#!/usr/bin/ruby
#--
#-------------------------------------------------------------------------------
#++
#
# == Introduction
#
#	This script ensures that the default client view offered to users
#	for new client workspaces is based on a template client specified
#	in the trigger definition.
#
# == Synopsis
#
#	defaultclient.rb <templatename> <clientname> <formfile>
#
# == Sample Trigger Definition
#
#	Using a trigger spec like this:
#
#  defaultclient out client "defaultclient.rb baseclient %formname% %formfile%"
#
#	would make the default client view offered to any user based on 
#	the view defined in the client called 'baseclient'. Changing that
#	client spec would change the default view.
#
#--
#-------------------------------------------------------------------------------
#++
require "P4"
    	
#
# Show a message explaining correct usage of this script and exit.
#
def croakusage()
    puts <<EOS

Usage: defaultclient.rb <templatename> <clientname> <formfile>

Where:
    <templatename>             - the name of an existing client workspace 
                                 on which all future client workspaces 
                                 should be based (by default).

    <clientname>               - The name of the client spec the user's 
                                 asking for

    <formfile>                 - The name of the temporary file in which the
                                 current client spec is stored

EOS
    exit( 1 )
end


#
# Check whether or not a client already exists.
#
def client_exists?( p4, name )
    p4.run_clients.each do
	|c|
	if( c[ "client" ] == name )
	    return true
	end
    end
    return false
end

#
# Load the skeleton spec from the formfile
#
def load_spec( formfile )
    f = File.open( formfile, "r" )
    buf = f.read
    f.close
    buf
end


#
# Update the existing formfile with a new spec. Since the comments 
# that appear at the top of a spec file are quite useful to the users,
# we preserve them and only update the end of the file with the new spec.
#
def write_spec( spec, formfile )
    comments = ""
    File.open( formfile, "r" ) do
	|f|
	f.each_line do
	    |line|
	    if( line[0...1] != '#' )
		break
	    end
	    comments += line
	end
    end
    comments += "\n" 

    File.open( formfile, "w" ) do
	|f|
	f.write( comments )
	f.write( spec )
    end
end

#--
#-------------------------------------------------------------------------------
# START OF MAIN SCRIPT
#-------------------------------------------------------------------------------
#++

croakusage() unless ARGV.length() == 3

template 	= ARGV.shift;
client 		= ARGV.shift;
formfile 	= ARGV.shift;

exit( 0 ) if( client == template)

p4 = P4.new
p4.parse_forms
p4.exception_level = 1
begin
    p4.connect
    exit( 0 ) if( client_exists?( p4, client ) )
    exit( 0 ) unless( client_exists?( p4, template ) )

    # First fetch the template spec. This will cause our Perforce
    # server to execute this script again in another thread/process
    # but because of the first test after argument parsing above we
    # don't get stuck in a loop. Remove that test at your peril.
    #
    # Note that this also gets the specdef for clients from this
    # server so that P4Ruby can cache it.

    tspec = p4.fetch_client( template )
    cspec = p4.parse_client( load_spec( formfile ) )

    # Now copy across the options and view from the template clientspec. For
    # the view, we have to replace the template name with the client name as
    # we copy.
    cspec[ "View" ] = tspec[ "View" ].collect do
	|mapping|
	mapping.sub( "//#{template}/", "//#{client}/" )
    end

    cspec[ "Options" ] 	= tspec[ "Options" ]


    # Now update the existing formfile with the new spec.
    write_spec( p4.format_client( cspec ), formfile )
rescue P4Exception
    puts( "A trigger script encountered an error:" )
    p4.errors.each do
	|e| 
	$stderr.puts( e )
	puts( "\t" + e )
    end
    puts( "Please contact your system administrator" )
    exit( 1 )
end