module nxt.ixes;

import std.meta : allSatisfy;
import std.range.primitives : isInputRange, isBidirectionalRange;

/** Get length of Common Prefix of $(D a) and $(D b).
    See_Also: http://forum.dlang.org/thread/bmbhovkgqomaidnyakvy@forum.dlang.org#post-bmbhovkgqomaidnyakvy:40forum.dlang.org
*/
auto commonPrefixLength(alias pred = "a == b", Rs...)(Rs rs)
if (rs.length >= 2 &&
	allSatisfy!(isInputRange, Rs))
{
    import std.algorithm.searching : commonPrefix;
    static if (rs.length == 2)
        return commonPrefix!pred(rs[0], rs[1]).length;
    else
    {
        static assert("TODO");
        import std.range : zip, StoppingPolicy;
        import std.algorithm : countUntil, count;
        const hit = zip(a, b).countUntil!(ab => ab[0] != ab[1]); // TODO: if countUntil return zip(a, b).count upon failre...
        return hit == -1 ? zip(a, b).count!pred : hit; // TODO: ..then this would not have been needed
    }
}

@safe pure unittest
{
    assert(commonPrefixLength(`åäö_`,
                              `åäö-`) == 6);
}

@safe pure nothrow unittest
{
    const x = [1, 2, 3, 10], y = [1, 2, 4, 10];
    void f() @safe pure nothrow @nogc
    {
        assert(commonPrefixLength(x, y) == 2);
    }
    f();
    assert(commonPrefixLength([1, 2, 3, 10],
                              [1, 2, 3]) == 3);
    assert(commonPrefixLength([1, 2, 3, 0, 4],
                              [1, 2, 3, 9, 4]) == 3);
}

/** Get length of Suffix of $(D a) and $(D b).
    See_Also: http://forum.dlang.org/thread/bmbhovkgqomaidnyakvy@forum.dlang.org#post-bmbhovkgqomaidnyakvy:40forum.dlang.org
*/
auto commonSuffixLength(Rs...)(Rs rs)
    if (rs.length == 2 &&
        allSatisfy!(isBidirectionalRange, Rs))
{
    import std.traits : isNarrowString;
    import std.range: retro;
    static if (isNarrowString!(typeof(rs[0])) &&
               isNarrowString!(typeof(rs[1])))
    {
        import std.string: representation;
        return commonPrefixLength(rs[0].representation.retro,
                                  rs[1].representation.retro);
    }
    else
        return commonPrefixLength(rs[0].retro,
                                  rs[1].retro);
}

@safe pure unittest
{
    const x = [1, 2, 3, 10, 11, 12];
    const y = [1, 2, 4, 10, 11, 12];
    void f() @safe pure nothrow @nogc
    {
        assert(commonPrefixLength(x, y) == 2);
    }
    f();
    assert(commonSuffixLength(x, y) == 3);
    assert(commonSuffixLength([10, 1, 2, 3],
                              [1, 2, 3]) == 3);
}

@safe pure unittest
{
    assert(commonSuffixLength(`_åäö`,
                              `-åäö`) == 6);
}

/** Get Count of Prefix of $(D a) and $(D b).
    See_Also: http://forum.dlang.org/thread/bmbhovkgqomaidnyakvy@forum.dlang.org#post-bmbhovkgqomaidnyakvy:40forum.dlang.org
*/
auto commonPrefixCount(alias pred = "a == b", Rs...)(Rs rs)
if (rs.length == 2 &&
	allSatisfy!(isInputRange, Rs))
{
    import std.algorithm.searching : commonPrefix, count;
    import std.traits : isNarrowString;
    static if (isNarrowString!(typeof(rs[0])) &&
               isNarrowString!(typeof(rs[1])))
    {
        import std.utf: byDchar;
        return commonPrefix!pred(rs[0].byDchar,
                                 rs[1].byDchar).count;
    }
    else
        return commonPrefix!pred(rs[0], rs[1]).count;
}

@safe pure unittest
{
    assert(commonPrefixCount([1, 2, 3, 10],
                             [1, 2, 3]) == 3);
    assert(commonPrefixCount(`åäö_`,
                             `åäö-`) == 3);
}

/** Get Common Suffix of $(D a) and $(D b).
    TODO: Copy implementation of commonPrefix into commonSuffix to splitter
*/
auto commonSuffix(Rs...)(Rs rs)
if (rs.length == 2 &&
	allSatisfy!(isBidirectionalRange, Rs))
{
    import std.range : retro;
    import std.array : array;
    import std.algorithm.searching : commonPrefix;
    return commonPrefix(rs[0].retro,
                        rs[1].retro).array.retro;
}

@safe pure unittest
{
    import std.algorithm.comparison : equal;
    assert(equal(commonSuffix(`_åäö`,
                              `-åäö`), `åäö`));
}

// @safe pure unittest
// {
//     import std.algorithm.comparison : equal;
//     import nxt.splitter_ex : splitterASCIIAmong;
//     import std.range : retro;
//     import std.range.primitives : ElementType;
//     import std.array : array;
//     assert(equal(commonSuffix(`_å-ä-ö`,
//                               `-å-ä-ö`).retro.splitterASCIIAmong!('-').array, // TODO: how should this be solved?
//                  [`ö`, `ä`, `å`]));
// }

/** Get Count of Common Suffix of $(D a) and $(D b).
    See_Also: http://forum.dlang.org/thread/bmbhovkgqomaidnyakvy@forum.dlang.org#post-bmbhovkgqomaidnyakvy:40forum.dlang.org
*/
auto commonSuffixCount(alias pred = "a == b", Rs...)(Rs rs)
if (rs.length == 2 &&
	allSatisfy!(isBidirectionalRange, Rs))
{
    import std.range : retro;
    return commonPrefixCount!pred(rs[0].retro,
                                  rs[1].retro);
}

@safe pure unittest
{
    assert(commonSuffixCount(`_`, `-`) == 0);
    assert(commonSuffixCount(`_å`, `-å`) == 1);
    assert(commonSuffixCount(`_åä`, `-åä`) == 2);
    assert(commonSuffixCount(`_åäö`, `-åäö`) == 3);

    import std.algorithm.comparison : among;
    assert(commonSuffixCount!((a, b) => (a == b && a == 'ö'))(`_åäö`, `-åäö`) == 1);
    assert(commonSuffixCount!((a, b) => (a == b && a.among!('ä', 'ö')))(`_åäö`, `-åäö`) == 2);
}

/** Get length of Common Prefix of rs $(D rs).
    See_Also: http://forum.dlang.org/thread/bmbhovkgqomaidnyakvy@forum.dlang.org#post-bmbhovkgqomaidnyakvy:40forum.dlang.org
*/
// auto commonPrefixLengthN(R...)(R rs) if (rs.length == 2)
// {
//     import std.range: zip;
//     return zip!((a, b) => a != b)(rs);
// }

// unittest
// {
//     assert(commonPrefixLengthN([1, 2, 3, 10],
//                               [1, 2, 4, 10]) == 2);
// }