#!/usr/bin/env python3
"""Expose `upsc <ups>` as JSON: GET /jsonstatus?=nutdev1@localhost"""
import json
import os
import re
import subprocess
from urllib.parse import unquote
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer

# upsname[@hostname[:port]] -- no leading '-', so it can't be parsed as a upsc flag
UPS_RE = re.compile(r"^[A-Za-z0-9_][A-Za-z0-9_.-]*(@[A-Za-z0-9_.\[\]:-]+)?$")
HOST = os.environ.get("LISTEN_HOST", "0.0.0.0")
PORT = int(os.environ.get("LISTEN_PORT", "8000"))

# keys that look numeric but must stay strings (leading zeros / identifiers)
KEEP_STRING = ("firmware", "productid", "vendorid", "model", "version")


def convert(key, value):
    if any(k in key for k in KEEP_STRING):
        return value
    try:
        f = float(value)
        return int(f) if f.is_integer() and "." not in value else f
    except ValueError:
        return value


def read_ups(ups):
    proc = subprocess.run(
        ["upsc", ups], capture_output=True, text=True, timeout=10
    )
    if proc.returncode != 0:
        raise RuntimeError(proc.stderr.strip() or f"upsc exited {proc.returncode}")

    data = {}
    for line in proc.stdout.splitlines():
        if ": " not in line:
            continue
        key, value = line.split(": ", 1)
        key = key.strip()
        if key.startswith("Init SSL"):
            continue
        data[key] = convert(key, value.strip())

    if "ups.status" not in data:
        raise RuntimeError("no ups.status in upsc output")

    status = str(data["ups.status"])
    return {
        "ups": ups,
        "online": "OL" in status.split(),
        "on_battery": "OB" in status.split(),
        "low_battery": "LB" in status.split(),
        "status": status,
        "charge": data.get("battery.charge"),
        "load": data.get("ups.load"),
        "input_voltage": data.get("input.voltage"),
        "raw": data,
    }


class Handler(BaseHTTPRequestHandler):
    def _send(self, code, payload):
        body = json.dumps(payload, indent=2).encode()
        self.send_response(code)
        self.send_header("Content-Type", "application/json")
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        self.wfile.write(body)

    def do_GET(self):
        path, _, query = self.path.partition("?")
        if path != "/jsonstatus":
            return self._send(404, {"error": "not found"})
        ups = unquote(query).lstrip("=").strip()
        if not ups:
            return self._send(400, {"error": "usage: /jsonstatus?=upsname@host"})
        if not UPS_RE.match(ups):
            return self._send(400, {"error": f"invalid ups name: {ups!r}"})
        try:
            self._send(200, read_ups(ups))
        except Exception as e:  # upsc missing, timeout, NUT down
            self._send(503, {"ups": ups, "online": False, "error": str(e)})

    def log_message(self, fmt, *args):
        pass  # keep journal quiet; remove to log every request


if __name__ == "__main__":
    print(f"listening on http://{HOST}:{PORT}/jsonstatus?=ups@host", flush=True)
    ThreadingHTTPServer((HOST, PORT), Handler).serve_forever()