<?php

class jwc_helper {

    /**
     * 返回semester学期中编号为coursenumber的课程中teachers下辖所有学生
     *
     * 返回数组，成员是用户id
     * 如无学生，返回空数组
     * 如远程学生没有可匹配的本地账号，存入nonexist_students数组
     * 如遇错误，返回false，return_msg里保存错误信息
     */
    public function get_students($coursenumber, array $teachers, $semester, &$return_msg, &$nonexist_students = null) {
        global $DB;

        $courses = $this->get_matched_courses($coursenumber, $teachers, $semester, $return_msg);
        if ($courses === false) {
            return false;
        } else if (empty($courses)) {
            $return_msg = '没有可同步的课程';
            return false;
        }

        $course = reset($courses);
        $return_msg = $course->kcname.'-对应'.count($courses).'个教务处选课';

        // 获取学生
        $students = array();
        foreach ($courses as $course) {
            $raw_students = $this->get_all_students($course->xkid, $return_msg);
            if (!$raw_students) {
                return false;
            }

            foreach ($raw_students as $item) {
                if ($userid = $DB->get_field('user', 'id', array('auth'=>'cas', 'username'=>$item->code, 'lastname'=>$item->name))) {
                    $students[$userid] = $userid;
                } else {
                    if (is_array($nonexist_students)) {
                        $nonexist_students[] = $item;
                    }
                }
            }
        }

        return $students;
    }

    /**
     * 得到编号为coursenumber的所有课程信息
     *
     * 返回数组，成员是课程对象
     * 如编号正确但无对应课程，返回空数组
     * 如遇错误，返回false
     */
    public function get_all_courses($coursenumber, $semester, &$error) {
        $params = array();
        $params['xq'] = $semester;
        $params['id'] = $coursenumber;
        $jwcstr = $this->access('http://xscj.hit.edu.cn/hitjwgl/lxw/getinfoD.asp', $params);

        if ($this->has_error($jwcstr, $error)) {
            return false;
        }

        $info = new SimpleXMLElement($jwcstr);
        $courses = array();
        foreach ($info->course->item as $item) {
            $courses[] = $item;
        }

        return $courses;
    }

    /**
     * 得到选课ID为xkid的课程中所有学生
     */
    public function get_all_students($xkid, &$return_msg) {
        $params = array();
        $params['id'] = $xkid;
        $jwcstr = $this->access('http://xscj.hit.edu.cn/hitjwgl/lxw/getinfoC.asp', $params);

        if ($this->has_error($jwcstr, $return_msg)) {
            return false;
        }

        $info = new SimpleXMLElement($jwcstr);
        return $info->stud->item;
    }

    /**
     * 返回semester学期中编号为coursenumber的课程中teachers对应的教务处课程
     *
     * 返回数组，成员是用户id
     * 如无对应选课，返回空数组
     * 如遇错误，返回false
     */
    public function get_matched_courses($coursenumber, array $teachers, $semester, &$return_msg) {
        global $DB;

        if (! $courses = $this->get_all_courses($coursenumber, $semester, $return_msg)) {
            return false;
        }

        // 匹配教师姓名，找出可同步的课程
        $matched = array();
        foreach ($courses as $course) {
            foreach ($teachers as $teacher) {
                if ($teacher->lastname == $course->jsname) {
                    $matched[] = $course;
                    break;  // 有一个教师与当前课匹配，就够了
                }
            }
        }

        return $matched;
    }

    public function export($xkid, $key, &$return_msg) {
        $url = "http://xscj.hit.edu.cn/hitjwgl/lxw/uploadgrade.asp?xkid=$xkid&key=$key";
        // echo $url.'<br />';
        $ret = download_file_content($url);

        if ($ret) {
            // 是否出错
            if (!strstr(strip_tags($ret), 'success')) {
               $return_msg = trim(strip_tags($ret));
               $ret = false;
            }
        }

        return $ret;
    }

    protected function access($url_base, $params) {
        global $CFG;

        if (empty($params)) {
            return false;
        }

        $param = '';
        foreach ($params as $var => $value) {
            //$value = textlib_get_instance()->convert($value, 'UTF-8', 'GBK');
            $value = urlencode($value);
            if (empty($param)) {
                $param = "$var=$value";
            } else {
                $param .= "&$var=$value";
            }
        }

        // 添加数字签名
        $prefix = get_config('enrol_jwc', 'signprefix');
        $suffix = get_config('enrol_jwc', 'signsuffix');
        $sign = md5($prefix.$param.$suffix);
        $param .= "&sign=$sign";

        $url = $url_base.'?'.$param;

        require_once("$CFG->libdir/filelib.php");
        return download_file_content($url);
    }

    protected function has_error($jwcstr, &$error) {
        $result = false; // no error

        if ($jwcstr === false) {
            $error = '访问教务处网站出错';
            $result = true;
        } else {
            $info = new SimpleXMLElement($jwcstr);
            if ($info->retu->flag == 0) {
                $error = $info->retu->errorinfo;
                $result = true;
            }
        }

        return $result;
    }
}