#!/bin/bash

# If this file has already been sourced, just return
test $(VARIABLES_QUEUE_SH+true) && return
declare -g VARIABLES_QUEUE_SH=true

source ${BASH_SOURCE%/*}/common.sh
source ${BASH_SOURCE%/*}/logger.sh
source ${BASH_SOURCE%/*}/variables.sh
source ${BASH_SOURCE%/*}/variables.atom.sh
source ${BASH_SOURCE%/*}/variables.arraylist.sh

variable::type::define ArrayQueue ArrayList

# == QUEUE ==
# 
# First In / First Out
#
# Queue commands act on a list data structure
#

proc variable::ArrayQueue::new {
    variable::new ArrayQueue $(@)
}

#
# Adds an item to the queue
#
proc variable::ArrayQueue::enqueue {
    if [[ ${VARIABLES_DEBUG} == 1 ]] { stderr "variable::ArrayQueue::enqueue $(@)" ; }

    declare token="$(1)"
    if ! variable::type::instanceOf $(token) ArrayQueue  {
        stderr "Variable [$(token)] is not of type ArrayQueue (actual type [$(RESULT)])"
        exit 1
    }

    variable::ArrayList::append $(@)
}

#
# Removes and returns the oldest item added to the queue
#
proc variable::ArrayQueue::dequeue {
    if [[ ${VARIABLES_DEBUG} == 1 ]] { stderr "variable::ArrayList::isEmpty_c $(@)" ; }
    declare token="$(1)"

    if ! variable::type::instanceOf $(token) ArrayQueue  {
        stderr "Variable [$(token)] is not of type ArrayQueue (actual type [$(RESULT)])"
        exit 1
    }

    if variable::ArrayList::isEmpty_c $(token)  {
        stderr "Cannot dequeue from an empty queue"
        exit 1
    }

    variable::ArrayQueue::peek $(token);    declare result=$RESULT
    variable::type $token;    declare type=$RESULT
    variable::ArrayList::rest $token;    declare value=$RESULT
    variable::set $token $type $value
    setglobal RESULT = $(result)
}

#
# Returns the oldest item added to the queue (does note remove it)
#
proc variable::ArrayQueue::peek {
    declare token="$(1)"

    if ! variable::type::instanceOf $(token) ArrayQueue  {
        stderr "Variable [$(token)] is not of type ArrayQueue (actual type [$(RESULT)])"
        exit 1
    }

    if variable::ArrayList::isEmpty_c $token  {
        stderr "Cannot peek from an empty queue"
        exit 1
    }
    # stderr "peeking at list [$(variable::value_p $token)] / first=$(variable::ArrayList::first_p $token)"
    variable::ArrayList::first $token;    declare result=$RESULT
    setglobal RESULT = $(result)
}
proc _variable::ArrayQueue::peek_p {
    variable::ArrayQueue::peek $(@)
    echo $RESULT
}



# ======================================================
if test $0 != $BASH_SOURCE {
    return
}

#
# QUEUE tests
#
variable::ArrayQueue::new ; setglobal vCode = $(RESULT)
variable::new String "first" ; variable::ArrayQueue::enqueue $(vCode) $(RESULT)
variable::new String "second" ; variable::ArrayQueue::enqueue $(vCode) $(RESULT)
variable::new String "third" ; variable::ArrayQueue::enqueue $(vCode) $(RESULT)

variable::ArrayQueue::peek $vCode ; variable::value $(RESULT) ; \
    assert::equals "first" $RESULT "queue:peek first"
variable::ArrayQueue::dequeue $vCode ; variable::value $(RESULT) ; \
    assert::equals "first" $RESULT "queue::dequeue first"
variable::ArrayQueue::peek $vCode ; variable::value $(RESULT) ; \
    assert::equals "second" $RESULT "queue:peek second"
variable::ArrayQueue::dequeue $vCode ; variable::value $(RESULT) ; \
    assert::equals "second" $RESULT "queue::dequeue second"

assert::report

if test $(1+isset) && test $1 == "debug" { 
    variable::printMetadata
}