#!/bin/bash
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
# shellcheck source=./mysql_common.sh
source "$SCRIPT_DIR/mysql_common.sh"

BASE_DIR="${BASE_DIR:-/home/admin/mysql_backup}"
DATE_FORMAT="${DATE_FORMAT:-%d-%m-%Y}"
ADD_TIME="${ADD_TIME:-0}"
RETENTION="${RETENTION:-7}"
ENABLE_COMPRESSION="${ENABLE_COMPRESSION:-1}"
LOG_FILE="${LOG_FILE:-/var/log/mysql_backup.log}"

timestamp() {
    date '+%Y-%m-%d %H:%M:%S'
}

log() {
    printf '[%s] %s\n' "$(timestamp)" "$*" | tee -a "$LOG_FILE"
}

dump_globals_file() {
    local output_file="$1"
    local tmp_file
    tmp_file="$(mktemp)"
    {
        echo "-- Global users and grants for MySQL"
        echo "-- Generated at $(timestamp)"
    } > "$tmp_file"

    while IFS=$'\t' read -r db_user db_host; do
        [ -n "$db_user" ] || continue
        [ -n "$db_host" ] || continue
        printf "DROP USER IF EXISTS '%s'@'%s';\n" "$db_user" "$db_host" >> "$tmp_file"
        mysql_exec mysql -Nse "SHOW CREATE USER '${db_user}'@'${db_host}'" >> "$tmp_file" || true
        echo ";" >> "$tmp_file"
        while IFS= read -r grant_line; do
            [ -n "$grant_line" ] || continue
            printf "%s;\n" "$grant_line" >> "$tmp_file"
        done < <(mysql_exec mysql -Nse "SHOW GRANTS FOR '${db_user}'@'${db_host}'" || true)
        echo >> "$tmp_file"
    done < <(
        mysql_exec mysql -Nse "
            SELECT user, host
            FROM mysql.user
            WHERE user <> ''
              AND user NOT IN ('mysql.sys', 'mysql.session', 'mysql.infoschema', 'mariadb.sys')
            ORDER BY user, host
        " || true
    )

    if [ "$ENABLE_COMPRESSION" = "1" ]; then
        gzip -9 < "$tmp_file" > "$output_file"
    else
        mv "$tmp_file" "$output_file"
        return 0
    fi
    rm -f "$tmp_file"
}

mysql_load_alt_credentials

mkdir -p "$BASE_DIR"

if [ "$ADD_TIME" = "1" ]; then
    DATE_STR="$(date +"${DATE_FORMAT}_%H-%M")"
else
    DATE_STR="$(date +"${DATE_FORMAT}")"
fi
BACKUP_DIR="${BASE_DIR}/${DATE_STR}"
mkdir -p "$BACKUP_DIR"

log "Start backupu MySQL do ${BACKUP_DIR}"

GLOBALS_FILE="${BACKUP_DIR}/_globals.sql"
if [ "$ENABLE_COMPRESSION" = "1" ]; then
    GLOBALS_FILE="${GLOBALS_FILE}.gz"
fi
dump_globals_file "$GLOBALS_FILE"
log "Zapisano ${GLOBALS_FILE##*/}"

while IFS= read -r db_name; do
    [ -n "$db_name" ] || continue
    target_file="${BACKUP_DIR}/${db_name}.sql"
    if [ "$ENABLE_COMPRESSION" = "1" ]; then
        mysqldump_exec --single-transaction --skip-lock-tables --routines --triggers --events --databases "$db_name" | gzip -9 > "${target_file}.gz"
        log "Backup ${db_name} -> ${target_file##*/}.gz"
    else
        mysqldump_exec --single-transaction --skip-lock-tables --routines --triggers --events --databases "$db_name" > "$target_file"
        log "Backup ${db_name} -> ${target_file##*/}"
    fi
done < <(mysql_non_system_databases)

if [ "$RETENTION" -gt 0 ]; then
    find "$BASE_DIR" -mindepth 1 -maxdepth 1 -type d -mtime +"$RETENTION" -exec rm -rf {} +
fi

log "Backup MySQL zakończony."