Add explosion animation when nuking working tree

I've been thinking about this for a while: I think it looks really cool if nuking your working tree
actually results in a nuke animation.

So I've added an opt-out config for it

pkg/gui/controllers/workspace_reset_controller.go

@@ -1,8 +1,13 @@
 package controllers
 
 import (
+	"bytes"
 	"fmt"
+	"math"
+	"math/rand"
+	"time"
 
+	"github.com/jesseduffield/gocui"
 	"github.com/jesseduffield/lazygit/pkg/gui/style"
 	"github.com/jesseduffield/lazygit/pkg/gui/types"
 )
@@ -29,6 +34,10 @@ func (self *FilesController) createResetMenu() error {
 					return self.c.Error(err)
 				}
 
+				if self.c.UserConfig.Gui.AnimateExplosion {
+					self.animateExplosion()
+				}
+
 				return self.c.Refresh(types.RefreshOptions{Mode: types.ASYNC, Scope: []types.RefreshableView{types.FILES}})
 			},
 			Key:     'x',
@@ -135,3 +144,102 @@ func (self *FilesController) createResetMenu() error {
 
 	return self.c.Menu(types.CreateMenuOptions{Title: "", Items: menuItems})
 }
+
+func (self *FilesController) animateExplosion() {
+	self.Explode(self.c.Views().Files, func() {
+		err := self.c.PostRefreshUpdate(self.c.Contexts().Files)
+		if err != nil {
+			self.c.Log.Error(err)
+		}
+	})
+}
+
+// Animates an explosion within the view by drawing a bunch of flamey characters
+func (self *FilesController) Explode(v *gocui.View, onDone func()) {
+	width := v.InnerWidth()
+	height := v.InnerHeight() + 1
+	styles := []style.TextStyle{
+		style.FgLightWhite.SetBold(),
+		style.FgYellow.SetBold(),
+		style.FgRed.SetBold(),
+		style.FgBlue.SetBold(),
+		style.FgBlack.SetBold(),
+	}
+
+	self.c.OnWorker(func(_ gocui.Task) {
+		max := 25
+		for i := 0; i < max; i++ {
+			image := getExplodeImage(width, height, i, max)
+			style := styles[(i*len(styles)/max)%len(styles)]
+			coloredImage := style.Sprint(image)
+			self.c.OnUIThread(func() error {
+				v.SetContent(coloredImage)
+				return nil
+			})
+			time.Sleep(time.Millisecond * 20)
+		}
+		self.c.OnUIThread(func() error {
+			v.Clear()
+			onDone()
+			return nil
+		})
+	})
+}
+
+// Render an explosion in the given bounds.
+func getExplodeImage(width int, height int, frame int, max int) string {
+	// Predefine the explosion symbols
+	explosionChars := []rune{'*', '.', '@', '#', '&', '+', '%'}
+
+	// Initialize a buffer to build our string
+	var buf bytes.Buffer
+
+	// Initialize RNG seed
+	rand.Seed(time.Now().UnixNano())
+
+	// calculate the center of explosion
+	centerX, centerY := width/2, height/2
+
+	// calculate the max radius (hypotenuse of the view)
+	maxRadius := math.Hypot(float64(centerX), float64(centerY))
+
+	// calculate frame as a proportion of max, apply square root to create the non-linear effect
+	progress := math.Sqrt(float64(frame) / float64(max))
+
+	// calculate radius of explosion according to frame and max
+	radius := progress * maxRadius * 2
+
+	// introduce a new radius for the inner boundary of the explosion (the shockwave effect)
+	var innerRadius float64
+	if progress > 0.5 {
+		innerRadius = (progress - 0.5) * 2 * maxRadius
+	}
+
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			// calculate distance from center, scale x by 2 to compensate for character aspect ratio
+			distance := math.Hypot(float64(x-centerX), float64(y-centerY)*2)
+
+			// if distance is less than radius and greater than innerRadius, draw explosion char
+			if distance <= radius && distance >= innerRadius {
+				// Make placement random and less likely as explosion progresses
+				if rand.Float64() > progress {
+					// Pick a random explosion char
+					char := explosionChars[rand.Intn(len(explosionChars))]
+					buf.WriteRune(char)
+				} else {
+					buf.WriteRune(' ')
+				}
+			} else {
+				// If not explosion, then it's empty space
+				buf.WriteRune(' ')
+			}
+		}
+		// End of line
+		if y < height-1 {
+			buf.WriteRune('\n')
+		}
+	}
+
+	return buf.String()
+}