textfmt/wrap.go

package textfmt

import "strings"

func getWords(text string) []string {
	var words []string
	raw := strings.Split(text, " ")
	for _, r := range raw {
		if r == "" {
			continue
		}

		words = append(words, r)
	}

	return words
}

func wrap(text string, width, firstIndent, restIndent int) string {
	var (
		lines       []string
		currentLine []string
		lineLen     int
	)

	words := getWords(text)
	for _, w := range words {
		if len(currentLine) == 0 {
			currentLine = []string{w}
			lineLen = len([]rune(w))
			continue
		}

		maxw := width - restIndent
		if len(lines) == 0 {
			maxw = width - firstIndent
		}

		if lineLen+1+len([]rune(w)) > maxw {
			lines = append(lines, strings.Join(currentLine, " "))
			currentLine = []string{w}
			lineLen = len([]rune(w))
			continue
		}

		currentLine = append(currentLine, w)
		lineLen += 1 + len([]rune(w))
	}

	lines = append(lines, strings.Join(currentLine, " "))
	return strings.Join(lines, "\n")
}