#!/bin/bash

BASE_PATH="/home/aadhavan/Programming/Bash/sitegen"


check_for_dirs() {
	if [ ! -d "${BASE_PATH}/source" ]; then
		echo "ERROR: 'source' folder does not exist. Your content is sourced from this folder."
		exit
	fi

	if [ ! -d "${BASE_PATH}/output" ]; then
		mkdir "${BASE_PATH}/output"
	fi

	if [ -d "${BASE_PATH}/temp" ]; then
		echo "ERROR: You have an existing 'temp' folder. Please delete this folder, and run the script again."
		exit
	fi

	if [ ! -f "${BASE_PATH}/header.html" ]; then
		echo "ERROR: You do not have a header.html file. This file is used as a global header. Please create this file, and run the script again."
		exit
	fi
	if [ ! -f "${BASE_PATH}/footer.html" ]; then
		echo "ERROR: You do not have a footer.html file. This file is used as a global footer. Please create this file, and run the script again."
		exit
	fi

}


setup_temp_dir() {
#	Check if 'temp' already exists
	mkdir "${BASE_PATH}/temp"
}

setup_output_dir() {
	rm -r output # Delete existing 'output' directory
	cp -r source output #Copy directory structure from 'source' to 'output'
}

del_files_in_output() {
	find $BASE_PATH/output -type f -name "*.md" -delete #Delete all .md files (which were copied over from 'source') in 'output'
}

read_metadata() {
#	Read the metadata from the top of a .md file into a string
	metadata=$(awk 'BEGIN{RS = "\n\n"} {print $0}; {exit}' $1)  # Reads from the .md file until a double-newline is encountered
}

convert_to_array() {
#	Converts the metadata into two arrays: one with the key, and the other with the value
	readarray -t meta_key < <(echo -e "$1" | awk -F: '{print $1}')
	readarray -t meta_value < <(echo -e "$1" | awk -F: '{st = index($0,":"); values = substr($0,st+1); print values}' | cut -c 2-)
}

add_date_to_array() {
	meta_key+=("date")
	meta_value+=("$(date -r $1 +'%b %d, %Y')")
}

add_header_and_footer() {
#	Add header
	cat $BASE_PATH/header.html | cat - $1 > $BASE_PATH/temp/temp.html

#	Add footer
	echo >> $BASE_PATH/temp/temp.html
	cat $BASE_PATH/footer.html >> $BASE_PATH/temp/temp.html

#	Move temp file to original location
	mv $BASE_PATH/temp/temp.html $1
}

replace_vars() {
#	Loop through 'meta_key' array, search for the first occurence of the values in the HTML doc, and replace them with corresponding values in 'meta_value'.
	for index in $(seq 0 `expr "${#meta_key[@]}" - 1`); do
		sed -i "0, /[\$][\$]${meta_key[$index]}[\$][\$]/ {s/[\$][\$]${meta_key[$index]}[\$][\$]/${meta_value[index]}/}" $1
	done

}

md_to_html() {
#	Convert .md files from 'source' and place them into the correct locations into 'output'

	files=$(find $BASE_PATH/source -name "*.md")

	for file in $files; do
		read_metadata $file # Sets the 'metadata' variable

		convert_to_array "$metadata" #Sets the 'meta_key' and 'meta_value' arrays
		add_date_to_array "$file" #Uses 'meta_key' and 'meta_value' arrays

#		Copy file to temp dir and strip metadata
		cp $file $BASE_PATH/temp/
		let num_lines=$(echo $metadata | wc -l)+1
		sed -i "1,${num_lines}d" $BASE_PATH/temp/`basename $file`

		pandoc -f markdown $BASE_PATH/temp/`basename $file` > $BASE_PATH/output/`basename $file .md`.html
		rm $BASE_PATH/temp/*
		html_file="$BASE_PATH/output/`basename $file .md`.html"

		add_header_and_footer $html_file
		replace_vars $html_file #Uses 'meta_key' and 'meta_value' arrays

		unset metadata meta_key meta_value
	done
}

clean_up() {
	rm -r ${BASE_PATH}/temp
}


check_for_dirs
setup_temp_dir
setup_output_dir
del_files_in_output
md_to_html
clean_up