"""Single prompt execution entry. Templates live in the DB; LLM egress only via Privacy Gateway."""
from __future__ import annotations

from typing import Any

import placeholder_system  # noqa: F401  registers system keys
import privacy_placeholders
from entitlements import EntitlementError, check_feature_access
from placeholders import PlaceholderError, resolve_template
from privacy_gateway import GatewayRequest, PrivacyGatewayError, complete


class EngineError(Exception):
    def __init__(self, code: str, message: str, status_code: int = 400):
        super().__init__(message)
        self.code = code
        self.message = message
        self.status_code = status_code


def preview_prompt(prompt: dict, context: dict[str, Any] | None = None) -> dict:
    template = prompt.get("template") or ""
    if prompt.get("prompt_type") != "base":
        raise EngineError("prompt_type_not_ready", "Pipeline- und Workflow-Typen sind vorbereitet, aber noch ohne Executor-Stufen.")
    try:
        rendered = resolve_template(template, context or {})
        privacy_tokens = privacy_placeholders.validate_tokens(template)
    except PlaceholderError as exc:
        raise EngineError(exc.code, exc.message) from exc
    return {
        "prompt_id": prompt["id"],
        "slug": prompt["slug"],
        "rendered": rendered,
        "privacy_tokens": privacy_tokens,
        "llm": False,
    }


def execute_prompt(prompt: dict, profile_id: str, purpose: str, data_class: str, context: dict[str, Any] | None = None) -> dict:
    preview = preview_prompt(prompt, context)
    feature_id = prompt.get("required_feature") or "ai_calls"
    try:
        check_feature_access(profile_id, feature_id)
    except EntitlementError as exc:
        raise EngineError(exc.code, exc.message, exc.status_code) from exc
    try:
        complete(
            GatewayRequest(
                prompt_id=prompt["id"],
                purpose=purpose,
                data_class=data_class,
                payload={"template_chars": len(preview["rendered"]), "privacy_tokens": preview["privacy_tokens"]},
            )
        )
    except PrivacyGatewayError as exc:
        raise EngineError(exc.code, exc.message, exc.status_code) from exc
    raise EngineError("provider_missing", "Gateway erlaubte einen Aufruf ohne konfigurierten Provider", 500)