Better paragraph splitting

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

pkg/xstrings/split.go

@@ -0,0 +1,72 @@
+package xstrings
+
+import (
+	"strings"
+)
+
+// SplitTextByLength splits text into chunks of specified maxLength,
+// preserving complete words and special characters like newlines.
+// It returns a slice of strings, each with length <= maxLength.
+func SplitParagraph(text string, maxLength int) []string {
+	// Handle edge cases
+	if maxLength <= 0 || len(text) == 0 {
+		return []string{text}
+	}
+
+	var chunks []string
+	remainingText := text
+
+	for len(remainingText) > 0 {
+		// If remaining text fits in a chunk, add it and we're done
+		if len(remainingText) <= maxLength {
+			chunks = append(chunks, remainingText)
+			break
+		}
+
+		// Try to find a good split point near the max length
+		splitIndex := maxLength
+
+		// Look backward from the max length to find a space or newline
+		for splitIndex > 0 && !isWhitespace(rune(remainingText[splitIndex])) {
+			splitIndex--
+		}
+
+		// If we couldn't find a good split point (no whitespace),
+		// look forward for the next whitespace
+		if splitIndex == 0 {
+			splitIndex = maxLength
+			// If we can't find whitespace forward, we'll have to split a word
+			for splitIndex < len(remainingText) && !isWhitespace(rune(remainingText[splitIndex])) {
+				splitIndex++
+			}
+
+			// If we still couldn't find whitespace, take the whole string
+			if splitIndex == len(remainingText) {
+				chunks = append(chunks, remainingText)
+				break
+			}
+		}
+
+		// Add the chunk up to the split point
+		chunk := remainingText[:splitIndex]
+
+		// Preserve trailing newlines with the current chunk
+		if splitIndex < len(remainingText) && remainingText[splitIndex] == '\n' {
+			chunk += string(remainingText[splitIndex])
+			splitIndex++
+		}
+
+		chunks = append(chunks, chunk)
+
+		// Remove leading whitespace from the next chunk
+		remainingText = remainingText[splitIndex:]
+		remainingText = strings.TrimLeftFunc(remainingText, isWhitespace)
+	}
+
+	return chunks
+}
+
+// Helper function to determine if a character is whitespace
+func isWhitespace(r rune) bool {
+	return r == ' ' || r == '\t' || r == '\n' || r == '\r'
+}