"""Robot abstraction layer.

This is the ONLY contract the rest of the application knows about. Nothing above
this layer (services, API, frontend) may import a vendor SDK, an HTTP client or a
ROS package. Adding a new robot means adding one file that implements
`RobotAdapter` and registering it in `factory.py`.
"""

from __future__ import annotations

import abc
import time
import uuid
from dataclasses import dataclass, field
from enum import Enum
from typing import Any, Awaitable, Callable, Dict, Optional


# --------------------------------------------------------------------------- #
# enums
# --------------------------------------------------------------------------- #
class RobotState(str, Enum):
    DISCONNECTED = "disconnected"
    CONNECTING = "connecting"
    CONNECTED = "connected"
    ERROR = "error"


class SpeechStage(str, Enum):
    """Lifecycle of a single utterance, mirrored 1:1 in the UI."""

    QUEUED = "queued"
    SENDING = "sending"          # request leaving the PC
    PROCESSING = "processing"    # robot accepted it, synthesising
    SPEAKING = "speaking"        # audio is coming out of the speaker
    COMPLETED = "completed"
    CANCELLED = "cancelled"
    FAILED = "failed"


TERMINAL_STAGES = {SpeechStage.COMPLETED, SpeechStage.CANCELLED, SpeechStage.FAILED}


# --------------------------------------------------------------------------- #
# errors
# --------------------------------------------------------------------------- #
class RobotError(Exception):
    """Base class for every robot-layer failure.

    `user_message` is safe to show in the browser; `str(exc)` may contain detail
    useful in the server log but noisy for an operator during a live demo.
    """

    code = "robot_error"
    user_message = "The robot reported an error."

    def __init__(self, message: str = "", user_message: Optional[str] = None) -> None:
        super().__init__(message or self.user_message)
        if user_message:
            self.user_message = user_message


class RobotNotConfigured(RobotError):
    code = "not_configured"
    user_message = "Robot is not configured. Set ROBOT_IP in the .env file."


class RobotUnreachable(RobotError):
    code = "unreachable"
    user_message = "Robot is offline. Check the robot IP address and network connection."


class RobotTimeout(RobotError):
    code = "timeout"
    user_message = "The robot did not respond in time."


class RobotBusy(RobotError):
    code = "busy"
    user_message = "The robot is already speaking."


class SpeechFailed(RobotError):
    code = "speech_failed"
    user_message = "Speech request failed."


class TransportNotAvailable(RobotError):
    code = "transport_unavailable"
    user_message = "The selected robot transport is not available on this PC."


# --------------------------------------------------------------------------- #
# value objects
# --------------------------------------------------------------------------- #
@dataclass(frozen=True)
class RobotCapabilities:
    """What this adapter can actually do, so the UI never offers a dead control."""

    native_tts: bool = True
    stop: bool = True
    progress_events: bool = True
    reports_completion: bool = True
    voice_selection: bool = False
    volume_control: bool = False


@dataclass(frozen=True)
class RobotInfo:
    name: str
    model: str
    mode: str
    transport: str
    address: str
    capabilities: RobotCapabilities

    def to_dict(self) -> Dict[str, Any]:
        return {
            "name": self.name,
            "model": self.model,
            "mode": self.mode,
            "transport": self.transport,
            "address": self.address,
            "capabilities": {
                "nativeTts": self.capabilities.native_tts,
                "stop": self.capabilities.stop,
                "progressEvents": self.capabilities.progress_events,
                "reportsCompletion": self.capabilities.reports_completion,
                "voiceSelection": self.capabilities.voice_selection,
                "volumeControl": self.capabilities.volume_control,
            },
        }


@dataclass
class SpeechRequest:
    text: str
    id: str = field(default_factory=lambda: uuid.uuid4().hex[:12])
    voice: Optional[str] = None
    language: Optional[str] = None
    created_at: float = field(default_factory=time.time)

    @property
    def preview(self) -> str:
        text = " ".join(self.text.split())
        return text if len(text) <= 80 else text[:77] + "..."


@dataclass
class SpeechProgress:
    """One lifecycle update for an utterance, pushed straight to the browser."""

    request_id: str
    stage: SpeechStage
    message: str = ""
    detail: Optional[str] = None
    error_code: Optional[str] = None
    elapsed_ms: Optional[int] = None
    at: float = field(default_factory=time.time)

    def to_dict(self) -> Dict[str, Any]:
        return {
            "requestId": self.request_id,
            "stage": self.stage.value,
            "message": self.message,
            "detail": self.detail,
            "errorCode": self.error_code,
            "elapsedMs": self.elapsed_ms,
            "at": self.at,
        }


@dataclass
class SpeechResult:
    request_id: str
    success: bool
    stage: SpeechStage
    # Time from "user pressed Speak" to the robot acknowledging the request. This
    # is the number that matters for a live demo - it is the perceived delay.
    ack_latency_ms: Optional[int] = None
    total_ms: Optional[int] = None
    error_code: Optional[str] = None
    error: Optional[str] = None

    def to_dict(self) -> Dict[str, Any]:
        return {
            "requestId": self.request_id,
            "success": self.success,
            "stage": self.stage.value,
            "ackLatencyMs": self.ack_latency_ms,
            "totalMs": self.total_ms,
            "errorCode": self.error_code,
            "error": self.error,
        }


ProgressCallback = Callable[[SpeechProgress], Awaitable[None]]


# --------------------------------------------------------------------------- #
# adapter contract
# --------------------------------------------------------------------------- #
class RobotAdapter(abc.ABC):
    """Every robot backend implements exactly this."""

    @property
    @abc.abstractmethod
    def info(self) -> RobotInfo:
        """Static description of the robot / connection."""

    @abc.abstractmethod
    async def connect(self) -> None:
        """Establish (or verify) the connection. Raises RobotError on failure."""

    @abc.abstractmethod
    async def disconnect(self) -> None:
        """Release sockets/clients. Must never raise."""

    @abc.abstractmethod
    async def health_check(self) -> bool:
        """Cheap liveness probe used by the connection manager."""

    @abc.abstractmethod
    async def speak(self, request: SpeechRequest, on_progress: ProgressCallback) -> SpeechResult:
        """Send text to the robot and report progress until the utterance ends."""

    @abc.abstractmethod
    async def stop_speaking(self) -> bool:
        """Interrupt the current utterance. Returns True if a stop was issued."""

    @property
    @abc.abstractmethod
    def is_connected(self) -> bool:
        """Last known connection state - must not perform I/O."""

    @property
    def is_speaking(self) -> bool:
        return False

    async def describe(self) -> Dict[str, Any]:
        """Optional richer diagnostics for the /api/robot/diagnostics endpoint."""
        return {}