package client

import (
	"fmt"
	"image"
	"image/color"
	"math"
	"sync"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/canvas"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/theme"
	"fyne.io/fyne/v2/widget"
	"github.com/iliadenisov/galaxy/client/world"
)

type Editor interface {
	BuildUI(fyne.Window)
}

type editor struct {
	world       *world.World
	drawer      *world.GGDrawer
	raster      *canvas.Raster
	canvasScale float32

	win fyne.Window

	// Coalescer for latest-wins refresh scheduling.
	co *RasterCoalescer[world.RenderParams]

	pan *PanController

	// Protected render params state. Stored as value to avoid aliasing issues.
	mu sync.RWMutex
	wp *world.RenderParams

	// Last viewport size we indexed the world for.
	lastViewportW int
	lastViewportH int

	// Optional: you can keep the last expanded canvas size to avoid reallocations.
	lastCanvasW int
	lastCanvasH int

	// Reusable viewport buffer to avoid per-frame allocations.
	viewportImg *image.RGBA
	viewportW   int
	viewportH   int

	hits []world.Hit
}

func (e *editor) CanvasScale() float32 { return e.canvasScale }

func (e *editor) ForceFullRedraw() {
	e.world.ForceFullRedrawNext()
}

// здесь определяю, изменились ли границы raster, если да - обновляю размеры viewport, margin и корректирую zoom
func (e *editor) updateSizes() {
	canvas := fyne.CurrentApp().Driver().CanvasForObject(e.raster)
	if canvas == nil {
		return
	}

	size := e.raster.Size()
	e.canvasScale = canvas.Scale()

	width := int(size.Width * e.canvasScale)
	height := int(size.Height * e.canvasScale)

	if width <= 0 || height <= 0 {
		return
	}

	if width != e.wp.ViewportWidthPx || height != e.wp.ViewportHeightPx {
		e.wp.ViewportWidthPx = width
		e.wp.ViewportHeightPx = height
		e.wp.MarginXPx = e.wp.ViewportWidthPx / 4
		e.wp.MarginYPx = e.wp.ViewportHeightPx / 4
		defer func() { e.co.Request(*e.wp) }()
	}
	if e.world != nil {
		e.wp.CameraZoom = e.world.CorrectCameraZoom(e.wp.CameraZoom, e.wp.ViewportWidthPx, e.wp.ViewportHeightPx)
		e.world.IndexOnViewportChange(e.wp.ViewportWidthPx, e.wp.ViewportHeightPx, e.wp.CameraZoom)
		e.world.ClampRenderParamsNoWrap(e.wp)
	}
}

func (e *editor) onScrolled(s *fyne.ScrollEvent) {
	vw := e.wp.ViewportWidthPx
	vh := e.wp.ViewportHeightPx
	if vw <= 0 || vh <= 0 {
		return
	}

	// Cursor position in viewport pixels (Fyne units -> px by multiplying).
	cxPx := int(float32(s.Position.X) * e.canvasScale)
	cyPx := int(float32(s.Position.Y) * e.canvasScale)

	if cxPx < 0 {
		cxPx = 0
	} else if cxPx > vw {
		cxPx = vw
	}
	if cyPx < 0 {
		cyPx = 0
	} else if cyPx > vh {
		cyPx = vh
	}

	oldZoom := e.wp.CameraZoom

	// Exponential zoom:
	// - Each "notch" multiplies zoom by a fixed factor.
	// - Using DY directly as exponent gives smooth trackpad behavior too.
	//
	// Tune base:
	//   base=1.10 => ~10% per wheel step (if DY≈1 per step)
	//   base=1.05 => ~5% per step
	//
	// In user settings, better store on percents userZoomLevelPercent = (0,100]: base = 1 + (userZoomLevelPercent) / 10
	const base = 1.005

	// Negative DY => zoom out, positive DY => zoom in (depending on platform settings).
	// If you want inverted direction, negate float64(s.Scrolled.DY).
	delta := float64(s.Scrolled.DY)

	newZoom := oldZoom * math.Pow(base, delta)

	// Clamp/correct (min/max + prevent wrap if needed).
	newZoom = e.world.CorrectCameraZoom(newZoom, vw, vh)
	if newZoom == oldZoom {
		return
	}

	oldZoomFp, err := world.CameraZoomToWorldFixed(oldZoom)
	if err != nil {
		return
	}
	newZoomFp, err := world.CameraZoomToWorldFixed(newZoom)
	if err != nil {
		return
	}

	newCamX, newCamY := world.PivotZoomCameraNoWrap(
		e.wp.CameraXWorldFp, e.wp.CameraYWorldFp,
		vw, vh,
		cxPx, cyPx,
		oldZoomFp, newZoomFp,
	)

	e.wp.CameraZoom = newZoom
	e.wp.CameraXWorldFp = newCamX
	e.wp.CameraYWorldFp = newCamY

	e.world.IndexOnViewportChange(vw, vh, e.wp.CameraZoom)

	// No-wrap clamp to avoid "detaching" from borders.
	e.world.ClampRenderParamsNoWrap(e.wp)

	// Zoom changes are best done as full redraw.
	e.world.ForceFullRedrawNext()

	e.co.Request(*e.wp)
}

func (e *editor) onDragged(ev *fyne.DragEvent) {
	e.pan.Dragged(ev)
}

func (e *editor) onDradEnd() {
	e.pan.DragEnd()
}

func (e *editor) onTapped(ev *fyne.PointEvent) {
	if e.world == nil {
		return
	}
	hits, err := e.world.HitTest(e.hits, e.wp, int(ev.Position.X*e.canvasScale), int(ev.Position.Y*e.canvasScale))
	if err != nil {
		panic(err)
	}
	m := func(v int) float64 {
		return float64(v) / float64(world.SCALE)
	}
	var coord string
	for _, hit := range hits {
		if hit.Kind == world.KindLine {
			coord = fmt.Sprintf("{%f,%f - %f,%f}", m(hit.X1), m(hit.Y1), m(hit.X2), m(hit.Y2))
		} else {
			coord = fmt.Sprintf("{%f,%f}", m(hit.X), m(hit.Y))
		}
		fmt.Println("hit:", hit.ID, "Coord:", coord)
	}
}

func (e *editor) onMapLayout(s fyne.Size) {
	e.updateSizes()
}

func (e *editor) BuildUI(w fyne.Window) {
	e.win = w

	mapCanvas := newInteractiveRaster(e, e.raster, e.onMapLayout, e.onScrolled, e.onDragged, e.onDradEnd, e.onTapped)
	mapCanvas.SetMinSize(fyne.NewSize(292, 292))

	toolbar := widget.NewToolbar(
		widget.NewToolbarAction(
			theme.FolderIcon(),
			func() { e.loadWorld(mockWorld()) }),
		widget.NewToolbarSeparator(),
		widget.NewToolbarAction(
			theme.NavigateBackIcon(),
			func() {}),
		widget.NewToolbarAction(
			theme.NavigateNextIcon(),
			func() {}),
	)

	tabs := container.NewAppTabs(
		container.NewTabItemWithIcon(
			"Map",
			theme.GridIcon(),
			mapCanvas),
		container.NewTabItemWithIcon(
			"Calculator",
			theme.ComputerIcon(),
			container.NewStack(widget.NewButton("Calc", func() {})),
		),
	)

	content := container.NewBorder(
		toolbar, // top
		nil,     // bottom
		nil,     // left
		nil,     // right
		tabs,    // center
	)

	w.CenterOnScreen()
	w.SetContent(content)
}

func (e *editor) loadWorld(w *world.World) {
	if e.world == nil {
		w.SetCircleRadiusScaleFp(world.SCALE / 4)
		e.world = w
		// TODO: store camera position in user settings
		e.wp.CameraXWorldFp = w.W / 2
		e.wp.CameraYWorldFp = w.H / 2
		e.world.SetTheme(world.ThemeDark)
		e.updateSizes()
	} else {
		if e.world.Theme().ID() == "theme.light.v1" {
			e.world.SetTheme(world.ThemeDark)
		} else {
			e.world.SetTheme(world.ThemeLight)
		}
	}
	e.RequestRefresh()
}

func NewEditor() *editor {
	e := &editor{
		world: nil,
		wp: &world.RenderParams{
			CameraZoom: 1.0,
			Options:    &world.RenderOptions{DisableWrapScroll: false},
		},
		canvasScale: 1.0,
		hits:        make([]world.Hit, 5),
	}

	// Create a drawer with some initial context; real size will be adjusted on first draw.
	e.drawer = &world.GGDrawer{DC: nil}

	// Create raster; its draw callback delegates to coalescer.
	e.raster = canvas.NewRaster(func(wPx, hPx int) image.Image {
		return e.draw(wPx, hPx)
	})

	e.pan = NewPanController(e)

	// Wire coalescer: it schedules raster.Refresh() on UI thread and renders once per draw call.
	exec := FyneExecutor{}
	e.co = NewRasterCoalescer(
		exec,
		e.raster, // Refresher
		func(wPx, hPx int, p world.RenderParams) image.Image {
			// This runs on UI thread (inside draw). It must return an image.
			return e.renderRasterImage(wPx, hPx, p)
		},
	)

	// Kick initial draw.
	e.RequestRefresh()

	return e
}

func mockWorld() *world.World {
	w := world.NewWorld(300, 300)
	mockWorldInit(w)
	return w
}

func mockWorldInit(w *world.World) {
	lineStyle := w.AddStyleLine(world.StyleOverride{
		StrokeColor:   color.RGBA{R: 0, G: 255, B: 0, A: 255},
		StrokeWidthPx: new(3.0),
		StrokeDashes:  new([]float64{10.}),
	})

	if _, err := w.AddCircle(150, 150, 50); err != nil {
		panic(err)
	}

	if _, err := w.AddCircle(150, 299, 30); err != nil {
		panic(err)
	}
	if _, err := w.AddCircle(299, 150, 30); err != nil {
		panic(err)
	}

	if _, err := w.AddLine(100, 20, 200, 30, world.LineWithStyleID(lineStyle), world.LineWithPriority(500)); err != nil {
		panic(err)
	}

	if _, err := w.AddLine(50, 50, 250, 100); err != nil {
		panic(err)
	}

	if _, err := w.AddPoint(10, 10); err != nil {
		panic(err)
	}

	if _, err := w.AddPoint(25, 255); err != nil {
		panic(err)
	}
}