#!/usr/bin/perl -w

# This code generates some plain HTML code about consumed electricity,
# either for one or several months, depending on the command line parameter.
# By default, the last monthly bill is generated, of a specific date given
# (must be specified in the form mm/dd/yy, where dd=01), or all months if
# "all" is given as parameter.

# Directories where the log files reside in, adjusted by configure script
# $sumdir="/home/chris/construction/BTUmetering/summarize";
$sumdir="MAINPROGROOT/log";

# extract commandline parameters; do first interpretation
if ($#ARGV != 0) {
    $shm="last";
} else {
    $shm=$ARGV[0];
}
# only leave alpanum and slashes in the string
$shm =~ s/[^\w\/]//g;

# summary file name
$sumfile="$sumdir/e_summaryfile";

# silly date conversion functions
@months=qw(x January February March April May June July August September October November December); 
sub mdytoymd { my @a=split '/', $_[0]; return "$a[2]-$a[0]-$a[1]";}
sub ymdtomdy { my @a=split '-', $_[0]; return "$a[1]/$a[2]/$a[0]";}
sub mdytotext { my @a=split '/', $_[0]; return "$months[$a[0]] 20$a[2]";}

#clear hash for readings
%readings = ();
%unithash = ();
%datehash = ();

# read in summary file
open(SUMFH, $sumfile) or die "cannot open file.";
while ($line = <SUMFH>) {
    ($unit, $date, $rest) = split " ", $line, 3;
    $readings{"$unit:$date"}=$rest;
    $unithash{$unit}=1;
    $datehash{$date}=1;
}

# Generate sorted lists of units and dates
@units = sort keys %unithash;
@dates = map {ymdtomdy($_)} sort map {mdytoymd($_)} keys %datehash;

# generate a list of months to display, depending on command line parameter
if (exists $datehash{$shm}) {
    @showdate=($shm);
} elsif ($shm eq "all") {
    @showdate=@dates;;
} else {
    @showdate=($dates[-1]);
}

# Finally, generate HTML code
foreach $month (reverse @showdate) {
    # convert into sensible time name
    $mtx=mdytotext($month);

    # Generate table header
    print "<h3>Electricity consumption for the $mtx reading</h3>\n";
    print "<p><table border=\"1\">
<tr><th>Unit</th>
<th>This reading<br>(kWh)</th>
<th>Last reading<br>(kWh)</th>
<th>Consumption<br>(kWh)</th></tr>\n";
    
    # go through all units for a given date and generate table rows
    $totalkwh = 0;
    foreach $unit (@units) {
	if (exists $readings{"$unit:$month"}) {
	    @rd=split ' ', $readings{"$unit:$month"};
	    print "<tr><td>$unit</td>";
	    print "<td>$rd[2]</td><td>$rd[3]</td><td>$rd[4]</td></tr>\n";
	    $totalkwh += $rd[4];
	    $lastread = $rd[1];
	}
    }
    
    # Generate total sum line and close the table
    print "<tr><td colspan=3><b>Total electricity consumed:</b></td>
<td><b>$totalkwh</b></td></tr>\n</table></p>\n";
    
    # final remark
    print "<p>Measurement time interval was from $lastread to $month.<br><br></p>\n";
}