// Package confline contains small lexical helpers shared by mpv.conf,
// input.conf, and script-options parsers.
package confline

// CommentIndex returns the byte index of the first unquoted, unescaped '#'.
// When requireWhitespace is true, '#' starts a comment only at the beginning
// of the line or after a space/tab; this preserves values such as #FF8232.
func CommentIndex(line string, requireWhitespace bool) int {
	var quote byte
	escaped := false
	for index := 0; index < len(line); index++ {
		character := line[index]
		if escaped {
			escaped = false
			continue
		}
		if character == '\\' {
			escaped = true
			continue
		}
		if quote != 0 {
			if character == quote {
				quote = 0
			}
			continue
		}
		if character == '\'' || character == '"' {
			quote = character
			continue
		}
		if character != '#' {
			continue
		}
		if !requireWhitespace || index == 0 || line[index-1] == ' ' || line[index-1] == '\t' {
			return index
		}
	}
	return -1
}