"""I2NP tunnel message types — TunnelData, TunnelGateway, TunnelBuild variants."""

import struct

from i2p_data.i2np import I2NPMessage


class TunnelDataMessage(I2NPMessage):
    """Type 18: tunnel_id(4) + data(1024 bytes)."""

    TYPE = 18
    RECORD_SIZE = 1024

    def __init__(self, tunnel_id: int, data: bytes):
        self.tunnel_id = tunnel_id
        self.data = data
        self._header_msg_id = 0
        self._header_expiration = 0

    def body_bytes(self) -> bytes:
        return struct.pack("!I", self.tunnel_id) + self.data

    @classmethod
    def _from_body(cls, body: bytes) -> "TunnelDataMessage":
        tunnel_id = struct.unpack("!I", body[:4])[0]
        return cls(tunnel_id, body[4:])


class TunnelGatewayMessage(I2NPMessage):
    """Type 19: tunnel_id(4) + length(2) + data."""

    TYPE = 19

    def __init__(self, tunnel_id: int, data: bytes):
        self.tunnel_id = tunnel_id
        self.data = data
        self._header_msg_id = 0
        self._header_expiration = 0

    def body_bytes(self) -> bytes:
        return struct.pack("!IH", self.tunnel_id, len(self.data)) + self.data

    @classmethod
    def _from_body(cls, body: bytes) -> "TunnelGatewayMessage":
        tunnel_id, length = struct.unpack("!IH", body[:6])
        return cls(tunnel_id, body[6:6 + length])


class TunnelBuildMessage(I2NPMessage):
    """Type 21: 8 records of 528 bytes each."""

    TYPE = 21
    NUM_RECORDS = 8
    RECORD_SIZE = 528

    def __init__(self, records: list[bytes]):
        if len(records) != self.NUM_RECORDS:
            raise ValueError(f"TunnelBuildMessage requires exactly {self.NUM_RECORDS} records, got {len(records)}")
        self.records = records
        self._header_msg_id = 0
        self._header_expiration = 0

    def body_bytes(self) -> bytes:
        return b"".join(self.records)

    @classmethod
    def _from_body(cls, body: bytes) -> "TunnelBuildMessage":
        records = [body[i * cls.RECORD_SIZE:(i + 1) * cls.RECORD_SIZE]
                   for i in range(cls.NUM_RECORDS)]
        return cls(records)


class TunnelBuildReplyMessage(I2NPMessage):
    """Type 22: 8 records of 528 bytes each."""

    TYPE = 22
    NUM_RECORDS = 8
    RECORD_SIZE = 528

    def __init__(self, records: list[bytes]):
        if len(records) != self.NUM_RECORDS:
            raise ValueError(f"TunnelBuildReplyMessage requires exactly {self.NUM_RECORDS} records")
        self.records = records
        self._header_msg_id = 0
        self._header_expiration = 0

    def body_bytes(self) -> bytes:
        return b"".join(self.records)

    @classmethod
    def _from_body(cls, body: bytes) -> "TunnelBuildReplyMessage":
        records = [body[i * cls.RECORD_SIZE:(i + 1) * cls.RECORD_SIZE]
                   for i in range(cls.NUM_RECORDS)]
        return cls(records)


class VariableTunnelBuildMessage(I2NPMessage):
    """Type 23: count(1) + N records of 528 bytes."""

    TYPE = 23
    RECORD_SIZE = 528

    def __init__(self, records: list[bytes]):
        self.records = records
        self._header_msg_id = 0
        self._header_expiration = 0

    def body_bytes(self) -> bytes:
        return struct.pack("!B", len(self.records)) + b"".join(self.records)

    @classmethod
    def _from_body(cls, body: bytes) -> "VariableTunnelBuildMessage":
        count = body[0]
        records = [body[1 + i * cls.RECORD_SIZE:1 + (i + 1) * cls.RECORD_SIZE]
                   for i in range(count)]
        return cls(records)


class VariableTunnelBuildReplyMessage(I2NPMessage):
    """Type 24: count(1) + N records of 528 bytes."""

    TYPE = 24
    RECORD_SIZE = 528

    def __init__(self, records: list[bytes]):
        self.records = records
        self._header_msg_id = 0
        self._header_expiration = 0

    def body_bytes(self) -> bytes:
        return struct.pack("!B", len(self.records)) + b"".join(self.records)

    @classmethod
    def _from_body(cls, body: bytes) -> "VariableTunnelBuildReplyMessage":
        count = body[0]
        records = [body[1 + i * cls.RECORD_SIZE:1 + (i + 1) * cls.RECORD_SIZE]
                   for i in range(count)]
        return cls(records)