package q68

var (
	emptyLine = make([]byte, 100)
	buf       = make([]byte, 100)
)

func init() {
	for i := range emptyLine {
		emptyLine[i] = ' '
	}
}

func emitLine(line []byte, words []string, justifyLeft bool) string {
	spaces := len(line)
	for i := range words {
		spaces -= len(words[i])
	}
	lenSep := spaces / max(len(words)-1, 1)
	leftover := spaces % max(len(words)-1, 1)

	offset := len(words[0])
	copy(line, words[0])
	for i := 1; i < len(words); i++ {
		var spaces = 1
		if !justifyLeft {
			spaces = lenSep
			if i <= leftover {
				spaces++
			}
		}
		offset += spaces
		copy(line[offset:], words[i])
		offset += len(words[i])
	}
	return string(line)
}

func fullJustify(words []string, maxWidth int) []string {
	ret := []string{}
	line := buf[:maxWidth]
	copy(line, emptyLine)

	i := 0
	lineLen := len(words[0])
	for j := 1; j < len(words); j++ {
		if lineLen+1+len(words[j]) <= maxWidth {
			lineLen += 1 + len(words[j])
			continue
		}

		ret = append(ret, emitLine(line, words[i:j], false))
		copy(line, emptyLine)

		i = j
		lineLen = len(words[j])
	}

	// Last line
	return append(ret, emitLine(line, words[i:], true))
}

var _ = fullJustify