"""
domain/exceptions/pipeline_exceptions.py
────────────────────────────────────────
Custom domain-specific exceptions for signal preprocessing, model inference,
and message broker operations.

Keeps clean architecture by remaining decoupled from infrastructure frameworks
(e.g. FastAPI, PyTorch, aio-pika).

Hierarchy (all extend DomainException):
    PreprocessingError   — signal preprocessing / ETL failure    → 422
    ModelInferenceError  — deep learning model failure           → 503
    BrokerError          — message broker publish/consume error  → 503
"""
from __future__ import annotations

from src.domain.exceptions.domain_exceptions import DomainException


class PreprocessingError(DomainException):
    """
    Raised when an error occurs during signal preprocessing or ETL.

    Examples:
        - Signal duration is too short for segmenting.
        - Resampling or filtering fails.
        - Visibility Graph calculation fails or produces invalid results.

    HTTP Status: 422 Unprocessable Entity
    """

    def __init__(self, step: str, reason: str, context: dict | None = None) -> None:
        message = f"Preprocessing failed at step '{step}': {reason}"
        ctx = {"step": step, "reason": reason}
        if context:
            ctx.update(context)
        super().__init__(message, context=ctx)
        self.step = step
        self.reason = reason


class ModelInferenceError(DomainException):
    """
    Raised when a deep learning model inference fails.

    Examples:
        - Missing weight checkpoints on disk.
        - Checkpoint layout does not match state_dict expectation.
        - PyTorch model forward pass fails.

    HTTP Status: 503 Service Unavailable
    """

    def __init__(self, model_name: str, reason: str, context: dict | None = None) -> None:
        message = f"Model '{model_name}' inference failed: {reason}"
        ctx = {"model_name": model_name, "reason": reason}
        if context:
            ctx.update(context)
        super().__init__(message, context=ctx)
        self.model_name = model_name
        self.reason = reason


class BrokerError(DomainException):
    """
    Raised when the message broker (RabbitMQ) is unreachable or a
    publish/consume operation fails.

    Wraps aio-pika / AMQP low-level errors so that domain and application
    layers never import broker-specific libraries directly.

    HTTP Status: 503 Service Unavailable

    Args:
        operation: The broker operation that failed (e.g. ``"publish"``, ``"connect"``).
        reason:    Human-readable description of what went wrong.
    """

    def __init__(self, operation: str, reason: str) -> None:
        message = f"Broker error during '{operation}': {reason}"
        super().__init__(message, context={"operation": operation, "reason": reason})
        self.operation = operation
        self.reason = reason