"""Zero-Django exception hierarchy for the InfraSynth kit.

These exceptions are raised by services and mapped to the namespaced error
envelope (``API-STANDARD.md`` §5) by ``infrasynth.api.exceptions``. They carry a
stable machine-readable ``code``, an HTTP ``status``, and a list of ``details``
so no caller has to parse a message.

This module must never import Django (``infrasynth.shared`` is zero-Django).
"""

from __future__ import annotations

from typing import Any

__all__ = [
    "AppError",
    "AuthError",
    "ConflictError",
    "EntitlementError",
    "NotFoundError",
    "RateLimitError",
    "ServerError",
    "ValidationAppError",
    "ENTITLEMENT_APP_NOT_OWNED",
    "ENTITLEMENT_EXPIRED",
    "ENTITLEMENT_LIMIT_REACHED",
    "ENTITLEMENT_PLAN_UPGRADE_REQUIRED",
    "ENTITLEMENT_REVOKED",
    "ENTITLEMENT_SUBSCRIPTION_PAST_DUE",
    "ENTITLEMENT_TENANT_SUSPENDED",
]

# --- Entitlement error codes (ENTITLEMENTS.md §7) ---------------------------

ENTITLEMENT_APP_NOT_OWNED = "ENTITLEMENT_APP_NOT_OWNED"
ENTITLEMENT_PLAN_UPGRADE_REQUIRED = "ENTITLEMENT_PLAN_UPGRADE_REQUIRED"
ENTITLEMENT_LIMIT_REACHED = "ENTITLEMENT_LIMIT_REACHED"
ENTITLEMENT_SUBSCRIPTION_PAST_DUE = "ENTITLEMENT_SUBSCRIPTION_PAST_DUE"
ENTITLEMENT_EXPIRED = "ENTITLEMENT_EXPIRED"
ENTITLEMENT_TENANT_SUSPENDED = "ENTITLEMENT_TENANT_SUSPENDED"
ENTITLEMENT_REVOKED = "ENTITLEMENT_REVOKED"


class AppError(Exception):
    """Base class for every expected, mappable application error."""

    default_code: str = "SERVER_ERROR"
    default_message: str = "An unexpected error occurred."
    default_status: int = 500

    def __init__(
        self,
        message: str | None = None,
        *,
        code: str | None = None,
        status: int | None = None,
        details: list[dict[str, Any]] | None = None,
    ) -> None:
        self.code = code or self.default_code
        self.message = message or self.default_message
        self.status = status or self.default_status
        self.details: list[dict[str, Any]] = list(details) if details else []
        super().__init__(self.message)

    def to_dict(self) -> dict[str, Any]:
        """Serializable error body (the ``error`` member of the envelope)."""
        return {"code": self.code, "message": self.message, "details": self.details}


class AuthError(AppError):
    """Authentication or authorization failure (``AUTH_*``)."""

    default_code = "AUTH_ERROR"
    default_message = "Authentication failed."
    default_status = 401


class EntitlementError(AppError):
    """Commercial access failure (``ENTITLEMENT_*``).

    Extra keyword arguments (``app``, ``plan``, ``feature``, ``limit``,
    ``current``, ``max``) are folded into a single ``details`` entry, matching
    ``ENTITLEMENTS.md`` §7::

        raise EntitlementError(
            code=ENTITLEMENT_PLAN_UPGRADE_REQUIRED, app="helpdesk", feature="tickets"
        )
    """

    default_code = ENTITLEMENT_APP_NOT_OWNED
    default_message = "This workspace does not have access to the requested app."
    default_status = 402

    def __init__(
        self,
        message: str | None = None,
        *,
        code: str | None = None,
        status: int | None = None,
        details: list[dict[str, Any]] | None = None,
        **context: Any,
    ) -> None:
        merged = list(details) if details else []
        extra = {key: value for key, value in context.items() if value is not None}
        if extra:
            merged.append(extra)
        super().__init__(message, code=code, status=status, details=merged)


class ValidationAppError(AppError):
    """Request payload failure (``VALIDATION_*``)."""

    default_code = "VALIDATION_ERROR"
    default_message = "The request payload is invalid."
    default_status = 400


class NotFoundError(AppError):
    """Resource not found (also used for cross-tenant access)."""

    default_code = "NOT_FOUND"
    default_message = "The requested resource was not found."
    default_status = 404


class ConflictError(AppError):
    """State or idempotency conflict (``CONFLICT_*``)."""

    default_code = "CONFLICT_ERROR"
    default_message = "The request conflicts with the current state."
    default_status = 409


class RateLimitError(AppError):
    """Throttling failure (``RATE_LIMIT_*``)."""

    default_code = "RATE_LIMIT_EXCEEDED"
    default_message = "Too many requests."
    default_status = 429


class ServerError(AppError):
    """Unhandled/internal error (``SERVER_*``). Never leaks a stack trace."""

    default_code = "SERVER_ERROR"
    default_message = "An unexpected error occurred."
    default_status = 500