package video

import (
	"strings"
	"testing"

	"mxl-pattern-generator/internal/flowdef"
)

const testVideoID = "b3bb5be7-9fe9-4324-a5bb-4c70e1084449"

func testConfig(t *testing.T, overlay OverlayConfig) Config {
	t.Helper()
	definition, err := flowdef.NewV210Video(
		testVideoID,
		1920,
		1080,
		flowdef.Rational{Numerator: 50, Denominator: 1},
	)
	if err != nil {
		t.Fatalf("NewV210Video: %v", err)
	}
	return Config{Definition: definition, Pattern: "ebu75", Overlay: overlay}
}

func TestBuildTextOverlayDisabled(t *testing.T) {
	overlay, err := buildTextOverlay(testConfig(t, OverlayConfig{}))
	if err != nil {
		t.Fatalf("buildTextOverlay: %v", err)
	}
	if overlay != nil {
		t.Fatal("buildTextOverlay returned an overlay for empty text")
	}
}

func TestBuildTextOverlayPositioning(t *testing.T) {
	tests := []struct {
		name    string
		overlay OverlayConfig
	}{
		{name: "explicit", overlay: OverlayConfig{Text: "MXL", X: 120, Y: 48}},
		{name: "preset", overlay: OverlayConfig{Text: "MXL", Position: "cc"}},
		{name: "preset ignores explicit coordinates", overlay: OverlayConfig{Text: "MXL", X: -1, Y: -1, Position: "cc"}},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			overlay, err := buildTextOverlay(testConfig(t, tc.overlay))
			if err != nil {
				t.Fatalf("buildTextOverlay: %v", err)
			}
			if overlay == nil {
				t.Fatal("buildTextOverlay returned nil")
			}
		})
	}
}

func TestBuildTextOverlayRejectsInvalidPosition(t *testing.T) {
	tests := []struct {
		name       string
		overlay    OverlayConfig
		wantErrSub string
	}{
		{name: "negative", overlay: OverlayConfig{Text: "MXL", X: -6}, wantErrSub: "must not be negative"},
		{name: "unaligned x", overlay: OverlayConfig{Text: "MXL", X: 7}, wantErrSub: "divisible by 6"},
		{name: "right overflow", overlay: OverlayConfig{Text: "MXL", X: 1902}, wantErrSub: "does not fit"},
		{name: "bottom overflow", overlay: OverlayConfig{Text: "MXL", Y: 1070}, wantErrSub: "does not fit"},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			_, err := buildTextOverlay(testConfig(t, tc.overlay))
			if err == nil || !strings.Contains(err.Error(), tc.wantErrSub) {
				t.Fatalf("error = %v, want substring %q", err, tc.wantErrSub)
			}
		})
	}
}