"""Unit tests for CropInterpolator in frame_processor.py."""

import pytest

from fansifter_clipper.frame_processor import CropInterpolator
from fansifter_clipper.models import CropKeyframe


def make_kf(time, x, y, scene_change=False, width=720, height=1280):
    return CropKeyframe(time=time, x=x, y=y, width=width, height=height,
                        scene_change=scene_change)


class TestCropInterpolatorInit:
    def test_requires_at_least_one_keyframe(self):
        with pytest.raises(ValueError, match="Need at least 1 keyframe"):
            CropInterpolator([], segment_start=0.0)

    def test_single_keyframe_constant(self):
        kf = make_kf(0.0, 100, 50)
        interp = CropInterpolator([kf], segment_start=0.0)
        assert interp.interpolation_method == "constant"
        assert interp.crop_width == 720
        assert interp.crop_height == 1280

    def test_multiple_keyframes_linear(self):
        kfs = [make_kf(0.0, 100, 50), make_kf(5.0, 200, 150)]
        interp = CropInterpolator(kfs, segment_start=0.0)
        assert interp.interpolation_method == "linear"

    def test_segments_split_at_scene_change(self):
        kfs = [
            make_kf(0.0, 100, 50),
            make_kf(2.0, 110, 60),
            make_kf(4.0, 800, 600, scene_change=True),
            make_kf(6.0, 810, 610),
        ]
        interp = CropInterpolator(kfs, segment_start=0.0)
        assert interp.interpolators is not None
        assert len(interp.interpolators) == 2


class TestCropInterpolatorSplitIntoSegments:
    def test_no_scene_changes(self):
        kfs = [make_kf(0.0, 100, 50), make_kf(1.0, 110, 60), make_kf(2.0, 120, 70)]
        interp = CropInterpolator(kfs, segment_start=0.0)
        segments = interp._split_into_segments(kfs)
        assert len(segments) == 1
        assert len(segments[0]) == 3

    def test_single_scene_change(self):
        kfs = [
            make_kf(0.0, 100, 50),
            make_kf(1.0, 110, 60),
            make_kf(2.0, 800, 600, scene_change=True),
            make_kf(3.0, 810, 610),
        ]
        interp = CropInterpolator([make_kf(0.0, 0, 0), make_kf(1.0, 1, 1)],
                                  segment_start=0.0)
        segments = interp._split_into_segments(kfs)
        assert len(segments) == 2
        assert len(segments[0]) == 2  # t=0, t=1
        assert len(segments[1]) == 2  # t=2 (scene_change), t=3

    def test_multiple_scene_changes(self):
        kfs = [
            make_kf(0.0, 100, 50),
            make_kf(2.0, 800, 600, scene_change=True),
            make_kf(4.0, 300, 400, scene_change=True),
        ]
        interp = CropInterpolator([make_kf(0.0, 0, 0), make_kf(1.0, 1, 1)],
                                  segment_start=0.0)
        segments = interp._split_into_segments(kfs)
        assert len(segments) == 3

    def test_scene_change_as_first_keyframe(self):
        kfs = [
            make_kf(0.0, 100, 50, scene_change=True),
            make_kf(1.0, 110, 60),
        ]
        interp = CropInterpolator([make_kf(0.0, 0, 0), make_kf(1.0, 1, 1)],
                                  segment_start=0.0)
        # scene_change on first keyframe doesn't split (no previous segment)
        segments = interp._split_into_segments(kfs)
        assert len(segments) == 1

    def test_empty_keyframes(self):
        interp = CropInterpolator([make_kf(0.0, 0, 0), make_kf(1.0, 1, 1)],
                                  segment_start=0.0)
        segments = interp._split_into_segments([])
        assert segments == []


class TestCropInterpolatorGetPosition:
    def test_single_keyframe_constant_position(self):
        # frame_height=1440 > crop_height=1280, so y=100 is valid
        kf = make_kf(0.0, 200, 100)
        interp = CropInterpolator([kf], segment_start=0.0)
        x, y = interp.get_position(0.0, frame_width=1920, frame_height=1440)
        assert x == 200
        assert y == 100

    def test_single_keyframe_position_at_different_times(self):
        kf = make_kf(0.0, 200, 100)
        interp = CropInterpolator([kf], segment_start=0.0)
        for t in [0.0, 1.5, 5.0]:
            x, y = interp.get_position(t, frame_width=1920, frame_height=1440)
            assert x == 200
            assert y == 100

    def test_linear_interpolation_midpoint(self):
        kfs = [make_kf(0.0, 0, 0), make_kf(2.0, 200, 100)]
        interp = CropInterpolator(kfs, segment_start=0.0)
        # At t=1.0, should be halfway between (0,0) and (200,100)
        x, y = interp.get_position(1.0, frame_width=1920, frame_height=1440)
        assert x == pytest.approx(100, abs=2)
        assert y == pytest.approx(50, abs=2)

    def test_position_clipped_to_frame_bounds(self):
        # frame_width=800, crop_width=720, so max x = 80
        # frame_height=1300, crop_height=1280, so max y = 20
        kf = make_kf(0.0, 500, 500)  # both x and y are out of bounds
        interp = CropInterpolator([kf], segment_start=0.0)
        x, y = interp.get_position(0.0, frame_width=800, frame_height=1300)
        assert x <= 800 - 720   # max valid x = frame_width - crop_width
        assert y <= 1300 - 1280  # max valid y = frame_height - crop_height

    def test_scene_boundary_uses_new_segment(self):
        """Position at scene boundary should use new scene's interpolator."""
        kfs = [
            make_kf(0.0, 100, 100),
            make_kf(2.0, 800, 100, scene_change=True),
            make_kf(4.0, 810, 100),
        ]
        interp = CropInterpolator(kfs, segment_start=0.0)
        # Before boundary: first segment
        x_before, _ = interp.get_position(1.0, frame_width=1920, frame_height=1440)
        # After boundary: second segment (x=800)
        x_after, _ = interp.get_position(2.0, frame_width=1920, frame_height=1440)
        # The two positions should come from different scenes (jump, not smooth)
        assert x_before < 500  # Still in first scene territory
        assert x_after >= 800  # At or after scene boundary position (clamped)

    def test_position_at_boundary_zero(self):
        kf = make_kf(0.0, 0, 0)
        interp = CropInterpolator([kf], segment_start=0.0)
        x, y = interp.get_position(0.0, frame_width=1920, frame_height=1440)
        assert x == 0
        assert y == 0