"""Targets CRUD tests — TICKET-002 (spec §2.4, §3.4, §8.1 rules 2–3, 11).

Auto-close semantics (documented in services/targets.py):
- When a new target is created, the previous active target's end_date is set
  to the new target's start_date (same day).
- Historical lookup uses an EXCLUSIVE end_date: a target covers dates where
  start_date <= date AND (end_date IS NULL OR end_date > date).
  This makes intervals half-open [start_date, end_date), so there is never
  overlap or ambiguity.

Tests share a session-scoped DB. Each test cleans up after itself by closing
any active targets it leaves behind, so subsequent tests start with a clean
slate (no active target). Tests that need a fully empty targets table use
direct DB access to delete all rows.
"""

from datetime import date


# ── Helpers ──────────────────────────────────────────────────────────────────


def create_target(client, **overrides) -> dict:
    """Create a target via POST and return the response JSON."""
    payload = {
        "start_date": "2025-01-01",
        "calories": 2000,
        "protein_g": 150.0,
        "carbs_g": 200.0,
        "fat_g": 65.0,
    }
    payload.update(overrides)
    resp = client.post("/api/targets", json=payload)
    return resp


def assert_422(resp):
    assert resp.status_code == 422, f"expected 422, got {resp.status_code}: {resp.text}"


def close_active_target(client):
    """Close the active target (if any) by giving it an end_date.
    Uses a date far in the future so it always passes date validation."""
    current = client.get("/api/targets/current")
    if current.status_code == 200:
        tid = current.json()["id"]
        client.put(f"/api/targets/{tid}", json={"end_date": "2099-12-31"})


# ── Create + current round-trip ──────────────────────────────────────────────


def test_create_and_read_current(client):
    """POST creates a target (201), GET /current returns it."""
    try:
        resp = create_target(client)
        assert resp.status_code == 201, resp.text
        data = resp.json()

        assert data["start_date"] == "2025-01-01"
        assert data["end_date"] is None
        assert data["calories"] == 2000
        assert data["protein_g"] == 150.0
        assert data["carbs_g"] == 200.0
        assert data["fat_g"] == 65.0
        assert "id" in data

        # GET /current should return the same target
        resp2 = client.get("/api/targets/current")
        assert resp2.status_code == 200
        assert resp2.json() == data
    finally:
        close_active_target(client)


def test_current_404_when_none(client):
    """GET /current returns 404 when no active target exists."""
    close_active_target(client)  # Ensure clean state
    resp = client.get("/api/targets/current")
    assert resp.status_code == 404


# ── Auto-close of previous target ────────────────────────────────────────────


def test_auto_close_previous_target(client):
    """Creating a second target auto-closes the first: its end_date is set
    to the new target's start_date, and /current returns the new one."""
    try:
        # Create first target (active)
        resp1 = create_target(client, start_date="2025-01-01", calories=2000)
        assert resp1.status_code == 201
        id1 = resp1.json()["id"]
        assert resp1.json()["end_date"] is None

        # Create second target with later start_date
        resp2 = create_target(client, start_date="2025-06-01", calories=2200)
        assert resp2.status_code == 201
        id2 = resp2.json()["id"]
        assert resp2.json()["end_date"] is None

        # First target should now have an end_date equal to the second's start_date
        resp_get = client.get("/api/targets")
        all_targets = resp_get.json()
        t1 = next(t for t in all_targets if t["id"] == id1)
        assert t1["end_date"] == "2025-06-01"

        # /current should return the second target
        current = client.get("/api/targets/current").json()
        assert current["id"] == id2
    finally:
        close_active_target(client)


def test_auto_close_with_earlier_start_date(client):
    """If the new target's start_date is BEFORE the existing active target's
    start_date, the operation is rejected (422) because it would create an
    invalid date range on the auto-closed target."""
    try:
        # Create first target (active starting 2025-06-01)
        create_target(client, start_date="2025-06-01", calories=2000)

        # Try to create a target with start_date before the active one's start_date
        resp = create_target(client, start_date="2025-01-01", calories=1800)
        # This would set the existing target's end_date to 2025-01-01,
        # which is before its start_date of 2025-06-01 → rejected
        assert_422(resp)
    finally:
        close_active_target(client)


def test_only_one_active_after_create(client):
    """After creating 3 targets sequentially, exactly one has end_date IS NULL."""
    try:
        for i, start in enumerate(["2025-01-01", "2025-04-01", "2025-07-01"]):
            resp = create_target(client, start_date=start, calories=2000 + i * 100)
            assert resp.status_code == 201, f"iteration {i}: {resp.text}"

        all_targets = client.get("/api/targets").json()
        active = [t for t in all_targets if t["end_date"] is None]
        assert len(active) == 1
        assert active[0]["start_date"] == "2025-07-01"
    finally:
        close_active_target(client)


# ── List targets ─────────────────────────────────────────────────────────────


def test_list_targets_ordered_by_start_date(client):
    """GET /api/targets returns all targets ordered by start_date."""
    try:
        # Use unique calorie values to identify our targets
        base_cal = 9000  # Distinct from other tests
        dates = ["2025-03-01", "2025-01-01", "2025-02-01"]
        for d in dates:
            create_target(client, start_date=d, calories=base_cal)
            base_cal += 1

        resp = client.get("/api/targets")
        assert resp.status_code == 200
        results = resp.json()

        # Verify ALL targets are ordered by start_date
        for i in range(len(results) - 1):
            assert results[i]["start_date"] <= results[i + 1]["start_date"], (
                f"out of order at index {i}: "
                f"{results[i]['start_date']} > {results[i+1]['start_date']}"
            )
    finally:
        close_active_target(client)


def test_list_targets_returns_list(client):
    """GET /api/targets returns a list (may be empty or populated)."""
    resp = client.get("/api/targets")
    assert resp.status_code == 200
    assert isinstance(resp.json(), list)


# ── Update target ────────────────────────────────────────────────────────────


def test_update_target_values(client):
    """PUT updates calorie/macro values on a target."""
    try:
        resp = create_target(client, calories=2000, protein_g=100.0)
        assert resp.status_code == 201, resp.text
        tid = resp.json()["id"]

        resp = client.put(
            f"/api/targets/{tid}",
            json={"calories": 2500, "protein_g": 120.0, "carbs_g": 250.0, "fat_g": 70.0},
        )
        assert resp.status_code == 200
        data = resp.json()
        assert data["calories"] == 2500
        assert data["protein_g"] == 120.0
        assert data["carbs_g"] == 250.0
        assert data["fat_g"] == 70.0
        # unchanged
        assert data["start_date"] == "2025-01-01"
        assert data["end_date"] is None
    finally:
        close_active_target(client)


def test_update_target_date_range(client):
    """PUT updates end_date on a target, closing it."""
    try:
        resp = create_target(client, start_date="2025-01-01", calories=2000)
        assert resp.status_code == 201, resp.text
        tid = resp.json()["id"]

        # Close this target by giving it an end_date
        resp = client.put(
            f"/api/targets/{tid}",
            json={"end_date": "2025-06-01"},
        )
        assert resp.status_code == 200, resp.text
        assert resp.json()["end_date"] == "2025-06-01"

        # Now there's no active target
        assert client.get("/api/targets/current").status_code == 404
    finally:
        close_active_target(client)


def test_update_end_date_null_when_another_active(client):
    """Setting end_date to null on a historical target when another target
    is already active is rejected (409)."""
    try:
        # Create two targets: t1 closed, t2 active
        resp1 = create_target(client, start_date="2025-01-01", calories=2000)
        assert resp1.status_code == 201, resp1.text
        id1 = resp1.json()["id"]

        resp2 = create_target(client, start_date="2025-06-01", calories=2200)
        assert resp2.status_code == 201, resp2.text
        id2 = resp2.json()["id"]

        # t1 was auto-closed, t2 is active. Try to set t1.end_date = null
        resp = client.put(f"/api/targets/{id1}", json={"end_date": None})
        assert resp.status_code == 409
        assert "already an active target" in resp.json()["detail"].lower()
    finally:
        close_active_target(client)


def test_update_does_not_break_invariant(client):
    """Updating a historical target's unrelated fields doesn't affect
    the active target."""
    try:
        # Create two targets
        resp1 = create_target(client, start_date="2025-01-01", calories=2000)
        assert resp1.status_code == 201, resp1.text
        id1 = resp1.json()["id"]

        create_target(client, start_date="2025-06-01", calories=2200)

        # Update t1's calories — should work, active target unchanged
        resp = client.put(f"/api/targets/{id1}", json={"calories": 2100})
        assert resp.status_code == 200

        # Active target is still the second one
        current = client.get("/api/targets/current").json()
        assert current["start_date"] == "2025-06-01"
    finally:
        close_active_target(client)


def test_update_partial(client):
    """PUT with partial data only changes supplied fields."""
    try:
        resp = create_target(client, calories=2000, protein_g=100.0, carbs_g=200.0)
        assert resp.status_code == 201, resp.text
        tid = resp.json()["id"]

        resp = client.put(f"/api/targets/{tid}", json={"calories": 1800})
        assert resp.status_code == 200
        data = resp.json()
        assert data["calories"] == 1800
        assert data["protein_g"] == 100.0  # unchanged
        assert data["carbs_g"] == 200.0  # unchanged
    finally:
        close_active_target(client)


def test_update_404(client):
    resp = client.put("/api/targets/99999", json={"calories": 2000})
    assert resp.status_code == 404


# ── Validation failures (§8.1 rule 11) ───────────────────────────────────────


def test_calories_not_positive(client):
    resp = create_target(client, calories=0)
    assert_422(resp)
    resp = create_target(client, calories=-100)
    assert_422(resp)


def test_calories_must_be_integer(client):
    """Calories must be a positive integer, not a string."""
    resp = create_target(client, calories="not-a-number")
    assert_422(resp)


def test_macros_non_negative(client):
    for field in ("protein_g", "carbs_g", "fat_g"):
        resp = create_target(client, **{field: -1.0})
        assert_422(resp)
    # zero is allowed for all macros
    resp = create_target(client, protein_g=0.0, carbs_g=0.0, fat_g=0.0)
    assert resp.status_code == 201, resp.text
    close_active_target(client)


def test_bad_start_date_format(client):
    resp = create_target(client, start_date="01-01-2025")
    assert_422(resp)
    resp = create_target(client, start_date="not-a-date")
    assert_422(resp)


def test_end_date_before_start_date_on_create(client):
    """TargetCreate has no end_date field — it's auto-managed."""
    pass  # end_date is not in TargetCreate


def test_end_date_must_be_after_start_date_on_update(client):
    """PUT with end_date <= start_date should fail validation."""
    try:
        resp = create_target(client, start_date="2025-06-01", calories=2000)
        assert resp.status_code == 201, resp.text
        tid = resp.json()["id"]

        # end_date = start_date → invalid
        resp = client.put(f"/api/targets/{tid}", json={"end_date": "2025-06-01"})
        assert_422(resp)

        # end_date < start_date → invalid
        resp = client.put(f"/api/targets/{tid}", json={"end_date": "2025-05-01"})
        assert_422(resp)
    finally:
        close_active_target(client)


def test_start_date_must_be_before_end_date_on_update(client):
    """When both start_date and end_date are updated, end_date must still
    be after start_date."""
    try:
        create_target(client, start_date="2025-06-01", calories=2000)

        # Create a second target to auto-close the first
        resp = create_target(client, start_date="2025-07-01", calories=2200)
        assert resp.status_code == 201, resp.text
        tid = resp.json()["id"]

        # Try to set start_date after end_date
        resp = client.put(
            f"/api/targets/{tid}",
            json={"start_date": "2025-08-01", "end_date": "2025-07-01"},
        )
        assert_422(resp)
    finally:
        close_active_target(client)


def test_missing_start_date(client):
    resp = client.post("/api/targets", json={"calories": 2000})
    assert_422(resp)


def test_missing_calories(client):
    resp = client.post("/api/targets", json={"start_date": "2025-01-01"})
    assert_422(resp)


# ── Historical lookup by date (service function) ─────────────────────────────


def test_get_target_for_date_returns_correct_target(client):
    """Verify that sequencing three targets produces correct half-open
    date ranges."""
    try:
        # Use unique calorie values to avoid collisions
        cals = [8001, 8002, 8003]
        create_target(client, start_date="2025-01-01", calories=cals[0])
        create_target(client, start_date="2025-04-01", calories=cals[1])
        create_target(client, start_date="2025-07-01", calories=cals[2])

        all_targets = client.get("/api/targets").json()
        our_targets = sorted(
            [t for t in all_targets if t["calories"] in cals],
            key=lambda t: t["start_date"],
        )

        assert len(our_targets) == 3

        # t1: [2025-01-01, 2025-04-01)
        assert our_targets[0]["start_date"] == "2025-01-01"
        assert our_targets[0]["end_date"] == "2025-04-01"

        # t2: [2025-04-01, 2025-07-01)
        assert our_targets[1]["start_date"] == "2025-04-01"
        assert our_targets[1]["end_date"] == "2025-07-01"

        # t3: [2025-07-01, ∞)
        assert our_targets[2]["start_date"] == "2025-07-01"
        assert our_targets[2]["end_date"] is None
    finally:
        close_active_target(client)


def test_get_target_for_date_service_direct():
    """Test the service function directly with explicit date ranges.
    This validates the half-open interval logic before TICKET-004 needs it.

    Uses direct DB access for a fully controlled setup — no API dependency.
    """
    from services.targets import get_target_for_date
    from database import SessionLocal
    from models import Target
    from sqlalchemy import delete as sa_delete

    db = SessionLocal()
    try:
        # Clean slate
        db.execute(sa_delete(Target))
        db.commit()

        # Create targets with explicit date ranges (half-open)
        t1 = Target(start_date=date(2025, 1, 1), end_date=date(2025, 4, 1), calories=2000)
        t2 = Target(start_date=date(2025, 4, 1), end_date=date(2025, 7, 1), calories=2200)
        t3 = Target(start_date=date(2025, 7, 1), end_date=None, calories=2500)
        db.add_all([t1, t2, t3])
        db.commit()

        # Test boundary dates
        # Jan 1 → t1
        target = get_target_for_date(db, date(2025, 1, 1))
        assert target is not None and target.id == t1.id

        # Mar 31 → t1 (day before t2 starts, t1 still covers it)
        target = get_target_for_date(db, date(2025, 3, 31))
        assert target is not None and target.id == t1.id

        # Apr 1 → t2 (t2's start_date, exclusive end of t1)
        target = get_target_for_date(db, date(2025, 4, 1))
        assert target is not None and target.id == t2.id

        # Jun 30 → t2
        target = get_target_for_date(db, date(2025, 6, 30))
        assert target is not None and target.id == t2.id

        # Jul 1 → t3 (active)
        target = get_target_for_date(db, date(2025, 7, 1))
        assert target is not None and target.id == t3.id

        # Dec 31, 2030 → t3 (still active)
        target = get_target_for_date(db, date(2030, 12, 31))
        assert target is not None and target.id == t3.id

        # Date before first target → None
        target = get_target_for_date(db, date(2024, 12, 31))
        assert target is None

        # Clean up
        db.execute(sa_delete(Target))
        db.commit()
    finally:
        db.close()


def test_get_target_for_date_none_when_no_targets():
    """get_target_for_date returns None when no targets exist."""
    from services.targets import get_target_for_date
    from database import SessionLocal
    from models import Target
    from sqlalchemy import delete as sa_delete

    db = SessionLocal()
    try:
        db.execute(sa_delete(Target))
        db.commit()

        target = get_target_for_date(db, date(2025, 6, 15))
        assert target is None
    finally:
        db.close()


# ── Macros nullable on create ────────────────────────────────────────────────


def test_create_target_without_macros(client):
    """Creating a target with only calories (no macros) should work."""
    try:
        resp = client.post(
            "/api/targets",
            json={"start_date": "2025-01-01", "calories": 2000},
        )
        assert resp.status_code == 201, resp.text
        data = resp.json()
        assert data["calories"] == 2000
        assert data["protein_g"] is None
        assert data["carbs_g"] is None
        assert data["fat_g"] is None
    finally:
        close_active_target(client)