#!/bin/sh
#
# dsv - Improved data sheet viewer
#
# Written 2010-2014, 2016 by Werner Almesberger
# Copyright 2010-2014, 2016 Werner Almesberger
#
# 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 later version.
#

#
# Theory of operation:
#
# We download data sheets from the Internet into local caches and provide a
# quick access mechanism for viewing the data sheets. A cache is a directory
# called .dsv/. Caches can be hierarchical. "dsv setup" generates a cache in
# the local directory. "dsv <component>" and "dsv ls" search the hierarchy,
# starting with the current directory.
#
# Caches contain two types of files: dsv-<ref> is the name or alias with
# which a data sheet is referenced. <ref>-<filename> is the actual data
# sheet, with <filename> being the name of the file we downloaded.
#

DSV_DIR=.dsv


usage()
{
	echo "usage: $0 [-p] [-u] <component>" 1>&2
	echo "       $0 help" 1>&2
	echo "       $0 [ls]" 1>&2
	echo "       $0 setup <info-file> ..." 1>&2
	echo 1>&2
	echo "  -p   show the path instead of displaying the file " 1>&2
	echo "  -u   show source URL instead of displaying the file " 1>&2
	exit 1
}


do_wget()
{
	wget -nv -U "dsv/1.0" "$@"
}


up()
{
	old=`pwd`
	cd ..
	new=`pwd`
	[ "$old" != "$new" ]
}


flush()
{
	eval nm=$name
	nm=`echo "$nm" | sed 's/%/%25/g;s|/|%2F|g'`
	[ -z "$nm" ] && return
	if [ -z "$url" ]; then
		echo "$nm: no URL" 1>&2
		exit 1
	fi
	ds=$nm-`basename "$url" | tr '?&' _`
	mkdir -p $DSV_DIR
	if [ ! -r "$DSV_DIR/$ds" ]; then
		if [ "$zip" ]; then
			inside=$zip
			zip=$ds.zip
		else
			inside=${url#*.[Zz][Ii][Pp] }
		fi
		if [ "$inside" = "$url" ]; then
			do_wget -O "$DSV_DIR/$ds" "$url"
			# @@@ should handle error
		else
			if [ -z "$zip" ]; then
				url=${url%`echo x"$inside" | sed 's/./?/g'`}
				zip=$nm-`basename "$url"`
			fi
			if [ ! -r "$DSV_DIR/$zip" ]; then
				do_wget -O "$DSV_DIR/$zip" "$url"
				# @@@ should handle error
			fi
			unzip -p "$DSV_DIR/$zip" "$inside" >"$DSV_DIR/$ds" ||
			    { rm -f "$DSV_DIR/$zip" "$DSV_DIR/$ds"; exit 1; }
		fi
	fi
	eval for n in $name $alias\; do \
	    'nm=`echo "$n" | sed "s/%/%25/g;s|/|%2F|g"`;' \
	    \{ echo '"$ds"'\; echo '"$url"'\; \} '>$DSV_DIR/dsv-$nm'\; \
	    done
	name=
	alias=
	url=
	zip=
}


set_value()
{
	case "$tag" in
		N:|n:)	flush
			name="\"$value\"";;
		A:|a:)	alias="$alias \"$value\"";;
		D:|d:)	url=$value;;
		Z:|z:)	zip=$value;;
		"")	;;	# first iteration
		*)	echo "unrecognized tag \"$tag\"" 1>&2
			exit 1;;
	esac
	value=
}


eof()
{
	flush
	tag=
}


setup()
{
	for n in "$@"; do
		if [ ! -r "$n" ]; then
			echo "$n: not found" 1>&2
			continue
		fi
		#
		# "read" doesn't recognize lines that don't end with a newline.
		# The cat-sed hack below works around this problems.
		#
		cat -E "$n" | sed 's/[^$]$/&\n/;s/$$//' | {
			while read line; do
				[ "$line" = "${line###}" ] || continue
				tmp=`echo "$line" |
				    awk '/^[^\t ]/ { print $1 }'`
				tail=`echo "$line" |
				    sed 's/^[^\t ]*[\t ]*//;s/[\t ]*$//'`
				if [ -z "$tmp" ]; then
					[ -z "$tail" ] || value="$value $tail"
				else
					set_value
					tag=$tmp
					value=$tail
				fi
			done
			set_value
			eof
		}
	done
}


list()
{
	while true; do
		if [ -d $DSV_DIR ]; then
			ls -b -1 $DSV_DIR | sed 's/^dsv-//p;d' |
			    sed 's|%2F|/|g;s/%25/%/g'
		fi
		up || break
	done | sort | uniq | column
}


view()
{
	${DSV_VIEWER:-${DSV_PDFVIEWER:-xdg-open}} "$@"
}


search()
{
	while true; do
		if [ -d $DSV_DIR ]; then
			name=`echo "$1" | sed 's/%/%25/g;s|/|%2F|g'`
			if [ -r "$DSV_DIR/dsv-$name" ]; then
				file=`sed 1q "$DSV_DIR/dsv-$name"`
				if [ ! -r "$DSV_DIR/$file" ]; then
					echo "$1 -> $file: does not exist" 1>&2
					exit 1
				fi
				if $path; then
					echo "`pwd`/$DSV_DIR/$file"
				elif ! $show_url; then
					view "$DSV_DIR/$file"
				fi
				if $show_url; then
					url=`sed 1d "$DSV_DIR/dsv-$name"`
					if [ "$url" ]; then
						echo "$url"
					else
						echo "$DSV_DIR/dsv-$name" \
						    "does not contain a URL" \
						    "- please regenerate" 1>&2
						exit 1
					fi
				fi
				exit
			fi
		fi
		if ! up; then
			echo "no data sheet found for \"$1\"" 1>&2
			exit 1
		fi
	done
}


path=false
show_url=false

while true; do
	case "$1" in
		-p)	path=true
			shift;;
		-u)	show_url=true
			shift;;
		-*)	usage;;
		*)	break;;
	esac
done

case "$1" in
	help|-*)	usage;;
	""|ls)		list;;
	setup)		shift
			[ "$1" ] || usage
			setup "$@";;
	*)		search "$@";;
esac