"""Unit tests for the @accepts / @returns contract decorators.

Exercises the decorators in isolation (not through a real controller): a plain
view function decorated with @accepts/@returns, driven inside a request context.
"""

from collections.abc import Callable
from functools import wraps
from io import BytesIO
from typing import Any, cast

import pytest
from flask import Flask, request
from flask.ctx import RequestContext
from pydantic import BaseModel, ConfigDict, Field
from sqlalchemy.orm import Session
from werkzeug.exceptions import RequestEntityTooLarge, UnprocessableEntity

from controllers.common.schema import register_response_schema_model, register_schema_model
from controllers.openapi import openapi_ns
from controllers.openapi._contract import (
    MULTIPART_HEADER_BYTES_PER_PART,
    CapRequestBody,
    accepts,
    multipart_header_allowance,
    paginated,
    returns,
)
from controllers.openapi._errors import RequestOverRouteLimits
from controllers.openapi._models import Hint, PaginationEnvelope
from controllers.openapi._upload import UploadPart
from tests.helpers.unit.controllers.openapi.auth._world import account_subject, make_ctx


class ContractQuery(BaseModel):
    model_config = ConfigDict(extra="forbid")

    page: int = Field(1, ge=1)
    limit: int = Field(20, ge=1, le=100)


class ContractBody(BaseModel):
    model_config = ConfigDict(extra="forbid")

    name: str


class ContractUploadBody(BaseModel):
    package: UploadPart


class ContractResp(BaseModel):
    value: int


@pytest.fixture(autouse=True, scope="module")
def _register_contract_test_models():
    # Register for @accepts(body=)/@returns name lookups; drop on teardown so these
    # test-only models don't leak into the shared openapi_ns / generated spec.
    register_schema_model(openapi_ns, ContractBody)
    register_schema_model(openapi_ns, ContractUploadBody)
    register_response_schema_model(openapi_ns, ContractResp)
    yield
    openapi_ns.models.pop(ContractBody.__name__, None)
    openapi_ns.models.pop(ContractUploadBody.__name__, None)
    openapi_ns.models.pop(ContractResp.__name__, None)


def _guard_like(view):
    """Stand-in for ``@subject_router.guard`` — an outermost @wraps layer."""

    @wraps(view)
    def wrapper(*args, **kwargs):
        return view(*args, **kwargs)

    return wrapper


class _Page(PaginationEnvelope[int]):
    pass


def test_paginated_fills_the_next_page_hint_from_the_call_and_leaves_the_rest_alone():
    @paginated("thing.list")
    def view(*, ctx, workspace_id, query):
        return _Page.build(page=query.page, limit=query.limit, total=50, items=[])

    result = view(ctx=object(), workspace_id="ws-1", query=ContractQuery(page=1, limit=20))
    assert result.hints == [
        Hint(summary="Next page", op="thing.list", input={"workspace_id": "ws-1", "page": 2, "limit": 20})
    ]
    assert view(ctx=object(), workspace_id="ws-1", query=ContractQuery(page=3, limit=20)).hints == []

    @paginated("thing.get")
    def plain(*, ctx):
        return ContractResp(value=1)

    assert plain(ctx=object()) == ContractResp(value=1)


def test_paginated_keeps_the_view_hints_and_adds_the_next_page() -> None:
    setup = Hint(summary="Set up", op="thing.describe", input={})

    @paginated("thing.list")
    def view(*, ctx: object, query: ContractQuery) -> _Page:
        page = _Page.build(page=query.page, limit=query.limit, total=50, items=[])
        page.hints = [setup]
        return page

    assert [h.op for h in view(ctx=object(), query=ContractQuery(page=1, limit=20)).hints] == [
        "thing.describe",
        "thing.list",
    ]

    own = Hint(summary="Next page", op="thing.list", input={"cursor": "c2"})

    @paginated("thing.list")
    def cursor_view(*, ctx: object, query: ContractQuery) -> _Page:
        page = _Page.build(page=query.page, limit=query.limit, total=50, items=[])
        page.hints = [own]
        return page

    assert cursor_view(ctx=object(), query=ContractQuery(page=1, limit=20)).hints == [own]


def test_accepts_injects_validated_query_with_defaults_for_absent_fields(app):
    @accepts(query=ContractQuery)
    def view(*, query):
        return query

    with app.test_request_context("/?page=3"):
        result = view()

    assert isinstance(result, ContractQuery)
    assert result.page == 3
    assert result.limit == 20


class ContractListQuery(BaseModel):
    tag: list[str] | None = None
    word: str | None = None


def test_accepts_fills_list_typed_query_fields_from_repeated_parameters(app: Flask) -> None:
    @accepts(query=ContractListQuery)
    def view(*, query: ContractListQuery) -> ContractListQuery:
        return query

    with app.test_request_context("/?tag=a&tag=b&word=x&word=y"):
        result = view()

    assert result.tag == ["a", "b"]
    assert result.word == "x"


@pytest.mark.parametrize("query_string", ["page=abc", "unknown=1"])
def test_accepts_rejects_invalid_query_with_422(app, query_string):
    @accepts(query=ContractQuery)
    def view(*, query):
        return query

    with app.test_request_context(f"/?{query_string}"):
        with pytest.raises(UnprocessableEntity):
            view()


def test_accepts_validation_error_is_sanitized_and_structured(app):
    """422 body is structured and leaks neither the pydantic docs url nor the user input."""

    @accepts(body=ContractBody)
    def view(*, body):
        return body

    with app.test_request_context("/", method="POST", json={"secret": "leak-me"}):
        with pytest.raises(UnprocessableEntity) as exc_info:
            view()

    data = cast(dict[str, Any], cast(Any, exc_info.value).data)
    assert data["message"] == "Request validation failed"
    assert isinstance(data["errors"], list)
    assert data["errors"]
    for err in data["errors"]:
        assert {"type", "loc", "msg"} <= err.keys()
        assert "url" not in err
        assert "input" not in err
    assert "leak-me" not in str(data)


def test_accepts_injects_validated_body(app):
    @accepts(body=ContractBody)
    def view(*, body):
        return body

    with app.test_request_context("/", method="POST", json={"name": "x"}):
        result = view()

    assert isinstance(result, ContractBody)
    assert result.name == "x"


def test_returns_serializes_model_with_decorator_status(app):
    @returns(200, ContractResp)
    def view():
        return ContractResp(value=7)

    with app.test_request_context("/"):
        body, status = view()

    assert status == 200
    assert body == {"value": 7}


@pytest.mark.parametrize("trailing", [(201,), (202, {"X-Test": "1"})], ids=["status", "status_and_headers"])
def test_returns_serializes_model_in_tuple_and_keeps_trailing_parts(app, trailing):
    @returns(200, ContractResp)
    def view():
        return ContractResp(value=9), *trailing

    with app.test_request_context("/"):
        body, *rest = view()

    assert body == {"value": 9}
    assert tuple(rest) == trailing


def test_returns_passes_through_non_model(app):
    sentinel = object()

    @returns(200, ContractResp)
    def view():
        return sentinel

    with app.test_request_context("/"):
        result = view()

    assert result is sentinel


# Swagger metadata (read off __apidoc__) must survive @wraps up through the guard layer.


def test_accepts_returns_emit_apidoc_through_guard_stack():
    @_guard_like
    @returns(200, ContractResp)
    @accepts(query=ContractQuery, body=ContractBody)
    def view(*, query, body):
        return ContractResp(value=1)

    apidoc = getattr(view, "__apidoc__", {})
    assert "page" in apidoc.get("params", {})  # from @accepts(query=)
    assert apidoc.get("expect")  # from @accepts(body=), via @openapi_ns.expect
    assert "200" in apidoc.get("responses", {})  # from @returns (flask_restx keys by str code)


_MIB = 1024 * 1024


def _post(app: Flask, size: int, **extra: str) -> RequestContext:
    data = {"package": (BytesIO(b"x" * size), "a.yaml"), **extra}
    return app.test_request_context("/x", method="POST", data=data, content_type="multipart/form-data")


@pytest.fixture
def view() -> Callable[[], str]:
    @accepts(body=ContractUploadBody)
    def handler(*, body: ContractUploadBody) -> str:
        return "ok"

    return handler


@pytest.mark.parametrize(
    ("size", "extra", "accepted"),
    [
        (1, {"note": '"y"'}, True),
        (2 * _MIB, {}, False),
        (1, {"note": '"y"', "other": '"z"'}, False),
    ],
)
def test_a_capped_route_sets_its_own_limits_and_names_them(
    app: Flask,
    sqlite_session: Session,
    view: Callable[[], str],
    size: int,
    extra: dict[str, str],
    accepted: bool,
) -> None:
    app.config["MAX_FORM_PARTS"] = 1
    cap = CapRequestBody(max_bytes=lambda: _MIB, max_parts=lambda: 2)
    with _post(app, size, **extra):
        cap.run(account_subject(), make_ctx(sqlite_session), sqlite_session)
        assert "form" not in request.__dict__
        if accepted:
            assert view() == "ok"
            return
        with pytest.raises(RequestOverRouteLimits, match="at most 2 parts and 1 MiB$"):
            view()


def test_an_uncapped_route_keeps_the_generic_413(app: Flask, view: Callable[[], str]) -> None:
    app.config["MAX_FORM_PARTS"] = 1
    with _post(app, 1, extra="y"), pytest.raises(RequestEntityTooLarge) as exc:
        view()
    assert not isinstance(exc.value, RequestOverRouteLimits)


def test_multipart_header_allowance_scales_with_the_part_count() -> None:
    assert multipart_header_allowance(0) == 0
    assert multipart_header_allowance(5002) == 5002 * MULTIPART_HEADER_BYTES_PER_PART