#!/bin/sh
# BUOC 1
# Ví dụ đơn giản về sử dụng shell script xây dựng ứng dụng album CD
# Dưới đây là các điều khoản thỏa thuận về bản quyền của mã nguồn miễn phí.
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your option)
# any older version.
# This program is distribute in the hopes that it will be useful, but
# WITHOUT ANY WARRANTY, without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details.
# You should have received a copy of the GNU General Public License along with this program;
# if not, write to the Free Software Foundation, Inc.
# 675 Mass Ave, Cambridge, MA 02139, USA.
# A few global variables we need. Put them here for clarity.

# BUOC 2
menu_choice=""
current_cd=""
title_file="title.cdb"
tracks_file="tracks.cdb"
temp_file=/tmp/cdb.$$
trap 'rm -f $temp_file' EXIT

# BUOC 3
get_return(){
	echo -e "Press return \c"
	read x
	return 0
}

get_confirm(){
	echo -e "Are you sure? \c"
	while true
	do
		read x
		case "$x" in
			y | yes | Y | Yes | YES )
				return 0;;
			n | no | N | No | NO )
				echo 
				echo "Cancelled"
				return 1;;
			*) echo "Please enter yes or no" ;;
		esac
	done
}

# BUOC 4
set_menu_choice(){
	clear
	echo "Option :-"
	echo
	echo "	a) Add new CD"
	echo "	f) Find CD"
	echo "	c) Count the CDs and tracks in the catalog"
	if [ "$cdcatnum" != "" ]; then
  	 echo "	l) List tracks on $cdtitle"
	 echo "	r) Remove $cdtitle"
	 echo "	u) Update track information for $cdtitle"
	fi
	echo "	q) Quit"
	echo
	echo -e "Please enter choice then press return \c"
	read menu_choice
	return
}

# BUOC 5
insert_title(){
	echo $* >> $title_file
	return
}

insert_track(){
	echo $* >> $tracks_file
	return
}

add_record_tracks(){
	echo "Enter track information for this CD"
	echo "When no more tracks enter q"
	cdtrack=1
	cdtitle=""
	while [ "$cdtitle" != "q" ]
	do
		echo -e "Track $cdtrack, track title? \c"
		read tmp
#		case "$tmp" in
#		"")	continue
#				;;
#		*,*	echo "Sorry, no commas allowed"	
#				continue
#				;;
#		esac
		cdtitle=${tmp%%,*}
		if [ "$tmp" != "$cdtitle" ]; then
			echo "Sorry, no commas allowed"
			continue
		fi
		if [ -n "$cdtitle" ]; then
			if [ "$cdtitle" != "q" ]; then
				insert_track $cdcatnum,$cdtrack,$cdtitle
			fi
		else
			cdtrack=$((cdtrack-1))
		fi
	cdtrack=$((cdtrack+1))	
	done
}

# BUOC 6
# This allows adding of a new CD
add_records(){
	# Prompt for the initial information
	
	echo -e "Enter catalog number \c"
	read tmp
	cdcatnum=${tmp%%,*}

	echo -e "Enter title \c"
	read tmp
	cdtitle=${tmp%%,*}

	echo -e "Enter type \c"
	read tmp
	cdtype=${tmp%%,*}
	
	echo -e "Enter artist/composer \c"
	read tmp
	cdac=${tmp%%,*}

	# Check that they want to enter the information
	
	echo "About to add new entry"
	echo "$cdcatnum $cdtitle $cdtype $cdac"

	# If confirmed then append it to the title file

# get_confirm && insert_title $cdcatnum, $cdtitle, $cdtype, $cdac
	if get_confirm ; then
		insert_title $cdcatnum, $cdtitle, $cdtype, $cdac
		add_record_tracks
	else
		remove_records
	fi
	return
}

# BUOC 7
find_cd(){
	if [ "$l" = "n" ]; then
		asklist=n
	else
		asklist=y
	fi
	cdcatnum=""
	echo -e "Enter a string to search for in the CD titles \c"
	read searchstr
	if [ "$searchstr" = "" ]; then
		return 0
	fi
	
	grep "$searchstr" $title_file > $temp_file

# set $(wc -l $temp_file)
# linesfound=$l
	linesfound=$(wc -l $temp_file)
	case "$linesfound" in
	0) 	echo "Sorry, nothing found"
			get_return
			return 0
			;;
	1)		;;
	2)		echo "Sorry, not unique."
			echo "Found the following"
			cat $temp_file
			get_return
			return 0
	esac

# Có thể đổi case theo cách sau
# if [ "$linesfound" = "0" ]; then
# 	echo "Sorry, nothing found"
#	get_return && return 0
# fi
# if [ "$linesfound" != "1" ]	; then
# 	echo "Sorry, not unique."
# 	echo "Found the following ..."
# 	cat $temp_file
#	get_return && return 0
# fi
# cdcatnum=$(cut -f 1 -d , $temp_file)
	
	IFS=","
	read cdcatnum cdtitle cdtype cdac < $temp_file
	IFS=" "

#	if [ "$cdcatnum" = "" ]; then
	if [ -z "$cdcatnum" ]; then
		echo "Sorry, could not extract catalog field from $temp_file"	
# cat $temp_file
	get_return
	return 0
 	fi

# cdtitle=$(cut -f 2 -d , $temp_file)
# cdtype=$(cut -f 3 -d , $temp_file)
# cdac=$(cut -f 4 -d , $temp_file)

	echo

	echo Catalog number $cdcatnum
	echo $cdtitle
	echo $cdtype
	echo $cdac
	echo
	get_return

	if [ "$asklist" = "y" ]; then
		echo -e "View tracks for this CD? \c"
			read x
		if [ "$x" = "y" ]; then
			echo
			list_tracks
			echo
		fi
	fi
	return 1
}

# BUOC 8
update_cd(){
	if [ -z "$cdcatnum" ]; then
		echo "You must select a CD first"
		find_cd n
	fi
	if [ -n "$cdcatnum" ]; then
		echo "Current tracks are :-"
		list_tracks
		echo
		echo "This will re-enter the tracks for $cdtitle"
		get_confirm && {
			grep -v "^$cdcatnum" $tracks_file > $temp_file
			mv $temp_file $tracks_file
#				cat $temp-file > $tracks_file	 	
			echo
			add_record_tracks
		}
	fi
	return
}

# BUOC 9
count_cds(){
	num_titles=$(wc -l $title_file)
	num_tracks=$(wc -l $tracks_file)
	echo "found $num_titles CDs, with a total of $num_tracks tracks"
	get_return
	return
}

# BUOC 10
remove_records(){
	if [ -z "$cdcatnum" ]; then
		echo "You must select a CD first"
		find_cd n
	fi
	if [ -n "$cdcatnum" ]; then
		echo "You are about to delete $cdtitle"
		get_confirm && {
			grep -v "^$cdcatnum" $title_file > $temp_file
			mv $temp_file $title_file
			grep -v "^$cdcatnum" $tracks_file > $temp_file
			mv $temp_file $tracks_file
			cdcatnum=""
			echo Entry removed
		}
	get_return
	fi
	return
}

# BUOC 11
list_tracks(){
	if [ "$cdcatnum" = "" ]; then
		echo "no CD selected yet"
		return
	else
		grep "$cdcatnum" $tracks_file > $temp_file
		set $(wc -l $temp_file)
		num_tracks=$l
		if [ "$num_tracks" = "0" ]; then
			echo "no tracks found for $cdtitle"
		else {
			echo
			echo "$cdtitle :-"
			echo
			cut -f 2- -d , $temp_file
			echo 
		}| more
		fi
	fi
	get_return
	return
} 

# BUOC 12
# Main routine starts here
#
# get the files in a known state

rm -f $temp_file

if [ ! -f $title_file ]; then
	touch $title_file
fi
if [ ! -f $tracks_file ]; then
	touch $tracks_file
fi

# Now the application proper

clear
echo
echo
echo "Mini CD manager"
sleep 3

quit=n
while [ "$quit" != "y" ];
do
	set_menu_choice
	case "$menu_choice" in
		a) add_records;;
		r) remove_records;;
		f) find_cd y;;
		u) update_cd;;
		c) count_cds;;
		l) list_tracks;;
		b)
			echo 
			more $title_file
			echo
			get_return;;
		q | Q ) quit=y;;
		*) echo "Sorry, choice not recognized";;
	esac
done

# Tidy up and leave

rm -f $temp_file
echo "Finished"
exit 0