use strict;
use warnings;

use File::Copy;     # copy files
use File::Spec;     # file path manipulation
use Term::ReadKey;  # read 'any key' for pause

# do some stuff.

archive_child_support_files();

# do other stuff.



# Copy child support files from foo to bar.  Display an on screen warning if
# any errors occur.
sub archive_child_support_files {
    my ($count, $errors) = copy_files( 'foo', 'bar', '.ls' );

    if ( $count or @$errors ) {
        my $error_count = @$errors;
        my $message = join "\n", 
            '',
            "Copied $count Files.",
            "Errors Detected: $error_count",
            format_errors($errors);

        my $pause = $error_count ? 1 : 0;
        my $clear = $error_count ? 1 : 0;
        my $color = $error_count ? 'cf' : '';

        display_message( $message, $clear, $pause, $color );
    }
    else {
        my $no_files_msg = <<'END_MSG';

No files were archived.

Please verify.


END_MSG
        display_message( $no_files_msg, 1, 1, 'cf' );    
    }
}


# Copy files that match extension pattern from the source to the target
# directories.
# Returns the number of files copied and an array ref containing error informaton.
# Error array structure:
#   [  [ source file 1, destination file 1, error message 1 ],
#      [ source file 2, destination file 2, error message 2 ],
#      ...
#      [ source file n, destination file n, error message n ],
#   ]
sub copy_files {
    my $source_dir = shift; # Source directory.  Copy from here.
    my $target_dir = shift; # Target directory.  Copy to here.
    my $extension  = shift; # File extension.

    # Read the source dir.  Return if error.
    opendir( my $source_dirh, $source_dir ) 
        or return 0, [[$source_dir, $target_dir, "Unable to read source directory - $!"]]; 

    # Get list of files to copy
    my @files_to_copy = grep {
        /\Q$extension\E$/
    } readdir $source_dirh;

    # Copy the files.
    my @errors;  #keep track of errors detected here.
    foreach my $file_name ( @files_to_copy ) {
        my $target = File::Spec->catfile( $target_dir, $file_name );
        my $source = File::Spec->catfile( $source_dir, $file_name );

        print "Copying $source to $target\n";

        if ( -e $target ) {
            push @errors, [ $source, $target, 'Target file exists.' ];

        }
        else {
            copy( $source, $target ) 
                or push @errors, [ $source, $target, $! ];
        }

    }

    return scalar @files_to_copy, \@errors;
}


# display a message on the screen.
# handles optional clear screen and color changes.
sub display_message {
    my $message = shift;    # Text to print.
    my $clear   = shift;    # Boolean.  If true clear screen
    my $pause   = shift;    # Boolean.  If true pause
    my $color   = shift;    # Text.  Color spec as per dos color command.

    system('cls') if $clear;
    system("color $color") if $color;

    print $message;

    pause() if $pause;

}

# Format the errors data structure for display.
# See copy_files() for information on the error structure.
sub format_errors {
    my $errors = shift || [];

    my $text = join "\n\n", map {
        "\tSource: $_->[0]\n\tTarget: $_->[1]\n\tError: $_->[2]\n"
    } @$errors;

    return $text;

}


# Print press any key and block until input is received.
sub pause {
    print "\nPress any key to continue.\n";

    ReadMode(4);
    ReadKey(0);

    system( 'color 0A' );

    return;
}