wip: refactoring tui

packages/tui/internal/styles/background.go

@@ -0,0 +1,123 @@
+package styles
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/charmbracelet/lipgloss"
+)
+
+var ansiEscape = regexp.MustCompile("\x1b\\[[0-9;]*m")
+
+func getColorRGB(c lipgloss.TerminalColor) (uint8, uint8, uint8) {
+	r, g, b, a := c.RGBA()
+
+	// Un-premultiply alpha if needed
+	if a > 0 && a < 0xffff {
+		r = (r * 0xffff) / a
+		g = (g * 0xffff) / a
+		b = (b * 0xffff) / a
+	}
+
+	// Convert from 16-bit to 8-bit color
+	return uint8(r >> 8), uint8(g >> 8), uint8(b >> 8)
+}
+
+// ForceReplaceBackgroundWithLipgloss replaces any ANSI background color codes
+// in `input` with a single 24‑bit background (48;2;R;G;B).
+func ForceReplaceBackgroundWithLipgloss(input string, newBgColor lipgloss.TerminalColor) string {
+	// Precompute our new-bg sequence once
+	r, g, b := getColorRGB(newBgColor)
+	newBg := fmt.Sprintf("48;2;%d;%d;%d", r, g, b)
+
+	return ansiEscape.ReplaceAllStringFunc(input, func(seq string) string {
+		const (
+			escPrefixLen = 2 // "\x1b["
+			escSuffixLen = 1 // "m"
+		)
+
+		raw := seq
+		start := escPrefixLen
+		end := len(raw) - escSuffixLen
+
+		var sb strings.Builder
+		// reserve enough space: original content minus bg codes + our newBg
+		sb.Grow((end - start) + len(newBg) + 2)
+
+		// scan from start..end, token by token
+		for i := start; i < end; {
+			// find the next ';' or end
+			j := i
+			for j < end && raw[j] != ';' {
+				j++
+			}
+			token := raw[i:j]
+
+			// fast‑path: skip "48;5;N" or "48;2;R;G;B"
+			if len(token) == 2 && token[0] == '4' && token[1] == '8' {
+				k := j + 1
+				if k < end {
+					// find next token
+					l := k
+					for l < end && raw[l] != ';' {
+						l++
+					}
+					next := raw[k:l]
+					if next == "5" {
+						// skip "48;5;N"
+						m := l + 1
+						for m < end && raw[m] != ';' {
+							m++
+						}
+						i = m + 1
+						continue
+					} else if next == "2" {
+						// skip "48;2;R;G;B"
+						m := l + 1
+						for count := 0; count < 3 && m < end; count++ {
+							for m < end && raw[m] != ';' {
+								m++
+							}
+							m++
+						}
+						i = m
+						continue
+					}
+				}
+			}
+
+			// decide whether to keep this token
+			// manually parse ASCII digits to int
+			isNum := true
+			val := 0
+			for p := i; p < j; p++ {
+				c := raw[p]
+				if c < '0' || c > '9' {
+					isNum = false
+					break
+				}
+				val = val*10 + int(c-'0')
+			}
+			keep := !isNum ||
+				((val < 40 || val > 47) && (val < 100 || val > 107) && val != 49)
+
+			if keep {
+				if sb.Len() > 0 {
+					sb.WriteByte(';')
+				}
+				sb.WriteString(token)
+			}
+			// advance past this token (and the semicolon)
+			i = j + 1
+		}
+
+		// append our new background
+		if sb.Len() > 0 {
+			sb.WriteByte(';')
+		}
+		sb.WriteString(newBg)
+
+		return "\x1b[" + sb.String() + "m"
+	})
+}