Switch buffer contents to string slice

src/buffer.go

@@ -2,18 +2,20 @@ package main
 
 import (
 	"fmt"
-	"github.com/gdamore/tcell/v2"
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
+
+	"github.com/gdamore/tcell/v2"
 )
 
 type Buffer struct {
 	Name     string
-	Contents string
+	Contents []string
 
-	CursorPos        int
-	OffsetX, OffsetY int
+	CursorPos Position
+	Offset    Position
 
 	Selection *Selection
 
@@ -22,8 +24,7 @@ type Buffer struct {
 }
 
 type Selection struct {
-	selectionStart int
-	selectionEnd   int
+	selectionStart, selectionEnd Position
 }
 
 var Buffers = make([]*Buffer, 0)
@@ -53,43 +54,50 @@ func drawBuffer(window *Window) {
 
 	bufferX, bufferY, _, _ := window.GetTextAreaDimensions()
 
-	for i, r := range buffer.Contents + " " {
-		if x-buffer.OffsetX >= bufferX && y-buffer.OffsetY >= bufferY {
-			// Default style
-			style := tcell.StyleDefault.Background(CurrentStyle.BufferAreaBg).Foreground(CurrentStyle.BufferAreaFg)
+	for lineIndex, line := range buffer.Contents {
+		for runeIndex, r := range line + " " {
+			drawPosition := Position{runeIndex, lineIndex}
 
-			// Change background if under cursor
-			if i == buffer.CursorPos {
-				style = style.Background(CurrentStyle.BufferAreaSel)
-			}
+			if x-buffer.Offset.X >= bufferX && y-buffer.Offset.Y >= bufferY {
+				// Default style
+				style := tcell.StyleDefault.Background(CurrentStyle.BufferAreaBg).Foreground(CurrentStyle.BufferAreaFg)
 
-			// Change background if selected
-			if buffer.Selection != nil {
-				if edge1, edge2 := buffer.GetSelectionEdges(); i >= edge1 && i <= edge2 {
+				// Change background if under cursor
+				if buffer.CursorPos.Equals(runeIndex, lineIndex) {
 					style = style.Background(CurrentStyle.BufferAreaSel)
+				}
 
-					// Show selection on entire tab space
-					if r == '\t' {
-						for j := 0; j < int(Config.TabIndentation); j++ {
-							window.screen.SetContent(x+j-buffer.OffsetX, y-buffer.OffsetY, r, nil, style)
+				// Change background if selected
+				if buffer.Selection != nil {
+					edge1, edge2 := buffer.GetSelectionEdges()
+
+					if ComparePositions(drawPosition, edge1) >= 0 && ComparePositions(drawPosition, edge2) <= 0 {
+						style = style.Background(CurrentStyle.BufferAreaSel)
+
+						// Show selection on entire tab space
+						if r == '\t' {
+							for j := 0; j < int(Config.TabIndentation); j++ {
+								window.screen.SetContent(x+j-buffer.Offset.X, y-buffer.Offset.Y, r, nil, style)
+							}
 						}
 					}
 				}
+
+				window.screen.SetContent(x-buffer.Offset.X, y-buffer.Offset.Y, r, nil, style)
 			}
 
-			window.screen.SetContent(x-buffer.OffsetX, y-buffer.OffsetY, r, nil, style)
-		}
-
-		// Change position for next character
-		if r == '\n' {
-			x = bufferX
-			y++
-		} else if r == '\t' {
-			x += int(Config.TabIndentation)
-		} else {
-			x++
+			// Change position for next character
+			if r == '\t' {
+				x += int(Config.TabIndentation)
+			} else {
+				x++
+			}
 		}
+		// Draw new line
+		x = bufferX
+		y++
 	}
+
 }
 
 func (buffer *Buffer) Load() error {
@@ -113,7 +121,7 @@ func (buffer *Buffer) Load() error {
 		return err
 	}
 
-	buffer.Contents = string(content)
+	buffer.Contents = strings.Split(string(content), "\n")
 	return nil
 }
 
@@ -133,12 +141,13 @@ func (buffer *Buffer) Save() error {
 		buffer.filename = filepath.Join(homedir, buffer.filename[2:])
 	}
 
-	// Append new line character at end of buffer contents if not present
-	if buffer.Contents == "" || buffer.Contents[len(buffer.Contents)-1] != '\n' {
-		buffer.Contents += "\n"
+	// Add newline at the end of buffer Contents
+	line := buffer.Contents[len(buffer.Contents)-1]
+	if len(line) != 0 {
+		buffer.Contents = append(buffer.Contents, "")
 	}
 
-	err := os.WriteFile(buffer.filename, []byte(buffer.Contents), 0644)
+	err := os.WriteFile(buffer.filename, []byte(buffer.GetContentsAsString()), 0644)
 	if err != nil {
 		return err
 	}
@@ -146,12 +155,60 @@ func (buffer *Buffer) Save() error {
 	return nil
 }
 
-func (buffer *Buffer) GetSelectionEdges() (int, int) {
-	if buffer.Selection == nil {
-		return -1, -1
+func (buffer *Buffer) GetContentsAsString() string {
+	finalText := strings.Builder{}
+	for i, line := range buffer.Contents {
+		for _, rune := range line {
+			finalText.WriteRune(rune)
+		}
+
+		if i != len(buffer.Contents)-1 {
+			finalText.WriteRune('\n')
+		}
 	}
 
-	if buffer.Selection.selectionStart < buffer.Selection.selectionEnd {
+	return finalText.String()
+}
+
+func (buffer *Buffer) PositionToAbsolutePosition(position Position) int {
+	i := 0
+	for lineIndex, line := range buffer.Contents {
+		if len(line) == 0 {
+			line += " "
+		}
+		for runeIndex, _ := range line + " " {
+			if position.Equals(runeIndex, lineIndex) {
+				return i
+			}
+			i++
+		}
+	}
+
+	return i
+}
+
+func (buffer *Buffer) AbsolutePositionToPosition(absolutePosition int) Position {
+	i := 0
+
+	for lineIndex, line := range buffer.Contents {
+		for runeIndex, _ := range line + " " {
+			if i == absolutePosition {
+				return Position{runeIndex, lineIndex}
+			}
+			i++
+		}
+	}
+
+	lastLine := buffer.Contents[len(buffer.Contents)-1]
+	return Position{len(buffer.Contents) - 1, len(lastLine) - 1}
+}
+
+func (buffer *Buffer) GetSelectionEdges() (Position, Position) {
+	if buffer.Selection == nil {
+		return Position{-1, -1}, Position{-1, -1}
+	}
+
+	if ComparePositions(buffer.Selection.selectionStart, buffer.Selection.selectionEnd) == -1 {
 		return buffer.Selection.selectionStart, buffer.Selection.selectionEnd
 	} else {
 		return buffer.Selection.selectionEnd, buffer.Selection.selectionStart
@@ -162,113 +219,75 @@ func (buffer *Buffer) GetSelectedText() string {
 	if buffer.Selection == nil {
 		return ""
 	}
-
 	if len(buffer.Contents) == 0 {
 		return ""
 	}
 
-	start := buffer.Selection.selectionStart
-	end := buffer.Selection.selectionEnd
+	edge1, edge2 := buffer.GetSelectionEdges()
 
-	if start >= len(buffer.Contents) {
-		start = len(buffer.Contents) - 1
-	}
-	if end >= len(buffer.Contents) {
-		end = len(buffer.Contents) - 1
+	selectedText := strings.Builder{}
+	if r := buffer.GetCharAtPosition(edge1); r != 0 {
+		selectedText.WriteRune(r)
 	}
 
-	if start <= end {
-		return buffer.Contents[start : end+1]
-	} else {
-		return buffer.Contents[end : start+1]
+	for ComparePositions(edge1, edge2) < 0 {
+		edge1.X++
+		if edge1.X > len(buffer.Contents[edge1.Y]) {
+			if edge1.Y < len(buffer.Contents) {
+				edge1.Y++
+				edge1.X = 0
+			} else {
+				edge1.X = len(buffer.Contents[edge1.Y])
+				break
+			}
+		}
+
+		if r := buffer.GetCharAtPosition(edge1); r != 0 {
+			selectedText.WriteRune(buffer.GetCharAtPosition(edge1))
+		}
 	}
+
+	return selectedText.String()
 }
 
 func (buffer *Buffer) CutText(window *Window) (string, int) {
 	if buffer.Selection == nil {
-		// Copy line
-		copiedText := ""
-		startOfLine := window.CurrentBuffer.CursorPos
-		endOfLine := window.CurrentBuffer.CursorPos
-
-		// Add current letter to copied text
-		if buffer.CursorPos < len(buffer.Contents) {
-			copiedText = string(buffer.Contents[buffer.CursorPos])
-		}
-
-		// Find end of line
-		for i := buffer.CursorPos + 1; i < len(buffer.Contents); i++ {
-			currentLetter := buffer.Contents[i]
-
-			endOfLine++
-			copiedText += string(currentLetter)
-			if currentLetter == '\n' {
-				break
-			}
-		}
-
-		// Find start of line
-		for i := buffer.CursorPos - 1; i >= 0; i-- {
-			currentLetter := buffer.Contents[i]
-			if currentLetter != '\n' {
-				startOfLine--
-				copiedText = string(currentLetter) + copiedText
-			} else {
-				break
-			}
-		}
+		// Cut current line
+		cutText := buffer.Contents[buffer.CursorPos.Y] + "\n"
 
 		// Remove line from buffer contents
-		buffer.Contents = buffer.Contents[:startOfLine] + buffer.Contents[endOfLine+1:]
-
-		return copiedText, 0
-	} else {
-		// Copy selection
-		copiedText := buffer.GetSelectedText()
-
-		// Remove selected text
-		edge1, edge2 := buffer.GetSelectionEdges()
-		if edge2 == len(buffer.Contents) {
-			edge2 = len(buffer.Contents) - 1
+		if len(buffer.Contents) == 1 {
+			buffer.Contents[0] = ""
+		} else {
+			buffer.Contents = slices.Delete(buffer.Contents, buffer.CursorPos.Y, buffer.CursorPos.Y+1)
 		}
 
-		buffer.Contents = buffer.Contents[:edge1] + buffer.Contents[edge2+1:]
-		window.SetCursorPos(edge1)
+		buffer.CursorPos.Y -= 1
+		if buffer.CursorPos.Y < 0 {
+			buffer.CursorPos = Position{0, 0}
+		}
+
+		return cutText, 0
+	} else {
+		// Cut selection
+		cutText := buffer.GetSelectedText()
+
+		// Remove selected text
+		_, edge2 := buffer.GetSelectionEdges()
+		buffer.CursorPos = edge2
+		buffer.Delete(len(cutText))
+
+		// Remove selection
 		buffer.Selection = nil
 
-		return copiedText, 1
+		return cutText, 1
 	}
 }
 
 func (buffer *Buffer) CopyText() (string, int) {
 	if buffer.Selection == nil {
-		// Copy line
-		copiedText := ""
-
-		// Add current letter to copied text
-		if buffer.CursorPos < len(buffer.Contents) {
-			copiedText = string(buffer.Contents[buffer.CursorPos])
-		}
-
-		// Find end of line
-		for i := buffer.CursorPos + 1; i < len(buffer.Contents); i++ {
-			currentLetter := buffer.Contents[i]
-
-			copiedText += string(currentLetter)
-			if currentLetter == '\n' {
-				break
-			}
-		}
-
-		// Find start of line
-		for i := buffer.CursorPos - 1; i >= 0; i-- {
-			currentLetter := buffer.Contents[i]
-			if currentLetter != '\n' {
-				copiedText = string(currentLetter) + copiedText
-			} else {
-				break
-			}
-		}
+		// Cut current line
+		copiedText := buffer.Contents[buffer.CursorPos.Y] + "\n"
 
 		return copiedText, 0
 	} else {
@@ -278,77 +297,232 @@ func (buffer *Buffer) CopyText() (string, int) {
 }
 
 func (buffer *Buffer) PasteText(window *Window, text string) {
-	str := buffer.Contents
+	contents := buffer.GetContentsAsString()
 
 	// Remove selected text
 	if buffer.Selection != nil {
 		edge1, edge2 := buffer.GetSelectionEdges()
-		if edge2 == len(buffer.Contents) {
-			edge2 = len(buffer.Contents) - 1
+		absEdge1 := buffer.PositionToAbsolutePosition(edge1)
+		absEdge2 := buffer.PositionToAbsolutePosition(edge2)
+
+		if absEdge2 == len(buffer.Contents) {
+			absEdge2 = len(buffer.Contents) - 1
 		}
 
-		str = str[:edge1] + str[edge2+1:]
-		buffer.Contents = str
-		window.SetCursorPos(edge1)
+		contents = contents[:absEdge1] + contents[absEdge2+1:]
+		buffer.Contents = strings.Split(contents, "\n")
+		buffer.CursorPos = buffer.AbsolutePositionToPosition(absEdge1)
 		buffer.Selection = nil
 	}
 
-	index := buffer.CursorPos
-
-	if index == len(str) {
-		str += text
-	} else {
-		str = str[:index] + text + str[index:]
-	}
-	buffer.Contents = str
-	window.SetCursorPos(buffer.CursorPos + len(text))
+	buffer.WriteString(text)
 }
 
-func (buffer *Buffer) FindSubstring(substring string, afterPos int) int {
+func (buffer *Buffer) FindSubstring(substring string, afterPos Position) Position {
 	// Return no match if afterPos is larger than the buffer contents size
-	if afterPos >= len(buffer.Contents) {
-		return -1
+	contents := buffer.GetContentsAsString()
+	absAfterPos := buffer.PositionToAbsolutePosition(afterPos)
+
+	if absAfterPos >= len(contents) {
+		return Position{-1, -1}
 	}
 
-	index := strings.Index(buffer.Contents[afterPos+1:], substring)
+	index := strings.Index(contents[absAfterPos+1:], substring)
 
 	if index != -1 {
-		index += afterPos + 1
+		index += absAfterPos + 1
 	}
-	return index
+	return buffer.AbsolutePositionToPosition(index)
 }
 
-func (buffer *Buffer) FindAndReplaceSubstring(substring, replacement string, afterPos int) int {
-	index := buffer.FindSubstring(substring, afterPos)
+func (buffer *Buffer) FindAndReplaceSubstring(substring, replacement string, afterPos Position) Position {
+	// Return no match if afterPos is larger than the buffer contents size
+	contents := buffer.GetContentsAsString()
+	absAfterPos := buffer.PositionToAbsolutePosition(afterPos)
 
-	// Return if substring isn't found
-	if index == -1 {
-		return -1
+	if absAfterPos >= len(contents) {
+		return Position{-1, -1}
+	}
+
+	index := strings.Index(contents[absAfterPos+1:], substring)
+
+	if index != -1 {
+		index += absAfterPos + 1
 	}
 
 	// Replace substring with replacement string
-	buffer.Contents = buffer.Contents[:index] + replacement + buffer.Contents[index+len(substring):]
+	contents = contents[:index] + replacement + contents[index+len(substring):]
 
-	return index
+	buffer.Contents = strings.Split(contents, "\n")
+
+	return buffer.AbsolutePositionToPosition(index)
 }
 
 func (buffer *Buffer) FindAndReplaceAll(substring, replacement string) int {
 	replacements := 0
-	index := 0
-	for index != -1 {
-		index = buffer.FindAndReplaceSubstring(substring, replacement, index)
-		if index != -1 {
+	position := Position{}
+	for position.X != -1 && position.Y != -1 {
+		position = buffer.FindAndReplaceSubstring(substring, replacement, position)
+		if position.X != -1 && position.Y != -1 {
 			replacements++
 		}
-
-		if index == 0 {
-			index++
-		}
 	}
 
 	return replacements
 }
 
+func (buffer *Buffer) MoveUp(i int) bool {
+	buffer.CursorPos.Y -= i
+	if buffer.CursorPos.Y < 0 {
+		buffer.CursorPos.Y = 0
+		return false
+	}
+
+	if buffer.CursorPos.X >= len(buffer.Contents[buffer.CursorPos.Y]) {
+		buffer.CursorPos.X = len(buffer.Contents[buffer.CursorPos.Y])
+	}
+
+	return true
+}
+
+func (buffer *Buffer) MoveDown(i int) bool {
+	buffer.CursorPos.Y += i
+	if buffer.CursorPos.Y >= len(buffer.Contents) {
+		buffer.CursorPos.Y = len(buffer.Contents) - 1
+		return false
+	}
+
+	if buffer.CursorPos.X >= len(buffer.Contents[buffer.CursorPos.Y]) {
+		buffer.CursorPos.X = len(buffer.Contents[buffer.CursorPos.Y])
+	}
+
+	return true
+}
+
+func (buffer *Buffer) MoveLeft(i int) bool {
+	remainingSteps := i
+
+	for remainingSteps > 0 {
+		buffer.CursorPos.X--
+		if buffer.CursorPos.X < 0 {
+			if buffer.CursorPos.Y > 0 {
+				buffer.CursorPos.Y--
+				buffer.CursorPos.X = len(buffer.Contents[buffer.CursorPos.Y])
+			} else {
+				buffer.CursorPos.X = 0
+				return false
+			}
+		}
+
+		remainingSteps--
+	}
+
+	return true
+}
+
+func (buffer *Buffer) MoveRight(i int) bool {
+	remainingSteps := i
+
+	for remainingSteps > 0 {
+		buffer.CursorPos.X++
+		if buffer.CursorPos.X > len(buffer.Contents[buffer.CursorPos.Y]) {
+			if buffer.CursorPos.Y < len(buffer.Contents)-1 {
+				buffer.CursorPos.Y++
+				buffer.CursorPos.X = 0
+			} else {
+				buffer.CursorPos.X = len(buffer.Contents[buffer.CursorPos.Y])
+				return false
+			}
+		}
+
+		remainingSteps--
+	}
+
+	return true
+}
+
+func (buffer *Buffer) WriteRune(r rune) {
+	if r == '\n' {
+		if buffer.CursorPos.Y == len(buffer.Contents) {
+			buffer.Contents = append(buffer.Contents, "")
+		} else {
+			buffer.Contents = slices.Insert(buffer.Contents, buffer.CursorPos.Y+1, "")
+		}
+
+		// Move line content after cursor X to the new line
+		line := buffer.Contents[buffer.CursorPos.Y]
+		buffer.Contents[buffer.CursorPos.Y+1] = line[buffer.CursorPos.X:] + buffer.Contents[buffer.CursorPos.Y+1]
+		buffer.Contents[buffer.CursorPos.Y] = line[:buffer.CursorPos.X]
+
+		buffer.MoveDown(1)
+		buffer.CursorPos.X = 0
+	} else {
+		line := buffer.Contents[buffer.CursorPos.Y]
+		buffer.Contents[buffer.CursorPos.Y] = line[:buffer.CursorPos.X] + string(r) + line[buffer.CursorPos.X:]
+		buffer.MoveRight(1)
+	}
+}
+
+func (buffer *Buffer) WriteString(str string) {
+	for _, r := range str {
+		buffer.WriteRune(r)
+	}
+}
+
+func (buffer *Buffer) Delete(i int) bool {
+	remainingSteps := i
+
+	for remainingSteps > 0 {
+		buffer.CursorPos.X--
+		if buffer.CursorPos.X < 0 {
+			if buffer.CursorPos.Y > 0 {
+				// Save deleted line text
+				deletedLine := buffer.Contents[buffer.CursorPos.Y]
+
+				buffer.CursorPos.Y--
+
+				// Delete line
+				buffer.Contents = slices.Delete(buffer.Contents, buffer.CursorPos.Y+1, buffer.CursorPos.Y+2)
+
+				// Append deleted line text to end of current line
+				buffer.Contents[buffer.CursorPos.Y] += deletedLine
+
+				buffer.CursorPos.X = len(buffer.Contents[buffer.CursorPos.Y]) - len(deletedLine)
+			} else {
+				buffer.CursorPos.X = 0
+				return false
+			}
+		} else {
+			line := buffer.Contents[buffer.CursorPos.Y]
+			buffer.Contents[buffer.CursorPos.Y] = line[:buffer.CursorPos.X] + line[buffer.CursorPos.X+1:]
+		}
+
+		remainingSteps--
+	}
+
+	return true
+}
+
+func (buffer *Buffer) GetCharAtPosition(position Position) rune {
+	if position.Y < 0 || position.Y >= len(buffer.Contents) {
+		return 0
+	}
+	line := buffer.Contents[position.Y]
+
+	if position.X == len(line) {
+		// Do not return newline for last line if it's empty
+		if position.Y == len(buffer.Contents)-1 && len(line) == 0 {
+			return 0
+		}
+
+		return '\n'
+	} else if position.X < 0 || position.X > len(line) {
+		return 0
+	}
+
+	return rune(line[position.X])
+}
+
 func GetOpenFileBuffer(filename string) *Buffer {
 	// Replace tilde with home directory
 	if filename != "~" && strings.HasPrefix(filename, "~/") {
@@ -415,8 +589,8 @@ func CreateFileBuffer(filename string, openNonExistentFile bool) (*Buffer, error
 
 	buffer := Buffer{
 		Name:      filename,
-		Contents:  "",
-		CursorPos: 0,
+		Contents:  make([]string, 1),
+		CursorPos: Position{0, 0},
 		canSave:   true,
 		filename:  abs,
 	}
@@ -438,8 +612,8 @@ func CreateFileBuffer(filename string, openNonExistentFile bool) (*Buffer, error
 func CreateBuffer(bufferName string) (*Buffer, error) {
 	buffer := Buffer{
 		Name:      bufferName,
-		Contents:  "",
-		CursorPos: 0,
+		Contents:  make([]string, 1),
+		CursorPos: Position{0, 0},
 		canSave:   true,
 		filename:  "",
 	}