"""FastAPI-Anwendung des Control Core (Phase-0-Minimalversion).

Endpunkte:
- GET /api/v1/system/health
- GET /api/v1/system/capabilities
- GET /api/v1/parameters
- POST /api/v1/commands  (parameter.set mit Revision-Prüfung und Idempotenz)
- POST /api/v1/commands/{command_id}/release
- GET /api/v1/diagnostics
- WS  /ws  (State-Snapshot + Updates)

Commands folgen §23.2: command_id, type, expected_revision, actor, payload.
"""

from __future__ import annotations

import asyncio
import uuid

from fastapi import FastAPI, HTTPException, WebSocket, WebSocketDisconnect
from hms_capabilities.probe import CapabilityReport
from hms_parameter.engine import (
    ControlSource,
    ParameterEngine,
    RevisionConflict,
)
from hms_protocol.idempotency import IdempotencyRegistry
from pydantic import BaseModel, Field


class SetParameterCommand(BaseModel):
    """parameter.set-Command (§23.2)."""

    command_id: str = Field(default_factory=lambda: str(uuid.uuid4()))
    type: str = "parameter.set"
    expected_revision: int | None = None
    actor: dict = Field(default_factory=lambda: {"type": "web", "id": "operator-session"})
    payload: dict


class ReleaseCommand(BaseModel):
    source: str = "web"


class _State:
    def __init__(self) -> None:
        self.engine = ParameterEngine()
        self.registry = IdempotencyRegistry()
        self.report = CapabilityReport()
        self.subscribers: list[asyncio.Queue] = []


def create_app() -> FastAPI:
    app = FastAPI(title="HMS MediaEngine Control Core", version="0.1.0")
    state = _State()

    def _broadcast(event: dict) -> None:
        for queue in list(state.subscribers):
            queue.put_nowait(event)

    @app.get("/api/v1/system/health")
    async def health() -> dict:
        return {"status": "ok", "phase": 0, "revision": state.engine.revision}

    @app.get("/api/v1/system/capabilities")
    async def capabilities() -> dict:
        return state.report.as_dict()

    @app.get("/api/v1/parameters")
    async def parameters() -> dict:
        snap = state.engine.snapshot()
        return {"revision": snap.revision, "values": snap.as_dict()}

    @app.post("/api/v1/commands")
    async def post_command(cmd: SetParameterCommand) -> dict:
        if cmd.type != "parameter.set":
            raise HTTPException(status_code=400, detail=f"unknown command type {cmd.type!r}")
        if not state.registry.register(cmd.command_id):
            prior = state.registry.result(cmd.command_id)
            if prior is not None:
                return {"status": "ack", "duplicate": True, "result": prior}
            raise HTTPException(status_code=409, detail="command already in flight")
        path = cmd.payload.get("parameter_path")
        value = cmd.payload.get("value")
        if not path or value is None:
            raise HTTPException(status_code=400, detail="payload requires parameter_path and value")
        try:
            revision = state.engine.set_value(
                path=path,
                value=float(value),
                source=ControlSource.WEB,
                expected_revision=cmd.expected_revision,
            )
        except RevisionConflict as exc:
            raise HTTPException(
                status_code=409,
                detail={
                    "error": "REVISION_CONFLICT",
                    "current": exc.current,
                    "expected": exc.expected,
                },
            ) from exc
        except ValueError as exc:
            raise HTTPException(status_code=400, detail=str(exc)) from exc
        result = {
            "status": "ack",
            "command_id": cmd.command_id,
            "revision": revision,
            "effective": state.engine.effective_value(path),
        }
        state.registry.complete(cmd.command_id, result)
        _broadcast(
            {
                "type": "parameter.update",
                "parameter_path": path,
                "value": value,
                "revision": revision,
            }
        )
        return result

    @app.post("/api/v1/commands/{command_id}/release")
    async def release_override(command_id: str) -> dict:
        # Release nach §11.3; command_id referenziert den ursprünglichen Command.
        return {"status": "not_implemented_in_phase0"}

    @app.get("/api/v1/diagnostics")
    async def diagnostics() -> dict:
        return {
            "renderer": "not_connected",  # IPC-Handshake folgt in Phase 1 (ADR-0003)
            "artnet": "not_started",
            "revision": state.engine.revision,
        }

    @app.websocket("/ws")
    async def websocket_endpoint(ws: WebSocket) -> None:
        await ws.accept()
        queue: asyncio.Queue = asyncio.Queue(maxsize=256)
        state.subscribers.append(queue)
        try:
            snap = state.engine.snapshot()
            await ws.send_json(
                {"type": "snapshot", "revision": snap.revision, "values": snap.as_dict()}
            )
            while True:
                try:
                    event = await asyncio.wait_for(queue.get(), timeout=15.0)
                    await ws.send_json(event)
                except TimeoutError:
                    await ws.send_json({"type": "heartbeat"})
        except WebSocketDisconnect:
            pass
        finally:
            state.subscribers.remove(queue)

    return app


app = create_app()