import os
import time
import json
import requests
from datetime import datetime
from pathlib import Path

# ===== SMS GATEWAY =====
SMS_USER = os.getenv("SMS_USER", "weatherbot")
SMS_PASS = os.getenv("SMS_PASS", "Cupakabra17")

RECEIVE_URL = "https://sms.internet-master.cz/receive/"
SEND_URL    = "https://sms.internet-master.cz/send/"

# Latency target: worst-case <= ~5s
POLL_INTERVAL = 1  # seconds

# Persistence
STATE_FILE = Path("weatherbot_state.json")
MAX_SEEN_OFFSETS = 5000  # cap memory/state growth

HEADERS = {
    "User-Agent": "weatherbot/1.0 (jakub@jimbuntu)"
}

session = requests.Session()
session.headers.update(HEADERS)

def fetch_inbox(limit=5):
    r = session.get(
        RECEIVE_URL,
        params={
            "username": SMS_USER,
            "password": SMS_PASS,
            "limit": limit
        },
        timeout=5
    )
    r.raise_for_status()
    return r.json()

def send_sms(number, message):
    r = session.get(
        SEND_URL,
        params={
            "number": number,
            "message": message,
            "username": SMS_USER,
            "password": SMS_PASS
        },
        timeout=5
    )
    r.raise_for_status()
    print("📤 SEND:", r.text)

def get_weather(city):
    r = session.get(f"https://wttr.in/{city}?format=j1", timeout=5)

    if r.status_code != 200:
        return f"❌ Weather unavailable for {city}"

    data = r.json()
    weather = data.get("weather", [])

    if len(weather) < 3:
        return f"❌ Weather unavailable for {city}"

    msg = f"🌦 Weather for {city}:\n"
    for day in weather[:3]:
        date = day["date"]
        avgtemp = day["avgtempC"]
        desc = day["hourly"][0]["weatherDesc"][0]["value"]
        weekday = datetime.strptime(date, "%Y-%m-%d").strftime("%a")
        msg += f"{weekday}: {avgtemp}°C, {desc}\n"

    return msg.strip()

def load_state():
    if not STATE_FILE.exists():
        return {"seen_offsets": []}
    try:
        with STATE_FILE.open("r", encoding="utf-8") as f:
            data = json.load(f)
        if not isinstance(data, dict):
            return {"seen_offsets": []}
        if "seen_offsets" not in data or not isinstance(data["seen_offsets"], list):
            data["seen_offsets"] = []
        return data
    except Exception:
        # If state is corrupt, start clean (but startup priming still prevents backlog replies)
        return {"seen_offsets": []}

def save_state(state):
    # Keep only the newest N offsets (as ints if possible)
    seen = state.get("seen_offsets", [])
    if len(seen) > MAX_SEEN_OFFSETS:
        seen = seen[-MAX_SEEN_OFFSETS:]
        state["seen_offsets"] = seen

    tmp = STATE_FILE.with_suffix(".json.tmp")
    with tmp.open("w", encoding="utf-8") as f:
        json.dump(state, f, ensure_ascii=False)
    tmp.replace(STATE_FILE)

def prime_seen_offsets(seen_set):
    """
    On startup, mark whatever is currently in the inbox as 'already seen'
    so we do NOT reply to backlog after a restart.
    """
    try:
        data = fetch_inbox(limit=20)
        inbox = data.get("inbox", [])
        primed = 0
        for sms in inbox:
            offset = sms.get("offset")
            if offset is None:
                continue
            if offset not in seen_set:
                seen_set.add(offset)
                primed += 1
        if primed:
            print(f"🧹 Primed {primed} existing message(s) as already-seen (no backlog replies).")
        else:
            print("🧹 No existing messages to prime.")
    except Exception as e:
        print("⚠ Prime failed (continuing):", e)

def add_seen(seen_set, seen_list, offset):
    # offset can be int/str depending on API; store exactly as returned
    if offset in seen_set:
        return False
    seen_set.add(offset)
    seen_list.append(offset)
    # cap list size
    if len(seen_list) > MAX_SEEN_OFFSETS:
        # drop oldest chunk
        drop = len(seen_list) - MAX_SEEN_OFFSETS
        for old in seen_list[:drop]:
            seen_set.discard(old)
        del seen_list[:drop]
    return True

# ===== MAIN =====
print("📡 SMS Weather Bot started (≤5s reply + persistent offsets)")

state = load_state()
seen_list = state.get("seen_offsets", [])
seen_set = set(seen_list)

# Prevent replying to old messages sitting in inbox after restart
prime_seen_offsets(seen_set)
# Sync list to set after priming (preserve order by appending primed ones)
# (We don't know which were primed vs existing; easiest is to rewrite list from set as a stable list)
# But to preserve bounded size, we just extend list with items missing:
for off in list(seen_set):
    if off not in seen_list:
        seen_list.append(off)
state["seen_offsets"] = seen_list
save_state(state)

while True:
    try:
        data = fetch_inbox(limit=5)
        inbox = data.get("inbox", [])

        for sms in inbox:
            offset = sms.get("offset")
            if offset is None:
                continue

            # If already processed, skip
            if offset in seen_set:
                continue

            phone = sms.get("phone", "")
            text = (sms.get("message") or "").strip()

            # Mark seen immediately to avoid duplicate replies if send fails mid-loop
            add_seen(seen_set, seen_list, offset)
            state["seen_offsets"] = seen_list
            save_state(state)

            print(f"📨 {phone}: {text}")

            reply = get_weather(text)
            send_sms(phone, reply)

            print(f"✅ Replied to {phone}")

    except Exception as e:
        print("⚠ ERROR:", e)
        # Keep latency target: no long backoff; next poll in 1s

    time.sleep(POLL_INTERVAL)