"""Deterministic ledger tasks. Each task_id -> (ledger csv, question, expected answer)."""
import random

KINDS = ["balance", "category_total", "duplicate", "largest_expense", "net_flow", "unmatched"]
# The server accepts any "<kind>-<n>" with n >= 1 (unbounded task pool); the
# submission lists 50 of them (the arena maximum).
TASK_IDS = [f"{k}-{i}" for k in KINDS for i in range(1, 9)] + ["balance-9", "category_total-9"]
ACCOUNTS = ["rent", "salary", "food", "travel", "tools", "tax"]


def build(task_id: str):
    kind, idx = task_id.rsplit("-", 1)
    if kind not in KINDS:
        raise KeyError(task_id)
    rng = random.Random(f"ledger-{task_id}")
    n = 8 + 2 * (int(idx) % 12)
    rows = []
    for i in range(1, n + 1):
        acct = rng.choice(ACCOUNTS)
        amt = round(rng.uniform(5, 900), 2)
        if acct == "salary":
            amt = round(rng.uniform(1000, 3000), 2)
        else:
            amt = -amt
        rows.append([f"T{i:02d}", acct, amt])
    if kind == "balance":
        opening = round(rng.uniform(500, 5000), 2)
        q = f"Opening balance is {opening:.2f}. What is the closing balance after all entries? Answer with a number, 2 decimals."
        ans = f"{opening + sum(r[2] for r in rows):.2f}"
    elif kind == "category_total":
        acct = rng.choice([r[1] for r in rows])
        q = f"What is the total (signed sum) of all entries in account '{acct}'? Answer with a number, 2 decimals."
        ans = f"{sum(r[2] for r in rows if r[1] == acct):.2f}"
    elif kind == "duplicate":
        j = rng.randrange(2, n)
        dup = list(rows[rng.randrange(0, j)])
        dup[0] = f"T{j+1:02d}x"
        rows.insert(j, dup)
        q = "Exactly one entry duplicates an earlier entry (same account and amount) with a later id. Which entry id is the duplicate?"
        ans = dup[0]
    elif kind == "largest_expense":
        q = "Which entry id is the largest expense (most negative amount)?"
        ans = min(rows, key=lambda r: r[2])[0]
    elif kind == "net_flow":
        q = "What is the sum of all positive entries minus the absolute sum of all negative entries (i.e. net flow)? Answer with a number, 2 decimals."
        ans = f"{sum(r[2] for r in rows):.2f}"
    else:  # unmatched
        k = rng.randrange(0, n)
        rows[k][1] = "unknown"
        q = "Exactly one entry has account 'unknown'. Which entry id is it?"
        ans = rows[k][0]
    csv = "id,account,amount\n" + "\n".join(f"{r[0]},{r[1]},{r[2]:.2f}" for r in rows)
    return csv, q, ans


def score(expected: str, given: str) -> float:
    g = given.strip().strip("'\"").replace(",", "")
    try:
        return 1.0 if abs(float(g) - float(expected)) < 0.005 else 0.0
    except ValueError:
        return 1.0 if g.lower() == expected.lower() else 0.0