#! /usr/bin/env perl
# -*- Mode: perl; -*-
# 
# This script is a replacement for several scripts that process source
# files, extracting information from them.  This file provides a set 
# of routines for processing files and maintaining a cache of the results.
# It uses a more sophisticated
# approach to avoid rescanning all files by keeping track of local changes
# It does this on a directory-by-directory basis as a comprimise between
# doing the minimal work but limiting the number and size of the "extra"
# files.  In this case, for each directory, the following dot file is 
# produced (with a <name> provided depending on use:
#   .<name>-cache
# This file contains lines of the form
# <dir>
# <file name="filename" info="date or md5 hash"/>
# ...
# </dir>
# <data>
# <fileinfo name="filename">
# data for this file extracted from file
# </fileinfo>
# ...
# </data>
# The file has a separate directory to speed reading of the list of 
# know files so that the comparisons for updates can be 
# computed quickly.
#
# In addition, this allows us to create lists of information by
# combining the directories in which we're interested, rather than
# all of the directories.  This will also make it possible to 
# update these tables at configure time with modules provided by other
# developers.
#
# Algorithm:
# For each directory (use readdir)
#    Get a list of matching files (filename pattern supplied, default is
#    *.[chi])
#    if a cache file is found 
#        read cache file directory
#        compare with source files
#            for each out-of-date or new file, extract information (see below)
#            else mark file as unchanged
#            check for deleted files
#        if any changes
#            read old cache file for info from unchanged files
#            write new directory and data entries
#    else
#       for each file
#            extract information
#       write new directory and data entries
#    (optional) if specified, call routine to process cache file contents
#      (e.g., generate a derived file).
#
# Data structures
# Within a directory
#   fileInfo{filename} = extracted info
#   filesUpdated[]     = array of file names that match critera
#   fileInCache{filename} = comparison info
#   
# -------------------------------------------------------------------------
use warnings;

$gDebug     = 0;
# verbose of 1 gives the least amount of data, higher values give
# increasing amount of detail. (0, of course, gives no detail)
$gVerbose   = 0;
$gUpdateAll = 0;
# -------------------------------------------------------------------------
# Return an array of regular files in the named directory
sub GetFileNamesInDirectory {
    my ($dir,$pattern) = @_;
    my @filesFound = ();

    opendir DIR, $dir || die "Could not open $dir\n";
    while (my $file = readdir DIR) {
	if (! -f "$dir/$file") { next; }
	if ($file =~ /^\.$/ || $file =~ /^\.\.$/) { next; }
	if ($file =~ /$pattern/) {
	    $filesFound[$#filesFound+1] = $file;
	}
    }
    closedir DIR;
    return @filesFound;
}
# Return a hash of files and their comparison information
sub ReadCacheDirectory {
    my ($dir, $cachefile) = @_;
    my %fileInCache = ();
    my $found = 0;

    if (! -f "$dir/$cachefile") { return %fileInCache; }
    open CFD, "<$dir/$cachefile" || return %fileInCache;
    # Look for directory
    while (<CFD>) {
	if (/<dir>/) { $found = 1; last; }
    }
    if ($found) {
	while (<CFD>) {
	    if (/<\/dir>/) { last; }
	    if (/<file\s+name=\"([^\"]+)\"\s+info=\"([^\"]+)\"\s*\/>/) {
		$fileInCache{$1} = $2;
		print "Found file $1 in cache\n" if $gDebug;
	    }
	}
    }
    close CFD;

    return %fileInCache;
}
# Return a hash of information from each, indexed by filename
sub ReadCacheContents {
    my ($dir, $cachefile) = @_;
    my %fileInfo = ();
    my $found = 0;
    
    if (! -f "$dir/$cachefile") { return %fileInfo; }
    open CFD, "<$dir/$cachefile" || return %fileInfo;
    # Look for data
    while (<CFD>) {
	if (/<data>/) { $found = 1; last; }
    }
    if ($found) {
	while (<CFD>) {
	    if (/<\/data>/) { last; }
	    if (/<fileinfo\s+name=\"([^\"]+)\">/) {
		my $filename = $1;
		my $info = "";
		while (<CFD>) {
		    if (/<\/fileinfo>/) { last; }
		    $info .= $_;
		}
		$fileInfo{$filename} = $info;
	    }
	}
    }
    close CFD;

    return %fileInfo;
}
# Print the cache.  Pass fileInfo by reference (\%fileInfo)
sub PrintCacheFile {
    my ($dir,$cachefile,$fileInfo) = @_;

    open CFD, ">$dir/$cachefile" || die "Could not open $dir/$cachefile\n";

    print CFD "<dir>\n";
    foreach my $file (keys(%$fileInfo)) {
	my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime) = 
	    stat "$dir/$file";
	print CFD "<file name=\"$file\" info=\"$mtime\"/>\n";
    }
    print CFD "</dir>\n";
    print CFD "<data>\n";
    foreach my $file (keys(%$fileInfo)) {
	print CFD "<fileinfo name=\"$file\">\n";
	print CFD $$fileInfo{$file};
	print CFD "</fileinfo>\n";
    }
    print CFD "</data>\n";
    close CFD;
}

sub processFiles {
    my ($dir,$cachefile,$pattern) = @_;

    my @files = &GetFileNamesInDirectory( $dir, $pattern );
    my %filesInCache = &ReadCacheDirectory( $dir, $cachefile );
    
    my @filesToScan = ();
    my @filesDeleted = ();
    my @filesUnchanged = ();
    my %filesInDir = ();

    print "Number of files matching pattern in $dir is $#files\n" if $gDebug;
    for (my $i=0; $i <= $#files; $i++) {
	$filesInDir{$files[$i]} = 1;
    }
    foreach my $file (keys(%filesInCache)) {
	# Get info on file
	if (-f "$dir/$file") {
	    print "Found $file\n" if $gDebug;
	    delete $filesInDir{$file};
	    my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime) = 
		stat "$dir/$file";
	    if ($mtime > $filesInCache{$file} || $gUpdateAll) {
		# File has been changed since last update
		$filesToScan[$#filesToScan+1] = $file;
	    }
	    else {
		$filesUnchanged[$#filesUnchanged+1] = $file;
	    }
	}
	else {
	    # This file has been deleted
	    print "File $dir/$file has been deleted since the cache was created\n" if $gDebug;
	    $filesDeleted[$#filesDeleted+1] = $file;
	}
    }
    my @filesCreated = keys(%filesInDir);
    
    # Check for unchanged
    if ($#filesCreated == -1 &&
	$#filesDeleted == -1 &&
	$#filesToScan  == -1) {
	# Nothing to do, we can leave the cache file as is
	print "Cache in $dir unchanged\n" if $gDebug || $gVerbose > 1;
    }
    else {
	if ($gDebug || $gVerbose > 0) {
	    # Give a detailed description
	    my $sep = "";
	    print "Changes in dir $dir: ";
	    if ($#fileCreated >= 0) {
		my $num = $#filesCreated + 1;
		print "created = $num";
		$sep = ", ";
		}
	    if ($#filesDeleted >= 0) {
		my $num = $#filesDeleted + 1;
		print "${sep}deleted = $num";
		$sep = ", ";
	    }
	    if ($#filesToScan >= 0) {
		my $num = $#filesToScan + 1;
		print "${sep}changed = $num";
	    }
	    print "\n";
	}
	# We need to scan some files, adding their info to fileInfo
	my %fileInfo = &ReadCacheContents( $dir, $cachefile );
	for (my $i=0; $i<=$#filesDeleted; $i++) {
	    delete $fileInfo{$filesDeleted[$i]};
	}
	foreach $file (@filesCreated,@filesToScan) {
	    print "Scanning file $dir/$file\n" if $gDebug;
	    $fileInfo{$file} = &$scanFile( "$dir/$file" );
	}
	&PrintCacheFile( $dir, $cachefile, \%fileInfo );
    }
}
sub processDirs {
    my ($dir, $cachefile, $pattern) = @_;

    print "Processing $dir...\n" if $gDebug;
    my @dirs = ();
    # Find the directories
    opendir DIR, "$dir" || die "Cannot open $dir\n";
    while (my $file = readdir DIR) {
	if (! -d "$dir/$file") { next; }
	if ($file =~ /^\./) { next; }
	if ($file =~ /^.svn/) { next; }
	if ($file =~ /autom4te.cache/) { next; }
	$dirs[$#dirs+1] = "$file";
    }
    closedir DIR;
    
    # For each of these, process it
    for (my $i=0; $i<=$#dirs; $i++) {
	my $ndir = "$dir/$dirs[$i]";
	&processDirs( $ndir, $cachefile, $pattern );
    }

    # process the files in this directory
    &processFiles( $dir, $cachefile, $pattern );
}

# This is a general routine to process directories
sub processDirsAndAction {
    my ($dir, $action, $actionData) = @_;

    print "Processing $dir...\n" if $gDebug;
    my @dirs = ();
    # Find the directories
    opendir DIR, "$dir" || die "Cannot open $dir\n";
    while (my $file = readdir DIR) {
	if (! -d "$dir/$file") { next; }
	if ($file =~ /^\./) { next; }
	if ($file =~ /^.svn/) { next; }
	if ($file =~ /autom4te.cache/) { next; }
	$dirs[$#dirs+1] = "$file";
    }
    closedir DIR;
    
    # For each of these, process it
    for (my $i=0; $i<=$#dirs; $i++) {
	my $ndir = "$dir/$dirs[$i]";
	&processDirsAndAction( $ndir, $action, $actionData );
    }

    # process the files in this directory
    &$action( $dir, $actionData );
}

1;