"""Tests for decision service: advance_decision, create_vote_session_for_step.

These are pure unit tests that mock the database layer to test
the service logic in isolation.
"""

from __future__ import annotations

import uuid
from datetime import datetime, timezone
from unittest.mock import AsyncMock, MagicMock, patch

import pytest

sqlalchemy = pytest.importorskip("sqlalchemy", reason="sqlalchemy required for decision service tests")

from app.services.decision_service import (  # noqa: E402
    advance_decision,
    create_vote_session_for_step,
)


# ---------------------------------------------------------------------------
# Helpers: mock objects that behave like SQLAlchemy models
# ---------------------------------------------------------------------------


def _make_step(
    step_id: uuid.UUID | None = None,
    decision_id: uuid.UUID | None = None,
    step_order: int = 0,
    step_type: str = "qualification",
    status: str = "pending",
    vote_session_id: uuid.UUID | None = None,
) -> MagicMock:
    """Create a mock DecisionStep."""
    step = MagicMock()
    step.id = step_id or uuid.uuid4()
    step.decision_id = decision_id or uuid.uuid4()
    step.step_order = step_order
    step.step_type = step_type
    step.title = None
    step.description = None
    step.status = status
    step.vote_session_id = vote_session_id
    step.outcome = None
    step.created_at = datetime.now(timezone.utc)
    return step


def _make_decision(
    decision_id: uuid.UUID | None = None,
    title: str = "Decision de test",
    decision_type: str = "document_change",
    status: str = "draft",
    voting_protocol_id: uuid.UUID | None = None,
    steps: list | None = None,
) -> MagicMock:
    """Create a mock Decision."""
    decision = MagicMock()
    decision.id = decision_id or uuid.uuid4()
    decision.title = title
    decision.description = None
    decision.context = None
    decision.decision_type = decision_type
    decision.status = status
    decision.voting_protocol_id = voting_protocol_id
    decision.created_by_id = None
    decision.created_at = datetime.now(timezone.utc)
    decision.updated_at = datetime.now(timezone.utc)
    decision.steps = steps or []
    return decision


def _make_protocol(
    protocol_id: uuid.UUID | None = None,
    duration_days: int = 30,
) -> MagicMock:
    """Create a mock VotingProtocol with formula_config."""
    protocol = MagicMock()
    protocol.id = protocol_id or uuid.uuid4()
    protocol.name = "Protocole standard"
    protocol.vote_type = "binary"
    protocol.formula_config = MagicMock()
    protocol.formula_config.duration_days = duration_days
    return protocol


def _make_db_for_advance(decision: MagicMock | None) -> AsyncMock:
    """Create a mock async database session for advance_decision."""
    db = AsyncMock()

    result = MagicMock()
    result.scalar_one_or_none.return_value = decision

    db.execute = AsyncMock(return_value=result)
    db.commit = AsyncMock()
    db.refresh = AsyncMock()

    return db


def _make_db_for_vote_session(
    decision: MagicMock | None,
    protocol: MagicMock | None = None,
) -> AsyncMock:
    """Create a mock async database session for create_vote_session_for_step.

    Sequential execute calls:
    1st -> decision lookup
    2nd -> protocol lookup
    """
    db = AsyncMock()

    call_results = []

    # Decision result
    decision_result = MagicMock()
    decision_result.scalar_one_or_none.return_value = decision
    call_results.append(decision_result)

    # Protocol result
    if protocol is not None:
        proto_result = MagicMock()
        proto_result.scalar_one_or_none.return_value = protocol
        call_results.append(proto_result)

    db.execute = AsyncMock(side_effect=call_results)
    db.commit = AsyncMock()
    db.refresh = AsyncMock()
    db.flush = AsyncMock()
    db.add = MagicMock()

    return db


# ---------------------------------------------------------------------------
# Tests: advance_decision
# ---------------------------------------------------------------------------


class TestAdvanceDecision:
    """Test decision_service.advance_decision."""

    @pytest.mark.asyncio
    async def test_advance_from_draft_activates_first_step(self):
        """Advancing a draft decision with pending steps activates the first one
        and moves decision to qualification."""
        decision_id = uuid.uuid4()
        step1 = _make_step(decision_id=decision_id, step_order=0, status="pending")
        step2 = _make_step(decision_id=decision_id, step_order=1, status="pending")

        decision = _make_decision(
            decision_id=decision_id,
            status="draft",
            steps=[step1, step2],
        )

        db = _make_db_for_advance(decision)

        result = await advance_decision(decision_id, db)

        assert step1.status == "active"
        assert step2.status == "pending"
        assert decision.status == "qualification"
        db.commit.assert_awaited_once()

    @pytest.mark.asyncio
    async def test_advance_completes_active_and_activates_next(self):
        """Advancing completes the current active step and activates the next pending one."""
        decision_id = uuid.uuid4()
        step1 = _make_step(decision_id=decision_id, step_order=0, status="active")
        step2 = _make_step(decision_id=decision_id, step_order=1, status="pending")

        decision = _make_decision(
            decision_id=decision_id,
            status="qualification",
            steps=[step1, step2],
        )

        db = _make_db_for_advance(decision)

        result = await advance_decision(decision_id, db)

        assert step1.status == "completed"
        assert step2.status == "active"
        db.commit.assert_awaited_once()

    @pytest.mark.asyncio
    async def test_advance_last_step_advances_status(self):
        """When the last active step is completed with no more pending steps,
        the decision status advances."""
        decision_id = uuid.uuid4()
        step1 = _make_step(decision_id=decision_id, step_order=0, status="completed")
        step2 = _make_step(decision_id=decision_id, step_order=1, status="active")

        decision = _make_decision(
            decision_id=decision_id,
            status="qualification",
            steps=[step1, step2],
        )

        db = _make_db_for_advance(decision)

        result = await advance_decision(decision_id, db)

        assert step2.status == "completed"
        assert decision.status == "review"
        db.commit.assert_awaited_once()

    @pytest.mark.asyncio
    async def test_advance_no_steps_advances_status(self):
        """A decision with no steps advances its status directly."""
        decision_id = uuid.uuid4()
        decision = _make_decision(
            decision_id=decision_id,
            status="draft",
            steps=[],
        )

        db = _make_db_for_advance(decision)

        result = await advance_decision(decision_id, db)

        assert decision.status == "qualification"
        db.commit.assert_awaited_once()

    @pytest.mark.asyncio
    async def test_advance_full_progression(self):
        """A decision with no steps can progress through all statuses."""
        decision_id = uuid.uuid4()
        decision = _make_decision(
            decision_id=decision_id,
            status="draft",
            steps=[],
        )

        statuses_seen = [decision.status]
        db = _make_db_for_advance(decision)

        # Advance through all states until closed
        for _ in range(10):  # safety limit
            # Recreate db mock for each call (side_effect is consumed)
            db = _make_db_for_advance(decision)
            await advance_decision(decision_id, db)
            statuses_seen.append(decision.status)
            if decision.status == "closed":
                break

        assert statuses_seen == [
            "draft",
            "qualification",
            "review",
            "voting",
            "executed",
            "closed",
        ]

    @pytest.mark.asyncio
    async def test_advance_closed_raises_error(self):
        """Advancing a closed decision raises ValueError."""
        decision_id = uuid.uuid4()
        decision = _make_decision(
            decision_id=decision_id,
            status="closed",
            steps=[],
        )

        db = _make_db_for_advance(decision)

        with pytest.raises(ValueError, match="deja cloturee"):
            await advance_decision(decision_id, db)

    @pytest.mark.asyncio
    async def test_advance_not_found_raises_error(self):
        """Advancing a non-existent decision raises ValueError."""
        db = _make_db_for_advance(None)

        with pytest.raises(ValueError, match="Decision introuvable"):
            await advance_decision(uuid.uuid4(), db)


# ---------------------------------------------------------------------------
# Tests: create_vote_session_for_step
# ---------------------------------------------------------------------------


class TestCreateVoteSessionForStep:
    """Test decision_service.create_vote_session_for_step."""

    @pytest.mark.asyncio
    async def test_create_vote_session_success(self):
        """A vote session is created and linked to the step."""
        decision_id = uuid.uuid4()
        step_id = uuid.uuid4()
        protocol_id = uuid.uuid4()

        step = _make_step(
            step_id=step_id,
            decision_id=decision_id,
            step_type="vote",
            status="active",
            vote_session_id=None,
        )

        decision = _make_decision(
            decision_id=decision_id,
            status="voting",
            voting_protocol_id=protocol_id,
            steps=[step],
        )

        protocol = _make_protocol(protocol_id=protocol_id, duration_days=14)
        db = _make_db_for_vote_session(decision, protocol)

        result = await create_vote_session_for_step(decision_id, step_id, db)

        # The step should now have a vote_session_id set
        assert step.vote_session_id is not None
        db.commit.assert_awaited_once()

    @pytest.mark.asyncio
    async def test_create_vote_session_decision_not_found(self):
        """ValueError when decision does not exist."""
        db = _make_db_for_vote_session(None)

        with pytest.raises(ValueError, match="Decision introuvable"):
            await create_vote_session_for_step(uuid.uuid4(), uuid.uuid4(), db)

    @pytest.mark.asyncio
    async def test_create_vote_session_step_not_found(self):
        """ValueError when step does not belong to the decision."""
        decision_id = uuid.uuid4()
        decision = _make_decision(decision_id=decision_id, steps=[])

        db = _make_db_for_vote_session(decision)

        with pytest.raises(ValueError, match="Etape introuvable"):
            await create_vote_session_for_step(decision_id, uuid.uuid4(), db)

    @pytest.mark.asyncio
    async def test_create_vote_session_step_already_has_session(self):
        """ValueError when step already has a vote session."""
        decision_id = uuid.uuid4()
        step_id = uuid.uuid4()
        existing_session_id = uuid.uuid4()

        step = _make_step(
            step_id=step_id,
            decision_id=decision_id,
            vote_session_id=existing_session_id,
        )

        decision = _make_decision(
            decision_id=decision_id,
            voting_protocol_id=uuid.uuid4(),
            steps=[step],
        )

        db = _make_db_for_vote_session(decision)

        with pytest.raises(ValueError, match="deja une session de vote"):
            await create_vote_session_for_step(decision_id, step_id, db)

    @pytest.mark.asyncio
    async def test_create_vote_session_no_protocol(self):
        """ValueError when decision has no voting protocol configured."""
        decision_id = uuid.uuid4()
        step_id = uuid.uuid4()

        step = _make_step(
            step_id=step_id,
            decision_id=decision_id,
            vote_session_id=None,
        )

        decision = _make_decision(
            decision_id=decision_id,
            voting_protocol_id=None,
            steps=[step],
        )

        db = _make_db_for_vote_session(decision)

        with pytest.raises(ValueError, match="Aucun protocole de vote"):
            await create_vote_session_for_step(decision_id, step_id, db)