#!/bin/sh
# the next line restarts using tclsh \
exec tclsh8.4 "$0" "$@"

proc ::main {argc argv} {

global pw_input_file
global pw_output_file

	

	get_commandline $argc $argv
        convert_to_xyz
}
##########################
#A procedure to read commandline
##########################
proc ::get_commandline {argc argv} {

global pw_input_file
global pw_output_file

        set fatzero 0

        if { $argc < 1} {
                puts stderr "Usage: pwo2xsf <pw output file> \[parameters\]"
                puts stderr "Parameters:"
		puts stderr "none at the moment "
		exit 1
        }

	if { $argc > 0 } {
		set state first
		foreach arg $argv {
   			switch -- $state {
      		first {
			set state flag
			#check if the infile exists
			set pw_input_file $arg
		        if { [file exists $pw_input_file] } {
                		puts "using input file $pw_input_file"
		        } else {
                		puts stderr "Input file $pw_input_file does not exits"
		                exit 1
        		}

		}

		flag {
         		switch -glob -- $arg {
            		default {
				puts stderr "unknown flag $arg" 
 				exit 2
				}
         		}
      		}
      		

                        }
                }
      }
      set pw_output_file "$pw_input_file.xyz"

}

proc ::convert_to_xyz {} {

global pw_input_file
global pw_output_file
global n_at
global lc_pos
 
	if [catch {open $pw_input_file r} fileId] {
                puts stderr "Cannot open $pw_input_file: $fileId"
                exit 1
        }
        set tmpfile [read $fileId]
        close $fileId
        if [catch {open $pw_output_file w} fileId] {
                puts stderr "Cannot open $pw_output_file: $fileId"
                exit 1
        }
	
	# read number of atoms
        if {![regexp -linestop -- {number of atoms/cell\s*=\s*([0-9]+)} $tmpfile match n_at]} {
		puts "Error reading n_at, exiting"
		exit 2
 	}
	if {![regexp -linestop -nocase -- {ATOMIC_POSITIONS\s*[{,(]\s*([a-z]+)\s*[},)]} $tmpfile match type] } {
        	puts "Error reading ATOMIC_POSITIONS, exiting"
        	exit 2
 	}
#Determine coordinate type
	puts "Coordinates are of '$type' type"
	if {[regexp -nocase -- {ang} $type]} {
		puts " activating angstrom coordinate mode "
        } else {
                if {![regexp -nocase -- {alat} $type]} {
	        	puts "...which means it is too difficult for me, bailing out"
			exit 2
                }
 	}

        puts "Coordinates will be written to $pw_output_file"
        set lc_pos 0
        
	while {[regexp -indices -start $lc_pos -nocase -- {ATOMIC_POSITIONS\s*\([a-z]+\)\s*} $tmpfile lc_pos] != 0 } {

	    set lc_pos [lindex [split $lc_pos] 1]
  	    puts "Found coordinates at index:$lc_pos in output file"

 	    puts $fileId "$n_at"
            puts $fileId ""
            #Read atoms
	    for {set i 0} {$i<$n_at} {incr i 1} {
		set search "regexp -start $lc_pos -linestop -nocase -- {\[a-z\]+\\s+-?\[0-9\]+\\.?\[0-9\]*\\s+-?\[0-9\]+\\.?\[0-9\]*\\s+-?\[0-9\]+\\.?\[0-9\]*} \$tmpfile match"
		eval $search
                puts $fileId $match
		set search "regexp -start $lc_pos -linestop -nocase -indices -- {\[a-z\]+\\s+-?\[0-9\]+\\.?\[0-9\]*\\s+-?\[0-9\]+\\.?\[0-9\]*\\s+-?\[0-9\]+\\.?\[0-9\]*\\s*} \$tmpfile match"
		eval $search
		set lc_pos [lindex [split $match] 1] 

	    }
      }
 
 close $fileId



}
main $argc $argv