#!/bin/sh
#
# dsv - Improved data sheet viewer
#
# Written 2010 by Werner Almesberger
# Copyright 2010 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 <component>" 2>&1
    echo "       $0 help" 2>&1
    echo "       $0 [ls]" 2>&1
    echo "       $0 setup <info-file> ..." 2>&1
    exit 1
}


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 "$nm: no URL" 2>&1
	exit 1
    fi
    ds=$nm-`basename "$url"`
    mkdir -p $DSV_DIR
    if [ ! -r "$DSV_DIR/$ds" ]; then
	wget -nv -O "$DSV_DIR/$ds" "$url"
	# @@@ should handle error
    fi
    eval for n in $name $alias\; do \
        'nm=`echo "$n" | sed "s/%/%25/g;s|/|%2F|g"`;' \
	echo '"$ds"' '>$DSV_DIR/dsv-$nm'\; \
    done
    name=
    alias=
    url=
}


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


eof()
{
    flush
    tag=
}


setup()
{
    for n in "$@"; do
	if [ ! -r "$n" ]; then
	    echo "$n: not found" 2>&1
	    continue
	fi
	#
	# "read" doesn't recognize lines that don't end with a newline.
	# The cat-sed hack below works around this problems.
	#
	cat -E "$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 ]*//'`
		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
}


search()
{
    while true; do
	if [ -d $DSV_DIR ]; then
    	    name=`echo "$1" | sed 's/%/%25/g;s|/|%2F|g'`
	    if [ -r "$DSV_DIR/dsv-$name" ]; then
		file=`cat "$DSV_DIR/dsv-$name"`
		if [ ! -r "$DSV_DIR/$file" ]; then
		    echo "$1 -> $file: does not exist" 2>&1
		    exit 1
		fi
		${DSV_PDFVIEWER:-xpdf} "$DSV_DIR/$file"
		exit
	    fi
	fi
	if ! up; then
	    echo "no data sheet found for \"$1\"" 2>&1
	    exit 1
	fi
    done
}


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