"""Request a real WhatsApp mobile-linking QR in an isolated background browser.

The official WhatsApp Web client creates the keys and requests the server ref.
This script reads the displayed QR payload and renders it locally. It does not
extract credentials from the existing Desktop account or implement fake pairing.
Requires: pip install websockets 'qrcode[pil]'
"""
from __future__ import annotations
import argparse, base64, datetime as dt, hashlib, json, os
from pathlib import Path
import socket, subprocess, sys, time, urllib.parse, urllib.request
import http.server,threading

from .common import BASE as ROOT
READ_QR=r'''(() => {
const element=Array.from(document.querySelectorAll('[data-ref]')).find(e=>{const v=e.getAttribute('data-ref');return v&&v.split(',').length>=4;});
const payload=element?.getAttribute('data-ref')??null;
let linked=false;
try {linked=!!require('WAWebUserPrefsMeUser').getMaybeMePnUser();}catch{}
let refreshRequested=false;
if(!linked&&!payload){const button=document.querySelector('[data-testid="link_device_qr_expired_refresh_button"]');if(button){button.click();refreshRequested=true;}}
return {payload,linked,refreshRequested,title:document.title,origin:location.origin};
})()'''

def chrome_path(explicit):
    if explicit:return Path(explicit).resolve()
    candidates=[Path(os.environ.get('PROGRAMFILES','C:/Program Files'))/'Google/Chrome/Application/chrome.exe',Path(os.environ.get('PROGRAMFILES(X86)','C:/Program Files (x86)'))/'Google/Chrome/Application/chrome.exe',Path(os.environ.get('LOCALAPPDATA',''))/'Google/Chrome/Application/chrome.exe']
    return next((p for p in candidates if p.is_file()),None)

def call(url,expression):
    from websockets.sync.client import connect
    with connect(url,open_timeout=10,max_size=1_000_000) as ws:
        ws.send(json.dumps({'id':1,'method':'Runtime.evaluate','params':{'expression':expression,'returnByValue':True}}))
        while True:
            result=json.loads(ws.recv(timeout=15))
            if result.get('id')!=1:continue
            if result.get('error') or result.get('result',{}).get('exceptionDetails'):raise RuntimeError('Page probe failed')
            return result['result']['result'].get('value')

def describe(payload):
    parts=payload.split(',')
    lengths=[]
    for part in parts[1:]:
        try:lengths.append(len(base64.b64decode(part,validate=True)))
        except Exception:lengths.append(None)
    return {'field_count':len(parts),'payload_length':len(payload),'sha256':hashlib.sha256(payload.encode()).hexdigest(),'base64_field_byte_lengths':lengths}

def write_qr(payload,out):
    import qrcode
    qr=qrcode.QRCode(error_correction=qrcode.constants.ERROR_CORRECT_M,box_size=10,border=4)
    qr.add_data(payload);qr.make(fit=True)
    qr.make_image(fill_color='black',back_color='white').save(out/'pairing-qr.png')
    # No raw QR payload, identity secret or session key is written to the report.
    report={'timestamp_utc':dt.datetime.now(dt.timezone.utc).isoformat(),'status':'waiting_for_mobile_scan','source':'Official WhatsApp Web QR DOM in isolated headless Chrome','qr_metadata':describe(payload),'note':'QR rotates and requires the matching browser session to remain running.'}
    (out/'pairing-status.json').write_text(json.dumps(report,indent=2),encoding='utf-8')
    (out/'pairing-qr.html').write_text('<!doctype html><html><head><meta charset="utf-8"><meta http-equiv="refresh" content="3"><title>WhatsApp test pairing</title></head><body style="font-family:Arial;text-align:center"><h1>Link your own WhatsApp phone</h1><p>WhatsApp → Linked devices → Link a device.</p><img src="pairing-qr.png" style="max-width:90vw"><p>This QR links the isolated Python test session. The image updates while the script runs.</p></body></html>',encoding='utf-8')

def serve_viewer(out):
    class Handler(http.server.SimpleHTTPRequestHandler):
        def __init__(self,*a,**kw):super().__init__(*a,directory=str(out),**kw)
        def log_message(self,*a):pass
        def do_GET(self):
            if urllib.parse.urlsplit(self.path).path not in ('/pairing-qr.html','/pairing-qr.png','/pairing-status.json'):
                self.send_error(404);return
            super().do_GET()
    server=http.server.ThreadingHTTPServer(('127.0.0.1',0),Handler)
    threading.Thread(target=server.serve_forever,daemon=True).start()
    return server,f'http://127.0.0.1:{server.server_port}/pairing-qr.html'

def main(argv=None):
    p=argparse.ArgumentParser(description=__doc__)
    p.add_argument('--browser',type=Path);p.add_argument('--profile',type=Path,default=ROOT/'whatsapp-pairing-profile');p.add_argument('--output-dir',type=Path,default=ROOT/'whatsapp-pairing');p.add_argument('--watch-seconds',type=int,default=300);p.add_argument('--startup-seconds',type=int,default=90)
    args=p.parse_args(argv);browser=chrome_path(args.browser)
    if not browser or not browser.is_file():p.error('Chrome executable missing; supply --browser')
    if not 10<=args.watch_seconds<=3600:p.error('--watch-seconds must be 10..3600')
    profile=args.profile.resolve();out=args.output_dir.resolve()
    if '5319275a.whatsappdesktop' in str(profile).lower():p.error('Refusing the existing WhatsApp Desktop profile')
    marker=profile/'python-pairing-profile.json'
    if profile.exists() and any(profile.iterdir()) and not marker.exists():p.error('Profile must be empty or created by this script')
    profile.mkdir(parents=True,exist_ok=True);out.mkdir(parents=True,exist_ok=True)
    marker.write_text(json.dumps({'purpose':'isolated official WhatsApp Web pairing test'}),encoding='utf-8')
    with socket.socket() as sock:sock.bind(('127.0.0.1',0));port=sock.getsockname()[1]
    command=[str(browser),'--headless=new','--no-first-run','--no-default-browser-check','--remote-debugging-address=127.0.0.1',f'--remote-debugging-port={port}',f'--user-data-dir={profile}','--window-size=1200,1000','https://web.whatsapp.com/']
    flags=subprocess.CREATE_NO_WINDOW if sys.platform=='win32' else 0
    proc=subprocess.Popen(command,stdout=subprocess.DEVNULL,stderr=subprocess.DEVNULL,creationflags=flags)
    viewer,viewer_url=serve_viewer(out)
    endpoint=f'http://127.0.0.1:{port}';(out/'pairing-runtime.json').write_text(json.dumps({'browser_pid':proc.pid,'cdp_endpoint':endpoint,'viewer_url':viewer_url,'profile':str(profile)},indent=2),encoding='utf-8')
    start=time.monotonic();last_payload=None;generated=0;linked=False
    print(f'Isolated background session started; QR output: {out}',flush=True)
    print(f'REA observation endpoint: {endpoint}',flush=True)
    print(f'QR viewer (auto-refresh): {viewer_url}',flush=True)
    try:
        while time.monotonic()-start<args.watch_seconds:
            if proc.poll() is not None:raise RuntimeError('Background browser exited')
            try:
                with urllib.request.urlopen(endpoint+'/json/list',timeout=3) as response:targets=json.load(response)
                target=next((t for t in targets if t.get('type')=='page' and urllib.parse.urlsplit(t.get('url','')).hostname=='web.whatsapp.com'),None)
                if not target:time.sleep(1);continue
                state=call(target['webSocketDebuggerUrl'],READ_QR)
            except (OSError,StopIteration):time.sleep(1);continue
            if not state or state.get('origin')!='https://web.whatsapp.com':
                if time.monotonic()-start>args.startup_seconds:raise RuntimeError('WhatsApp page did not commit before startup timeout')
                time.sleep(1);continue
            if state.get('linked'):
                linked=True;(out/'pairing-status.json').write_text(json.dumps({'status':'linked','timestamp_utc':dt.datetime.now(dt.timezone.utc).isoformat(),'profile':str(profile),'note':'Browser is kept alive until the watch timeout; credentials remain only in its isolated profile.'},indent=2),encoding='utf-8')
                if last_payload is not None:print('Mobile linking confirmed.',flush=True);last_payload=None
            elif state.get('payload') and state['payload']!=last_payload:
                last_payload=state['payload'];write_qr(last_payload,out);generated+=1
                print(f'QR refreshed ({generated}); scan pairing-qr.png from your own phone.',flush=True)
            elif state.get('refreshRequested'):
                print('Expired QR: requested a fresh reference through the official reload button.',flush=True)
            elif not generated and time.monotonic()-start>args.startup_seconds:raise RuntimeError('No pairing QR appeared before startup timeout')
            time.sleep(2)
        return 0 if generated or linked else 1
    except KeyboardInterrupt:return 0
    finally:
        viewer.shutdown();viewer.server_close()
        try:
            with urllib.request.urlopen(endpoint+'/json/version',timeout=3) as response:version=json.load(response)
            with connect(version['webSocketDebuggerUrl'],open_timeout=3) as ws:ws.send(json.dumps({'id':1,'method':'Browser.close'}))
        except Exception:proc.terminate()
        try:proc.wait(timeout=10)
        except subprocess.TimeoutExpired:proc.kill()
        (out/'pairing-runtime.json').write_text(json.dumps({'running':False,'linked':linked,'qr_refreshes':generated},indent=2),encoding='utf-8')
        if not linked and (out/'pairing-status.json').exists():
            report=json.loads((out/'pairing-status.json').read_text());report['status']='expired_browser_closed';(out/'pairing-status.json').write_text(json.dumps(report,indent=2),encoding='utf-8')

if __name__=='__main__':raise SystemExit(main())