<?php

namespace WP_CLI;

use RuntimeException;

/**
 * Class WpOrgApi.
 *
 * This is an abstraction of the WordPress.org API.
 *
 * @see https://codex.wordpress.org/WordPress.org_API
 *
 * @package WP_CLI
 */
final class WpOrgApi {

    /**
     * WordPress.org API root URL.
     *
     * @var string
     */
    const API_ROOT = 'https://api.wordpress.org';

    /**
     * WordPress.org API root URL.
     *
     * @var string
     */
    const DOWNLOADS_ROOT = 'https://downloads.wordpress.org';

    /**
     * Core checksums endpoint.
     *
     * @see https://codex.wordpress.org/WordPress.org_API#Checksum
     *
     * @var string
     */
    const CORE_CHECKSUMS_ENDPOINT = self::API_ROOT . '/core/checksums/1.0/';

    /**
     * Plugin checksums endpoint.
     *
     * @var string
     */
    const PLUGIN_CHECKSUMS_ENDPOINT = self::DOWNLOADS_ROOT . '/plugin-checksums/';

    /**
     * Plugin info endpoint.
     *
     * @var string
     */
    const PLUGIN_INFO_ENDPOINT = self::API_ROOT . '/plugins/info/1.2/';

    /**
     * Theme info endpoint.
     *
     * @var string
     */
    const THEME_INFO_ENDPOINT = self::API_ROOT . '/themes/info/1.2/';

    /**
     * Salt endpoint.
     *
     * @see https://codex.wordpress.org/WordPress.org_API#Secret_Key
     *
     * @var string
     */
    const SALT_ENDPOINT = self::API_ROOT . '/secret-key/1.1/salt/';

    /**
     * Version check endpoint.
     *
     * @see https://codex.wordpress.org/WordPress.org_API#Version_Check
     *
     * @var string
     */
    const VERSION_CHECK_ENDPOINT = self::API_ROOT . '/core/version-check/1.7/';

    /**
     * Options to pass onto the Requests library for executing the remote calls.
     *
     * @var array
     */
    private $options;

    /**
     * WpOrgApi constructor.
     *
     * @param array $options Associative array of options to pass to the API abstraction.
     */
    public function __construct( $options = [] ) {
        $this->options = $options;
    }

    /**
     * Gets the checksums for the given version of WordPress core.
     *
     * @param string $version Version string to query.
     * @param string $locale  Optional. Locale to query. Defaults to 'en_US'.
     * @return bool|array False on failure. An array of checksums on success.
     * @throws RuntimeException If the remote request fails.
     */
    public function get_core_checksums( $version, $locale = 'en_US' ) {
        $data = [
            'version' => $version,
            'locale'  => $locale,
        ];

        $url = sprintf(
            '%s?%s',
            self::CORE_CHECKSUMS_ENDPOINT,
            http_build_query( $data, '', '&' )
        );

        $response = $this->json_get_request( $url );

        if (
            ! is_array( $response )
            || ! isset( $response['checksums'] )
            || ! is_array( $response['checksums'] )
        ) {
            return false;
        }

        return $response['checksums'];
    }

    /**
     * Gets a core version check.
     *
     * @param string $locale Optional. Locale to request a version check for. Defaults to 'en_US'.
     * @return array|false False on failure. Associative array of the offer on success.
     * @throws RuntimeException If the remote request failed.
     */
    public function get_core_version_check( $locale = 'en_US' ) {
        $url = sprintf(
            '%s?%s',
            self::VERSION_CHECK_ENDPOINT,
            http_build_query( [ 'locale' => $locale ], '', '&' )
        );

        $response = $this->json_get_request( $url );

        if ( ! is_array( $response ) ) {
            return false;
        }

        return $response;
    }

    /**
     * Gets a download offer.
     *
     * @param string $locale Optional. Locale to request an offer from. Defaults to 'en_US'.
     * @return array|false False on failure. Associative array of the offer on success.
     * @throws RuntimeException If the remote request failed.
     */
    public function get_core_download_offer( $locale = 'en_US' ) {
        $response = $this->get_core_version_check( $locale );

        if (
            ! is_array( $response )
            || ! isset( $response['offers'] )
            || ! is_array( $response['offers'] )
        ) {
            return false;
        }

        $offer = $response['offers'][0];

        if ( ! array_key_exists( 'locale', $offer ) || $locale !== $offer['locale'] ) {
            return false;
        }

        return $offer;
    }

    /**
     * Gets the checksums for the given version of plugin.
     *
     * @param string $plugin  Plugin slug to query.
     * @param string $version Version string to query.
     * @return bool|array False on failure. An array of checksums on success.
     * @throws RuntimeException If the remote request fails.
     */
    public function get_plugin_checksums( $plugin, $version ) {
        $url = sprintf(
            '%s%s/%s.json',
            self::PLUGIN_CHECKSUMS_ENDPOINT,
            $plugin,
            $version
        );

        $response = $this->json_get_request( $url );

        if (
            ! is_array( $response )
            || ! isset( $response['files'] )
            || ! is_array( $response['files'] )
        ) {
            return false;
        }

        return $response['files'];
    }

    /**
     * Gets a plugin's info.
     *
     * @param string $plugin Plugin slug to query.
     * @param string $locale Optional. Locale to request info for. Defaults to 'en_US'.
     * @param array $fields Optional. Fields to include/omit from the response.
     * @return array|false False on failure. Associative array of the offer on success.
     * @throws RuntimeException If the remote request failed.
     */
    public function get_plugin_info( $plugin, $locale = 'en_US', array $fields = [] ) {
        $action  = 'plugin_information';
        $request = [
            'locale' => $locale,
            'slug'   => $plugin,
        ];

        if ( ! empty( $fields ) ) {
            $request['fields'] = $fields;
        }

        $url = sprintf(
            '%s?%s',
            self::PLUGIN_INFO_ENDPOINT,
            http_build_query( compact( 'action', 'request' ), '', '&' )
        );

        $response = $this->json_get_request( $url );

        if ( ! is_array( $response ) ) {
            return false;
        }

        return $response;
    }

    /**
     * Gets a theme's info.
     *
     * @param string $theme  Theme slug to query.
     * @param string $locale Optional. Locale to request info for. Defaults to 'en_US'.
     * @param array $fields Optional. Fields to include/omit from the response.
     * @return array|false False on failure. Associative array of the offer on success.
     * @throws RuntimeException If the remote request failed.
     */
    public function get_theme_info( $theme, $locale = 'en_US', array $fields = [] ) {
        $action  = 'theme_information';
        $request = [
            'locale' => $locale,
            'slug'   => $theme,
        ];

        if ( ! empty( $fields ) ) {
            $request['fields'] = $fields;
        }

        $url = sprintf(
            '%s?%s',
            self::THEME_INFO_ENDPOINT,
            http_build_query( compact( 'action', 'request' ), '', '&' )
        );

        $response = $this->json_get_request( $url );

        if ( ! is_array( $response ) ) {
            return false;
        }

        return $response;
    }

    /**
     * Gets a set of salts in the format required by `wp-config.php`.
     *
     * @return string A string of PHP define() statements.
     * @throws RuntimeException If the remote request fails.
     */
    public function get_salts() {
        return $this->get_request( self::SALT_ENDPOINT );
    }

    /**
     * Execute a remote GET request.
     *
     * @param string $url     URL to execute the GET request on.
     * @param array  $headers Optional. Associative array of headers.
     * @param array  $options Optional. Associative array of options.
     * @return mixed|false False on failure. Decoded JSON on success.
     * @throws RuntimeException If the JSON could not be decoded.
     */
    private function json_get_request( $url, $headers = [], $options = [] ) {
        $headers = array_merge(
            [
                'Accept' => 'application/json',
            ],
            $headers
        );

        $response = $this->get_request( $url, $headers, $options );

        if ( false === $response ) {
            return $response;
        }

        $data = json_decode( $response, true );

        if ( JSON_ERROR_NONE !== json_last_error() ) {
            throw new RuntimeException( 'Failed to decode JSON: ' . json_last_error_msg() );
        }

        return $data;
    }

    /**
     * Execute a remote GET request.
     *
     * @param string $url     URL to execute the GET request on.
     * @param array  $headers Optional. Associative array of headers.
     * @param array  $options Optional. Associative array of options.
     * @return string Response body.
     * @throws RuntimeException If the remote request fails.
     */
    private function get_request( $url, $headers = [], $options = [] ) {
        $options = array_merge(
            $this->options,
            [
                'halt_on_error' => false,
            ],
            $options
        );

        $response = Utils\http_request( 'GET', $url, null, $headers, $options );

        if (
            ! $response->success
            || 200 > (int) $response->status_code
            || 300 <= $response->status_code
        ) {
            throw new RuntimeException(
                "Couldn't fetch response from {$url} (HTTP code {$response->status_code})."
            );
        }

        return trim( $response->body );
    }
}