package main

import (
	"fmt"
	"image"
	"math"
	"math/rand"
	"strconv"
	"strings"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/data/binding"
	"fyne.io/fyne/v2/driver/desktop"
	"fyne.io/fyne/v2/layout"
	"fyne.io/fyne/v2/widget"
)

// PixelMask stores per-pixel occupancy for placement and collision checks.
type PixelMask struct {
	Width  int
	Height int
	Data   []uint8
}

// NewPixelMask creates a mask for width and height and is used for feature occupancy.
func NewPixelMask(width, height int) *PixelMask {
	if width <= 0 || height <= 0 {
		return &PixelMask{}
	}
	return &PixelMask{
		Width:  width,
		Height: height,
		Data:   make([]uint8, width*height),
	}
}

// index returns the slice index for coordinates and is used by mask helpers.
func (m *PixelMask) index(x, y int) int {
	return y*m.Width + x
}

// InBounds reports whether x,y are inside the mask and is used to guard access.
func (m *PixelMask) InBounds(x, y int) bool {
	return m != nil && x >= 0 && y >= 0 && x < m.Width && y < m.Height
}

// GetXY returns occupancy at x,y and is used for collision checks.
func (m *PixelMask) GetXY(x, y int) bool {
	if !m.InBounds(x, y) {
		return false
	}
	return m.Data[m.index(x, y)] != 0
}

// SetXY marks x,y as occupied and is used when placing features.
func (m *PixelMask) SetXY(x, y int) {
	if m.InBounds(x, y) {
		m.Data[m.index(x, y)] = 1
	}
}

// ClearXY clears occupancy at x,y and is used for mask edits.
func (m *PixelMask) ClearXY(x, y int) {
	if m.InBounds(x, y) {
		m.Data[m.index(x, y)] = 0
	}
}

// GetPoint returns occupancy at a point and is used with image.Point helpers.
func (m *PixelMask) GetPoint(p image.Point) bool {
	return m.GetXY(p.X, p.Y)
}

// SetPoint marks a point as occupied and is used with image.Point helpers.
func (m *PixelMask) SetPoint(p image.Point) {
	m.SetXY(p.X, p.Y)
}

// Merge ORs another mask into this one and is used to combine feature masks.
func (m *PixelMask) Merge(other *PixelMask) {
	if m == nil || other == nil || m.Width != other.Width || m.Height != other.Height {
		return
	}
	for i := range m.Data {
		if other.Data[i] != 0 {
			m.Data[i] = 1
		}
	}
}

// AddPoints marks a slice of points as occupied and is used for lake/road masks.
func (m *PixelMask) AddPoints(points []image.Point) {
	for _, p := range points {
		m.SetPoint(p)
	}
}

// ToPoints returns occupied points and is used to extract anchors.
func (m *PixelMask) ToPoints() []image.Point {
	if m == nil {
		return nil
	}
	pts := make([]image.Point, 0)
	for y := 0; y < m.Height; y++ {
		row := y * m.Width
		for x := 0; x < m.Width; x++ {
			if m.Data[row+x] != 0 {
				pts = append(pts, image.Point{X: x, Y: y})
			}
		}
	}
	return pts
}

// BuildMaskFromLakes builds a water mask from lake point sets for later merges.
func BuildMaskFromLakes(width, height int, lakes [][]image.Point) *PixelMask {
	mask := NewPixelMask(width, height)
	for _, lake := range lakes {
		mask.AddPoints(lake)
	}
	return mask
}

// SeedProvider provides a deterministic stream of seeds for generation steps.
type SeedProvider struct {
	rand *rand.Rand
}

// NewSeedProvider creates a SeedProvider for splitting a root seed into steps.
func NewSeedProvider(seed int64) *SeedProvider {
	return &SeedProvider{
		rand: rand.New(rand.NewSource(seed)),
	}
}

// Next returns the next random seed and is used to drive independent generators.
func (sp *SeedProvider) Next() int64 {
	return sp.rand.Int63()
}

// averageImageDimension returns (width+height)/2 and is used for percent scaling.
func averageImageDimension(width, height int) float64 {
	return (float64(width) + float64(height)) / 2.0
}

// clamp clamps v to [lo, hi] and is used for settings normalization.
func clamp(v, lo, hi float64) float64 {
	if v < lo {
		return lo
	}
	if v > hi {
		return hi
	}
	return v
}

// clamp01 clamps v to [0,1] and is used for normalized weights.
func clamp01(v float64) float64 {
	return clamp(v, 0, 1)
}

// abs returns the absolute value of an int and is used in raster helpers.
func abs(x int) int {
	if x < 0 {
		return -x
	}
	return x
}

// cloneMask copies a PixelMask and is used when mutating temporary masks.
func cloneMask(src *PixelMask) *PixelMask {
	if src == nil {
		return nil
	}
	dst := NewPixelMask(src.Width, src.Height)
	copy(dst.Data, src.Data)
	return dst
}

// averagePoint returns the average of points and is used for centroids.
func averagePoint(points []image.Point) image.Point {
	if len(points) == 0 {
		return image.Point{}
	}
	var sx, sy int
	for _, p := range points {
		sx += p.X
		sy += p.Y
	}
	return image.Point{X: sx / len(points), Y: sy / len(points)}
}

// estimateWallTangent approximates the tangent at a wall pixel and is used to align roads and gates.
func estimateWallTangent(mid image.Point, wallMask *PixelMask) (float64, float64, bool) {
	if wallMask == nil {
		return 0, 0, false
	}
	const r = 4
	var pts [][2]float64
	for dy := -r; dy <= r; dy++ {
		y := mid.Y + dy
		if y < 0 || y >= wallMask.Height {
			continue
		}
		for dx := -r; dx <= r; dx++ {
			x := mid.X + dx
			if x < 0 || x >= wallMask.Width {
				continue
			}
			if wallMask.GetXY(x, y) {
				pts = append(pts, [2]float64{float64(x), float64(y)})
			}
		}
	}
	if len(pts) < 3 {
		return 0, 0, false
	}

	var mx, my float64
	for _, p := range pts {
		mx += p[0]
		my += p[1]
	}
	mx /= float64(len(pts))
	my /= float64(len(pts))

	var sxx, syy, sxy float64
	for _, p := range pts {
		dx := p[0] - mx
		dy := p[1] - my
		sxx += dx * dx
		syy += dy * dy
		sxy += dx * dy
	}
	if sxx+syy < 0.001 {
		return 0, 0, false
	}
	theta := 0.5 * math.Atan2(2*sxy, sxx-syy)
	return math.Cos(theta), math.Sin(theta), true
}

type tappableImage struct {
	widget.BaseWidget
	image          *fyne.Container
	onTapped       func(*fyne.PointEvent)
	onSecondaryTap func(*fyne.PointEvent)
	onHover        func(fyne.Position)
	onHoverEnd     func()
}

// newTappableImage wraps a container so taps can trigger image interactions.
func newTappableImage(img *fyne.Container, tapped func(*fyne.PointEvent)) *tappableImage {
	ti := &tappableImage{
		image:    img,
		onTapped: tapped,
	}
	ti.ExtendBaseWidget(ti)
	return ti
}

// CreateRenderer builds the renderer for tappableImage and is used by Fyne.
func (t *tappableImage) CreateRenderer() fyne.WidgetRenderer {
	return widget.NewSimpleRenderer(t.image)
}

// Tapped invokes the handler and is used for click interactions.
func (t *tappableImage) Tapped(ev *fyne.PointEvent) {
	if t.onTapped != nil {
		t.onTapped(ev)
	}
}

// TappedSecondary invokes the secondary handler and is used for right-click interactions.
func (t *tappableImage) TappedSecondary(ev *fyne.PointEvent) {
	if t.onSecondaryTap != nil {
		t.onSecondaryTap(ev)
	}
}

// MouseMoved forwards hover updates and is used for preview positioning.
func (t *tappableImage) MouseMoved(ev *desktop.MouseEvent) {
	if t.onHover != nil {
		t.onHover(ev.Position)
	}
}

// MouseIn is required by desktop.Hoverable.
func (t *tappableImage) MouseIn(*desktop.MouseEvent) {}

// MouseOut clears hover state and is used when previews leave the canvas.
func (t *tappableImage) MouseOut() {
	if t.onHoverEnd != nil {
		t.onHoverEnd()
	}
}

// numericInputSlider combines a slider and text entry for numeric input.
type numericInputSlider struct {
	widget.BaseWidget
	value      binding.Float
	min, max   float64
	step       float64
	slider     *widget.Slider
	entry      *widget.Entry
	format     string
	errorLabel *widget.Label
	label      *widget.Label
}

type numericInputSliderRenderer struct {
	slider       *numericInputSlider
	label        *widget.Label
	entry        *widget.Entry
	sliderWidget *widget.Slider
	errorLabel   *widget.Label
	layout       fyne.Layout
	objects      []fyne.CanvasObject
}

func (r *numericInputSliderRenderer) MinSize() fyne.Size {
	return r.layout.MinSize(r.objects)
}

func (r *numericInputSliderRenderer) Layout(size fyne.Size) {
	r.layout.Layout(r.objects, size)
}

func (r *numericInputSliderRenderer) Objects() []fyne.CanvasObject {
	return r.objects
}

func (r *numericInputSliderRenderer) Refresh() {
	r.label.SetText(r.slider.label.Text)
}

func (r *numericInputSliderRenderer) Destroy() {}

// newNumericInputSlider creates a slider+entry pair for numeric settings.
func newNumericInputSlider(min, max float64, initialValue float64, format string, labelText string) *numericInputSlider {
	s := &numericInputSlider{
		min:    min,
		max:    max,
		format: format,
		step:   0,
	}
	s.ExtendBaseWidget(s)

	s.label = widget.NewLabel(labelText)
	s.value = binding.NewFloat()
	s.value.Set(initialValue)

	s.slider = widget.NewSlider(min, max)
	s.slider.Bind(s.value)

	s.entry = widget.NewEntry()
	s.value.AddListener(binding.NewDataListener(func() {
		val, _ := s.value.Get()
		s.entry.SetText(fmt.Sprintf(s.format, val))
	}))

	s.errorLabel = widget.NewLabel("")
	s.errorLabel.Hide()

	return s
}

// newNumericInputSliderWithStep creates a numeric slider that snaps to increments.
func newNumericInputSliderWithStep(min, max, initialValue, step float64, format string, labelText string) *numericInputSlider {
	s := newNumericInputSlider(min, max, initialValue, format, labelText)
	if step > 0 {
		s.step = step
		s.slider.Step = step
		rounded := min + math.Round((initialValue-min)/step)*step
		s.value.Set(rounded)
	}
	return s
}

// validate checks entry input and is used for slider text validation.
func (s *numericInputSlider) validate(text string, onError func(bool)) {
	text = strings.TrimSpace(text)
	text = strings.TrimSuffix(text, "px")
	text = strings.TrimSuffix(text, "%")
	text = strings.TrimSuffix(text, "°")
	text = strings.TrimSpace(text)
	val, err := strconv.ParseFloat(text, 64)
	if err != nil {
		s.errorLabel.SetText("Not a number")
		s.errorLabel.Show()
		onError(true)
		return
	}

	if val < s.min || val > s.max {
		s.errorLabel.SetText(fmt.Sprintf(
			"Out of range (%s-%s)",
			strconv.FormatFloat(s.min, 'f', -1, 64),
			strconv.FormatFloat(s.max, 'f', -1, 64),
		))
		s.errorLabel.Show()
		onError(true)
		return
	}
	if s.step > 0 {
		steps := math.Round((val - s.min) / s.step)
		snapped := s.min + steps*s.step
		if math.Abs(val-snapped) > 1e-9 {
			s.errorLabel.SetText(fmt.Sprintf("Use increments of %s", strconv.FormatFloat(s.step, 'f', -1, 64)))
			s.errorLabel.Show()
			onError(true)
			return
		}
		val = snapped
	}

	s.errorLabel.Hide()
	onError(false)
	s.value.Set(val)
}

// CreateRenderer builds the widget layout and is used by Fyne.
func (s *numericInputSlider) CreateRenderer() fyne.WidgetRenderer {
	r := &numericInputSliderRenderer{
		slider:       s,
		label:        s.label,
		entry:        s.entry,
		sliderWidget: s.slider,
		errorLabel:   s.errorLabel,
	}

	r.layout = layout.NewGridLayout(1)
	r.objects = []fyne.CanvasObject{
		container.NewGridWithColumns(2, r.label, r.entry),
		r.sliderWidget,
		r.errorLabel,
	}

	return r
}