package main

// Protocol: pipe-delimited, newline-terminated messages.
// REQ|<seq>|<op>|<arg0>|<arg1>|...
// OK|<seq>|<result>
// ERR|<seq>|<errmsg>

func tsItoa(n int32) (s string) {
	if n == 0 {
		return "0"
	}
	buf := []byte{:0:20}
	neg := n < 0
	if neg {
		n = -n
	}
	for n > 0 {
		push(buf, byte('0'+n%10))
		n /= 10
	}
	if neg {
		push(buf, '-')
	}
	for i, j := 0, len(buf)-1; i < j; i, j = i+1, j-1 {
		buf[i], buf[j] = buf[j], buf[i]
	}
	return string(buf)
}

func tsAtoi(s string) (n int32) {
	if len(s) == 0 {
		return 0
	}
	neg := false
	pos := int32(0)
	if s[0] == '-' {
		neg = true
		pos = 1
	} else if s[0] == '+' {
		pos = 1
	}
	for pos < int32(len(s)) {
		c := s[pos]
		if c < '0' || c > '9' {
			break
		}
		n = n*10 + int32(c-'0')
		pos++
	}
	if neg {
		n = -n
	}
	return n
}

func parseMsg(msg string) (seq int32, op string, args []string) {
	parts := splitMsg(msg)
	if len(parts) < 3 {
		return 0, "", nil
	}
	seq = tsAtoi(parts[1])
	op = parts[2]
	if len(parts) > 3 {
		args = parts[3:]
	}
	return seq, op, args
}

func formatOK(seq int32, result string) (s string) {
	return "OK|" | tsItoa(seq) | "|" | result | "\n"
}

func formatERR(seq int32, errmsg string) (s string) {
	return "ERR|" | tsItoa(seq) | "|" | errmsg | "\n"
}

func parseOK(line string) (result string) {
	parts := splitMsg(line)
	if len(parts) >= 3 {
		return parts[2]
	}
	return ""
}

func parseOKMulti(line string) (results []string) {
	return splitMsg(line)
}

func parseERR(line string) (errmsg string) {
	parts := splitMsg(line)
	if len(parts) >= 3 {
		return parts[2]
	}
	return ""
}

func splitMsg(d string) (parts []string) {
	if len(d) == 0 {
		return nil
	}
	n := int32(1)
	for i := int32(0); i < int32(len(d)); i++ {
		if d[i] == '|' {
			n++
		}
	}
	parts = []string{:0:n}
	start := int32(0)
	for i := int32(0); i <= int32(len(d)); i++ {
		isDelim := false
		if i < int32(len(d)) {
			isDelim = d[i] == '|' || d[i] == '\n'
		}
		if i == int32(len(d)) || isDelim {
			push(parts, string(d[start:i]))
			start = i + 1
			if i < int32(len(d)) && d[i] == '\n' {
				break
			}
		}
	}
	return parts
}