#!/usr/bin/perl
# Davor Ocelic, docelic@mail.inet.hr
# Simple perl script that creates random text database files.
# (This should be used just for test, to create random-content
# databases of desired characteristics - such as value lengths or
# total number of records).

#
# PURPOSE:
#	dbgen.pl can be used to quickly create sample Minivend
#	or Interchange databases. It should come handy during the
#	test phase.
#
#	It creates text, TAB delimited files.
#
#	The generated data will, of course, be meaningless, but the
#	user can specify column names and types, which should allow
#	him to test the engine on arbitrary number of random-generated
#	records.
#
# QUICKSTART:
# perl dbgen -c 10 -r /usr/share/dict/words > products/products.txt
#
# COMMAND LINE OPTIONS:
#	-f --fields          : Set column names
#	-v --values          : Specify data types for the columns.
#	                       Use the same order in which you specified --fields
#	-c --count           : The number of records to generate
#	-d --debug --nodebug : Print few lines of debug data
#	-r --chartable       : Load in the charset/symbols to use from a file.
#
# USAGE:
# 	Use program defaults for column names and types, and print out
# 	5 sample records:
#	 perl dbgen.pl
#
#	Which is equal to:
#	 perl dbgen.pl --fields='sku|description|price'
#	               --values='INC(0,1)|STRAND(8)|RAND(1500,"%.2f")'
#	               --count=5
#
# SYNTAX:
#	--values='INC(0,1)|STRAND(8)|RAND(1500,"%.2f")' can also be specified as:
#	--values='INC(0,1)|STRAND(8)' --values='RAND(1500,"%.2f")'
#
#	The pipe (|) character is used as the element separator.
#
#	The "fields" option just accepts the column names, where their order
#	in the database file is the same as the one on the command line.
#	For example, this specifies a 5-column db:
#	  --fields="sku|description|price" --fields="desc_long|quant"
#
#
#	The "values" field accepts column specifications, and can be any
#	combination of:
#	  INC(st,inc) - start from "st", and increment by "inc". Useful for
#	    auto-increment fields or unique keys (SKUs for example).
#	    For example, --fields=sku --values='INC(0,2)' --count 4
#	    would create a single-column table with SKUs 0,2,4 and 8 (start from 0
#	    and increment by 2 in each of 4 iterations).
#	  RAND(num,'fmt') - generate a random number, not greater than "num",
#	    and output it via the standard printf routine, using "fmt" as the
#	    format specification.
#	  STRAND(len) - Using the characters available in a specified character
#	    map, create a random string of length "len". When specifying a custom
#	    character map, each "character" has to be alone in it's own line.
#	    It is also possible to specify /usr/share/dict/words or something
#	    similar as the "chartable" file, but then the generated string lengths
#	    would not be exact (they would be equal, or few characters larger than
#	    the length you specified).
#	  SET("something") - Fixed-content field. Anything you specify will be
#	    inserted in the database verbatim.
#
#

use Getopt::Long;

# Basic init
my @fields = ();
my @values = ();
my $count = 5;
my @chartable = ();
my $current_field_num = 0;
my $debug = 0;
my @defchartable = qw/a b c d e f g h i j k l m n o p q r s t u w x y z _/;
push (@defchartable, " ");

# GetOptions
unless ( GetOptions (
	"f|fields=s"	=> \@fields,
	"v|values=s"	=> \@values,
	"c|count=s" 	=> \$count,

	"d|debug!"	=> \$debug,
	"r|chartable=s"	=> \$chartablefile

)) { die "Can't process command line options\n" } ;

# Option checks
@fields = split(/\|/, join('|', @fields));
@values = split(/\|/, join('|', @values));
unless ($chartablefile) {
	@chartable = @defchartable;
} else {
	open(CHARTABLE, "< $chartablefile")
		or die "Can't open character table file '$chartablefile' for reading ($!)\n";
	while (<CHARTABLE>) {
		chomp;
		push (@chartable, $_);
	}
	close(CHARTABLE);
}

# Okay, set defaults here.
scalar(@fields) or @fields = qw/sku description price/;
scalar(@values) or @values = qw/INC(0,1) STRAND(16) RAND(1500,'%.2f')/;

# Check for fields/values match
die "Field/value parameters do not match\n" unless (scalar(@fields) == scalar(@values));

# Print out summary
if ($debug) {
		print STDERR "FIELDS(", scalar(@fields), "): ", join(',', @fields), "\n";
		print STDERR "VALUES(", scalar(@values), "): ", join(',', @values), "\n";
		print STDERR "CHARTABLE: ", join(',', @chartable), ".\n";
		print STDERR "    COUNT: ", $count, "\n";
}

# Let's prepare the array we will use in a loop to produce results
for (my $p = 0; $p < scalar(@fields); $p++ ) {
	# So, each entry has an array which holds its definition and a value from the previous pass
	$runtime[$p] = $values[$p];
	$oldval[$p] = '';
}


# Okay, let's begin
print join("\t", @fields), "\n";


for (my $l = 0; $l < $count; $l++ ) {
	for (my $p = 0; $p < scalar(@runtime); $p++ ) {
		$current_field_num = $p;
		my $res = eval ( $runtime[$p] );
		print $res;
		print $p < $#runtime ? "\t" : "\n";
		$oldval[$p] = $res;
	}
}







## Helper functions
# strand(length) - generate a random string of specified 'length'
sub STRAND {
	my $len = shift;
	my $rndstring = '';
	# ascii space from 65 to 91

	unless ( $len =~ m/^\d+$/ ) { die "STRAND argument '$len' is invalid\n" };

	for (my $p = 0; $p < $len; $p++ ) {
		my $rndchr = $chartable[int(rand(scalar(@chartable)))];
		$rndstring .= $rndchr;
		length($rndchr) > 1 and $rndstring .= " ";
		# Just to cover the case of specifying /usr/share/dict/words
		# as the character table file
		last if ( length($rndstring) >= $len );
	}

	return $rndstring;
}


# random number
sub RAND {
	my $max = shift;
	my $fmtstring = shift;
	my $last = shift;

	my $rndnumber = rand($max);
	return printf($fmtstring, $rndnumber);

}

# inc: starts with x, and increments by y in each pass
sub INC {
	my $start = shift;
	my $inc = shift;

	return "$oldval[$current_field_num]" ne ''  ? $oldval[$current_field_num] + $inc : $start;
}

# Simple user-defined value for a field
sub SET { return shift; }