"""Budgets: category-kind restriction, one-budget-per-category, and the
spent/remaining/over-budget math behind the Budget page's progress bars.
"""
from decimal import Decimal

from httpx import AsyncClient

from tests.helpers import money, txn_payload


async def test_budget_rejects_income_category(client: AsyncClient, categories):
    resp = await client.post(
        "/budgets", json={"category_id": categories["Salary"]["id"], "monthly_limit": "500.00"}
    )
    assert resp.status_code == 400


async def test_budget_rejects_duplicate_category(client: AsyncClient, categories):
    category_id = categories["Groceries"]["id"]
    first = await client.post("/budgets", json={"category_id": category_id, "monthly_limit": "300.00"})
    assert first.status_code == 201

    second = await client.post("/budgets", json={"category_id": category_id, "monthly_limit": "400.00"})
    assert second.status_code == 400


async def test_status_reports_spent_remaining_and_over_budget(client: AsyncClient, account_id, categories):
    category_id = categories["Groceries"]["id"]
    await client.post("/budgets", json={"category_id": category_id, "monthly_limit": "100.00"})

    for amount in ["60.00", "60.00"]:  # 120.00 total, over a 100.00 limit
        await client.post(
            "/transactions",
            json=txn_payload(account_id, amount=amount, category_id=category_id, date="2026-08-10"),
        )

    resp = await client.get("/budgets/status", params={"year": 2026, "month": 8})
    item = resp.json()["items"][0]
    assert money(item["spent"]) == Decimal("120.00")
    assert money(item["remaining"]) == Decimal("-20.00")
    assert item["percent"] == 120.0
    assert item["is_over_budget"] is True


async def test_status_only_counts_the_selected_month(client: AsyncClient, account_id, categories):
    category_id = categories["Groceries"]["id"]
    await client.post("/budgets", json={"category_id": category_id, "monthly_limit": "100.00"})
    await client.post(
        "/transactions", json=txn_payload(account_id, amount="90.00", category_id=category_id, date="2026-07-15")
    )

    resp = await client.get("/budgets/status", params={"year": 2026, "month": 8})
    item = resp.json()["items"][0]
    assert money(item["spent"]) == 0
    assert item["is_over_budget"] is False


async def test_status_is_empty_list_when_no_budgets_exist(client: AsyncClient):
    resp = await client.get("/budgets/status", params={"year": 2026, "month": 8})
    assert resp.json()["items"] == []


async def test_update_budget_changes_the_limit(client: AsyncClient, categories):
    category_id = categories["Groceries"]["id"]
    created = await client.post("/budgets", json={"category_id": category_id, "monthly_limit": "100.00"})
    budget_id = created.json()["id"]

    resp = await client.patch(f"/budgets/{budget_id}", json={"monthly_limit": "250.00"})
    assert resp.status_code == 200
    assert money(resp.json()["monthly_limit"]) == Decimal("250.00")


async def test_delete_budget_removes_it_from_status(client: AsyncClient, account_id, categories):
    category_id = categories["Groceries"]["id"]
    created = await client.post("/budgets", json={"category_id": category_id, "monthly_limit": "100.00"})
    budget_id = created.json()["id"]

    delete_resp = await client.delete(f"/budgets/{budget_id}")
    assert delete_resp.status_code == 204

    status = await client.get("/budgets/status", params={"year": 2026, "month": 8})
    assert status.json()["items"] == []


async def _subcategory(client: AsyncClient, parent_id: int, name: str = "Rent") -> int:
    resp = await client.post(
        "/categories",
        json={"name": name, "kind": "expense", "color": "#7a869a", "parent_id": parent_id},
    )
    return resp.json()["id"]


async def test_budget_on_a_parent_category_counts_spending_in_its_subcategories(
    client: AsyncClient, account_id, categories
):
    """The Dashboard breakdown and the category report both roll a
    subcategory's spending up into its parent (coalesce(parent_id, id)). A
    budget set on the parent has to agree with them, or the same month reads
    as 900 spent on one screen and 0 on the other."""
    parent_id = categories["Housing & Utilities"]["id"]
    child_id = await _subcategory(client, parent_id)
    await client.post("/budgets", json={"category_id": parent_id, "monthly_limit": "1000.00"})
    await client.post(
        "/transactions", json=txn_payload(account_id, category_id=child_id, amount="900.00", date="2026-03-10")
    )

    status = (await client.get("/budgets/status?year=2026&month=3")).json()["items"][0]
    dashboard = (await client.get("/dashboard/summary?year=2026&month=3")).json()

    assert money(status["spent"]) == money("900.00")
    assert money(status["remaining"]) == money("100.00")
    # The two screens must show the same number for the same category.
    parent_slice = next(s for s in dashboard["spending_by_category"] if s["category_id"] == parent_id)
    assert money(parent_slice["amount"]) == money(status["spent"])


async def test_a_subcategory_keeps_its_own_budget_separate(client: AsyncClient, account_id, categories):
    """Rolling children into a parent's budget must not swallow a budget set
    on the child itself — both bars track the same spending, each against its
    own limit."""
    parent_id = categories["Housing & Utilities"]["id"]
    child_id = await _subcategory(client, parent_id)
    await client.post("/budgets", json={"category_id": parent_id, "monthly_limit": "1000.00"})
    await client.post("/budgets", json={"category_id": child_id, "monthly_limit": "800.00"})
    await client.post(
        "/transactions", json=txn_payload(account_id, category_id=child_id, amount="900.00", date="2026-03-10")
    )

    items = {item["category_id"]: item for item in (await client.get("/budgets/status?year=2026&month=3")).json()["items"]}

    assert money(items[child_id]["spent"]) == money("900.00")
    assert items[child_id]["is_over_budget"] is True
    assert money(items[parent_id]["spent"]) == money("900.00")
    assert items[parent_id]["is_over_budget"] is False


async def test_budget_status_counts_a_split_transactions_share(client: AsyncClient, account_id, categories):
    """A receipt split between Groceries and Shopping must count its 70.00
    slice toward the Groceries budget, not the full 100.00 or nothing."""
    groceries = categories["Groceries"]["id"]
    shopping = categories["Shopping"]["id"]
    await client.post("/budgets", json={"category_id": groceries, "monthly_limit": "100.00"})
    await client.post(
        "/transactions",
        json=txn_payload(
            account_id,
            amount="100.00",
            category_id=None,
            date="2026-08-10",
            splits=[
                {"category_id": groceries, "amount": "70.00"},
                {"category_id": shopping, "amount": "30.00"},
            ],
        ),
    )

    resp = await client.get("/budgets/status", params={"year": 2026, "month": 8})
    item = resp.json()["items"][0]
    assert money(item["spent"]) == Decimal("70.00")