"""Shared diagnostics and structured errors."""

from __future__ import annotations

from dataclasses import dataclass, field
from typing import Any


@dataclass(frozen=True)
class Diagnostic:
    """A structured finding emitted by engine operations."""

    severity: str
    code: str
    message: str
    details: dict[str, Any] = field(default_factory=dict)

    def to_dict(self) -> dict[str, Any]:
        return {
            "severity": self.severity,
            "code": self.code,
            "message": self.message,
            "details": dict(self.details),
        }


@dataclass(frozen=True)
class OperationFailure:
    """Structured operation failure suitable for API and batch envelopes."""

    code: str
    message: str
    operation: str
    correlation_id: str
    details: dict[str, Any] = field(default_factory=dict)
    remediation: str | None = None

    def to_dict(self) -> dict[str, Any]:
        data: dict[str, Any] = {
            "code": self.code,
            "message": self.message,
            "operation": self.operation,
            "correlation_id": self.correlation_id,
            "details": dict(self.details),
        }
        if self.remediation:
            data["remediation"] = self.remediation
        return data


@dataclass(frozen=True)
class BatchItemResult:
    """One item result inside a batch operation envelope."""

    item_id: str
    operation: str
    success: bool
    result_ref: dict[str, Any] = field(default_factory=dict)
    error: OperationFailure | None = None

    @classmethod
    def succeeded(
        cls,
        *,
        item_id: str,
        operation: str,
        result_ref: dict[str, Any] | None = None,
    ) -> "BatchItemResult":
        return cls(
            item_id=item_id,
            operation=operation,
            success=True,
            result_ref=dict(result_ref or {}),
        )

    @classmethod
    def failed(
        cls,
        *,
        item_id: str,
        operation: str,
        error: OperationFailure,
    ) -> "BatchItemResult":
        return cls(item_id=item_id, operation=operation, success=False, error=error)

    def to_dict(self) -> dict[str, Any]:
        data: dict[str, Any] = {
            "item_id": self.item_id,
            "operation": self.operation,
            "success": self.success,
        }
        if self.result_ref:
            data["result_ref"] = dict(self.result_ref)
        if self.error:
            data["error"] = self.error.to_dict()
        return data


@dataclass(frozen=True)
class BatchOperationResult:
    """Compact result envelope for batch operations with partial failures."""

    operation: str
    correlation_id: str
    items: tuple[BatchItemResult, ...] = ()
    audit_event_id: str | None = None

    def __post_init__(self) -> None:
        object.__setattr__(self, "items", tuple(self.items))

    @property
    def total(self) -> int:
        return len(self.items)

    @property
    def succeeded(self) -> int:
        return sum(1 for item in self.items if item.success)

    @property
    def failed(self) -> int:
        return self.total - self.succeeded

    @property
    def partial(self) -> bool:
        return self.succeeded > 0 and self.failed > 0

    @property
    def outcome(self) -> str:
        if self.partial:
            return "partial"
        if self.failed:
            return "failed"
        return "success"

    def to_dict(self) -> dict[str, Any]:
        data: dict[str, Any] = {
            "operation": self.operation,
            "correlation_id": self.correlation_id,
            "outcome": self.outcome,
            "total": self.total,
            "succeeded": self.succeeded,
            "failed": self.failed,
            "partial": self.partial,
            "items": [item.to_dict() for item in self.items],
        }
        if self.audit_event_id:
            data["audit_event_id"] = self.audit_event_id
        return data


class KontextualError(Exception):
    """Base class for explicit engine failures."""

    code = "kontextual.error"

    def __init__(self, message: str, *, details: dict[str, Any] | None = None) -> None:
        super().__init__(message)
        self.details = details or {}

    def diagnostic(self, *, severity: str = "error") -> Diagnostic:
        return Diagnostic(
            severity=severity,
            code=self.code,
            message=str(self),
            details=dict(self.details),
        )

    def to_operation_failure(
        self,
        *,
        operation: str,
        correlation_id: str,
        remediation: str | None = None,
    ) -> OperationFailure:
        return OperationFailure(
            code=str(self.details.get("code") or self.code),
            message=str(self),
            operation=operation,
            correlation_id=correlation_id,
            details=dict(self.details),
            remediation=remediation,
        )


class NotFoundError(KontextualError):
    code = "kontextual.not_found"


class DuplicateResourceError(KontextualError):
    code = "kontextual.duplicate"


class ValidationError(KontextualError):
    code = "kontextual.validation"


class AuthorizationError(KontextualError):
    code = "kontextual.authorization"


class AdapterUnavailableError(KontextualError):
    code = "kontextual.adapter_unavailable"