"""Tally: quorum, threshold, and the counting rules of Article 5.

Vote counts in these tests are chosen so the expected outcome is the
same under every sane denominator convention (yes/(yes+no), yes/turnout,
yes/eligible) — the suite pins outcomes, not one arithmetic style.
"""

from __future__ import annotations

import pytest

from tests.helpers import (
    cast_ballot,
    create_proposal,
    proposal_id_of,
    passed_of,
    quorum_met,
    run_tally,
    yes_count,
    no_count,
)


@pytest.fixture()
def proposal_id(repo, citizens):
    prop = create_proposal(
        repo,
        proposer_id=citizens[0]["id"],
        title="Tally unit-test proposal",
        changes={"constitution/userland/tally-test-module.yaml": "id: tally-test\ntitle: Tally test\n"},
    )
    return proposal_id_of(prop)


def _ballots(repo, citizens, proposal_id, choices):
    out = []
    for citizen, choice in zip(citizens, choices):
        out.append(cast_ballot(citizen, proposal_id, choice, repo=repo))
    return out


def test_clear_pass(repo, citizens, eligible_ids, proposal_id):
    # 4 yes, 1 no, 6 eligible; quorum 0.5, threshold 0.6.
    ballots = _ballots(repo, citizens, proposal_id, ["yes", "yes", "yes", "yes", "no"])
    result = run_tally(ballots, eligible_ids, quorum=0.5, threshold=0.6)
    assert yes_count(result) == 4
    assert no_count(result) == 1
    assert quorum_met(result)
    assert passed_of(result)


def test_quorum_failure_blocks(repo, citizens, proposal_id):
    # One yes ballot against an electorate of ten: 10% turnout, quorum 0.5.
    ballots = _ballots(repo, citizens[:1], proposal_id, ["yes"])
    electorate = [c["id"] for c in citizens] + [f"cit-ghost-{i}" for i in range(4)]
    assert len(electorate) == 10
    result = run_tally(ballots, electorate, quorum=0.5, threshold=0.5)
    assert not quorum_met(result)
    assert not passed_of(result)


def test_supermajority_threshold_failure_blocks(repo, citizens, eligible_ids, proposal_id):
    # 3 yes, 3 no out of 6: 50% support fails a 2/3 threshold under any convention.
    ballots = _ballots(repo, citizens, proposal_id, ["yes", "yes", "yes", "no", "no", "no"])
    result = run_tally(ballots, eligible_ids, quorum=0.5, threshold=2 / 3)
    assert yes_count(result) == 3
    assert no_count(result) == 3
    assert quorum_met(result)
    assert not passed_of(result)


def test_ineligible_ballots_are_not_counted(repo, citizens, proposal_id):
    # Five eligible citizens; a sixth ballot arrives from outside the electorate.
    eligible = [c["id"] for c in citizens[:5]]
    ballots = _ballots(repo, citizens[:4], proposal_id, ["yes"] * 4)
    intruder = citizens[5]  # in the registry, but excluded from this electorate
    ballots.append(cast_ballot(intruder, proposal_id, "yes", repo=repo))
    result = run_tally(ballots, eligible, quorum=0.5, threshold=0.5)
    assert yes_count(result) == 4, "a ballot from outside the electorate must not count"


def test_unanimous_no_fails(repo, citizens, eligible_ids, proposal_id):
    ballots = _ballots(repo, citizens, proposal_id, ["no"] * 6)
    result = run_tally(ballots, eligible_ids, quorum=0.5, threshold=0.5)
    assert yes_count(result) == 0
    assert not passed_of(result)


def test_zero_ballots_fails(repo, eligible_ids):
    result = run_tally([], eligible_ids, quorum=0.5, threshold=0.5)
    assert not passed_of(result)
    assert not quorum_met(result)