Tinky

use Tinky;


# A class that will use the workflow
# it can have any attributes or methods
# required by your application

class Ticket does Tinky::Object {
    has Str $.ticket-number = (^100000).pick.fmt("%08d");
    has Str $.owner;
}

# Set up some states as required by the application
my $state-new         = Tinky::State.new(name => 'new');
my $state-open        = Tinky::State.new(name => 'open');
my $state-rejected    = Tinky::State.new(name => 'rejected');
my $state-in-progress = Tinky::State.new(name => 'in-progress');
my $state-stalled     = Tinky::State.new(name => 'stalled');
my $state-complete    = Tinky::State.new(name => 'complete');

# Each state has an 'enter-supply' and a 'leave-supply' which get the
# object which the state was applied to.

$state-rejected.enter-supply.act( -> $object { say "** sending rejected e-mail for Ticket '{ $object.ticket-number }' **"});

# Create some transitions to describe pre-determined change of state
# A method will be created on the Tinky::Object for each transition name

my $open              = Tinky::Transition.new(name => 'open', from => $state-new, to => $state-open);

# Where  more than one transition has the same name, the transition which matches the object's 
# current state will be use.
my $reject-new        = Tinky::Transition.new(name => 'reject', from => $state-new, to => $state-rejected);
my $reject-open       = Tinky::Transition.new(name => 'reject', from => $state-open, to => $state-rejected);
my $reject-stalled    = Tinky::Transition.new(name => 'reject', from => $state-stalled, to => $state-rejected);

my $stall-open        = Tinky::Transition.new(name => 'stall', from => $state-open, to => $state-stalled);
my $stall-progress    = Tinky::Transition.new(name => 'stall', from => $state-in-progress, to => $state-stalled);

# The transition supply allows specific logic for the transition to be performed

$stall-progress.supply.act( -> $object { say "** rescheduling tickets for '{ $object.owner }' on ticket stall **"});

my $unstall           = Tinky::Transition.new(name => 'unstall', from => $state-stalled, to => $state-in-progress);

my $take              = Tinky::Transition.new(name => 'take', from => $state-open, to => $state-in-progress);

my $complete-open     = Tinky::Transition.new(name => 'complete', from => $state-open, to => $state-complete);
my $complete-progress = Tinky::Transition.new(name => 'complete', from => $state-in-progress, to => $state-complete);

my @transitions = $open, $reject-new, $reject-open, $reject-stalled, $stall-open, $stall-progress, $unstall, $take, $complete-open, $complete-progress;

# The Workflow object allows the relation between states and transitions to be calculate
# and generates the methods that will be applied to the ticket object.  The initial-state
# will be applied to the object if there is no existing state on the state.
my $workflow = Tinky::Workflow.new(:@transitions, name => 'ticket-workflow', initial-state => $state-new );

# The workflow aggregates the Supplies of the transitions and the states.
# This could be to a logging subsystem for instance. 

$workflow.transition-supply.act(-> ($trans, $object) { say "Ticket '{ $object.ticket-number }' went from { $trans.from.name }' to '{ $trans.to.name }'" });

# The final-supply emits the state and the object when a state is reached where there are no
# further transitions available

$workflow.final-supply.act(-> ( $state, $object) { say "** updating performance stats with Ticket '{ $object.ticket-number }' entered State '{ $state.name }'" });

# Create an instance of the Tinky::Object.
# A 'state' can be supplied to initialise if, for example, the data was retrieved from a database.
my $ticket-a = Ticket.new(owner => "Operator A");

# Applying the workflow will set the initial state if one is configured and will
# apply a role that provides the transition methods.
# The workflow object can be configured to check whether the object to which it
# is being applied is suitable and throw an exception if not.

$ticket-a.apply-workflow($workflow);

# Exercise the transition methods.
# Other mechanisms are available for performing the transitions whuch may be more
# suitable if the next state is to be calculated.

# State new -> open
$ticket-a.open;

# State open -> in-progress
$ticket-a.take;

# Get the names of the states which are now available for the object
# [stalled complete]
$ticket-a.next-states>>.name.say;

# Directly assigning the state will be validated, an exception will
# be thrown if this is not a valid transition at the time
$ticket-a.state = $state-stalled;

# State stalled -> rejected
# This is a final state and no further transitions are available.
$ticket-a.reject;