#!/bin/bash

# This software is released into public domain.
# It is provided "as is", without warranties or conditions of any kind.
# Anyone is free to modify, redistribute and do anything with this software.

# pomf2gomf.bash: convert pomf-style flat folders with uploads to gomf storage

set -eu

for req in basename sha1sum cut xxd base64 tr touch; do
	if ! type "$req" >/dev/null; then
		printf "fatal error: missing command %s\n" "$req" >&2
		exit 1
	fi
done

usage() {
	printf "usage: %s POMF_DIR GOMF_DIR\n" "$(basename "$0")"
	printf "  where POMF_DIR is a flat directory with files named after their file IDs and\n"
	printf "  extensions and GOMF_DIR is the root dir (created if necessary) of gomf-web\n"
}

if [ $# -ne 2 ]; then
	usage >&2
	exit 2
fi

pomf="$1"
gomf="$2"

if ! [ -d "$pomf" ]; then
	printf "directory %s does not exist\n" "$pomf" >&2
	exit 1
fi

mkdir -p "$gomf/upload/files"
mkdir -p "$gomf/upload/ids"

for file in "$pomf"/*; do
	name="$(basename "$file")"
	id="${name%%.*}"
	ext="${name#*.}"
	sha="$(sha1sum -b "$file" | cut -d' ' -f1 | xxd -r -p | base64 | tr -d = | tr '+/' '-_')"
	if [ "$name" = "$ext" ]; then # no ext
		ext=
	else
		ext=".$ext"
	fi
	while [ ${#id} -lt 3 ]; do
		id="_$id"
	done
	id1="${id:0:1}" # first letter
	id2="${id:1:2}" # second and third letter
	hash1="${sha:0:1}" # first letter
	hash2="${sha:1:2}" # second and third letter

	hashd="$gomf/upload/files/$hash1/$hash2/$sha"
	idd="$gomf/upload/ids/$id1/$id2/$id"
	mkdir -p "$hashd"
	cp -va "$file" "$hashd/file"
	mkdir -p "$idd"
	ln -vs "../../../../files/$hash1/$hash2/$sha/file" "$idd/file$ext" # relative link to $gomf/upload/ids file
	touch --no-dereference --reference "$file" "$idd/file$ext"
done