#!/usr/bin/env ucode

let common = require("core.common");

let as_string = common.as_string;

function str_last_index(value, needle) {
    value = as_string(value);
    needle = as_string(needle);
    if (needle == "")
        return length(value);

    for (let i = length(value) - length(needle); i >= 0; i--)
        if (substr(value, i, length(needle)) == needle)
            return i;

    return -1;
}

function first_index_any(value, needles, start) {
    value = as_string(value);
    start = int(start || 0);

    for (let i = start; i < length(value); i++) {
        let c = substr(value, i, 1);
        for (let needle in needles)
            if (c == needle)
                return i;
    }

    return -1;
}

function hex_digit_value(value) {
    value = ord(lc(as_string(value)));
    if (value >= 48 && value <= 57)
        return value - 48;
    if (value >= 97 && value <= 102)
        return value - 87;
    return -1;
}

function decode(value) {
    value = as_string(value);
    let result = "";

    for (let i = 0; i < length(value); i++) {
        let c = substr(value, i, 1);
        if (c == "+") {
            result += " ";
            continue;
        }
        if (c == "%") {
            let high = i + 1 < length(value) ? hex_digit_value(substr(value, i + 1, 1)) : -1;
            let low = i + 2 < length(value) ? hex_digit_value(substr(value, i + 2, 1)) : -1;
            if (high >= 0 && low >= 0) {
                result += chr(high * 16 + low);
                i += 2;
                continue;
            }
        }
        result += c;
    }

    return result;
}

function scheme(value) {
    value = as_string(value);
    let marker = index(value, "://");
    return marker >= 0 ? lc(substr(value, 0, marker)) : "";
}

function fragment(value) {
    value = as_string(value);
    let marker = index(value, "#");
    return marker >= 0 ? decode(substr(value, marker + 1)) : "";
}

function strip_fragment(value) {
    value = as_string(value);
    let marker = index(value, "#");
    return marker >= 0 ? substr(value, 0, marker) : value;
}

function strip_anchored_scheme(value) {
    value = as_string(value);
    let marker = index(value, "://");
    if (marker < 0)
        return value;

    let prefix = substr(value, 0, marker);
    if (index(prefix, "/") >= 0 || index(prefix, "?") >= 0)
        return value;

    return substr(value, marker + 3);
}

function strip_first_scheme_marker(value) {
    value = as_string(value);
    let marker = index(value, "://");
    return marker >= 0 ? substr(value, marker + 3) : value;
}

function authority(value) {
    value = strip_first_scheme_marker(value);
    let at = str_last_index(value, "@");
    if (at >= 0)
        value = substr(value, at + 1);

    let end = first_index_any(value, ["/", "?", "#"], 0);
    return end >= 0 ? substr(value, 0, end) : value;
}

function host(value) {
    let value_authority = authority(value);
    if (substr(value_authority, 0, 1) == "[") {
        let end = index(value_authority, "]");
        return end > 0 ? substr(value_authority, 1, end - 1) : value_authority;
    }

    let colon = index(value_authority, ":");
    if (colon < 0)
        return value_authority;

    return str_last_index(value_authority, ":") == colon ? substr(value_authority, 0, colon) : value_authority;
}

function port(value) {
    let value_authority = authority(value);
    if (substr(value_authority, 0, 1) == "[") {
        let end = index(value_authority, "]");
        if (end > 0 && substr(value_authority, end + 1, 1) == ":")
            return substr(value_authority, end + 2);
        return "";
    }

    let colon = index(value_authority, ":");
    if (colon < 0 || str_last_index(value_authority, ":") != colon)
        return "";

    return substr(value_authority, colon + 1);
}

function userinfo(value) {
    let value_authority = strip_first_scheme_marker(strip_fragment(value));
    let end = first_index_any(value_authority, ["/", "?", "#"], 0);
    value_authority = end >= 0 ? substr(value_authority, 0, end) : value_authority;
    let at = str_last_index(value_authority, "@");
    return at >= 0 ? decode(substr(value_authority, 0, at)) : "";
}

function path(value) {
    value = strip_anchored_scheme(value);
    let slash = index(value, "/");
    value = slash >= 0 ? substr(value, slash) : "";

    let query = index(value, "?");
    if (query >= 0)
        value = substr(value, 0, query);

    return value;
}

function query_params(value) {
    let result = {};
    value = as_string(value);
    let question = index(value, "?");
    if (question < 0)
        return result;

    let query = substr(value, question + 1);
    let hash = index(query, "#");
    if (hash >= 0)
        query = substr(query, 0, hash);

    for (let pair in split(query, "&")) {
        if (pair == "")
            continue;
        let equals = index(pair, "=");
        let key = decode(equals >= 0 ? substr(pair, 0, equals) : pair);
        let value = equals >= 0 ? decode(substr(pair, equals + 1)) : "";
        if (key != "")
            result[key] = value;
    }
    return result;
}

return {
    decode,
    scheme,
    fragment,
    strip_fragment,
    strip_anchored_scheme,
    host,
    port,
    userinfo,
    path,
    query_params
};