#!/usr/local/bin/perl
##############################################################################
#  Program     : candidate.pl                                                #
#                                                                            #
#  Programmer  : Bridget Thomson McInnes                                     #
#                                                                            #
#  Description : This program checks to see if a given word is found in      #
#                a specified dictionary file. If the word is not found, a    #
#                list of candidate corrections is printed to standard out.   #
#                                                                            #
#  Usage       : perl canidate.pl <word> <dictionary file>                   #
#                                                                            #
##############################################################################
use Text::English;

#  Get the possible misspelled word
my $word = shift @ARGV;  my @chars = split(//, $word); 

#  Initialize my hash tables
my %lexicon = (); my %canidates = (); 

#  Set the alphabet
my @alphabet = ('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z');

#  Get the dictionary
while(<>) { chomp; $lexicon{$_}++; }

#  Check to see if the word exists in the dictionary
if(exists $lexicon{$word}) {
    print "Word, $word, exists in the dictionary\n"; 
    exit;
}

#  Get the stem of the word if it exists
my @stem = Text::English::stem( $word );

#  Check if the stem exists in the dictionary
foreach (@stem) {

#  Check to see if the word exists in the dictionary
if(exists $lexicon{$word}) {
    print "Word, $word, exists in the dictionary\n"; 
    exit;
}
    if(exists $lexicon{$_}) {
	print "Word, $word, exists in the dictionary\n"; 
	exit;
    }
}
	
#  Get the candiates based on a simple insertion, 
#  transposition, substitution or deletion
for $x(0..$#chars) {
    for $y(0..$#alphabet) {
       
	#  Deletion -  del[x,y]
	@del = @chars; $del[$x] .= $alphabet[$y];
	if(exists $lexicon{(join "", @del)}) { 
	    $canidates{(join "", @del)}++;
	}
	
	#  Substitution - sub[x,y]
	@subs = @chars; $subs[$x] = $alphabet[$y];
	if(exists $lexicon{(join "", @subs)}) {
	    $canidates{(join "", @subs)}++;
	}
    }
    
    #  Insertion - ins[x,y]
    @ins = @chars; $ins[$x] = "";
    if(exists $lexicon{(join "", @ins)}) {
	$canidates{(join "", @ins)}++;
    }

    #  Transposition - trans[x,y]
    @trans = @chars; 
    $first = $trans[$x]; $second = $trans[$x+1];
    $trans[$x] = $second; $trans[$x+1] = $first;
    if(exists $lexicon{(join "", @trans)}) {
	$canidates{(join "", @trans)}++;
    }
}

print "$word\n";
#  Print the canidates
foreach $canidate (sort keys %canidates) { print "$canidate\n"; }