<?php

/**
 * This file contain fetch class, which is used to communicate with NTFY.sh
 * REST api. It makes that HTTP request using buildin CURL extension is 
 * much easier, and looks better in high level code.
 * 
 * @package phpnotify
 * @author Cixo (Cixo Electronic)
 */
namespace phpnotify;

use \TypeError as TypeError;
use \RuntimeException as RuntimeException;

use \CurlHandle as CurlHandle;
use \curl_init as curl_init;
use \curl_setopt as curl_setopt;
use \curl_close as curl_close;
use \curl_exec as curl_exec;
use \curl_error as curl_error;
use \curl_errno as curl_errno;

require('response.php');

/**
 * This class is responsible for downloading data from the server. It uses 
 * buildin CURL extension to make HTTP request. It not parsing response 
 * directly, but use {@link response} 
 */
class fetch {
    
    /**
     * This store content of the requst body.
     * @var ?string
     */
    private ?string $content;

    /**
     * This store type of content.
     * @var ?string
     */
    private ?string $content_type;

    /**
     * This store method of the request.
     * @var string
     */
    private string $method;

    /**
     * This store url to fetch.
     * @var string
     */
    private string $url;

    /**
     * This store headers of the request.
     * @var array
     */
    private array $headers;

    /**
     * This create new fetch request. It is alias of constructor.
     * 
     * @link fetch::__construct()
     * @static 
     * @param string $url URL to fetch.
     * @return fetch New fetch object.
     */
    public static function create(string $url): object {
        return new self($url);
    }

    /**
     * This initialize new fetch request by given URL. Default method for 
     * the request is GET. If do not want to use new, see create.
     * 
     * @link fetch::create()
     * @param string $url URL to work with.
     */
    public function __construct(string $url) {
        $this->content = null;
        $this->content_type = null;
        $this->method = 'GET';
        $this->headers = array();
        $this->url = $url;
    }

    /**
     * This function could be use send array in the fetch request. Be careful
     * because this function verify that method of the request is not GET or
     * HEAD, which can not contain body. Property method must be set before.
     * 
     * @param array $content Content which must be send.
     * @return fetch Itself to chain load.
     */
    public function send_array(array $content): object {
        $content = json_encode($content);
        $type = 'application/json';

        $this->send_raw($content, $type);
        return $this;
        
    }

    /**
     * This function is similar to {@link fetch::send_array()}, but work on 
     * raw string data. Also content type must be set. Be careful, because
     * it check that method of the request is not GET or HEAD, which can 
     * not contain body content.
     * 
     * @param string $content Content of the body to send.
     * @param string $type Type of the content, like "text/plain".
     * @return fetch Self to chan loading.
     */
    public function send_raw(string $content, string $type): object {
        if ($this->method === 'GET' or $this->method === 'HEAD') {
            throw new TypeError('GET or HEAD request can not contain body.');
        }

        $this->content = $content;
        $this->content_type = $type;

        return $this;
    }

    /**
     * That add new header to the request. Name of the header must be full 
     * featured header name, like 'Cache-Control'. It also had been validated
     * and when name had been blacklisted, it raise RuntimeException. It also
     * raise RuntimeException when name has any white chars. Content had been 
     * validating, and it could not have new lines. Name and content would be
     * trimed before processing.
     * 
     * Blacklisted headers:
     * Content-Type, Content-Length
     * 
     * @param string $name Name of the header.
     * @param string $content Content of the header.
     * @return fetch Self to chain processing.
     */
    public function add_header(string $name, string $content): object {
        $name = trim($name);
        $content = trim($content);

        if (strpos($name, ' ') !== false) {
            throw new RuntimeException(
                'Header "'.$name.'" contains white char.'
            );
        }

        $check_content = strpos($content, ' ') !== false;
        $check_content = $check_content || strpos($content, "\r") !== false;
        $check_content = $check_content || strpos($content, "\n") !== false;

        if ($check_content) {
            throw new RuntimeException(
                'Header content "'.$content.'" contains invalid white char.'
            );
        }

        if ($name === 'Content-Type') {
            throw new RuntimeException('Content-Type header is automatic.');
        }

        if ($name === 'Content-Lenght') {
            throw new RuntimeException('Content-Lenght header is automatic.');
        }

        $header = $name.': '.$content;
        array_push($this->headers, $header);
        
        return $this;
    }

    /**
     * This function set method of the request. Be careful, because it check 
     * that any content is not set, and when content is not null, but trying
     * to set GET or HEAD method, it throw TypeError.
     * 
     * @param string $name Name of the method.
     * @return fetch Self to chain loading.
     */
    public function set_method(string $name): object {
        if ($this->content === null) {
            $this->method = $name;
            return $this;
        }

        if ($name === 'GET' || $name === 'HEAD') {
            throw new TypeError('GET or HEAD request can not contain body.');
        }

        $this->method = $name;
        return $this;
    }
    
    /**
     * That function make request to the server, from fetch config, which
     * had been config previously. It return response in parsed form, as 
     * instance of response class. Be careful, it raise an RuntimeException
     * when server does not response correctly.
     *
     * @return response Response from the server.
     */
    public function request(): response {
        $headers = $this->headers;
        $request = curl_init($this->url);

        curl_setopt($request, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($request, CURLOPT_FAILONERROR, true);
        curl_setopt($request, CURLOPT_HEADER, true);
        curl_setopt($request,CURLOPT_CUSTOMREQUEST, $this->method);

        if ($this->content !== null) {
            array_push($headers, 'Content-Type: '.$this->content_type);
            curl_setopt($request, CURLOPT_POSTFIELDS, $this->content);
        }

        curl_setopt($request, CURLOPT_HTTPHEADER, $headers);
        
        $result = curl_exec($request);
        $error = curl_error($request);
        $error_number = curl_errno($request);
        
        curl_close($request);
        
        if ($result !== false and $error_number === 0) {
            return new response($result);
        }

        throw new RuntimeException(
            'Can not fetch request. Error code '
            .strval($error_number)
            .': "'.$error.'".'
        );
    }

}