#!/usr/bin/env perl

use strict;
use warnings;

use List::Util qw<min>;
use File::Find qw<find>;
use IPC::System::Simple qw<capture>;

@ARGV ge 1 || die "Usage: $0 [opts] <dir1> [<dir2> ...]

Opts:  --dislike|-d <path>    Dislike directory (reduce priority)
       --yes    |-y           Don't ask for confirmation when there's a single choice
       --debug                Print extra debug info
";

# CLI options
my $yes = 0;
my $debug = 0;
my @preferences;

my %sizes;
my %md5s;

sub fill_sizes {
    return if -d "$_"; # Skip directories

    my $size = capture("stat", "--printf=%s", $_);
    $sizes{$size} ||= [];
    push @{$sizes{$size}}, $File::Find::name;
}

sub closeness {
    my ($file, $dir) = @_;
    my ($diffpath) = Cwd::abs_path($file) =~ /^$dir(.*)$/;
    if ($diffpath) {
        return () = $diffpath =~ /\//g;
    } else {
        return -1;
    }
}

sub guess_best_choices {
    my @best_guesses = @_;

    foreach my $pref (@preferences) {
        if ($pref->{"type"} eq "dislike") {
            print STDERR "PREF: DISLIKE $pref->{dir}\n" if $debug;
            my $best_index = 0;
            my @files = @best_guesses;
            foreach my $file (@files) {
                my $dislikability = closeness($file, $pref->{"dir"});
                print STDERR "CLOSENESS($file, $pref->{dir}) = $dislikability\n" if $debug;
                if ($best_index != -1 && ($dislikability == -1 || $dislikability > $best_index)) {
                    @best_guesses = ($file);
                    $best_index = $dislikability;
                } elsif ($dislikability == $best_index) {
                    push @best_guesses, $file;
                }
                print STDERR "BEST: [$best_index] @best_guesses\n" if $debug;
            }
        }
    }

    return @best_guesses;
}

sub keep {
    my ($choice, @rest) = @_;
    my @delete = grep { $_ ne $choice } @rest;
    print STDERR "\tKEEPING $choice, DELETING @delete\n" if $debug;
    unlink foreach @delete;
}

print STDERR "Collecting file sizes...\n";
while (my $arg = shift) {
    if ($arg eq "-y" || $arg eq "--yes") {
        $yes = 1;
    } elsif ($arg eq "--debug") {
        $debug = 1;
    } elsif ($arg eq "-d" || $arg eq "--dislike") {
        push @preferences, {"type" => "dislike", "dir" => Cwd::abs_path(shift) . "/"};
    } else {
        find(\&fill_sizes, $arg);
    }
}

print STDERR "Computing md5s of files with same size...\n";
my @progress = (0, 0, scalar(keys(%sizes)));
foreach my $size (keys(%sizes)) {
    $progress[0]++;
    $progress[1] = 0;
    my @same_size_files = @{$sizes{$size}};
    next unless @same_size_files gt 1; # Discard unique sizes

    foreach my $file (@same_size_files) {
        $progress[1]++;
        print STDERR "$progress[0].$progress[1] / $progress[2]\r";
        STDERR->flush();

        my ($md5) = capture("md5sum", "-z", $file) =~ m/^([^ ]+)/;
        $md5s{$md5} ||= [];
        push @{$md5s{$md5}}, $file;
    }
}

print "\n";

foreach my $md5 (keys(%md5s)) {
    my @same_md5_files = @{$md5s{$md5}};
    next unless @same_md5_files gt 1; # Discard unique hashes

    print "\nFound duplicate files:\n";
    foreach my $file (@same_md5_files) {
        print "\t$file\n";
    }

    if (my @best_choices = guess_best_choices(@same_md5_files)) {
        if (@best_choices == 1) {
            my $best_choice = $best_choices[0];
            my $gogo = $yes;
            unless ($gogo) {
                print "\n\tBest choice is '$best_choice', do you want to delete the others? (yes/y) ";
                my $resp = <STDIN>;
                chomp $resp;
                $gogo = $resp eq "yes" || $resp eq "y";
            }
            if ($gogo) {
                keep($best_choice, @same_md5_files);
            }
        } else {
            print "\n\tPlease choose one to keep (or press 'enter' to skip):\n";
            for (my $i = 0; $i < @best_choices; $i++) {
                my $choice = $best_choices[$i];
                print "\t  [$i] $choice\n";
            }
            print "\t> ";
            my $index = <STDIN>;
            chomp $index;
            if ($index ne "") {
                $index = int($index);
                if ($index >= 0 && $index < @best_choices) {
                    keep($best_choices[$index], @same_md5_files);
                } else {
                    print "\n!!\t Index outside of range, ignoring\n";
                }
            }
        }
    }
}

printf STDERR "Done!\n";