"""Unit tests for cluster_sr_zones() in app.services.sr_service."""

from app.services.sr_service import cluster_sr_zones


def _level(price: float, strength: int = 50) -> dict:
    """Helper to build a level dict."""
    return {"price_level": price, "strength": strength}


class TestClusterSrZonesEmptyAndEdge:
    """Edge cases: empty input, max_zones boundaries."""

    def test_empty_levels_returns_empty(self):
        assert cluster_sr_zones([], current_price=100.0) == []

    def test_max_zones_zero_returns_empty(self):
        levels = [_level(100.0)]
        assert cluster_sr_zones(levels, current_price=100.0, max_zones=0) == []

    def test_max_zones_negative_returns_empty(self):
        levels = [_level(100.0)]
        assert cluster_sr_zones(levels, current_price=100.0, max_zones=-1) == []

    def test_single_level(self):
        levels = [_level(95.0, 60)]
        zones = cluster_sr_zones(levels, current_price=100.0)
        assert len(zones) == 1
        z = zones[0]
        assert z["low"] == 95.0
        assert z["high"] == 95.0
        assert z["midpoint"] == 95.0
        assert z["strength"] == 60
        assert z["type"] == "support"
        assert z["level_count"] == 1


class TestClusterSrZonesMerging:
    """Greedy merge behaviour."""

    def test_two_levels_within_tolerance_merge(self):
        # 100 and 101 are 1% apart; tolerance=2% → should merge
        levels = [_level(100.0, 30), _level(101.0, 40)]
        zones = cluster_sr_zones(levels, current_price=200.0, tolerance=0.02)
        assert len(zones) == 1
        z = zones[0]
        assert z["low"] == 100.0
        assert z["high"] == 101.0
        assert z["midpoint"] == 100.5
        assert z["strength"] == 70
        assert z["level_count"] == 2

    def test_two_levels_outside_tolerance_stay_separate(self):
        # 100 and 110 are 10% apart; tolerance=2% → separate
        levels = [_level(100.0, 30), _level(110.0, 40)]
        zones = cluster_sr_zones(levels, current_price=200.0, tolerance=0.02)
        assert len(zones) == 2

    def test_all_same_price_merge_into_one(self):
        levels = [_level(50.0, 20), _level(50.0, 30), _level(50.0, 10)]
        zones = cluster_sr_zones(levels, current_price=100.0)
        assert len(zones) == 1
        assert zones[0]["strength"] == 60
        assert zones[0]["level_count"] == 3

    def test_levels_at_tolerance_boundary(self):
        # midpoint of cluster starting at 100 is 100. 2% of 100 = 2.
        # A level at 102 is exactly at the boundary → should merge
        levels = [_level(100.0, 25), _level(102.0, 25)]
        zones = cluster_sr_zones(levels, current_price=200.0, tolerance=0.02)
        assert len(zones) == 1


class TestClusterSrZonesStrength:
    """Strength capping and computation."""

    def test_strength_capped_at_100(self):
        levels = [_level(100.0, 80), _level(100.5, 80)]
        zones = cluster_sr_zones(levels, current_price=200.0, tolerance=0.02)
        assert len(zones) == 1
        assert zones[0]["strength"] == 100

    def test_strength_sum_when_under_cap(self):
        levels = [_level(100.0, 10), _level(100.5, 20)]
        zones = cluster_sr_zones(levels, current_price=200.0, tolerance=0.02)
        assert zones[0]["strength"] == 30


class TestClusterSrZonesTypeTagging:
    """Support vs resistance tagging."""

    def test_support_when_midpoint_below_current(self):
        levels = [_level(90.0, 50)]
        zones = cluster_sr_zones(levels, current_price=100.0)
        assert zones[0]["type"] == "support"

    def test_resistance_when_midpoint_above_current(self):
        levels = [_level(110.0, 50)]
        zones = cluster_sr_zones(levels, current_price=100.0)
        assert zones[0]["type"] == "resistance"

    def test_resistance_when_midpoint_equals_current(self):
        # "else resistance" per spec
        levels = [_level(100.0, 50)]
        zones = cluster_sr_zones(levels, current_price=100.0)
        assert zones[0]["type"] == "resistance"


class TestClusterSrZonesSorting:
    """Sorting by strength descending."""

    def test_sorted_by_strength_descending(self):
        levels = [_level(50.0, 20), _level(150.0, 80), _level(250.0, 50)]
        zones = cluster_sr_zones(levels, current_price=100.0, tolerance=0.001)
        strengths = [z["strength"] for z in zones]
        assert strengths == sorted(strengths, reverse=True)


class TestClusterSrZonesMaxZones:
    """max_zones filtering."""

    def test_max_zones_limits_output(self):
        levels = [_level(50.0, 20), _level(150.0, 80), _level(250.0, 50)]
        zones = cluster_sr_zones(
            levels, current_price=100.0, tolerance=0.001, max_zones=2
        )
        assert len(zones) == 2
        # Balanced selection: 1 support (strength 20) + 1 resistance (strength 80)
        types = {z["type"] for z in zones}
        assert "support" in types
        assert "resistance" in types
        assert zones[0]["strength"] == 80
        assert zones[1]["strength"] == 20

    def test_max_zones_none_returns_all(self):
        levels = [_level(50.0, 20), _level(150.0, 80), _level(250.0, 50)]
        zones = cluster_sr_zones(
            levels, current_price=100.0, tolerance=0.001, max_zones=None
        )
        assert len(zones) == 3

    def test_max_zones_larger_than_count_returns_all(self):
        levels = [_level(50.0, 20)]
        zones = cluster_sr_zones(
            levels, current_price=100.0, max_zones=10
        )
        assert len(zones) == 1


class TestClusterSrZonesBalancedSelection:
    """Balanced interleave selection behaviour (Requirements 1.1, 1.2, 1.3, 1.5, 1.6)."""

    def test_mixed_input_produces_balanced_output(self):
        """3 support + 3 resistance with max_zones=4 → 2 support + 2 resistance."""
        levels = [
            _level(80.0, 70),   # support
            _level(85.0, 50),   # support
            _level(90.0, 30),   # support
            _level(110.0, 60),  # resistance
            _level(115.0, 40),  # resistance
            _level(120.0, 20),  # resistance
        ]
        zones = cluster_sr_zones(levels, current_price=100.0, tolerance=0.001, max_zones=4)
        assert len(zones) == 4
        support_count = sum(1 for z in zones if z["type"] == "support")
        resistance_count = sum(1 for z in zones if z["type"] == "resistance")
        assert support_count == 2
        assert resistance_count == 2

    def test_all_support_fills_from_support_only(self):
        """When no resistance levels exist, all slots filled from support."""
        levels = [
            _level(80.0, 70),
            _level(85.0, 50),
            _level(90.0, 30),
        ]
        zones = cluster_sr_zones(levels, current_price=200.0, tolerance=0.001, max_zones=2)
        assert len(zones) == 2
        assert all(z["type"] == "support" for z in zones)

    def test_all_resistance_fills_from_resistance_only(self):
        """When no support levels exist, all slots filled from resistance."""
        levels = [
            _level(110.0, 60),
            _level(115.0, 40),
            _level(120.0, 20),
        ]
        zones = cluster_sr_zones(levels, current_price=50.0, tolerance=0.001, max_zones=2)
        assert len(zones) == 2
        assert all(z["type"] == "resistance" for z in zones)

    def test_single_zone_edge_case(self):
        """Only 1 level total → returns exactly 1 zone."""
        levels = [_level(95.0, 45)]
        zones = cluster_sr_zones(levels, current_price=100.0, max_zones=5)
        assert len(zones) == 1
        assert zones[0]["strength"] == 45

    def test_both_types_present_when_max_zones_gte_2(self):
        """When both types exist and max_zones >= 2, at least one of each is present."""
        levels = [
            _level(70.0, 90),   # support (strongest overall)
            _level(75.0, 80),   # support
            _level(80.0, 70),   # support
            _level(130.0, 10),  # resistance (weakest overall)
        ]
        zones = cluster_sr_zones(levels, current_price=100.0, tolerance=0.001, max_zones=2)
        types = {z["type"] for z in zones}
        assert "support" in types
        assert "resistance" in types