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#! /usr/local/bin/nom

use Test;

role Event {
    method Str {
        sub event() { self.^name }
        sub name($attr) { $attr.name.substr(2) }
        sub value($attr) { $attr.get_value(self) }

        "{event}[{map { ":{name $_}<{value $_}>" }, self.^attributes}]"
    }
}

class Hanoi::DiskMoved does Event {
    has $.disk;
    has $.source;
    has $.target;
}

class Hanoi::AchievementUnlocked does Event {
}

class Hanoi::AchievementLocked does Event {
}

class Hanoi::DiskRemoved does Event {
    has $.disk;
    has $.source;
}

class Hanoi::DiskAdded does Event {
    has $.disk;
    has $.target;
}

class X::Hanoi is Exception {
}

class X::Hanoi::LargerOnSmaller is X::Hanoi {
    has $.larger;
    has $.smaller;

    method message($_:) {
        "Cannot put the {.larger} on the {.smaller}"
    }
}

class X::Hanoi::NoSuchRod is X::Hanoi {
    has $.rod;
    has $.name;

    method message($_:) {
        "No such {.rod} rod '{.name}'"
    }
}

class X::Hanoi::RodHasNoDisks is X::Hanoi {
    has $.name;

    method message($_:) {
        "Cannot move from the {.name} rod because there is no disk there"
    }
}

class X::Hanoi::CoveredDisk is X::Hanoi {
    has $.disk;
    has @.covered_by;

    method message($_:) {
        sub last_and(@things) {
            map { "{'and ' if $_ == @things.end}@things[$_]" }, ^@things
        }
        my $disklist = @.covered_by > 1
            ?? join ', ', last_and map { "the $_" }, @.covered_by
            !! "the @.covered_by[0]";
        "Cannot move the {.disk}: it is covered by $disklist"
    }
}

class X::Hanoi::ForbiddenDiskRemoval is X::Hanoi {
    has $.disk;

    method message($_:) {
        "Removing the {.disk} is forbidden"
    }
}

class X::Hanoi::DiskHasBeenRemoved is X::Hanoi {
    has $.disk;
    has $.action;

    method message($_:) {
        "Cannot {.action} the {.disk} because it has been removed"
    }
}

class X::Hanoi::NoSuchDisk is X::Hanoi {
    has $.disk;
    has $.action;

    method message($_:) {
        "Cannot {.action} a {.disk} because there is no such disk"
    }
}

class X::Hanoi::DiskAlreadyOnARod is X::Hanoi {
    has $.disk;

    method message($_:) {
        "Cannot add the {.disk} because it is already on a rod"
    }
}

class Hanoi::Game {
    my @disks = <tiny small medium large huge> X~ ' disk';
    my %size_of = @disks Z 1..5;

    has %!state =
        left => [reverse @disks],
        middle => [],
        right => [],
    ;

    has $!achievement = 'locked';

    method move($source is copy, $target) {
        if $source eq any @disks {
            $source = self!rod_with_disk($source, 'move');
        }
        die X::Hanoi::NoSuchRod.new(:rod<source>, :name($source))
            unless %!state.exists($source);
        die X::Hanoi::NoSuchRod.new(:rod<target>, :name($target))
            unless %!state.exists($target);
        my @source_rod := %!state{$source};
        die X::Hanoi::RodHasNoDisks.new(:name($source))
            unless @source_rod;
        my @target_rod := %!state{$target};
        my $moved_disk = @source_rod[*-1];
        if @target_rod {
            my $covered_disk = @target_rod[*-1];
            if %size_of{$moved_disk} > %size_of{$covered_disk} {
                die X::Hanoi::LargerOnSmaller.new(
                    :larger($moved_disk),
                    :smaller($covered_disk)
                );
            }
        }
        my @events
            = Hanoi::DiskMoved.new(:disk($moved_disk), :$source, :$target);
        if %!state<right> == @disks-1
           && $target eq 'right'
           && $!achievement eq 'locked' {
            @events.push(Hanoi::AchievementUnlocked.new);
        }
        if $moved_disk eq 'small disk' && $!achievement eq 'unlocked' {
            @events.push(Hanoi::AchievementLocked.new);
        }
        self!apply($_) for @events;
        return @events;
    }

    method remove($disk) {
        die X::Hanoi::NoSuchDisk.new(:action<remove>, :$disk)
            unless $disk eq any(@disks);
        my $source = self!rod_with_disk($disk, 'remove');
        die X::Hanoi::ForbiddenDiskRemoval.new(:$disk)
            unless $disk eq 'tiny disk';
        my @events = Hanoi::DiskRemoved.new(:$disk, :$source);
        self!apply($_) for @events;
        return @events;
    }

    method add($disk, $target) {
        die X::Hanoi::NoSuchDisk.new(:action<add>, :$disk)
            unless $disk eq any(@disks);
        die X::Hanoi::NoSuchRod.new(:rod<target>, :name($target))
            unless %!state.exists($target);
        die X::Hanoi::DiskAlreadyOnARod.new(:$disk)
            if grep { $disk eq any(@$_) }, %!state.values;
        my @events = Hanoi::DiskAdded.new(:$disk, :$target);
        if %!state<right> == @disks-1
           && $target eq 'right'
           && $!achievement eq 'locked' {
            @events.push(Hanoi::AchievementUnlocked.new);
        }
        self!apply($_) for @events;
        return @events;
    }

    # The method will throw X::Hanoi::CoveredDisk if the disk is not topmost,
    # or X::Hanoi::DiskHasBeenRemoved if the disk isn't found on any rod.
    method !rod_with_disk($disk, $action) {
        for %!state -> (:key($rod), :value(@disks)) {
            if $disk eq any(@disks) {
                sub smaller_disks {
                    grep { %size_of{$_} < %size_of{$disk} }, @disks;
                }
                die X::Hanoi::CoveredDisk.new(:$disk, :covered_by(smaller_disks))
                    unless @disks[*-1] eq $disk;
                return $rod;
            }
        }
        die X::Hanoi::DiskHasBeenRemoved.new(:$disk, :$action);
    }

    # RAKUDO: private multimethods NYI
    method !apply(Event $_) {
        when Hanoi::DiskMoved {
            my @source_rod := %!state{.source};
            my @target_rod := %!state{.target};
            @target_rod.push( @source_rod.pop );
        }
        when Hanoi::AchievementUnlocked {
            $!achievement = 'unlocked';
        }
        when Hanoi::AchievementLocked {
            $!achievement = 'locked';
        }
        when Hanoi::DiskRemoved {
            my @source_rod := %!state{.source};
            @source_rod.pop;
        }
        when Hanoi::DiskAdded {
            my @target_rod := %!state{.target};
            @target_rod.push(.disk);
        }
    }
}

multi MAIN('hanoi') {
    my Hanoi::Game $game .= new;
    my @disks = <tiny small medium large huge> X~ ' disk';
    my @rods = <left middle right>;

    sub params($method) {
        $method.signature.params
            ==> grep { .positional && !.invocant }
            ==> map { .name.substr(1) }
    }
    my %commands = map { $^m.name => params($m) }, $game.^methods;
    my @all_events;

    sub print_board() {
        my %s =
            left => [reverse @disks],
            middle => [],
            right => [],
        ;
        for @all_events {
            when Hanoi::DiskMoved { %s{.target}.push: %s{.source}.pop }
            when Hanoi::DiskRemoved { %s{.source}.pop }
            when Hanoi::DiskAdded { %s{.target}.push: .disk }
        }

        say "";
        for reverse ^6 -> $line {
            my %disks =
                'none' => ' | ',
                'tiny disk' => ' = ',
                'small disk' => ' === ',
                'medium disk' => ' ===== ',
                'large disk' => ' ======= ',
                'huge disk' => ' ========= ',
            ;

            sub disk($rod) {
                my $disk = %s{$rod}[$line] // 'none';
                %disks{ $disk };
            }

            say join ' ', map &disk, @rods;
        }
        say join '--', '-----------' xx @rods;
        say "";
    }

    print_board();
    loop {
        my $command = prompt('> ');
        unless defined $command {
            say "";
            last;
        }
        given lc $command {
            when 'q' | 'quit' { last }
            when 'h' | 'help' {
                say "Goal: get all the disks to the right rod.";
                say "You can never place a larger disk on a smaller one.";
                say "Available commands:";
                for %commands.sort {
                    say " {.key} {map { "<$_>" }, .value.list}";
                }
                say " q[uit]";
                say " h[elp]";
                say " s[how]";
                say "";
                say "Disks: ", join ', ', @disks;
                say "Rods: ", join ', ', @rods;
            }
            when 's' | 'show' { print_board() }

            sub munge { $^s.subst(/' disk'»/, '_disk', :g) }
            sub unmunge { $^s.subst(/'_disk'»/, ' disk', :g) }
            my $verb = .&munge.words[0].&unmunge;
            my @args = .&munge.words[1..*]».&unmunge;
            when %commands.exists($verb) {
                my @req_args = %commands{$verb}.list;
                when @args != @req_args {
                    say "You passed in {+@args} arguments, but $verb requires {+@req_args}.";
                    say "The arguments are {map { "<$_>" }, @req_args}.";
                    say "'help' for more help.";
                }
                my @events = $game."$verb"(|@args);
                push @all_events, @events;
                print_board();
                for @events {
                    when Hanoi::AchievementUnlocked { say "Achievement unlocked!" }
                    when Hanoi::AchievementLocked { say "Achievement locked!" }
                }
                CATCH {
                    when X::Hanoi { say .message }
                }
            }

            default {
                say "Sorry, the game doesn't recognize that command. :/";
                say "'help' if you're confused as well.";
            }
        }
        say "";
    }
}

sub throws_exception(&code, $ex_type, $message, &followup?) {
    &code();
    ok 0, $message;
    if &followup {
        diag 'Not running followup because an exception was not triggered';
    }
    CATCH {
        default {
            ok 1, $message;
            my $type_ok = $_.WHAT === $ex_type;
            ok $type_ok , "right exception type ({$ex_type.^name})";
            if $type_ok {
                &followup($_);
            } else {
                diag "Got: {$_.WHAT.gist}\n"
                    ~"Expected: {$ex_type.gist}";
                diag "Exception message: $_.message()";
                diag 'Not running followup because type check failed';
            }
        }
    }
}

multi MAIN('test', 'hanoi') {
    {
        my $game = Hanoi::Game.new();

        is $game.move('left', 'middle'),
           Hanoi::DiskMoved.new(
                :disk('tiny disk'),
                :source<left>,
                :target<middle>
           ),
           'moving a disk (+)';

        throws_exception
            { $game.move('left', 'middle') },
            X::Hanoi::LargerOnSmaller,
            'moving a disk (-) larger disk on smaller',
            {
                is .larger, 'small disk', '.larger attribute';
                is .smaller, 'tiny disk', '.smaller attribute';
                is .message,
                   'Cannot put the small disk on the tiny disk',
                   '.message attribute';
            };

        throws_exception
            { $game.move('gargle', 'middle') },
            X::Hanoi::NoSuchRod,
            'moving a disk (-) no such source rod',
            {
                is .rod, 'source', '.rod attribute';
                is .name, 'gargle', '.name attribute';
                is .message,
                   q[No such source rod 'gargle'],
                   '.message attribute';
            };

        throws_exception
            { $game.move('middle', 'clown') },
            X::Hanoi::NoSuchRod,
            'moving a disk (-) no such target rod',
            {
                is .rod, 'target', '.rod attribute';
                is .name, 'clown', '.name attribute';
                is .message,
                   q[No such target rod 'clown'],
                   '.message attribute';
            };

        throws_exception
            { $game.move('right', 'middle') },
            X::Hanoi::RodHasNoDisks,
            'moving a disk (-) rod has no disks',
            {
                is .name, 'right', '.name attribute';
                is .message,
                   q[Cannot move from the right rod because there is no disk there],
                   '.message attribute';
            };
    }

    {
        my $game = Hanoi::Game.new();

        multi hanoi_moves($source, $, $target, 1) {
            # A single disk, easy; just move it directly.
            $source, 'to', $target
        }
        multi hanoi_moves($source, $helper, $target, $n) {
            # $n-1 disks on to; move them off to the $helper rod first...
            hanoi_moves($source, $target, $helper, $n-1),
            # ...then move over the freed disk at the bottom...
            hanoi_moves($source, $helper, $target, 1),
            # ...and finally move the rest from $helper to $target.
            hanoi_moves($helper, $source, $target, $n-1)
        }

        # Let's play out the thing to the end. 32 moves.
        my @moves = hanoi_moves("left", "middle", "right", 5);
        # RAKUDO: .splice doesn't do WhateverCode yet: wanted *-3
        my @last_move = @moves.splice(@moves.end-2);

        lives_ok {
            for @moves -> $source, $, $target {
                my ($event, @rest) = $game.move($source, $target);
                die "Unexpected event type: {$event.name}"
                    unless $event ~~ Hanoi::DiskMoved;
                die "Unexpected extra events: @rest"
                    if @rest;
            }
        }, 'making all the moves to the end of the game works';

        {
            my ($source, $, $target) = @last_move;
            is $game.move($source, $target), (
                Hanoi::DiskMoved.new(:disk('tiny disk'), :$source, :$target),
                Hanoi::AchievementUnlocked.new(),
            ), 'putting all disks on the right rod unlocks achievement';

            $game.move($target, $source);
            is $game.move($source, $target), (
                Hanoi::DiskMoved.new(:disk('tiny disk'), :$source, :$target),
            ), 'moving things back and forth does not unlock achievement again';
        }

        {
            $game.move('right', 'middle');
            is $game.move(my $source = 'right', my $target = 'left'), (
                Hanoi::DiskMoved.new(:disk('small disk'), :$source, :$target),
                Hanoi::AchievementLocked.new(),
            ), 'removing two disks from the right rod locks achievement';
        }

        {
            $game.move('left', 'right');
            $game.remove('tiny disk');
            is $game.add(my $disk = 'tiny disk', my $target = 'right'), (
                Hanoi::DiskAdded.new(:$disk, :$target),
                Hanoi::AchievementUnlocked.new(),
            ), 'you can also unlock achievement by adding the disk';
        }
    }

    {
        my $game = Hanoi::Game.new();

        is $game.move('tiny disk', my $target = 'middle'),
           Hanoi::DiskMoved.new(:disk('tiny disk'), :source<left>, :$target),
           'naming source disk instead of the rod (+)';
    }

    {
        my $game = Hanoi::Game.new();

        throws_exception
            { $game.move('large disk', 'right') },
            X::Hanoi::CoveredDisk,
            'naming source disk instead of the rod (-)',
            {
                is .disk, 'large disk', '.disk attribute';
                is .covered_by, ['medium disk', 'small disk', 'tiny disk'],
                    '.covered_by attribute';
                is .message,
                   'Cannot move the large disk: it is covered by '
                   ~ 'the medium disk, the small disk, and the tiny disk',
                   '.message attribute';
            };
    }

    {
        my $game = Hanoi::Game.new();

        throws_exception
            { $game.move('small disk', 'right') },
            X::Hanoi::CoveredDisk,
            'naming source disk instead of the rod (-) no and for one-item lists',
            {
                is .message,
                   'Cannot move the small disk: it is covered by the tiny disk',
                   '.message attribute';
            };
    }

    {
        my $game = Hanoi::Game.new();

        is $game.remove('tiny disk'),
           Hanoi::DiskRemoved.new(:disk('tiny disk'), :source<left>),
           'removing a disk (+)';

        throws_exception
            { $game.remove('small disk') },
            X::Hanoi::ForbiddenDiskRemoval,
            'removing a disk (-) removing disk is forbidden',
            {
                is .disk, 'small disk', '.disk attribute';
                is .message,
                   'Removing the small disk is forbidden',
                   '.message attribute';
            };

        throws_exception
            { $game.remove('medium disk') },
            X::Hanoi::CoveredDisk,
            'removing a disk (-) the disk is covered',
            {
                is .disk, 'medium disk', '.disk attribute';
                is .covered_by, ['small disk'],
                    '.covered_by attribute';
            };

        $game.move('small disk', 'middle');
        throws_exception
            { $game.remove('medium disk') },
            X::Hanoi::ForbiddenDiskRemoval,
            'removing a disk (-) uncovered, removal is still forbidden',
            {
                is .disk, 'medium disk', '.disk attribute';
            };
    }

    {
        my $game = Hanoi::Game.new();

        $game.remove('tiny disk');

        throws_exception
            { $game.remove('tiny disk') },
            X::Hanoi::DiskHasBeenRemoved,
            'removing a disk (-) the disk had already been removed',
            {
                is .disk, 'tiny disk', '.disk attribute';
                is .action, 'remove', '.action attribute';
                is .message,
                   'Cannot remove the tiny disk because it has been removed',
                   '.message attribute';
            };

        throws_exception
            { $game.move('tiny disk', 'middle') },
            X::Hanoi::DiskHasBeenRemoved,
            'moving a disk (-) the disk had already been removed',
            {
                is .disk, 'tiny disk', '.disk attribute';
                is .action, 'move', '.action attribute';
                is .message,
                    'Cannot move the tiny disk because it has been removed',
                    '.message attribute';
            };

        throws_exception
            { $game.add('tiny disk', 'pineapple') },
            X::Hanoi::NoSuchRod,
            'moving a disk (-) the rod does not exist',
            {
                is .rod, 'target', '.rod attribute';
                is .name, 'pineapple', '.name attribute';
            };

        is $game.add('tiny disk', 'left'),
           Hanoi::DiskAdded.new(:disk('tiny disk'), :target<left>),
           'adding a disk (+)';

        throws_exception
            { $game.add('humongous disk', 'middle') },
            X::Hanoi::NoSuchDisk,
            'adding a disk (-) there is no such disk',
            {
                is .action, 'add', '.action attribute';
                is .disk, 'humongous disk', '.disk attribute';
                is .message,
                    'Cannot add a humongous disk because there is no such disk',
                    '.message attribute';
            };

        throws_exception
            { $game.add('tiny disk', 'right') },
            X::Hanoi::DiskAlreadyOnARod,
            'adding a disk (-) the disk is already on a rod',
            {
                is .disk, 'tiny disk', '.disk attribute';
                is .message,
                    'Cannot add the tiny disk because it is already on a rod',
                    '.message attribute';
            };
    }

    {
        my $game = Hanoi::Game.new();

        throws_exception
            { $game.remove('masakian disk') },
            X::Hanoi::NoSuchDisk,
            'removing a disk (-) the disk does not exist',
            {
                is .action, 'remove', '.action attribute';
                is .disk, 'masakian disk', '.disk attribute';
                is .message,
                   'Cannot remove a masakian disk because there is no such disk',
                   '.message attribute';
            };

    }

    done;
}
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