#!/bin/bash

set -e
#set -x

src="$1"
dest="$2"

if [ -z "$dest" ]; then
	echo >&2 "usage: $0 src dest"
	exit 1
fi

seen_files=$(mktemp)

mkdir -p "$dest" || true

cur=$(ipfs name resolve --nocache "$src")

ipfs ls "$cur" | while read HASH SIZE FILENAME; do
	FILENAME="${FILENAME%$'\r'}"
	dest_file="$dest/$FILENAME"

	if [ -e "$dest_file" ]; then
		ipfs_file_size=$(ipfs files stat --format='<size>' "/ipfs/$HASH")
		if [ $( stat -c %s "$dest_file") -eq "$ipfs_file_size" ]; then
			echo $FILENAME >> "$seen_files"
			continue
		fi
	fi
	echo >&2 "Retrieving $HASH => $dest_file"
	ipfs cat "$HASH" > "$dest_file"
	echo $FILENAME >> "$seen_files"
done

after_files=$(mktemp)
ls "$dest" > "$after_files"

comm --nocheck-order -13 "$seen_files" "$after_files" | while read INTRUDER; do
	rm -f "$dest/$INTRUDER"
done

rm -f "$seen_files"
rm -f "$after_files"

echo "$cur"