import time
import struct
import pandas as pd
from typing import Dict, Any, List, Optional
from pymodbus.client import ModbusTcpClient

EXCEL_PATH = "modbus_registers/pv_inverter_registers.xlsx"

# Bis EXKLUSIVE 40206 (also max. 40205)
MAX_ADDR_EXCLUSIVE = 40206


class PvInverter:
    def __init__(self, device_name: str, ip_address: str, port: int = 502, unit: int = 1):
        """
        device_name : Anzeigename (z.B. 'master' oder 'slave')
        ip_address  : IP des Wechselrichters oder Modbus-Gateways
        port        : TCP-Port (Standard 502)
        unit        : Modbus Unit-ID (1 = Master, 3 = Slave)
        """
        self.device_name = device_name
        self.ip = ip_address
        self.port = port
        self.unit = unit
        self.client: Optional[ModbusTcpClient] = None
        self.registers: Dict[int, Dict[str, Any]] = {}

        self.connect_to_modbus()
        self.load_registers(EXCEL_PATH)

    # ---------- Verbindung ----------
    def connect_to_modbus(self):
        self.client = ModbusTcpClient(self.ip, port=self.port, timeout=3.0)
        if not self.client.connect():
            print(f"❌ Verbindung zu {self.device_name} ({self.ip}:{self.port}) fehlgeschlagen.")
            raise SystemExit(1)
        print(f"✅ Verbindung hergestellt zu {self.device_name} ({self.ip}:{self.port}, unit={self.unit})")

    def close(self):
        if self.client:
            self.client.close()
            self.client = None

    # ---------- Register-Liste ----------
    def load_registers(self, excel_path: str):
        xls = pd.ExcelFile(excel_path)
        df = xls.parse()

        # Passe Spaltennamen an deine Excel an
        cols = ["MB Adresse", "Beschreibung", "Variabel Typ"]
        df = df[cols].dropna()
        df["MB Adresse"] = df["MB Adresse"].astype(int)

        # Nur Register unterhalb der Grenze übernehmen
        df = df[df["MB Adresse"] < MAX_ADDR_EXCLUSIVE]

        self.registers = {
            int(row["MB Adresse"]): {
                "desc": str(row["Beschreibung"]).strip(),
                "type": str(row["Variabel Typ"]).strip()
            }
            for _, row in df.iterrows()
        }

    # ---------- Low-Level Lesen ----------
    def _try_read(self, fn_name: str, address: int, count: int) -> Optional[List[int]]:
        """
        Ruft die pymodbus-Funktion mit fester unit-ID auf (kein Fallback).
        """
        fn = getattr(self.client, fn_name)
        res = fn(address=address, count=count, slave=self.unit)
        if res is None or (hasattr(res, "isError") and res.isError()):
            return None
        return getattr(res, "registers", None)

    def _read_any(self, address: int, count: int) -> Optional[List[int]]:
        regs = self._try_read("read_holding_registers", address, count)
        if regs is None:
            regs = self._try_read("read_input_registers", address, count)
        return regs

    # ---------- Decoding ----------
    @staticmethod
    def _to_i16(u16: int) -> int:
        return struct.unpack(">h", struct.pack(">H", u16))[0]

    @staticmethod
    def _to_f32_from_two(u16_hi: int, u16_lo: int, msw_first: bool = True) -> float:
        b = struct.pack(">HH", u16_hi, u16_lo) if msw_first else struct.pack(">HH", u16_lo, u16_hi)
        return struct.unpack(">f", b)[0]

    # Wie viele Register braucht der Typ?
    @staticmethod
    def _word_count_for_type(rtype: str) -> int:
        rt = (rtype or "").lower()
        if "uint32" in rt or "real" in rt or "float" in rt or "string(32)" in rt:
            return 2
        return 1

    # ---------- Lesen ----------
    def read_one(self, address_excel: int, rtype: str) -> Optional[float]:
        """
        Liest einen Wert nach Typ ('INT', 'REAL' etc.) mit fixer Unit-ID.
        """
        addr = int(address_excel)
        words = self._word_count_for_type(rtype)

        # Grenze prüfen
        if addr + words - 1 >= MAX_ADDR_EXCLUSIVE:
            return None

        if words == 2:
            regs = self._read_any(addr, 2)
            if not regs or len(regs) < 2:
                return None
            return self._to_f32_from_two(regs[0], regs[1])
        else:
            regs = self._read_any(addr, 1)
            if not regs:
                return None
            return float(self._to_i16(regs[0]))

    def get_state(self) -> Dict[str, Any]:
        """
        Liest alle gültigen Register und gibt ein dict zurück.
        """
        data = {"Zeit": time.strftime("%Y-%m-%d %H:%M:%S")}
        for address, meta in sorted(self.registers.items()):
            words = self._word_count_for_type(meta["type"])
            if address + words - 1 >= MAX_ADDR_EXCLUSIVE:
                continue
            val = self.read_one(address, meta["type"])
            if val is None:
                continue
            key = f"{address} - {meta['desc']}"
            data[key] = val
        return data