<?php
/**
 * Client for the LeanPixel optimization service.
 *
 * Nothing in this class runs until the site owner has connected the plugin
 * by requesting or entering an API key.
 *
 * @package LeanPixel
 */

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

class LeanPixel_API {

	/** Compact reply format: a JSON header followed by the raw files. */
	const BUNDLE_TYPE = 'application/vnd.leanpixel.bundle';

	/**
	 * Ask the service for a new free key.
	 *
	 * @param string $email Contact email for the key.
	 * @return array|WP_Error { api_key, account }
	 */
	public static function register( $email ) {
		// The service calls this site back to check the request really comes from here.
		$result = self::request(
			'POST',
			'/register',
			array(
				'headers' => array( 'Content-Type' => 'application/json' ),
				'body'    => wp_json_encode(
					array(
						'email'       => $email,
						'site_url'    => home_url(),
						'site_secret' => LeanPixel_Verify::new_secret(),
					)
				),
				'timeout' => 45,
			),
			''
		);
		LeanPixel_Verify::forget_secret();
		return $result;
	}

	/**
	 * Confirm the email address of a new free key with the emailed code.
	 *
	 * @param string $code The 6-digit code.
	 * @return array|WP_Error { account }
	 */
	public static function confirm( $code ) {
		$result = self::request(
			'POST',
			'/confirm',
			array(
				'headers' => array( 'Content-Type' => 'application/json' ),
				'body'    => wp_json_encode( array( 'code' => $code ) ),
				'timeout' => 20,
			)
		);
		if ( ! is_wp_error( $result ) && isset( $result['account'] ) ) {
			self::remember_account( $result['account'] );
		}
		return $result;
	}

	/**
	 * Ask for a new confirmation code.
	 *
	 * @return array|WP_Error
	 */
	public static function resend() {
		return self::request( 'POST', '/resend', array( 'timeout' => 30 ) );
	}

	/**
	 * Fetch plan and usage for a key.
	 *
	 * @param string|null $key Key to check, or null for the stored key.
	 * @return array|WP_Error
	 */
	public static function account( $key = null ) {
		$result = self::request( 'GET', '/account', array( 'timeout' => 20 ), $key );
		if ( ! is_wp_error( $result ) && null === $key ) {
			self::remember_account( $result['account'] );
		}
		return $result;
	}

	/**
	 * Send one image file for optimization.
	 *
	 * @param string $file Absolute path.
	 * @param string $mime  Mime type of the file.
	 * @param string $image Id shared by every file of one image, so the image is counted once.
	 * @return array|WP_Error Decoded response; file data is still base64.
	 */
	public static function optimize( $file, $mime, $image = '' ) {
		$settings = LeanPixel_Settings::all();

		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- local file.
		$body = file_get_contents( $file );
		if ( false === $body ) {
			return new WP_Error( 'unreadable', __( 'The file could not be read.', 'lean-pixel' ) );
		}

		$query = array(
			'image'         => $image,
			'level'         => $settings['level'],
			'webp'          => $settings['webp'] ? 1 : 0,
			'avif'          => $settings['avif'] ? 1 : 0,
			'keep_metadata' => $settings['keep_metadata'] ? 1 : 0,
		);

		$result = self::request(
			'POST',
			'/optimize?' . http_build_query( $query ),
			array(
				'headers' => array(
					'Content-Type' => $mime,
					'Accept'       => self::BUNDLE_TYPE . ', application/json',
				),
				'body'    => $body,
				'timeout' => 120,
				// The reply holds at most three files, none larger than the upload.
				'limit_response_size' => 3 * strlen( $body ) + MB_IN_BYTES,
			)
		);
		unset( $body );

		if ( ! is_wp_error( $result ) && isset( $result['account'] ) ) {
			self::remember_account( $result['account'] );
		}
		return $result;
	}

	/** Last known plan and usage, without a network call. */
	public static function cached_account() {
		$account = get_option( LeanPixel_Settings::ACCOUNT, array() );
		return is_array( $account ) ? $account : array();
	}

	public static function remember_account( $account ) {
		if ( ! is_array( $account ) ) {
			return;
		}
		// Keep only the fields the plugin shows, each forced to its expected type.
		$clean = array();
		foreach ( array( 'email', 'plan', 'plan_name', 'period', 'resets_at' ) as $field ) {
			if ( isset( $account[ $field ] ) && is_scalar( $account[ $field ] ) ) {
				$clean[ $field ] = substr( sanitize_text_field( (string) $account[ $field ] ), 0, 190 );
			}
		}
		// Whether the plan includes AVIF. Services older than this field included it for everyone.
		$clean['avif'] = ( ! isset( $account['avif'] ) || ! empty( $account['avif'] ) ) ? 1 : 0;
		foreach ( array( 'limit', 'used', 'max_file_bytes', 'max_sites' ) as $field ) {
			if ( isset( $account[ $field ] ) && is_numeric( $account[ $field ] ) ) {
				$clean[ $field ] = absint( $account[ $field ] );
			}
		}
		update_option( LeanPixel_Settings::ACCOUNT, $clean, false );
	}

	/**
	 * Read a bundle reply: 4 bytes holding the length of a JSON header, the
	 * header, then the files it lists, in the order optimized, webp, avif.
	 *
	 * @param string $body Raw response body.
	 * @return array|null The header with each file's bytes added, or null if malformed.
	 */
	private static function parse_bundle( $body ) {
		if ( strlen( $body ) < 4 ) {
			return null;
		}
		$length = unpack( 'N', substr( $body, 0, 4 ) );
		$length = (int) $length[1];
		if ( $length < 2 || $length > strlen( $body ) - 4 || $length > MB_IN_BYTES ) {
			return null;
		}
		$data   = json_decode( substr( $body, 4, $length ), true );
		if ( ! is_array( $data ) ) {
			return null;
		}
		$offset = 4 + $length;
		foreach ( array( 'optimized', 'webp', 'avif' ) as $name ) {
			if ( empty( $data[ $name ] ) || ! is_array( $data[ $name ] ) ) {
				$data[ $name ] = null;
				continue;
			}
			$size  = isset( $data[ $name ]['size'] ) ? (int) $data[ $name ]['size'] : 0;
			$bytes = $size > 0 ? substr( $body, $offset, $size ) : '';
			if ( $size < 1 || strlen( $bytes ) !== $size ) {
				return null;
			}
			$data[ $name ]['bytes'] = $bytes;
			$offset                += $size;
		}
		return $data;
	}

	/**
	 * @param string      $method HTTP method.
	 * @param string      $path   Path below the API base URL.
	 * @param array       $args   wp_remote_request arguments.
	 * @param string|null $key    Key to use; null for the stored key, '' for none.
	 * @return array|WP_Error
	 */
	private static function request( $method, $path, array $args, $key = null ) {
		if ( null === $key ) {
			$key = (string) LeanPixel_Settings::get( 'api_key' );
			if ( '' === $key ) {
				return new WP_Error( 'not_connected', __( 'LeanPixel is not connected yet.', 'lean-pixel' ) );
			}
		}

		$args['method']  = $method;
		$args['headers'] = array_merge(
			array( 'Accept' => 'application/json' ),
			isset( $args['headers'] ) ? $args['headers'] : array(),
			array( 'X-Site-Url' => home_url() )
		);
		if ( '' !== $key ) {
			$args['headers']['X-Api-Key'] = $key;
		}
		$args['user-agent'] = 'LeanPixel/' . LEANPIXEL_VERSION . '; ' . home_url();

		$response = wp_remote_request( untrailingslashit( LEANPIXEL_API_URL ) . $path, $args );
		if ( is_wp_error( $response ) ) {
			return new WP_Error(
				'connection_failed',
				/* translators: %s: error detail */
				sprintf( __( 'Could not reach the optimization service: %s', 'lean-pixel' ), $response->get_error_message() )
			);
		}

		$status = (int) wp_remote_retrieve_response_code( $response );
		$type   = (string) wp_remote_retrieve_header( $response, 'content-type' );
		$data   = 0 === stripos( $type, self::BUNDLE_TYPE )
			? self::parse_bundle( wp_remote_retrieve_body( $response ) )
			: json_decode( wp_remote_retrieve_body( $response ), true );

		if ( ! is_array( $data ) ) {
			return new WP_Error(
				'bad_response',
				/* translators: %d: HTTP status code */
				sprintf( __( 'The optimization service returned an unexpected response (HTTP %d).', 'lean-pixel' ), $status )
			);
		}
		if ( empty( $data['ok'] ) ) {
			$code    = isset( $data['error']['code'] ) ? sanitize_key( $data['error']['code'] ) : 'api_error';
			$message = isset( $data['error']['message'] ) ? sanitize_text_field( $data['error']['message'] ) : __( 'The optimization service reported an error.', 'lean-pixel' );
			return new WP_Error( $code, $message );
		}
		return $data;
	}
}