bin/tagd

#!/bin/bash
# tagd is a simple script that will rebuild ctag files when files are edited.
# This script also acts as a wrapper for ctags.
# Author: Skiqqy

set -B
files=( )

usage ()
{
	cat << EOF
tagd ~ The ctags daemon.

Usage: tagd [options]

Options
-------
-h    Shows this message.
-o    Specify where the tags file should be put (default is curr directory).
-s    Specify the source directory that ctags must generate tags for (default is crr directory).
-g    Generate ctags and then exit.
-r    How often to refresh the tags file (in seconds).
-R    Recursively the directory (identical to ctags -R).
-d    Daemonize.
EOF
}

# set ${files[@]} to contain files in src with thier edited times.
set_files ()
{
	files=( )
	res=$(stat -c "%y|%n" "$src"/{*.c,*.h} | sort -r) # The sort is so when looping over the array if a time is found less than the last $iter the loop may exit (this is an optimization).

	IFS=$'\n'
	for file in $res # I want splitting.
	do
		files+=( "$file" )
	done
	IFS=" " # Reset IFS
}

# Usage: build <options> <output dir> <source dir>
build ()
{
	echo "Building tags file."

	ctags $1 "$3/"* # I want splitting
	if [ ! "$2" = "$(pwd)" ]
	then
		mv tags "$2"
	fi
}

# Convert a date.
# Usage: conv_date <date>
conv_date() {
	date --date="$1" +"%Y-%m-%d %H:%M:%S"
}

# Usage: comp_date <date1> <date2>
# Returns 0 if date1 < date 2, 1 date2 < date1
comp_date ()
{
	[[ $(conv_date "$1") < $(conv_date "$2") ]]
}

main ()
{
	# Vars
	tags=$(pwd)
	src=.
	daemonize=false # TODO: Implement daemonize feature.
	gen=false
	iter=$(date)
	refresh=60
	copts=

	while getopts "ho:s:dgr:R" opt
	do
		case $opt in
			h)
				usage
				exit
				;;
			o)
				tags=$(realpath "$OPTARG")
				if [ ! -d "$OPTARG" ]
				then
					echo "-o must specify a valid directory."
					exit 1
				fi
				;;
			s)
				src=$(realpath "$OPTARG")
				if [ ! -d "$OPTARG" ]
				then
					echo "-s must specify a valid directory."
					exit 1
				fi
				;;
			d)
				daemonize=true
				;;
			g)
				gen=true
				;;
			r)
				if [[ ! "$OPTARG" =~ ^[0-9]+(\.[0-9]+)?$ ]] || [[ "$OPTARG" =~ ^0(\.0*)?$ ]]
				then
					echo "-r must be a non zero real."
					exit 1
				fi
				refresh="$OPTARG"
				;;
			R)
				copts="-R"
				;;
			*)
				usage
				exit 1
				;;
		esac
	done

	# Build tags file before starting main loop.
	build "$copts" "$tags" "$src"

	if "$gen"
	then
		exit
	fi

	# Start
	for ((;;))
	do
		sleep "$refresh"
		set_files
		for file in "${files[@]}"
		do
			time=$(echo "$file" | cut -d "|" -f 1 | cut -d\. -f 1)
			file=$(echo "$file" | cut -d "|" -f 2)
			
			if comp_date "$iter" "$time"
			then
				echo "Change detected!"
				iter=$(date)
				build "$copts" "$tags" "$src"
				break # Yes I know that techinically we only have to look at the first item, but this loop is to allow for the script to be extended.
			fi
		done
	done
}

main "$@"