#!/bin/sh
assume_yes=0
verbose=0

die ()
{
	# always print errors
	if [ "$verbose" -eq 1 ] || echo "$1" | grep -q "^E:"
	then
		echo "$1" >&2
	fi
}

help ()
{
	local verbose=1
	die "ladd [OPTION [ARG]...] [FILE]
        -c CATEGORY
        -d DESCRIPTION
        -f FILE
        -h                        display help
        -l LINK
        -v                        verbose
        -y                        assume 'yes'"
}

alias shiftt='
if [ $# -gt 0 ]
then
	shift
else
	die "E: No argument provided."
	exit 1
fi'

ftest ()
{
	if [ ! -f "$1" ]; then
		die "E: '$1' not found."
		exit 1
	fi
}

# Main execution

if [ $# -eq 0 ]
then
	help
	exit
fi
while [ $# -ne 0 ]
do
	case "$1" in
		'-c')
			shiftt
			category="$(echo "$1" | tr '[:lower:]' '[:upper:]')" 
			die "I: category -> '$category'"
			shiftt
			;;
		'-d')
			shiftt
			description="$1"
			die "I: description -> '$description'"
			shiftt
			;;
		'-f')
			shiftt
			test -n "$1" &&
				ftest "$1"
			file="$1"
			shiftt
			die "I: file -> '$file'"
			;;
		'-l')
			shiftt
			link="$1"
			die "I: link -> '$link'"
			shiftt
			;;
		'-v')
			verbose=1
			die "I: verbose -> $verbose"
			shiftt
			;;
		'-y')
			assume_yes=1
			die "I: assume_yes -> $assume_yes"
			shiftt
			;;
		'-h')
			help
			exit 1
			;;
		*)
			if [ ! "$file" ]
			then
				ftest "$1"
				file="$1"
				die "I: file -> '$file'"
				shiftt
			else
				die "E: not a valid argument."
				help
				exit 1
			fi
			;;
	esac
done

# Tests
# Check on file and/or link
if [ -z "$file" ] || [ -z "$link" ]
then
	die "E: no file and/or link supplied."
	exit 1
fi
# Check on valid category
categories="$(pup -f "$file" -p 'h2 text{}' |
	tr '\n' ',' | sed 's/,$//')"
die ""
die "categories: $categories"
if ! echo "$categories" | grep -q "$category"
then
	die "E: '$category' is not a valid category."
fi
# Check on empty values
for var in category description
do
	eval value=\$$var
	if [ -z "$value" ]
	then
		die "W: $var is empty"
		if [ "$assume_yes" -eq 0 ]
		then
			die "W: are you sure you want to proceed? (Y/n)"
			echo -n ">" >&2
			read input
			test "$input" = "n" &&
				exit 1
		fi
		eval $var="'UNDEFINED'"
		die "I: $var -> $(eval echo "\$$var")"
	fi
done
# Checks if the link has already been added
if grep -q "$link" "$file"
then
	die "E: link already in $file"
	exit 1
fi

# constructing the tag
tag="<li><a href=\"$link\">$link</a> - $description</li>"
die "tag: $tag"

die "I: appending tag"
# use grep line numbers to add link after match of the category header
# header will have an <ul> element this one is used with -A 1 | tail -1
sed -i "$(grep -n "<h2.*$category" -A 1 "$file" |
	tail -n 1 |
	cut -f 1 -d '-')a $tag" "$file"