import urllib.request
import re
from datetime import datetime
import threading
import time

HEADERS = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36',
    'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
    'Accept-Language': 'en-US,en;q=0.5'
}

_cache = {
    "data": None,
    "last_fetched": 0
}
_lock = threading.Lock()

def clean_num(val: str) -> float:
    if not val:
        return 0.0
    val = val.replace(',', '').replace('+', '').replace('$', '').strip()
    try:
        return float(val)
    except:
        return 0.0

FA_NAMES = {
    "Copper": "مس (Copper)",
    "Tin": "قلع (Tin)",
    "Lead": "سرب (Lead)",
    "Zinc": "روی (Zinc)",
    "Aluminium": "آلومینیوم (Aluminium)",
    "Nickel": "نیکل (Nickel)",
    "Aluminium Alloy": "آلیاژ آلومینیوم",
    "NASAAC": "نازاک (NASAAC)"
}

def fetch_raw():
    url = 'https://www.westmetall.com/en/markdaten.php'
    req = urllib.request.Request(url, headers=HEADERS)
    with urllib.request.urlopen(req, timeout=12) as resp:
        html = resp.read().decode('utf-8', errors='ignore')

    tables = re.findall(r'<table[^>]*>([\s\S]*?)</table>', html)
    if len(tables) < 2:
        return None

    # Table 0: Official LME Prices
    t0_rows = re.findall(r'<tr[^>]*>([\s\S]*?)</tr>', tables[0])
    date_str = ""
    prices = []
    if t0_rows:
        header_cells = re.findall(r'<t[dh][^>]*>([\s\S]*?)</t[dh]>', t0_rows[0])
        if len(header_cells) > 1:
            date_str = re.sub(r'<.*?>', '', header_cells[1]).strip()

        for r in t0_rows[2:]:
            cells = [re.sub(r'<.*?>', '', c).replace('&nbsp;', ' ').strip() for c in re.findall(r'<t[dh][^>]*>([\s\S]*?)</t[dh]>', r)]
            if len(cells) >= 3 and cells[0]:
                prices.append({
                    "metal": cells[0],
                    "name_fa": FA_NAMES.get(cells[0], cells[0]),
                    "cash": clean_num(cells[1]),
                    "cash_str": cells[1],
                    "three_months": clean_num(cells[2]),
                    "three_months_str": cells[2],
                    "unit": "USD/mt"
                })

    # Table 1: LME Stocks
    t1_rows = re.findall(r'<tr[^>]*>([\s\S]*?)</tr>', tables[1])
    stocks = []
    if len(t1_rows) > 2:
        for r in t1_rows[2:]:
            cells = [re.sub(r'<.*?>', '', c).replace('&nbsp;', ' ').strip() for c in re.findall(r'<t[dh][^>]*>([\s\S]*?)</t[dh]>', r)]
            if len(cells) >= 3 and cells[0]:
                stocks.append({
                    "metal": cells[0],
                    "name_fa": FA_NAMES.get(cells[0], cells[0]),
                    "stocks": clean_num(cells[1]),
                    "stocks_str": cells[1],
                    "change": clean_num(cells[2]),
                    "change_str": cells[2],
                    "unit": "mt"
                })

    # Combine Prices + Stocks by metal
    combined_metals = []
    stocks_map = {s["metal"]: s for s in stocks}
    for p in prices:
        m_name = p["metal"]
        s_data = stocks_map.get(m_name, {})
        spread = round(p["three_months"] - p["cash"], 2)
        combined_metals.append({
            "metal": m_name,
            "name_fa": p["name_fa"],
            "cash_settlement": p["cash"],
            "cash_str": p["cash_str"],
            "three_months": p["three_months"],
            "three_months_str": p["three_months_str"],
            "spread": spread,
            "spread_str": f"{spread:+,.2f}",
            "market_condition": "Contango" if spread > 0 else ("Backwardation" if spread < 0 else "Flat"),
            "stocks": s_data.get("stocks", 0),
            "stocks_str": s_data.get("stocks_str", "-"),
            "stocks_change": s_data.get("change", 0),
            "stocks_change_str": s_data.get("change_str", "-"),
            "unit": "USD/mt"
        })

    # Table 2: FX Rates
    fx = []
    if len(tables) > 2:
        for r in re.findall(r'<tr[^>]*>([\s\S]*?)</tr>', tables[2])[1:]:
            cells = [re.sub(r'<.*?>', '', c).replace('&nbsp;', ' ').strip() for c in re.findall(r'<t[dh][^>]*>([\s\S]*?)</t[dh]>', r)]
            if len(cells) >= 2 and cells[0]:
                fx.append({
                    "pair": cells[0],
                    "rate": clean_num(cells[1]),
                    "rate_str": cells[1]
                })

    # Table 4: Precious Metals
    precious = []
    if len(tables) > 4:
        for r in re.findall(r'<tr[^>]*>([\s\S]*?)</tr>', tables[4])[1:]:
            cells = [re.sub(r'<.*?>', '', c).replace('&nbsp;', ' ').strip() for c in re.findall(r'<t[dh][^>]*>([\s\S]*?)</t[dh]>', r)]
            if len(cells) >= 2 and cells[0]:
                precious.append({
                    "name": cells[0],
                    "price_str": cells[1]
                })

    return {
        "source": "Westmetall GmbH / London Metal Exchange (LME)",
        "source_url": "https://www.westmetall.com/en/markdaten.php",
        "date": date_str or datetime.utcnow().strftime("%d. %B %Y"),
        "updated_at": datetime.utcnow().isoformat(),
        "metals": combined_metals,
        "stocks": stocks,
        "exchange_rates": fx,
        "precious_metals": precious
    }

def get_lme_data(ttl_seconds: int = 180):
    now = time.time()
    with _lock:
        if _cache["data"] and (now - _cache["last_fetched"]) < ttl_seconds:
            return _cache["data"]
        try:
            fresh = fetch_raw()
            if fresh:
                _cache["data"] = fresh
                _cache["last_fetched"] = now
                return fresh
        except Exception as e:
            if _cache["data"]:
                return _cache["data"]
            raise e
        return _cache["data"]