module std+, uri {

    private import rt::c;

    private var
        rfc3986_table(256) char = 0,
        html5_table(256) char = 0;

    func urlencode_init() {
        forvar i int = 0; i < 256; i++ {
            if isalnum(i) or i == '~' or i == '-' or i == '.' or i == '_' {
                rfc3986_table[i] = i;
            else
                rfc3986_table[i] = '\0';
            }
            if isalnum(i) or i == '*' or i == '-' or i == '.' or i == '_' {
                html5_table[i] = i;
            else
                if i == ' ' {
                    html5_table[i] = '+';
                else
                    html5_table[i] = '\0';
                }
            }
        }
    }

    private func urlencode(table. char, str. char, upper bool = false) .char {
        static lower_charset() char = "0123456789abcdef";
        static upper_charset() char = "0123456789ABCDEF";
        var charset. char;
        if upper {
            charset = &upper_charset;
        else
            charset = &lower_charset;
        }
        var len size_t = strlen(str);
        var enc. char = (func = malloc((len * 3) + 1));
        forvar i size_t = 0; i < len; i++ {
            var b byte = str[i];
            var c char = table[b];
            if c {
                .enc++ = c;
            else
                .enc++ = '%';
                .enc++ = charset[b >> 4];
                .enc++ = charset[b & 15];
            }
        }
        .enc = '\0';
    }

    inline urlencode_rfc3986(str. char, upper bool = false) .char {
        return urlencode(&rfc3986_table, str, upper);
    }

    inline urlencode_html5(str. char, upper bool = false) .char {
        return urlencode(&html5_table, str, upper);
    }

    func urldecode(str. char) .char {
        var len size_t = strlen(str);
        var dec. char = (func = malloc(len + 1));
        forvar i size_t = 0; i < len; i++ {
            var c char = str[i];
            if c == '%' {
                if i + 2 < len {
                    lambda from_hex(c char) char [
                        if islower(c) {
                            return c - 'a' + 10;
                        elseif isupper(c);
                            return c - 'A' + 10;
                        elseif isdigit(c);
                            return c - '0';
                        }
                        return 0;
                    ];
                    .dec++ =
                        from_hex(str[i + 1]) << 4 |
                        from_hex(str[i + 2]);
                    i += 2;
                else
                    break;
                }
            elseif c == '+';
                .dec++ = ' ';
            else
                .dec++ = c;
            }
        }
        .dec = '\0';
    }

}