package headers

import (
	"fmt"
)

func readKey(str string, separator byte) (string, string) {
	i := 0
	for i < len(str) && str[i] != '=' && str[i] != separator {
		i++
	}
	return str[:i], str[i:]
}

func readValue(origstr string, str string, separator byte) (string, string, error) {
	if len(str) > 0 && str[0] == '"' {
		i := 1
		for {
			if i >= len(str) {
				return "", "", fmt.Errorf("apexes not closed (%v)", origstr)
			}

			if str[i] == '"' {
				return str[1:i], str[i+1:], nil
			}

			i++
		}
	}

	i := 0
	for {
		if i >= len(str) || str[i] == separator {
			return str[:i], str[i:], nil
		}
		i++
	}
}

func keyValParse(str string, separator byte) (map[string]string, error) {
	ret := make(map[string]string)
	origstr := str

	for len(str) > 0 {
		var k string
		k, str = readKey(str, separator)

		if len(str) > 0 && str[0] == '=' {
			var v string
			var err error
			v, str, err = readValue(origstr, str[1:], separator)
			if err != nil {
				return nil, err
			}

			ret[k] = v
		} else {
			ret[k] = ""
		}

		// skip separator
		if len(str) > 0 && str[0] == separator {
			str = str[1:]
		}

		// skip spaces
		for len(str) > 0 && str[0] == ' ' {
			str = str[1:]
		}
	}

	return ret, nil
}