package processing

import "strings"

// LooksLikeMySQLTupleLine reports whether line starts a mysqldump VALUES tuple.
func LooksLikeMySQLTupleLine(line string) bool {
	s := strings.TrimLeft(line, " \t")
	return strings.HasPrefix(s, "(")
}

// ParseMySQLTupleFields parses all fields from the first (...) tuple on the line.
func ParseMySQLTupleFields(line string) []string {
	return ParseMySQLTupleFieldsN(line, 0)
}

// ParseMySQLTupleFieldsN parses up to maxFields (0 = all) from the first (...) tuple.
func ParseMySQLTupleFieldsN(line string, maxFields int) []string {
	start := strings.Index(line, "(")
	if start < 0 {
		return nil
	}
	body := line[start+1:]
	var out []string
	for i := 0; i < len(body); {
		if maxFields > 0 && len(out) >= maxFields {
			break
		}
		for i < len(body) && (body[i] == ' ' || body[i] == '\t' || body[i] == ',') {
			i++
		}
		if i >= len(body) || body[i] == ')' {
			break
		}
		if body[i] == '\'' {
			i++
			var b strings.Builder
			for i < len(body) {
				ch := body[i]
				if ch == '\\' && i+1 < len(body) {
					b.WriteByte(body[i+1])
					i += 2
					continue
				}
				if ch == '\'' {
					if i+1 < len(body) && body[i+1] == '\'' {
						b.WriteByte('\'')
						i += 2
						continue
					}
					i++
					break
				}
				b.WriteByte(ch)
				i++
			}
			out = append(out, b.String())
			continue
		}
		j := i
		for j < len(body) && body[j] != ',' && body[j] != ')' {
			j++
		}
		out = append(out, strings.TrimSpace(body[i:j]))
		i = j
	}
	return out
}