#!/usr/bin/tclsh

#
# \brief  Extract subtree from device-tree source
# \author Norman Feske
# \date   2021-05-17
#

##
# Return true if command-line switch was specified
#
proc get_cmd_switch { arg_name } {
	global argv
	return [expr [lsearch $argv $arg_name] >= 0]
}


##
# Return command-line argument value
#
# If a argument name is specified multiple times, a
# list of argument values is returned.
#
proc get_cmd_arg { arg_name default_value } {
	global argv

	# find argument name in argv list
	set arg_idx_list [lsearch -all $argv $arg_name]

	if {[llength $arg_idx_list] == 0} { return $default_value }

	set result {}
	foreach arg_idx $arg_idx_list {
		set next_idx [expr $arg_idx + 1]

		# stop if argv ends with the argument name
		if {$next_idx >= [llength $argv]} continue

		# return list element following the argument name
		lappend result [lindex $argv $next_idx]
	}

	# if argument occurred only once, return its value
	if {[llength $result] == 1} { return [lindex $result 0] }

	# if argument occurred multiple times, contain list of arguments
	return $result
}


#################################################
## Read input and fill internal representation ##
#################################################

##
# Find location of 'parse'
#
# We expect to find 'parse' in the same directory as we are located. The
# question is: Where are we?
##
proc parse_file { } {
	global argv0

	set path $argv0

	if {[file type $path] == "link"} {
		set path [file readlink $path] }

	set parse_file "[file dirname $path]/parse"

	if {![file exists $parse_file]} {
		puts stderr "Error: Could not find 'parse' in '$path'."
		exit -1
	}
	return $parse_file
}


set input_source [lindex $argv end]
if {[catch {
		set tokens [exec [parse_file] $input_source]
}]} {
	foreach line {
	        ""
	        "Extract subtree from device-tree source"
	        "\n  usage: extract \[options\] <dts_file>"
	        ""
	        "Supported options are:"
	        ""
	        " --nodes           Print list of DTS nodes"
	        " --labels          Print list of labels with their DTS paths"
	        " --references      Print referenced labels for each DTS node"
	        " --dot-graph       Generate dot file for graphviz"
	        " --select <label>  Print DTS related to specified label,"
	        "                   can be specified multiple times"
	        ""
	        "Alternatively to specifying a dts file as argument, the input"
	        "data can be passed via standard input by specifying '-' as"
	        "file name."
	        ""
	        "The result of the conversion will be written to stdout."
	        ""
	} { puts stderr $line }
	exit -1;
}


foreach token $tokens {
	set name [lindex $token 0]
	set line [lindex $token 1]
	set text [lindex $token 2]
	set tok_text($name) "$text"
	set tok_line($name) $line
}

if {![info exists tok_text(content0)]} {
	puts stderr "Error: input contains no root token 'content0'."
	exit -1
}


proc tok_type {token} {
	regexp {[a-z]+} $token type
	return $type
}


##
# Find and return a sub token of the specified type
#
proc sub_token {token token_type} {
	global tok_text

	if {$token == ""} { return "" }
	if {[regexp "§($token_type\\d+)°" $tok_text($token) dummy sub_token]} {
		return $sub_token
	} else {
		return ""
	}
}


##
# Return label references present at the specified node of the syntax tree
#
proc labels_referenced_by_node {token} {
	global tok_text

	set output $tok_text($token)

	set result {}

	while {$output != ""} {

		# consume plain text
		if {[regexp {^[^§]+} $output plain]} {
			regsub {^[^§]+} $output "" output }

		# consume token
		if {[regexp {§(.+?)°} $output dummy subtoken]} {

			# collect label reference
			if {[tok_type $subtoken] == "reflabelname"} {
				lappend result $tok_text($subtoken) }

			# search tree for label references but don't traverse sub nodes
			if {[tok_type $subtoken] != "node"} {
				set result [concat $result [labels_referenced_by_node $subtoken]]
			}
			regsub {§(.+?)°} $output "" output
		}
	}
	return [lsort -unique $result]
}


proc joined_path {curr_path path_elem} {

	if {$curr_path == "" && $path_elem == "/"} {
		return "/" }

	if {$curr_path == "/"} {
		return "/$path_elem" }

	return "$curr_path/$path_elem"
}


proc collect_label_and_references_of_node {token path} {
	global tok_text
	global labels
	global references
	global selected

	set node_text $tok_text($token)

	foreach ref [labels_referenced_by_node $token] {
		lappend references($path) $ref }

	set selected($path) 0

	if {[regexp {§(labeldef\d+)°} $node_text dummy]} {
		set label_name $tok_text([sub_token [sub_token $token labeldef] labelname])
		set labels($label_name) $path
	}

	collect_labels_and_references [sub_token $token block] $path
}


##
# Return path of sub node if token refers to a node or nodesupplement
#
# Otherwise the path is returned unmodified
#
proc sub_node_path {token path} {
	global tok_text
	global labels

	if {[tok_type $token] == "node"} {
		set path_elem $tok_text([sub_token $token nodename])
		set path [joined_path $path $path_elem]
	}

	if {[tok_type $token] == "nodesupplement"} {
		set label_name $tok_text([sub_token [sub_token $token reflabel] reflabelname])
		if {[info exists labels($label_name)]} {
			set path $labels($label_name) }
	}

	return $path
}


##
# Populate the global 'labels' and 'references' arrays
#
# This function also initializes the 'selected' array with a key for
# each path found and the value to 0. So the existing paths can be
# queried by iterating over the 'selected' array names.
#
proc collect_labels_and_references {{token content0} {curr_path ""}} {
	global tok_text

	set output $tok_text($token)

	while {$output != ""} {

		# consume plain text
		if {[regexp {^[^§]+} $output plain]} {
			regsub {^[^§]+} $output "" output }

		# consume token
		if {[regexp {§(.+?)°} $output dummy token]} {

			# try to enter node or nodesupplement
			set path [sub_node_path $token $curr_path]

			if {$path != $curr_path} {
				collect_label_and_references_of_node $token $path }

			regsub {§(.+?)°} $output "" output
		}
	}
}


proc dump_selected_source {{token content0} {curr_path ""}} {
	global tok_text
	global selected

	set output $tok_text($token)

	while {$output != ""} {

		# consume plain text
		if {[regexp {^[^§]+} $output plain]} {
			regsub -all {³}  $plain "\\&" plain

			if {[info exists selected($curr_path)] && $selected($curr_path)} {
				puts -nonewline $plain }

			regsub {^[^§]+} $output "" output
		}

		# consume token
		if {[regexp {§(.+?)°} $output dummy token]} {
			dump_selected_source $token [sub_node_path $token $curr_path]
			regsub {§(.+?)°} $output "" output
		}
	}
}


proc children {parent_path} {
	global selected

	set result {}
	foreach path [array names selected] {
		if {[string match "$parent_path*" $path]} {
			lappend result $path } }

	return $result
}


##
# Return most specific label for the given node
#
proc label_of_path {path} {
	global labels

	set longest_match 0
	set label ""
	foreach l [array names labels] {

		if {$labels($l) == $path} {
			return $l }

		if {[string match "$labels($l)*" $path]} {
			set len [string length $l]
			if {$len > $longest_match} {
				set longest_match $len
				set label $l
			}
		}
	}
	return $label
}


proc select_children {parent_path} {
	global selected

	foreach path [children $parent_path] {
		select $path }
}


proc select_dependencies {path} {
	global references
	global labels

	if {![info exists references($path)]} {
		return }

	foreach label $references($path) {
		select $labels($label) }
}


proc select {path} {
	global selected

	if {!$selected($path)} {
		set selected($path) 1
		select_children $path
		select_dependencies $path
	}
}


###############
## Front end ##
###############

collect_labels_and_references


foreach arg [get_cmd_arg --select {}] {

	# distinguish DTS path argument (starting with /) from label argument
	if {[string match "/*" $arg]} {

		if {![info exists selected($arg)]} {
			puts stderr "Error: path '$arg' not present in device-tree source"
			exit -1
		}
		set path $arg

	} else {

		if {![info exists labels($arg)]} {
			puts stderr "Error: label '$arg' not present in device-tree source"
			exit -1
		}
		set path $labels($arg)
	}

	select $path
}


# select all nodes between each selected node and the root
foreach path [array names selected] {
	if {$selected($path)} {
		while {[regexp {(.*)/.+$} $path dummy parent]} {
			set selected($parent) 1
			select_dependencies $parent
			set path $parent
		}
		set selected(/) 1
		select_dependencies /
	}
}


if {[get_cmd_switch --labels]} {
	foreach n [lsort [array names labels]] {
		puts "$n\t$labels($n)" } }


if {[get_cmd_switch --nodes]} {
	foreach n [lsort [array names selected]] {
		puts "$n" } }


if {[get_cmd_switch --references]} {
	foreach n [lsort [array names references]] {
		puts "$n\t$references($n)" } }


if {[get_cmd_switch --dot-graph]} {
	puts "digraph {"
	puts {  rankdir=LR; nodesep=0.01;}
	puts {  node[shape=polygon, height=0, color=gray, fontsize=12, margin="0.1,0.01"];}

	# declare nodes using the DTS label as node name
	foreach l [array names labels] {
		puts "  \"$l\"" }

	set relations {}

	# gather label-reference dependencies
	foreach l [array names labels] {
		set path $labels($l)

		set subtree_nodes $path
		foreach child_path [children $path] {
			lappend subtree_nodes $child_path }

		foreach path $subtree_nodes {
			set label [label_of_path $path]
			if {[info exists references($path)]} {
				foreach ref $references($path) {
					if {$label != $ref} {
						lappend relations "\"$label\" -> \"$ref\"" } } }
		}
	}

	# gather parent-child dependencies
	foreach path [array names selected] {
		set label [label_of_path $path]
		while {[regexp {(.*)/.+$} $path dummy parent]} {

			set parent_label [label_of_path $parent]
			if {$parent_label != "" && $parent_label != $label} {
				lappend relations "\"$parent_label\" -> \"$label\"" }

			set path $parent
		}
	}

	foreach relation [lsort -unique $relations] {
		puts "  $relation" }

	puts "}"
}

dump_selected_source