"""登录链路：base64 账号密码、图形验证码识别、ITLMS 换票。"""
import base64
import re
import time

from . import http

_OCR = None


def b64(text):
    return base64.b64encode(str(text).encode("utf-8")).decode()


def ocr():
    """4 位图形验证码：ddddocr 离线识别。"""
    global _OCR
    if _OCR is None:
        try:
            import ddddocr
        except Exception as e:
            raise RuntimeError("登录要过图形验证码，需要先装 ddddocr（pip install ddddocr）：%s" % e)
        _OCR = ddddocr.DdddOcr(show_ad=False)
    return _OCR


def captcha(s):
    raw = s.get(http.G + "/login/readCaptcha.action?d=%.6f" % time.time(), timeout=30).text
    return base64.b64decode(raw.strip().strip('"').split(",", 1)[-1])


def login_error(s):
    html = s.get(http.G + "/login.jsp", timeout=30).text
    m = re.search(r'id="errorText"[^>]*>([^<]*)<', html)
    return (m.group(1).strip() if m else "")


def sso(s):
    """jsglpt 会话换 ITLMS 票，票按 `ITLMS-xxx||ticketId` 两段交给 jsxx。

    交接入口来自 jsglpt 首页那个隐藏表单：
    `GET https://jsxx.gds.edu.cn/nts/loginToStoreByAccount?ticket=&ticketId=`
    """
    r = s.post(http.G + "/teacher/ssoItlmsGxkTicket.action?verificaCode=true&page=", timeout=30)
    ticket = (r.text or "").strip()
    if not ticket.startswith("ITLMS-") or "||" not in ticket:
        raise http.expired("取 ITLMS 票失败：%s" % (ticket[:80] or "空响应"))
    t, tid = ticket.split("||", 1)
    q = s.get(http.X + "/nts/loginToStoreByAccount", params={"ticket": t, "ticketId": tid}, timeout=30)
    if "logout" not in q.text and "我的课程" not in q.text:
        raise http.expired("带票进学习平台失败，票可能已失效")
    return s