package main

import (
	"testing"

	"mxl-player/internal/playback"
)

func TestVideoDropTracker(t *testing.T) {
	tests := []struct {
		name         string
		observations [][2]uint64
		want         []uint64
	}{
		{
			name:         "counts gaps within generation",
			observations: [][2]uint64{{1, 10}, {1, 11}, {1, 15}},
			want:         []uint64{0, 0, 3},
		},
		{
			name:         "higher index from new generation resets baseline",
			observations: [][2]uint64{{1, 10}, {2, 1000000}, {2, 1000001}},
			want:         []uint64{0, 0, 0},
		},
		{
			name:         "lower index from new generation resets baseline",
			observations: [][2]uint64{{1, 100}, {2, 5}, {2, 7}},
			want:         []uint64{0, 0, 1},
		},
		{
			name:         "index restart within generation resets baseline",
			observations: [][2]uint64{{1, 100}, {1, 0}, {1, 1}},
			want:         []uint64{0, 0, 0},
		},
		{
			name:         "zero is a valid first index",
			observations: [][2]uint64{{1, 0}, {1, 2}},
			want:         []uint64{0, 1},
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			var tracker videoDropTracker
			source := playback.FeedConfig{Domain: "/mxl", UUID: "video"}
			for index, observation := range test.observations {
				got := tracker.Observe(observation[0], source, observation[1])
				if got != test.want[index] {
					t.Fatalf("Observe(%d, %d) = %d, want %d",
						observation[0], observation[1], got, test.want[index])
				}
			}
		})
	}
}

func TestVideoDropTrackerResetsWhenSourceChanges(t *testing.T) {
	var tracker videoDropTracker
	first := playback.FeedConfig{Domain: "/mxl", UUID: "first"}
	second := playback.FeedConfig{Domain: "/mxl", UUID: "second"}

	if got := tracker.Observe(1, first, 10); got != 0 {
		t.Fatalf("first Observe() = %d, want 0", got)
	}
	if got := tracker.Observe(1, second, 1000000); got != 0 {
		t.Fatalf("source-changing Observe() = %d, want 0", got)
	}
	if got := tracker.Observe(1, second, 1000002); got != 1 {
		t.Fatalf("same-source Observe() = %d, want 1", got)
	}
}