#!/usr/bin/env perl

require 5.010;
use warnings FATAL => 'all';
use feature 'say';
use Stats::LikeR;
use Test::Exception; # die_ok
use Test::More;
use Test::LeakTrace 'no_leaks_ok';
use Devel::Confess 'color';

# -------------------------------------------------------------------
# Hash-of-Hashes — return type
# -------------------------------------------------------------------

ok( ref(transpose({ a => { 'x' => 1 } })) eq 'HASH', 'transpose HoH: returns a hash ref' );

# -------------------------------------------------------------------
# Hash-of-Hashes — shapes & data
# -------------------------------------------------------------------

my $hoh = { a => { 'x' => 1, 'y' => 2 }, b => { 'x' => 3, 'y' => 4 } };
is_deeply(
  transpose($hoh),
  { 'x' => { a => 1, b => 3 }, 'y' => { a => 2, b => 4 } },
  'transpose HoH: basic square'
);

is_deeply(
  transpose({ a => { 'x' => 10 }, b => { 'x' => 20 }, c => { 'x' => 30 } }),
  { 'x' => { a => 10, b => 20, c => 30 } },
  'transpose HoH: tall (more rows than cols)'
);

is_deeply(
  transpose({ a => { 'x' => 1, 'y' => 2, z => 3 } }),
  { 'x' => { a => 1 }, 'y' => { a => 2 }, z => { a => 3 } },
  'transpose HoH: wide (more cols than rows)'
);

# sparse: row 'a' has {x,y}, row 'b' has {x,z} — no shared expectation of uniform keys
is_deeply(
  transpose({ a => { 'x' => 1, 'y' => 2 }, b => { 'x' => 3, z => 4 } }),
  { 'x' => { a => 1, b => 3 }, 'y' => { a => 2 }, z => { b => 4 } },
  'transpose HoH: non-uniform (sparse) inner keys'
);

is_deeply(
  transpose({ r1 => { c1 => 'foo', c2 => 'bar' }, r2 => { c1 => 'baz', c2 => 'qux' } }),
  { c1 => { r1 => 'foo', r2 => 'baz' }, c2 => { r1 => 'bar', r2 => 'qux' } },
  'transpose HoH: string values preserved'
);

{
    # undef in a slot should round-trip
    is_deeply(
        transpose({ a => { 'x' => 1, 'y' => undef }, b => { 'x' => undef, 'y' => 4 } }),
        { 'x' => { a => 1, b => undef }, 'y' => { a => undef, b => 4 } },
        'transpose HoH: undef values preserved'
    );
}

is_deeply( transpose({}),                  {},  'transpose HoH: empty outer hash' );
is_deeply( transpose({ a => {}, b => {} }), {}, 'transpose HoH: empty inner hashes collapse to empty output' );

{
    my $hoh = { a => { 'x' => 1, 'y' => 2 }, b => { 'x' => 3, 'y' => 4 } };
    is_deeply( transpose(transpose($hoh)), $hoh, 'transpose HoH: double transpose is identity' );
}

{
    my $input = { a => { 'x' => 1 }, b => { 'x' => 2 } };
    my $snap  = { a => { 'x' => 1 }, b => { 'x' => 2 } };
    transpose($input);
    is_deeply( $input, $snap, 'transpose HoH: input not mutated' );
}

# -------------------------------------------------------------------
# Hash-of-Hashes — errors
# -------------------------------------------------------------------

dies_ok { transpose(42)              } 'transpose: scalar input dies';
dies_ok { transpose(\"foo")          } 'transpose: scalar ref input dies';
dies_ok { transpose({ a => 1 })      } 'transpose HoH: inner scalar dies';
dies_ok { transpose({ a => [1, 2] }) } 'transpose HoH: inner array ref dies';

# -------------------------------------------------------------------
# Array-of-Arrays — return type
# -------------------------------------------------------------------

ok( ref(transpose([[1,2],[3,4]])) eq 'ARRAY', 'transpose AoA: returns an array ref' );

# -------------------------------------------------------------------
# Array-of-Arrays — shapes & data
# -------------------------------------------------------------------

is_deeply( transpose([[1,2,3],[4,5,6]]),           [[1,4],[2,5],[3,6]],         'transpose AoA: 2x3' );
is_deeply( transpose([[1,2],[3,4],[5,6]]),         [[1,3,5],[2,4,6]],           'transpose AoA: 3x2' );
is_deeply( transpose([[1,2,3],[4,5,6],[7,8,9]]),   [[1,4,7],[2,5,8],[3,6,9]],   'transpose AoA: 3x3 square' );
is_deeply( transpose([[1,2,3]]),                   [[1],[2],[3]],               'transpose AoA: single row' );
is_deeply( transpose([[1],[2],[3]]),               [[1,2,3]],                   'transpose AoA: single column' );
is_deeply( transpose([[42]]),                      [[42]],                      'transpose AoA: 1x1' );
is_deeply( transpose([]),                          [],                          'transpose AoA: empty outer array' );
is_deeply( transpose([[],[]]),                     [],                          'transpose AoA: empty inner arrays' );

{
    is_deeply(
        transpose([['foo','bar'],['baz','qux']]),
        [['foo','baz'],['bar','qux']],
        'transpose AoA: string values preserved'
    );
}

{
    # undef in a slot should round-trip, not be fabricated as 0 or ''
    is_deeply(
        transpose([[1, undef],[2, 3]]),
        [[1, 2],[undef, 3]],
        'transpose AoA: undef values preserved'
    );
}

{
    # Physical array holes (uninitialized slots, where av_fetch returns NULL)
    my @row1; $row1[2] = 3; # [undef, undef, 3]
    my @row2; $row2[2] = 6; # [undef, undef, 6]
    is_deeply( 
        transpose([\@row1, \@row2]), 
        [[undef, undef], [undef, undef], [3, 6]], 
        'transpose AoA: inner array physical holes coalesce to undef' 
    );
}

{
    my $aoa = [[1,2,3],[4,5,6]];
    is_deeply( transpose(transpose($aoa)), $aoa, 'transpose AoA: double transpose is identity' );
}

{
    my $input = [[1,2],[3,4]];
    my $snap  = [[1,2],[3,4]];
    transpose($input);
    is_deeply( $input, $snap, 'transpose AoA: input not mutated' );
}

# -------------------------------------------------------------------
# Shallow Copy / Aliasing validation
# -------------------------------------------------------------------

{
    my $deep_ref = { val => 1 };
    my $input    = [[ $deep_ref ]];
    my $output   = transpose($input);
    
    # Modifying the deep reference in the transposed structure...
    $output->[0][0]{val} = 42;
    
    # ...should affect the original, because transpose does a shallow copy of values.
    is( $input->[0][0]{val}, 42, 'transpose: performs a shallow copy of nested reference values' );
}

# -------------------------------------------------------------------
# Perl Magic & Objects
# -------------------------------------------------------------------

{
    # Triggering Perl 'magic' on scalar extraction
    my $str1 = "abc"; my $str2 = "def";
    my $str3 = "ghi"; my $str4 = "jkl";
    
    my $aoa = [
        [ substr($str1, 1, 1), substr($str2, 1, 1) ],
        [ substr($str3, 1, 1), substr($str4, 1, 1) ]
    ];
    
    # If SvGETMAGIC is missing, this might fetch garbage SVs instead of 'b', 'e', etc.
    is_deeply( 
        transpose($aoa), 
        [['b','h'], ['e','k']], 
        'transpose AoA: properly evaluates magical scalars' 
    );
}

# -------------------------------------------------------------------
# Array-of-Arrays — errors
# -------------------------------------------------------------------

dies_ok { transpose([1, 2, 3])            } 'transpose AoA: inner scalars die';
dies_ok { transpose([{a => 1},{b => 2}])  } 'transpose AoA: inner hash refs die';
dies_ok { transpose([[1,2],[3]])          } 'transpose AoA: ragged array (short row) dies';
dies_ok { transpose([[1],[2,3]])          } 'transpose AoA: ragged array (long row) dies';

{
    my @bad_arr;
    $bad_arr[1] = [1, 2]; # Hole at index 0
    dies_ok { transpose(\@bad_arr) } 'transpose AoA: missing outer row (physical hole) dies';
}

# -------------------------------------------------------------------
# Memory leaks
# -------------------------------------------------------------------

no_leaks_ok {
	eval { transpose({ a => { 'x' => 1, 'y' => 2 }, b => { 'x' => 3, 'y' => 4 } }) }
} 'transpose HoH: no memory leaks' unless $INC{'Devel/Cover.pm'};

no_leaks_ok {
	eval { transpose({ a => { 'x' => 1, 'y' => 2 }, b => { 'x' => 3, z => 4 } }) }
} 'transpose HoH: no leaks with sparse inner keys' unless $INC{'Devel/Cover.pm'};

no_leaks_ok {
	eval { transpose([[1,2,3],[4,5,6],[7,8,9]]) }
} 'transpose AoA: no memory leaks' unless $INC{'Devel/Cover.pm'};

no_leaks_ok {
    # Testing leaks with explicitly scoped assignment to catch RETVAL mortal leaks
    my $result;
	eval { $result = transpose([[1,2],[3,4]]); };
} 'transpose AoA: no memory leaks on scoped assignment (RETVAL check)' unless $INC{'Devel/Cover.pm'};

no_leaks_ok {
	eval { transpose(42) }
} 'transpose: no leaks on invalid input' unless $INC{'Devel/Cover.pm'};

no_leaks_ok {
	eval { transpose({ a => 42 }) }
} 'transpose HoH: no leaks on invalid inner value' unless $INC{'Devel/Cover.pm'};

no_leaks_ok {
	eval { transpose([[1,2],[3]]) }
} 'transpose AoA: no leaks on ragged array' unless $INC{'Devel/Cover.pm'};

done_testing();
