from ipaddress import ip_address
from typing import Literal

from pydantic import BaseModel, ConfigDict, Field, field_validator, model_validator


SUPPORTED_FUNCTION_CODES = {1, 2, 3, 4}
SUPPORTED_POINT_TYPES = {
    "bool",
    "int16",
    "uint16",
    "int32",
    "uint32",
    "int64",
    "uint64",
    "float32",
    "float64",
}


class ModbusBaseRequest(BaseModel):
    model_config = ConfigDict(extra="forbid")

    device_type: Literal["ModbusTCP"] = "ModbusTCP"
    ip: str = Field(min_length=1)
    port: int = Field(ge=1, le=65535)
    word_byte_order: Literal["ABCD", "BADC", "CDAB", "DCBA"] = "ABCD"
    address_base: int = Field(default=0, ge=0)
    slave_id: int = Field(default=1, ge=0, le=247)

    @field_validator("ip")
    @classmethod
    def validate_ip(cls, value: str) -> str:
        try:
            ip_address(value)
        except ValueError as exc:
            raise ValueError("ip must be a valid IP address") from exc
        return value


class ModbusReadSpec(BaseModel):
    model_config = ConfigDict(extra="forbid")

    function_code: int
    address: int = Field(ge=0)
    quantity: int = Field(ge=1, le=125)

    @field_validator("function_code")
    @classmethod
    def validate_function_code(cls, value: int) -> int:
        if value not in SUPPORTED_FUNCTION_CODES:
            raise ValueError("function_code must be one of 1, 2, 3, 4")
        return value


class ModbusRawReadRequest(ModbusBaseRequest):
    read: ModbusReadSpec


class ModbusPointSpec(BaseModel):
    model_config = ConfigDict(extra="forbid")

    function_code: int
    address: int = Field(ge=0)
    type: str
    bit: int | None = Field(default=None, ge=0, le=15)

    @field_validator("function_code")
    @classmethod
    def validate_function_code(cls, value: int) -> int:
        if value not in SUPPORTED_FUNCTION_CODES:
            raise ValueError("function_code must be one of 1, 2, 3, 4")
        return value

    @field_validator("type")
    @classmethod
    def validate_type(cls, value: str) -> str:
        normalized = value.lower()
        if normalized not in SUPPORTED_POINT_TYPES:
            raise ValueError("type must be one of bool, int16, uint16, int32, uint32, int64, uint64, float32, float64")
        return normalized

    @model_validator(mode="after")
    def validate_point(self) -> "ModbusPointSpec":
        if self.function_code in {1, 2} and self.type != "bool":
            raise ValueError("function_code 1 and 2 only support bool points")
        if self.function_code in {1, 2} and self.bit is not None:
            raise ValueError("bit is only supported for register points")
        return self


class ModbusPointReadRequest(ModbusBaseRequest):
    points: list[ModbusPointSpec] = Field(min_length=1)