module nxt.capitalization;

import std.traits : isSomeString;

/** Check if `s` starts with a capital letter followed by a lower letter.
 */
bool isCapitalizedSimple(S)(S s)
if (isSomeString!S)
{
    import std.range.primitives : empty, front, popFront;
    import std.uni : isUpper, isLower;

    if (s.empty) { return false; }

    const firstUpper = s.front.isUpper;
    if (!firstUpper) return false;
    s.popFront();

    if (s.empty) { return false; }
    return s.front.isLower;
}

@safe pure unittest
{
    assert(!`A`.isCapitalizedSimple);
    assert(!`a`.isCapitalizedSimple);
    assert(!`alpha`.isCapitalizedSimple);
    assert(!`ALPHA`.isCapitalizedSimple);
    assert(!`aThing`.isCapitalizedSimple);
    assert(`Alpha`.isCapitalizedSimple);
    assert(`Jack London`.isCapitalizedSimple);
}

/** Check if `s` starts with a capital letter followed by a lower letter.
 */
bool isCapitalizedASCIIEasy(S)(S s)
if (isSomeString!S)
{
    import std.ascii : isUpper, isLower;
    return (s.length >= 2 &&
            s[0].isUpper &&
            s[1].isLower);
}

@safe pure unittest
{
    assert(!`A`.isCapitalizedASCIIEasy);
    assert(!`a`.isCapitalizedASCIIEasy);
    assert(!`alpha`.isCapitalizedASCIIEasy);
    assert(!`ALPHA`.isCapitalizedASCIIEasy);
    assert(!`aThing`.isCapitalizedASCIIEasy);
    assert(`Alpha`.isCapitalizedASCIIEasy);
    assert(`Jack London`.isCapitalizedASCIIEasy);
}

import std.uni : isLower;

/** Check if `s` lowercased, that is only contains lower-case characters.
 */
bool isLowercased(S, alias pred = isLower)(S s)
if (isSomeString!S)
{
    import std.algorithm.searching : all;
    import std.traits : isNarrowString;
    import std.utf : byUTF;
    // TODO: functionize
    static if (isNarrowString!S)
    {
        return s.byUTF!dchar.all!(ch => pred(ch));
    }
    else
    {
        return t.map!(ch => pred(ch));
    }
}

///
@safe pure unittest
{
    assert(!`A`.isLowercased);
    assert(`a`.isLowercased);
    assert(!`Ä`.isLowercased);
    assert(`ä`.isLowercased);
}

/** Check if `s` uppercased, that is only contains upper-case characters.
 */
import std.uni : isUpper;
bool isUppercased(S, alias pred = isUpper)(S s)
if (isSomeString!S)
{
    import std.algorithm.searching : all;
    import std.traits : isNarrowString;
    import std.utf : byUTF;
    // TODO: functionize
    static if (isNarrowString!S)
    {
        return s.byUTF!dchar.all!(ch => pred(ch));
    }
    else
    {
        return t.map!(ch => pred(ch));
    }
}

@safe pure unittest
{
    assert(`A`.isUppercased);
    assert(!`a`.isUppercased);
    assert(`Ä`.isUppercased);
    assert(!`ä`.isUppercased);
}

/** Check if `s` has proper noun capitalization.
 *
 * That is, `s` starts with a capital letter followed by only lower letters.
 */
bool isCapitalized(S)(S s)
if (isSomeString!S)
{
    import std.range.primitives : empty, front, popFront;

    if (s.empty) { return false; }

    import std.ascii : isDigit;
    import std.uni : isUpper;
    const firstDigit = s.front.isDigit;
    const firstUpper = s.front.isUpper;

    if (!(firstDigit ||
          firstUpper))
        return false;

    s.popFront();

    if (s.empty)
    {
        return firstDigit;
    }
    else
    {
        import std.uni : isLower;
        import std.algorithm.searching : all;
        return s.all!(x => (x.isDigit ||
                            x.isLower));
    }
}

///
@safe pure unittest
{
    assert(!``.isCapitalized);
    assert(!`alpha`.isCapitalized);
    assert(!`ALPHA`.isCapitalized);
    assert(!`aThing`.isCapitalized);
    assert(`Alpha`.isCapitalized);
    assert(!`Jack London`.isCapitalized);
}

/** Return `true` if `s` has proper name capitalization, such as in
 * "Africa" or "South Africa".
 */
bool isProperNameCapitalized(S)(S s)
if (isSomeString!S)
{
    import nxt.splitter_ex : splitterASCII;
    import std.algorithm.comparison : among;
    import std.algorithm.searching : all;
    import std.ascii : isWhite;
    import std.uni : isUpper;
    size_t index = 0;
    foreach (const word; s.splitterASCII!(s => (s.isWhite || s == '-')))
    {
        const bool ok = ((index >= 1 &&
                          (word.all!(word => word.isUpper) || // Henry II
                           word.among!(`of`, `upon`))) ||
                         word.isCapitalized);
        if (!ok) { return false; }
        index += 1;
    }
    return true;
}

///
@safe pure unittest
{
    assert(!`alpha`.isProperNameCapitalized);
    assert(!`alpha centauri`.isProperNameCapitalized);
    assert(!`ALPHA`.isProperNameCapitalized);
    assert(!`ALPHA CENTAURI`.isProperNameCapitalized);
    assert(!`aThing`.isProperNameCapitalized);
    assert(`Alpha`.isProperNameCapitalized);
    assert(`Alpha Centauri`.isProperNameCapitalized);
    assert(`11104 Airion`.isProperNameCapitalized);
    assert(`New York City`.isProperNameCapitalized);
    assert(`1-Hexanol`.isProperNameCapitalized);
    assert(`11-Hexanol`.isProperNameCapitalized);
    assert(`22nd Army`.isProperNameCapitalized);
    assert(!`22nd army`.isProperNameCapitalized);
    assert(`2nd World War`.isProperNameCapitalized);
    assert(`Second World War`.isProperNameCapitalized);
    assert(`Värmland`.isProperNameCapitalized);
    assert(!`The big sky`.isProperNameCapitalized);
    assert(`Suur-London`.isProperNameCapitalized);
    assert(`Kingdom of Sweden`.isProperNameCapitalized);
    assert(`Stratford upon Avon`.isProperNameCapitalized);
    assert(`Henry II`.isProperNameCapitalized);
}