#!/usr/bin/env python3
import serial
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer

import os

PORT = os.environ["CLEVEROS_SERIAL"]
BAUD = 9600
BUFFER = []

class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        if self.path == "/stream":
            self.send_response(200)
            self.send_header("Content-Type", "text/plain; charset=utf-8")
            self.end_headers()
            self.wfile.write("\n".join(BUFFER[-200:]).encode("utf-8"))
            return

        self.send_response(200)
        self.send_header("Content-Type", "text/html; charset=utf-8")
        self.end_headers()
        self.wfile.write(b"<pre id='log'></pre><script>setInterval(async()=>{log.textContent=await fetch('/stream').then(r=>r.text())},500)</script>")

def read_serial():
    with serial.Serial(PORT, BAUD, timeout=1) as uart:
        while True:
            line = uart.readline().decode("utf-8", errors="replace").rstrip()
            if line:
                BUFFER.append(line)

# Production version in COS/tools/uart_viewer.py adds pause, clear, save-log, and status controls.