#!/bin/bash
# Usage: db-dump PROJECT DATABASE week|day
# Dump a MariaDB database to ~/.local/share/PROJECT/dumps with login ~/.config/PROJECT/dump.cnf.
# week: per-ISO-week files, keeping the two newest; day: per-weekday files (seven self-rotating copies).
set -euo pipefail

if (($# != 3)) || [[ $3 != week && $3 != day ]]; then
    echo "usage: ${0##*/} PROJECT DATABASE week|day" >&2
    exit 2
fi
project=$1 db=$2 mode=$3

cnf=${XDG_CONFIG_HOME:-$HOME/.config}/$project/dump.cnf
dir=${XDG_DATA_HOME:-$HOME/.local/share}/$project/dumps
if [[ $mode == week ]]; then
    out=$dir/$db-$(date +%G-W%V).sql.gz
else
    out=$dir/$db-$(LC_ALL=C date +%a).sql.gz
fi
keep=2

umask 077
mkdir -p "$dir"

# Write to a temporary file so a failed dump never replaces a good one
tmp=$(mktemp "$dir/.dump.XXXXXX")
trap 'rm -f "$tmp"' EXIT

mariadb-dump --defaults-extra-file="$cnf" --single-transaction --databases "$db" | gzip > "$tmp"
mv "$tmp" "$out"

# Weekly names sort by week, so all but the last $keep are the old ones
if [[ $mode == week ]]; then
    dumps=("$dir/$db"-[0-9][0-9][0-9][0-9]-W[0-9][0-9].sql.gz)
    if ((${#dumps[@]} > keep)); then
        rm -f -- "${dumps[@]:0:${#dumps[@]}-keep}"
    fi
fi