
     * @param string $endpoint API endpoint.
     * @param array  $data     Request body data.
     * @param bool   $include_company Whether to include company ID.
     * @return array|WP_Error Response data or error.
     */
    public static function patch( $endpoint, $data = array(), $include_company = true ) {
        return self::request( 'PATCH', $endpoint, $data, $include_company );
    }

    /**
     * DELETE request
     *
     * @param string $endpoint API endpoint.
     * @param bool   $include_company Whether to include company ID.
     * @return array|WP_Error Response data or error.
     */
    public static function delete( $endpoint, $include_company = true ) {
        return self::request( 'DELETE', $endpoint, array(), $include_company );
    }

    /**
     * Get all companies
     *
     * @return array|WP_Error Array of companies or error.
     */
    public static function get_companies() {
        return self::get( '/companies', array(), false );
    }

    /**
     * Get items with pagination support
     *
     * @param int    $top  Number of items to fetch.
     * @param int    $skip Number of items to skip.
     * @param string $select Fields to select.
     * @return array|WP_Error Response data or error.
     */
    public static function get_items( $top = 100, $skip = 0, $select = '' ) {
        $params = array(
            '$top'  => $top,
            '$skip' => $skip,
        );

        if ( ! empty( $select ) ) {
            $params['$select'] = $select;
        }

        return self::get( '/items', $params );
    }

    /**
     * Get customers with optional filter
     *
     * @param string $filter OData filter expression.
     * @return array|WP_Error Response data or error.
     */
    public static function get_customers( $filter = '' ) {
        $params = array();

        if ( ! empty( $filter ) ) {
            $params['$filter'] = $filter;
        }

        return self::get( '/customers', $params );
    }

    /**
     * Create a customer
     *
     * @param array $data Customer data.
     * @return array|WP_Error Response data or error.
     */
    public static function create_customer( $data ) {
        return self::post( '/customers', $data );
    }

    /**
     * Create a sales order
     *
     * @param array $data Sales order data.
     * @return array|WP_Error Response data or error.
     */
    public static function create_sales_order( $data ) {
        return self::post( '/salesOrders', $data );
    }

    /**
     * Create a sales order line
     *
     * @param string $order_id Sales order ID.
     * @param array  $data     Sales order line data.
     * @return array|WP_Error Response data or error.
     */
    public static function create_sales_order_line( $order_id, $data ) {
        return self::post( '/salesOrders(' . $order_id . ')/salesOrderLines', $data );
    }

    /**
     * Escape a string value for use in OData filter expressions
     *
     * @param string $value The value to escape.
     * @return string Escaped value safe for OData filters.
     */
    public static function escape_odata_string( $value ) {
        return str_replace( "'", "''", $value );
    }

    /**
     * Build the OData V4 base URL for custom endpoints
     *
     * @return string|WP_Error Base URL or error if company name not configured.
     */
    private static function get_odata_base_url() {
        $tenant_id = WBC_OAuth::get_tenant_id();
        $environment = WBC_OAuth::get_environment();
        $company_name = get_option( 'wbc_company_name', '' );

        if ( empty( $company_name ) ) {
            return new WP_Error( 'wbc_missing_company_name', __( 'Company Name is not configured (required for OData endpoints).', 'woo-business-central' ) );
        }

        return sprintf( self::ODATA_URL, $tenant_id, $environment, rawurlencode( $company_name ) );
    }

    /**
     * GET request to a custom OData V4 endpoint
     *
     * @param string $endpoint OData endpoint name (e.g. 'ItemByLocation').
     * @param array  $params   OData query parameters ($filter, $select, etc.).
     * @return array|WP_Error Response data or error.
     */
    public static function odata_get( $endpoint, $params = array() ) {
        $base_url = self::get_odata_base_url();

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

        $url = $base_url . '/' . $endpoint;

        if ( ! empty( $params ) ) {
            $url .= '?' . http_build_query( $params );
        }

        // Get access token
        $token = WBC_OAuth::get_access_token();

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

        WBC_Logger::debug( 'API', 'OData GET request', array( 'url' => $url ) );

        $ch = curl_init();

        curl_setopt_array( $ch, array(
            CURLOPT_URL            => $url,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT        => self::TIMEOUT,
            CURLOPT_HTTPGET        => true,
            CURLOPT_HTTPHEADER     => array(
                'Authorization: Bearer ' . $token,
                'Accept: application/json',
            ),
        ) );

        $response = curl_exec( $ch );
        $http_code = curl_getinfo( $ch, CURLINFO_HTTP_CODE );
        $curl_error = curl_error( $ch );

        curl_close( $ch );

        if ( $response === false ) {
            WBC_Logger::error( 'API', 'OData cURL error', array( 'error' => $curl_error, 'url' => $url ) );
            return new WP_Error( 'wbc_curl_error', $curl_error );
        }

        $data = json_decode( $response, true );

        // Handle 401 - retry with fresh token
        if ( $http_code === 401 ) {
            WBC_OAuth::clear_token_cache();
            $token = WBC_OAuth::get_access_token( true );

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

            $ch = curl_init();
            curl_setopt_array( $ch, array(
                CURLOPT_URL            => $url,
                CURLOPT_RETURNTRANSFER => true,
                CURLOPT_TIMEOUT        => self::TIMEOUT,
                CURLOPT_HTTPGET        => true,
                CURLOPT_HTTPHEADER     => array(
                    'Authorization: Bearer ' . $token,
                    'Accept: application/json',
                ),
            ) );

            $response = curl_exec( $ch );
            $http_code = curl_getinfo( $ch, CURLINFO_HTTP_CODE );
            curl_close( $ch );

            $data = json_decode( $response, true );
        }

        if ( $http_code >= 400 ) {
            $error_message = isset( $data['error']['message'] ) ? $data['error']['message'] : __( 'OData request failed', 'woo-business-central' );
            WBC_Logger::error( 'API', 'OData request failed', array(
                'http_code' => $http_code,
                'error'     => $data['error'] ?? null,
                'url'       => $url,
            ) );
            return new WP_Error( 'wbc_odata_error', $error_message, array( 'status' => $http_code ) );
        }

        WBC_Logger::debug( 'API', 'OData request successful', array( 'http_code' => $http_code, 'url' => $url ) );

        return $data;
    }

    /**
     * Get a specific item by number
     *
     * @param string $item_number Item number.
     * @return array|WP_Error Response data or error.
     */
    public static function get_item_by_number( $item_number ) {
        $params = array(
            '$filter' => "number eq '" . self::escape_odata_string( $item_number ) . "'",
        );

        return self::get( '/items', $params );
    }
}