package client

import (
	"testing"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/test"

	"github.com/stretchr/testify/require"

	"galaxy/client/world"
)

type fakeClient struct {
	scale float32
	p     world.RenderParams

	forced  bool
	updates int
	refresh int
}

func (e *fakeClient) CanvasScale() float32 { return e.scale }

func (e *fakeClient) UpdateParams(fn func(p *world.RenderParams)) {
	fn(&e.p)
	e.updates++
}

func (e *fakeClient) RequestRefresh() { e.refresh++ }

func (e *fakeClient) ForceFullRedraw() { e.forced = true }

func TestPanController_DraggedUpdatesCameraByDeltaPx(t *testing.T) {
	t.Parallel()

	fe := &fakeClient{
		scale: 1.0, // 1 fyne unit == 1 px for the test
		p: world.RenderParams{
			CameraZoom:     1.0,
			CameraXWorldFp: 5 * world.SCALE,
			CameraYWorldFp: 5 * world.SCALE,
		},
	}

	pc := NewPanController(fe)

	// Drag right by +3 px and down by +2 px.
	pc.Dragged(&fyne.DragEvent{
		Dragged: fyne.Delta{DX: 3, DY: 2},
	})

	require.Equal(t, 1, fe.updates)

	// Map follows pointer => camera moves opposite to pointer delta.
	require.Equal(t, 5*world.SCALE-3*world.SCALE, fe.p.CameraXWorldFp)
	require.Equal(t, 5*world.SCALE-2*world.SCALE, fe.p.CameraYWorldFp)
}

func TestPanController_DraggedUsesCanvasScaleByMultiplying(t *testing.T) {
	t.Parallel()

	fe := &fakeClient{
		scale: 2.0, // 2 px per fyne unit
		p: world.RenderParams{
			CameraZoom:     1.0,
			CameraXWorldFp: 0,
			CameraYWorldFp: 0,
		},
	}

	pc := NewPanController(fe)

	// Dragged.DX=1 fyne unit => 2 px after scaling.
	pc.Dragged(&fyne.DragEvent{
		Dragged: fyne.Delta{DX: 1, DY: 0},
	})

	require.Equal(t, -2*world.SCALE, fe.p.CameraXWorldFp)
}

func TestPanController_DragEndForcesFullRedrawAndRefresh(t *testing.T) {
	t.Parallel()

	fe := &fakeClient{
		scale: 1.0,
		p: world.RenderParams{
			CameraZoom:     1.0,
			CameraXWorldFp: 0,
			CameraYWorldFp: 0,
		},
	}

	pc := NewPanController(fe)

	// Simulate a drag start.
	pc.Dragged(&fyne.DragEvent{PointEvent: fyne.PointEvent{Position: fyne.Position{X: 1, Y: 1}}})

	pc.DragEnd()
	require.True(t, fe.forced)
	require.Equal(t, 1, fe.refresh)
}

// Optional: demonstrate use of fyne/test package to ensure types are available.
// (Not strictly needed, but keeps fyne dependency "active" in tests.)
func TestFyneTestDriverIsUsable(t *testing.T) {
	t.Parallel()
	_ = test.NewApp()
}