"""Dashboard summary: the arithmetic and month-scoping behind the Overview
page's four stat cards and the spending-by-category donut.
"""
from decimal import Decimal

from httpx import AsyncClient

from tests.helpers import money, txn_payload as _txn


async def test_summary_is_zero_for_a_month_with_no_transactions(client: AsyncClient):
    resp = await client.get("/dashboard/summary", params={"year": 2030, "month": 1})
    body = resp.json()
    assert money(body["real_income"]) == 0
    assert money(body["spent"]) == 0
    assert money(body["net"]) == 0
    assert body["spending_by_category"] == []


async def test_income_expense_and_net_only_count_the_selected_month(client: AsyncClient, account_id, categories):
    groceries = categories["Groceries"]["id"]
    salary = categories["Salary"]["id"]

    # In scope: August 2026.
    await client.post(
        "/transactions", json=_txn(account_id, type="income", amount="3000.00", category_id=salary, date="2026-08-01")
    )
    await client.post(
        "/transactions", json=_txn(account_id, type="expense", amount="1200.00", category_id=groceries, date="2026-08-20")
    )
    # Out of scope: same categories, different month — must not leak in.
    await client.post(
        "/transactions", json=_txn(account_id, type="income", amount="9999.00", category_id=salary, date="2026-07-31")
    )
    await client.post(
        "/transactions", json=_txn(account_id, type="expense", amount="9999.00", category_id=groceries, date="2026-09-01")
    )

    resp = await client.get("/dashboard/summary", params={"year": 2026, "month": 8})
    body = resp.json()
    assert money(body["real_income"]) == Decimal("3000.00")
    assert money(body["spent"]) == Decimal("1200.00")
    assert money(body["net"]) == Decimal("1800.00")


async def test_transfers_are_excluded_from_income_and_spent(client: AsyncClient, account_id, categories):
    other = await client.post("/accounts", json={"name": "Savings", "type": "savings", "currency": "USD"})
    other_id = other.json()["id"]
    await client.post(
        "/transactions",
        json=_txn(account_id, type="transfer", amount="500.00", transfer_account_id=other_id, date="2026-08-05"),
    )
    await client.post(
        "/transactions",
        json=_txn(account_id, type="income", amount="100.00", category_id=categories["Salary"]["id"], date="2026-08-05"),
    )

    resp = await client.get("/dashboard/summary", params={"year": 2026, "month": 8})
    body = resp.json()
    assert money(body["real_income"]) == Decimal("100.00")
    assert money(body["spent"]) == 0
    assert money(body["transferred_out"]) == Decimal("500.00")


async def test_spending_by_category_amounts_and_percent(client: AsyncClient, account_id, categories):
    groceries = categories["Groceries"]["id"]
    dining = categories["Dining Out"]["id"]
    await client.post(
        "/transactions", json=_txn(account_id, amount="75.00", category_id=groceries, date="2026-08-01")
    )
    await client.post(
        "/transactions", json=_txn(account_id, amount="25.00", category_id=dining, date="2026-08-02")
    )

    resp = await client.get("/dashboard/summary", params={"year": 2026, "month": 8})
    breakdown = {row["name"]: row for row in resp.json()["spending_by_category"]}

    assert money(breakdown["Groceries"]["amount"]) == Decimal("75.00")
    assert breakdown["Groceries"]["percent"] == 75.0
    assert money(breakdown["Dining Out"]["amount"]) == Decimal("25.00")
    assert breakdown["Dining Out"]["percent"] == 25.0


async def test_more_than_eight_expense_categories_roll_up_into_other(client: AsyncClient, account_id, categories):
    expense_categories = [c for c in categories.values() if c["kind"] == "expense"]
    # The default seed only ships 8 expense categories (see app/db/seed.py) —
    # add a 9th ourselves rather than depending on that number ever changing.
    extra = await client.post(
        "/categories", json={"name": "Extra Expense", "kind": "expense", "color": "#123456", "sort_order": 99}
    )
    expense_categories.append(extra.json())
    assert len(expense_categories) == 9

    # Distinct amounts so we can tell which ones survive as their own slice.
    for index, category in enumerate(expense_categories[:9]):
        await client.post(
            "/transactions",
            json=_txn(account_id, amount=f"{(9 - index) * 10}.00", category_id=category["id"], date="2026-08-01"),
        )

    resp = await client.get("/dashboard/summary", params={"year": 2026, "month": 8})
    breakdown = resp.json()["spending_by_category"]

    assert len(breakdown) == 9  # 8 explicit categories + one "Other" rollup
    other = [row for row in breakdown if row["category_id"] is None]
    assert len(other) == 1
    assert other[0]["name"] == "Other"
    # The 9th (smallest, index 8) category's 10.00 must be folded into Other,
    # not silently dropped from the total.
    assert money(other[0]["amount"]) == Decimal("10.00")