"""Per-tenant code hooks.

Most customers differ only in *data* (colours, logo, prompt, PDF template) and
need no code here. For the few that need genuine behaviour changes, drop an
`overrides.py` into their tenant folder defining a `Hooks(TenantHooks)` subclass
that overrides only the methods it needs. Core stays untouched, so core updates
keep flowing.

Example  tenants/acme/overrides.py:

    from core.hooks import TenantHooks

    class Hooks(TenantHooks):
        def build_prompt(self, base, ctx):
            return base + "\\nBevorzuge Fachterminologie aus der Orthopädie."

        def extra_routes(self, app):
            @app.get("/health/acme")
            def _h():
                return {"ok": True}
"""
from __future__ import annotations

import importlib.util
from pathlib import Path

from core.contract import HOOK_API


class TenantHooks:
    """Default (no-op) behaviour. Override selectively per tenant."""

    def build_prompt(self, base_prompt: str, ctx: dict) -> str:
        """Adjust the system prompt sent to the LLM. ctx carries the form fields."""
        return base_prompt

    def transform_transcript(self, transcript: str, ctx: dict) -> str:
        """Post-process the transcript before summarisation/delivery."""
        return transcript

    def pdf_context(self, context: dict) -> dict:
        """Last chance to enrich/alter the data passed to the PDF template."""
        return context

    def extra_routes(self, app) -> None:
        """Register tenant-specific FastAPI routes."""
        return None


def load_hooks(tenant_dir: Path) -> TenantHooks:
    override = tenant_dir / "overrides.py"
    if not override.exists():
        return TenantHooks()
    spec = importlib.util.spec_from_file_location(f"tenant_overrides_{tenant_dir.name}", override)
    module = importlib.util.module_from_spec(spec)
    assert spec and spec.loader
    spec.loader.exec_module(module)
    declared = getattr(module, "HOOK_API", HOOK_API)          # fehlt die Deklaration, gilt die aktuelle Version
    if declared != HOOK_API:
        raise RuntimeError(f"{override}: HOOK_API={declared} wird von diesem Core nicht unterstützt (Core: {HOOK_API})")
    hooks_cls = getattr(module, "Hooks", None)
    if hooks_cls is None:
        return TenantHooks()
    return hooks_cls()