#!/usr/bin/perl

# allhelp.pl for Linux
# Display help for the Bourne Shell's internal commands and reserved words
# Written by Rob van der Woude
# http://www.robvanderwoude.com

use strict;
use warnings;
use Config;
use CGI qw(escapeHTML);

my $scriptver = '1.02';

# Abort if not running on Linux
if ( lc( $Config{osname} ) ne 'linux' ) {
	print "This script will run on Linux systems only.";
	exit 1;
}

my @cmds;
my @builtins;
my @coreutils;
my @reserved;
my %helplong;
my %helpshort;
my $outfile = 'allhelp_bash.html';

# Create a list of all internal commands for which help is available
open( SHELL, "-|", "bash", "-c", "compgen -b" );
while( <SHELL> ) {
	chomp;
	push( @builtins, $_ );
}
close( SHELL );

# Create a list of all reserved words for which help is available
open( SHELL, "-|", "bash", "-c", "compgen -k" );
while( <SHELL> ) {
	chomp;
	push( @reserved, $_ );
}
close( SHELL );

# Create a list of coreutils
open( SHELL, '-|', 'bash', '-c', 'info | grep -F "(coreutils)"');
while ( <SHELL> ) {
	chomp;
	if ( $_ =~ m/^\*\s+([a-z][a-z0-9]+):\s+\(coreutils\)\1/ ) {
		$_ =~ /^\*\s+([a-z][a-z0-9]+):\s+\(coreutils\)\1\s[^.]+\.\s+(.+)$/;
		push( @coreutils, $1 );
		my $anchor = &Anchor( $1 );
		$helpshort{ $anchor } = $2;
	}
}
close( SHELL );


# Merge the lists of commands
push( @cmds, @builtins );
push( @cmds, @reserved );
push( @cmds, @coreutils );

# Sort the list of commands, punction and numbers first
@cmds = sort {
	if ( $a =~ m/^[a-z]/i and $b !~ m/^[a-z]/i ) {
		return 1;
	} elsif ( $a !~ m/^[a-z]/i and $b =~ m/^[a-z]/i ) {
		return -1;
	} else {
		return $a cmp $b;
	}
} @cmds;

# Calculate available column width for 3 columns display with 3 characters spacing
my $cols = `tput cols`;
my $rows = `tput lines`;
my $colwidth = int( ( $cols - 6 ) / 3 );

# First display the Linux version
print &LinuxVer( ) . "\n\n";

# Display the list of commands in 3 columns
for ( my $i = 0; $i < @cmds; $i += 3 ) {
	printf '%-' . $colwidth . 's', $cmds[$i];
	if ( $i + 1 < @cmds ) { printf '   %-' . $colwidth . 's', $cmds[$i+1]; }
	if ( $i + 2 < @cmds ) { printf '   %-' . $colwidth . 's', $cmds[$i+2]; }
	print "\n";
}

# Display help for each command in the array
foreach my $cmd ( @cmds ) {
	print "\nHelp for '$cmd'\n\n";
	my $anchor = &Anchor( $cmd );
	my $helptext = '';
	if ( grep { $_ eq $cmd } @coreutils ) {
		# Use info command for coreutils
		open( SHELL, "-|", "bash", "-c", "info $cmd | grep -F \"\"" );
		# Read resulting help text from STDOUT
		while ( <SHELL> ) {
			$helptext .= $_;
		}
		close( SHELL );
		if ( $helptext ) {
			$helptext =~ s/\342\200\230/'/g;
			$helptext =~ s/\342\200\231/'/g;
			$helptext =~ s/^\/([^\n]*\n){3}\d+\.\d+\s+//;
			$helptext =~ s/\n=+\n/\n/g;
			$helplong{ $anchor } = $helptext;
		}
	} else {
		# Use help command for reserved words and builtin commands
		# Escape the commands, otherwise bash may break on parenthesis
		my $esccmd = quotemeta( $cmd );
		# Run help command with escaped command name
		open( SHELL, "-|", "bash", "-c", "help $esccmd 2> /dev/null" );
		# Read resulting help text from STDOUT
		while ( <SHELL> ) {
			$helptext .= $_;
		}
		close( SHELL );
		if ( "$helptext" !~ m/^\s*$/g ) {
			$helplong{ $anchor } = $helptext;
			# Display help text
			print escapeHTML( $helptext );
			# Get short help text summary
			my $firstline = $cmd . ': ' . $cmd . '[^\n]*\n\s+';
			if ( $cmd ne $esccmd ) {
				$firstline = $esccmd . '[^a-z:\n]*: ' . $esccmd . '[^\n]*\n\s+';
			}
			"$helptext" =~ /$firstline((.|\n)*?)\n\s*\n/;
			$helpshort{ $anchor } = $1;
		}
	}
}

print "\n\n";

# Remove commands from list if no help is available
# Use reverse order to prevent skipping 1 each time an element is removed from the array
for ( my $i = @cmds - 1; $i >= 0; $i-- ) {
	my $cmd = $cmds[$i];
	my $anchor = &Anchor( $cmd );
	unless ( exists( $helplong{ $anchor } ) ) {
		my $index = 0;
		$index++ until $cmds[$index] eq $cmd or $index == @cmds;
		splice( @cmds, $index, 1 );
	}
}

# Write the help to a HTML file
my $htmlhelp = &HTMLHead( );
$htmlhelp .= &HTMLList( );
foreach my $cmd ( @cmds ) {
	$htmlhelp .= &HTMLCommand( $cmd );
}
$htmlhelp .= &HTMLFoot( );
open( HTML, ">", $outfile ) or die( "Error writing HTML to file \"$outfile\"." );
print HTML $htmlhelp;
close( HTML );

# Open the newly created HTML file in the default browser (may generate warning messages with Firefox)
if ( `which sensible-browser` ) {
	exec( 'sensible-browser', $outfile );
} elsif ( `which xdg-open > /dev/null` ) {
	exec( 'xdg-open', $outfile );
} elsif ( `which gnome-open > /dev/null` ) {
	exec( 'gnome-open', $outfile );
} elsif ( `which x-www-browser` ) {
	exec( 'x-www-browser', $outfile );
} else {
	my $browser = `gconftool -g /desktop/gnome/url-handlers/http/command 2> /dev/null`;
	if ( $browser ) {
		exec( $browser, $outfile );
	} else {
		die "Unable to locate default browser; open \"$outfile\" manually.";
	}
}




sub Alphabet( ) {
	my $html = "<table class=\"Alphabet\">\n<tr>\n";
	my $found = 0;
	foreach my $c ( @cmds ) {
		my $A = uc( substr( $c, 0, 1 ) );
		if ( $A !~ /[A-Z]/ ) {
			$found = 1;
		}
	}
	if ( $found ) {
		$html .= "\t<th><a href=\"#Punc\">#</a></th>\n";
	} else {
		$html .= "\t<th style=\"color: gray;\">#</th>\n";
	}
	foreach my $a ( 'a' .. 'z' ) {
		my $A = uc( $a );
		my $found = 0;
		foreach my $c ( @cmds ) {
			if ( lc( substr( $c, 0, 1 ) ) eq $a ) {
				$found = 1;
			}
		}
		if ( $found ) {
			$html .= "\t<th><a href=\"#$A\">$A</a></th>\n";
		} else {
			$html .= "\t<th style=\"color: gray;\">$A</th>\n";
		}
	}
	$html .= "</tr>\n</table>\n";
	return $html;
}


sub Anchor( ) {
	my $cmd = $_[0];
	my $firstchar = substr( $cmd, 0, 1 );
	my $anchor = $cmd;
	if ( $firstchar eq "." ) { $anchor = "dot"; }
	if ( $firstchar eq ":" ) { $anchor = "colon"; }
	if ( $firstchar eq '!' ) { $anchor = "exclamation"; }
	if ( $firstchar eq "(" ) { $anchor = "parentheses"; }
	if ( $firstchar eq "[" ) { $anchor = "brackets"; }
	if ( $firstchar eq "{" ) { $anchor = "braces"; }
	return $anchor;
}


sub HTMLCommand( ) {
	my $cmd = $_[0];
	my $anchor = &Anchor( $cmd );
	my $type;
	my $class;
	if ( grep { $_ eq $cmd } @coreutils ) {
		$class = 'CoreUtils';
		$type = "<p><strong>coreutils</strong></p>\n\n";
	} elsif ( grep { $_ eq $cmd } @builtins ) {
		$class = 'BuiltIn';
		$type = "<p><strong>builtin command</strong></p>\n\n";
	} elsif ( grep { $_ eq $cmd } @reserved ) {
		$class = 'ReservedWord';
		$type = "<p><strong>reserved word</strong></p>\n\n";
	} else {
		$class = '';
		$type = '';
	}
	my $html = '';
	if ( $class ne '' ) {
		$html .= "<div class=\"$class\">\n\n";
	}
	$html .= "<h2 id=\"$anchor\">$cmd</h2>\n\n$type<pre>";
	$html .= escapeHTML( $helplong{ $anchor } );
	$html .= "</pre>\n\n<div class=\"Center\"><a href=\"#\">Back to the top of this page</a></div>\n\n<p>&nbsp;</p>\n\n";
	if ( $class ne '' ) {
		$html .= "</div>\n\n";
	}
	return $html;
}


sub HTMLFoot( ) {
	my @now = localtime( );
	my $html = "<table>\n<tr id=\"Note\">\n\t<td class=\"Bold Top\">Note:</td>\n\t<td>&nbsp;</td>\n";
	$html .= "\t<td>Not all reserved words are listed here, only the ones for which help is available.</td>\n</tr>\n</table>\n\n";
	$html .= "<p>&nbsp;</p>\n\n<div class=\"Center\">\n\n<p>This HTML help was generated on ";
	$html .= sprintf( "%4d-%02d-%02d", $now[5] + 1900, $now[4], $now[3] );
	$html .= " by <a href=\"http://www.robvanderwoude.com/perlexamples.php#allhelp\">";
	$html .= "allhelp.pl</a>, Version $scriptver<br />\n";
	$html .= "Written by Rob van der Woude<br />\n";
	$html .= "<a href=\"http://www.robvanderwoude.com/\">http://www.robvanderwoude.com</a></p>\n\n";
	$html .= "</div>\n\n</div>\n\n</div>\n\n<p>&nbsp;</p>\n\n</body>\n</html>";
}


sub HTMLHead( ) {
	my $title = &LinuxVer( );
	my $html = <<"END_OF_HTML";
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7;FF=3;OtherUA=4">
<meta name="robots" content="index,follow">
<meta name="generator" content="allhelp.pl, Version $scriptver, by Rob van der Woude, www.robvanderwoude.com">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta http-equiv="Content-Style-Type" content="text/css">

<title>Help for $title</title>

<style type="text/css">
a, a.visited
{
	color: blue;
}

td.Command
{
	vertical-align: top;
	padding-left: 10px;
	padding-right: 5px;
	font-weight: bold;
	white-space: nowrap;
}

th
{
	vertical-align: top;
}

table.Alphabet
{
	border: 2px solid blue;
	margin: 0 auto 0 auto;
	text-align: center;
	vertical-align: middle;
	width: 100%;
}

table.Alphabet th
{
	padding: 5px;
	width: 4%;
}

table.List
{
	margin: 0 auto 0 auto;
	width: 100%;
}

table.List th
{
	background-color: blue;
	color: white;
	font-size: 120%;
	font-weight: bold;
	padding-left: 10px;
}

pre
{
	white-space: pre-wrap;
}

.Bold
{
	font-weight: bold;
}

.Center
{
	text-align: center;
	margin-left: auto;
	margin-right: auto;
}

.Left
{
	text-align: left;
}

.Smallfont
{
	font-size: 60%;
}

.Top
{
	vertical-align: top;
}
</style>

</head>
<body>

<h2 class="Center">Help for</h2>

<h1 class="Center">CoreUtils, internal Bash commands</h1>

<h2 class="Center">and reserved words&nbsp;<sup>(<a href="#Note">*</a>)</sup></h2>

<h3 class="Center">$title</h3>

<p>&nbsp;</p>

<div class="Center" style="width: 50em;">

<div class="Left" style="width: 50em;">

END_OF_HTML

	$html .= Alphabet( );
	return $html;
}


sub HTMLList( ) {
	my $lastfirstchar = '';
	my $html = "<table class=\"List\">\n";
	$html .= "<tr id=\"Punc\">\n\t<th colspan=\"2\">Punctuation</th>\n</tr>\n";
	$html .= "<tr>\n\t<td colspan=\"2\">&nbsp;</td>\n</tr>\n";
	foreach my $cmd ( @cmds ) {
		my $firstchar = '';
		if ( "$cmd" =~ m/^[a-z]/ ) {
			"$cmd" =~ /^([a-z])/;
			$firstchar = uc( $1 );
			if ( $firstchar ) {
				if ( $firstchar ne $lastfirstchar ) {
					$html .= "<tr>\n\t<td colspan=\"2\">&nbsp;</td>\n</tr>\n";
					$html .= "<tr id=\"$firstchar\">\n\t<th colspan=\"2\">$firstchar</th>\n</tr>\n";
					$html .= "<tr>\n\t<td colspan=\"2\">&nbsp;</td>\n</tr>\n";
				}
			}
		}
		$lastfirstchar = $firstchar;
		my $anchor = &Anchor( $cmd );
		my $help = escapeHTML( $helpshort{ $anchor } );
		my $class;
		if ( grep { $_ eq $cmd } @coreutils ) {
			$class = ' class="CoreUtils"';
		} elsif ( grep { $_ eq $anchor } @builtins ) {
			$class = ' class="BuiltIn"';
		} elsif ( grep { $_ eq $anchor } @reserved ) {
			$class = ' class="ReservedWord"';
		} else {
			$class = '';
		}
		$help =~ s/[\t ]+/ /g;
		$html .= "<tr$class>\n\t<td class=\"Command\"><a href=\"#$anchor\">$cmd</a></td>\n\t<td>$help</td>\n</tr>\n";
	}
	$html .= "</table>\n\n<p>&nbsp;</p>\n\n";
	return $html;
}


sub LinuxVer( ) {
	my $os = '';
	open( SHELL, "-|", "bash", "-c", "uname -sirv" );
	while( <SHELL> ) {
		chomp( $os = $_ );
	}
	close( SHELL );
	if ( $os eq '' ) {
		$os = "$Config{osname} $Config{osvers}";
	}
	return $os;
}