#!/usr/bin/bash
# backupd - v1.0.0
# a simple backup script
#
# Copyright (c) 2025 Tianyi CodeLab, under the MIT License.

DATA_DIR="$(cd "$(dirname "$0")" && pwd)"
RCLONE_DEST_NAME="dest"
ZSTD_LEVEL=13

main() {
    local backup_name backup_remote
    backup_name="backups_$(hostname)_$(date +%Y-%m-%d)_$(date +%H:%M:%S)"
    backup_remote="$RCLONE_DEST_NAME:server-$(hostname)"
    check_files

    # shellcheck disable=SC1091
    . "$DATA_DIR/passwd"
    if [ -z "$AES_PASSWD" ]; then
        echo -ne "\033[1;31mAES_PASSWD is not set in file 'passwd'. Using default hostname as password.\033[0m\n"
        echo -ne "\033[1;31mWarning: THIS IS NOT SECURE!\033[0m\n"
        AES_PASSWD="$(hostname)"
    fi
    if [ -z "$ITER_COUNT" ]; then
        echo -ne "\033[1;31mITER_COUNT is not set in file 'passwd'. Using default value 100000.\033[0m\n"
        ITER_COUNT=100000
    fi

    local ctx 
    local tar_file zst_file enc_file ext_list inc_list
    local tar_hash zst_hash enc_hash
    ctx="$(mktemp -d)"
    tar_file="$ctx/$backup_name.tar"
    zst_file="$ctx/$backup_name.tar.zst"
    enc_file="$ctx/$backup_name.tar.zst.enc"
    ext_list="$DATA_DIR/excludes"
    inc_list="$DATA_DIR/includes"
    echo  -ne   "\033[1;33mCreating backup $backup_name\033[0m\n"
    exec_hooks   pre
    echo  -ne   "\033[1;33mCreating archive $tar_file\033[0m\n"
    tar   -cvf  "$tar_file" -X "$ext_list" -T "$inc_list"
    echo   -ne  "\033[1;33mCompressing archive $zst_file\033[0m\n"
    zstd  -T    -${ZSTD_LEVEL} "$tar_file" -o "$zst_file"
    echo  -ne  "\033[1;33mEncrypting archive $enc_file\033[0m\n"
    openssl enc -aes-256-cbc -salt -pbkdf2 -iter "$ITER_COUNT" -in "$zst_file" -out "$enc_file" -k "$AES_PASSWD"
    tar_hash="$(sha256sum "$tar_file" | cut -d ' ' -f 1)"
    zst_hash="$(sha256sum "$zst_file" | cut -d ' ' -f 1)"
    enc_hash="$(sha256sum "$enc_file" | cut -d ' ' -f 1)"
    echo  -ne   "\033[1;34mArchive hash:    $tar_hash\033[0m\n"
    echo  -ne   "\033[1;34mCompressed hash: $zst_hash\033[0m\n"
    echo  -ne   "\033[1;34mEncrypted hash:  $enc_hash\033[0m\n"
    echo  -ne   "\033[1;33mUploading archive to remote...\033[0m\n"
    echo  -ne   "\033[1;34mRemote filename: $backup_remote\033[0m\n"
    RCLONE_CONFIG="$DATA_DIR/rclone.conf" rclone copy \
        -vv --checksum --no-traverse --s3-no-check-bucket --metadata \
        --metadata-set "sha256-enc=$enc_hash" \
        --metadata-set "sha256-zst=$zst_hash" \
        --metadata-set "sha256-tar=$tar_hash" \
        -P "$enc_file" "$backup_remote"
    exec_hooks   post
    rm    -rvf  "$ctx"
    echo  -ne   "\033[1;34m------------ backup done ------------\033[0m\n"
}

check_files() {
    if [ ! -f "$DATA_DIR/includes" ]; then
        echo -ne "\033[1;31mCreating configuration file 'includes'...\033[0m\n"
        touch "$DATA_DIR/includes"
    fi

    if [ ! -f "$DATA_DIR/excludes" ]; then
        echo -ne "\033[1;31mCreating configuration file 'excludes'...\033[0m\n"
        touch "$DATA_DIR/excludes"
    fi

    if [ ! -d "$DATA_DIR/hooks-pre.d" ]; then
        echo -ne "\033[1;31mCreating directory 'hooks-pre.d'...\033[0m\n"
        mkdir -p "$DATA_DIR/hooks-pre.d"
    fi

    if [ ! -d "$DATA_DIR/hooks-post.d" ]; then
        echo -ne "\033[1;31mCreating directory 'hooks-post.d'...\033[0m\n"
        mkdir -p "$DATA_DIR/hooks-post.d"
    fi
}

exec_hooks() {
    local hook_type="$1"
    echo -ne "\033[1;32mRunning $hook_type hooks...\033[0m\n"
    for hook in "$DATA_DIR/hooks-$hook_type.d"/*; do
        if [ -x "$hook" ]; then
            echo -ne "------------ Running hook: $hook\n"
            "$hook"
        fi
    done
}

main "$@"