"""FC-5: /api/migrate API tests."""
import io
import json

import pytest
from werkzeug.datastructures import FileStorage

import backend.app.tasks.migration  # noqa: F401 — register celery task
from backend.app import create_app
from backend.app.celery_app import celery

pytestmark = pytest.mark.integration


def _file_storage(payload: dict, filename: str = "export.json") -> FileStorage:
    return FileStorage(
        stream=io.BytesIO(json.dumps(payload).encode("utf-8")),
        filename=filename,
        content_type="application/json",
    )


@pytest.fixture
async def app():
    return create_app()


@pytest.fixture
async def client(app):
    async with app.test_client() as c:
        yield c


@pytest.mark.asyncio
async def test_post_backup_returns_202_and_id(client, monkeypatch):
    monkeypatch.setattr(
        "backend.app.api.migrate.run_migration",
        type("F", (), {"delay": lambda self, *a, **k: None})(),
    )
    resp = await client.post("/api/migrate/backup", json={})
    assert resp.status_code == 202
    body = await resp.get_json()
    assert "run_id" in body
    assert body["status"] == "pending"


@pytest.mark.asyncio
async def test_post_rejects_unknown_kind(client):
    resp = await client.post("/api/migrate/destroy", json={})
    assert resp.status_code == 400
    body = await resp.get_json()
    assert body["error"] == "unknown_kind"


@pytest.mark.asyncio
async def test_post_ingest_rejects_missing_file(client):
    resp = await client.post("/api/migrate/gs_ingest", form={})
    assert resp.status_code == 400
    body = await resp.get_json()
    assert body["error"] == "missing_export_file"


@pytest.mark.asyncio
async def test_post_ingest_accepts_multipart_file(client, monkeypatch):
    monkeypatch.setattr(
        "backend.app.api.migrate._has_recent_pre_migration_backup",
        lambda: True,  # pretend backup exists
    )
    monkeypatch.setattr(
        "backend.app.api.migrate.run_migration",
        type("F", (), {"delay": lambda self, *a, **k: None})(),
    )

    export = {
        "source_app": "gallerysubscriber", "schema_version": 1,
        "subscriptions": [], "credentials": [],
    }
    resp = await client.post(
        "/api/migrate/gs_ingest",
        form={"dry_run": "false"},
        files={"export_file": _file_storage(export, "gs-export.json")},
    )
    assert resp.status_code == 202


@pytest.mark.asyncio
async def test_post_apply_without_backup_rejected(client, monkeypatch):
    monkeypatch.setattr(
        "backend.app.api.migrate._has_recent_pre_migration_backup",
        lambda: False,
    )
    export = {
        "source_app": "gallerysubscriber", "schema_version": 1,
        "subscriptions": [], "credentials": [],
    }
    resp = await client.post(
        "/api/migrate/gs_ingest",
        form={"dry_run": "false"},
        files={"export_file": _file_storage(export, "gs-export.json")},
    )
    assert resp.status_code == 400
    body = await resp.get_json()
    assert body["error"] == "no_backup"


@pytest.mark.asyncio
async def test_post_dry_run_allowed_without_backup(client, monkeypatch):
    monkeypatch.setattr(
        "backend.app.api.migrate._has_recent_pre_migration_backup",
        lambda: False,
    )
    monkeypatch.setattr(
        "backend.app.api.migrate.run_migration",
        type("F", (), {"delay": lambda self, *a, **k: None})(),
    )
    export = {
        "source_app": "gallerysubscriber", "schema_version": 1,
        "subscriptions": [], "credentials": [],
    }
    resp = await client.post(
        "/api/migrate/gs_ingest",
        form={"dry_run": "true"},
        files={"export_file": _file_storage(export, "gs-export.json")},
    )
    assert resp.status_code == 202


@pytest.mark.asyncio
async def test_get_run_404_unknown(client):
    resp = await client.get("/api/migrate/runs/9999999")
    assert resp.status_code == 404


def test_run_migration_task_registered():
    assert "backend.app.tasks.migration.run_migration" in celery.tasks