"""Tests for BE-CAL-006: Calendar overlap detection.

Covers:
  - No conflict when slots don't overlap
  - Conflict detected for overlapping time ranges
  - Create vs edit scenarios (edit excludes own slot)
  - Skipped/aborted slots are not considered
  - Virtual (plan-generated) slots are checked
  - Edge cases: adjacent slots, exact same time, partial overlap
"""

import pytest
from datetime import date, time

from app.models.calendar import (
    SchedulePlan,
    SlotStatus,
    SlotType,
    EventType,
    TimeSlot,
    DayOfWeek,
)
from app.services.overlap import (
    check_overlap,
    check_overlap_for_create,
    check_overlap_for_edit,
)


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------

TARGET_DATE = date(2026, 4, 1)  # A Wednesday
USER_ID = 1
USER_ID_2 = 2


def _make_slot(db, *, scheduled_at, duration=30, status=SlotStatus.NOT_STARTED, user_id=USER_ID, slot_date=TARGET_DATE, plan_id=None):
    """Insert a real TimeSlot and return it."""
    slot = TimeSlot(
        user_id=user_id,
        date=slot_date,
        slot_type=SlotType.WORK,
        estimated_duration=duration,
        scheduled_at=scheduled_at,
        status=status,
        priority=0,
        plan_id=plan_id,
    )
    db.add(slot)
    db.flush()
    return slot


def _make_plan(db, *, at_time, duration=30, user_id=USER_ID, on_day=None, is_active=True):
    """Insert a SchedulePlan and return it."""
    plan = SchedulePlan(
        user_id=user_id,
        slot_type=SlotType.WORK,
        estimated_duration=duration,
        at_time=at_time,
        on_day=on_day,
        is_active=is_active,
    )
    db.add(plan)
    db.flush()
    return plan


@pytest.fixture(autouse=True)
def _ensure_users(seed):
    """All overlap tests need seeded users (id=1, id=2) for FK constraints."""
    pass


# ---------------------------------------------------------------------------
# No-conflict cases
# ---------------------------------------------------------------------------

class TestNoConflict:

    def test_empty_calendar(self, db):
        """No existing slots → no conflicts."""
        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert conflicts == []

    def test_adjacent_before(self, db):
        """Existing 09:00-09:30, proposed 09:30-10:00 → no overlap."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 30), 30,
        )
        assert conflicts == []

    def test_adjacent_after(self, db):
        """Existing 10:00-10:30, proposed 09:30-10:00 → no overlap."""
        _make_slot(db, scheduled_at=time(10, 0), duration=30)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 30), 30,
        )
        assert conflicts == []

    def test_different_user(self, db):
        """Slot for user 2 should not conflict with user 1's new slot."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30, user_id=USER_ID_2)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert conflicts == []

    def test_different_date(self, db):
        """Same time on a different date → no conflict."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30, slot_date=date(2026, 4, 2))
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert conflicts == []


# ---------------------------------------------------------------------------
# Conflict detection
# ---------------------------------------------------------------------------

class TestConflictDetected:

    def test_exact_same_time(self, db):
        """Same start + same duration = overlap."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert len(conflicts) == 1
        assert conflicts[0].conflicting_slot_id is not None
        assert "overlaps" in conflicts[0].message

    def test_partial_overlap_start(self, db):
        """Existing 09:00-09:30, proposed 09:15-09:45 → overlap."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 15), 30,
        )
        assert len(conflicts) == 1

    def test_partial_overlap_end(self, db):
        """Existing 09:15-09:45, proposed 09:00-09:30 → overlap."""
        _make_slot(db, scheduled_at=time(9, 15), duration=30)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert len(conflicts) == 1

    def test_proposed_contains_existing(self, db):
        """Proposed 09:00-10:00 contains existing 09:15-09:45."""
        _make_slot(db, scheduled_at=time(9, 15), duration=30)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 50,
        )
        assert len(conflicts) == 1

    def test_existing_contains_proposed(self, db):
        """Existing 09:00-10:00 contains proposed 09:15-09:30."""
        _make_slot(db, scheduled_at=time(9, 0), duration=50)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 15), 15,
        )
        assert len(conflicts) == 1

    def test_multiple_conflicts(self, db):
        """Proposed overlaps with two existing slots."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30)
        _make_slot(db, scheduled_at=time(9, 20), duration=30)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 10), 30,
        )
        assert len(conflicts) == 2


# ---------------------------------------------------------------------------
# Inactive slots excluded
# ---------------------------------------------------------------------------

class TestInactiveExcluded:

    def test_skipped_slot_ignored(self, db):
        """Skipped slot at same time should not cause conflict."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30, status=SlotStatus.SKIPPED)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert conflicts == []

    def test_aborted_slot_ignored(self, db):
        """Aborted slot at same time should not cause conflict."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30, status=SlotStatus.ABORTED)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert conflicts == []

    def test_ongoing_slot_conflicts(self, db):
        """Ongoing slot should still cause conflict."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30, status=SlotStatus.ONGOING)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert len(conflicts) == 1

    def test_deferred_slot_conflicts(self, db):
        """Deferred slot should still cause conflict."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30, status=SlotStatus.DEFERRED)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert len(conflicts) == 1


# ---------------------------------------------------------------------------
# Edit scenario (exclude own slot)
# ---------------------------------------------------------------------------

class TestEditExcludeSelf:

    def test_edit_no_self_conflict(self, db):
        """Editing a slot to the same time should not conflict with itself."""
        slot = _make_slot(db, scheduled_at=time(9, 0), duration=30)
        db.commit()

        conflicts = check_overlap_for_edit(
            db, USER_ID, slot.id, TARGET_DATE, time(9, 0), 30,
        )
        assert conflicts == []

    def test_edit_still_detects_others(self, db):
        """Editing a slot detects overlap with *other* slots."""
        slot = _make_slot(db, scheduled_at=time(9, 0), duration=30)
        _make_slot(db, scheduled_at=time(9, 30), duration=30)
        db.commit()

        # Move slot to overlap with the second one
        conflicts = check_overlap_for_edit(
            db, USER_ID, slot.id, TARGET_DATE, time(9, 20), 30,
        )
        assert len(conflicts) == 1

    def test_edit_self_excluded_others_fine(self, db):
        """Moving a slot to a free spot should report no conflicts."""
        slot = _make_slot(db, scheduled_at=time(9, 0), duration=30)
        _make_slot(db, scheduled_at=time(10, 0), duration=30)
        db.commit()

        # Move to 11:00 — no overlap
        conflicts = check_overlap_for_edit(
            db, USER_ID, slot.id, TARGET_DATE, time(11, 0), 30,
        )
        assert conflicts == []


# ---------------------------------------------------------------------------
# Virtual slot (plan-generated) overlap
# ---------------------------------------------------------------------------

class TestVirtualSlotOverlap:

    def test_conflict_with_virtual_slot(self, db):
        """A plan that generates a virtual slot at 09:00 should conflict."""
        # TARGET_DATE is 2026-04-01 (Wednesday)
        _make_plan(db, at_time=time(9, 0), duration=30, on_day=DayOfWeek.WED)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert len(conflicts) == 1
        assert conflicts[0].conflicting_virtual_id is not None
        assert conflicts[0].conflicting_slot_id is None

    def test_no_conflict_with_inactive_plan(self, db):
        """Cancelled plan should not generate a virtual slot to conflict with."""
        _make_plan(db, at_time=time(9, 0), duration=30, on_day=DayOfWeek.WED, is_active=False)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert conflicts == []

    def test_no_conflict_with_non_matching_plan(self, db):
        """Plan for Monday should not generate a virtual slot on Wednesday."""
        _make_plan(db, at_time=time(9, 0), duration=30, on_day=DayOfWeek.MON)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        assert conflicts == []

    def test_materialized_plan_not_double_counted(self, db):
        """A plan that's already materialized should only be counted as a real slot, not also virtual."""
        plan = _make_plan(db, at_time=time(9, 0), duration=30, on_day=DayOfWeek.WED)
        _make_slot(db, scheduled_at=time(9, 0), duration=30, plan_id=plan.id)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        # Should only have 1 conflict (the real slot), not 2
        assert len(conflicts) == 1
        assert conflicts[0].conflicting_slot_id is not None


# ---------------------------------------------------------------------------
# Conflict message content
# ---------------------------------------------------------------------------

class TestConflictMessage:

    def test_message_has_time_info(self, db):
        """Conflict message should include time range information."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 15), 30,
        )
        assert len(conflicts) == 1
        msg = conflicts[0].message
        assert "09:00" in msg
        assert "overlaps" in msg

    def test_to_dict(self, db):
        """SlotConflict.to_dict() should return a proper dict."""
        _make_slot(db, scheduled_at=time(9, 0), duration=30)
        db.commit()

        conflicts = check_overlap_for_create(
            db, USER_ID, TARGET_DATE, time(9, 0), 30,
        )
        d = conflicts[0].to_dict()
        assert "scheduled_at" in d
        assert "estimated_duration" in d
        assert "slot_type" in d
        assert "message" in d
        assert "conflicting_slot_id" in d