import json
from typing import Optional

from fastapi import FastAPI, HTTPException
from fastapi.testclient import TestClient
from pydantic import BaseModel, Field

from app.middleware.logging import LoggingMiddleware
from app.middleware.errors import register_exception_handlers


class Item(BaseModel):
    name: str = Field(..., min_length=3)
    quantity: int = Field(..., ge=1)


def build_test_app() -> FastAPI:
    app = FastAPI()
    app.add_middleware(LoggingMiddleware, log_requests=False, log_responses=False)
    register_exception_handlers(app)

    @app.get("/http-error")
    async def http_error():
        raise HTTPException(status_code=403, detail="Forbidden action")

    @app.post("/validation")
    async def validation_endpoint(item: Item):  # noqa: F841
        return {"ok": True}

    @app.get("/crash")
    async def crash():
        raise RuntimeError("Boom")

    return app


def assert_envelope(resp, status: int, code: str, has_details: bool, expected_cid: Optional[str] = None):
    assert resp.status_code == status
    data = resp.json()
    assert data["success"] is False
    assert data["error"]["status"] == status
    assert data["error"]["code"] == code
    assert isinstance(data["error"]["message"], str) and data["error"]["message"]
    if has_details:
        assert "details" in data["error"]
    else:
        assert "details" not in data["error"]

    # Correlation id in body and header
    assert "correlation_id" in data and isinstance(data["correlation_id"], str)
    header_cid = resp.headers.get("X-Correlation-ID")
    assert header_cid == data["correlation_id"]
    if expected_cid is not None:
        assert header_cid == expected_cid


def test_http_exception_envelope_and_correlation_id_echo():
    app = build_test_app()
    client = TestClient(app)
    cid = "abc-12345-test"
    resp = client.get("/http-error", headers={"X-Correlation-ID": cid})
    assert_envelope(resp, 403, "http_error", has_details=False, expected_cid=cid)


def test_validation_exception_envelope_and_correlation_id_echo():
    app = build_test_app()
    client = TestClient(app)
    cid = "cid-validation-67890"
    # Missing fields to trigger 422
    resp = client.post("/validation", json={"name": "ab"}, headers={"X-Correlation-ID": cid})
    assert_envelope(resp, 422, "validation_error", has_details=True, expected_cid=cid)


def test_unhandled_exception_envelope_and_generated_correlation_id():
    app = build_test_app()
    client = TestClient(app, raise_server_exceptions=False)
    resp = client.get("/crash")
    # Should have generated a correlation id and not echo None
    assert_envelope(resp, 500, "internal_error", has_details=False)
    assert resp.headers.get("X-Correlation-ID")