# -------------------------------------------------------------------------------------
# A backup and restore strategy for PostgreSQL with "pg_dump" and "pg_restore" commands.
# -------------------------------------------------------------------------------------

check_command "pg_dump"
check_command "psql"
check_command "pg_restore"

# Make use of PostgreSQL 9.3+ options if available
if [[ ${psql_majorminor} -ge 9003 ]]; then
    PG_PARALLEL="-j 5"
    PG_SNAPSHOT_OPT="--no-synchronized-snapshots"
fi

function prepare_backup_db {
    check_config_var "CONFLUENCE_BACKUP_DB_TMP"
    check_config_var "POSTGRES_USERNAME"
    check_config_var "POSTGRES_HOST"
    check_config_var "POSTGRES_PORT"
    check_config_var "CONFLUENCE_DB"
}

function backup_db {
    [ -d "${CONFLUENCE_BACKUP_DB_TMP}" ] && rm -r "${CONFLUENCE_BACKUP_DB_TMP}"
    mkdir -p "${CONFLUENCE_BACKUP_DB_TMP}"
    run pg_dump -U "${POSTGRES_USERNAME}" -h "${POSTGRES_HOST}" --port=${POSTGRES_PORT} ${PG_PARALLEL} -Fd -d "${CONFLUENCE_DB}" ${PG_SNAPSHOT_OPT} -f "${CONFLUENCE_BACKUP_DB_TMP}"
    perform_rsync_compress_db
}

function prepare_restore_db {
    check_config_var "POSTGRES_USERNAME"
    check_config_var "POSTGRES_HOST"
    check_config_var "POSTGRES_PORT"
    check_var "CONFLUENCE_RESTORE_DB"

    if run psql -U "${POSTGRES_USERNAME}" -h "${POSTGRES_HOST}" --port=${POSTGRES_PORT} -d "${CONFLUENCE_DB}" -c "" 2>/dev/null; then
        local table_count=$(psql -U "${POSTGRES_USERNAME}" -h "${POSTGRES_HOST}" --port=${POSTGRES_PORT} -d "${CONFLUENCE_DB}" -tqc '\dt' | grep -v "^$" | wc -l)
        if [ "${table_count}" -gt 0 ]; then
            error "Database '${CONFLUENCE_DB}' already exists and contains ${table_count} tables"
        else
            error "Database '${CONFLUENCE_DB}' already exists"
        fi
        bail "Cannot restore over existing database '${CONFLUENCE_DB}', please ensure it does not exist before restoring"
    fi
}

function restore_db {
    run pg_restore -U "${POSTGRES_USERNAME}" -h "${POSTGRES_HOST}" --port=${POSTGRES_PORT} ${PG_PARALLEL} \
        -d postgres -C -Fd "${CONFLUENCE_RESTORE_DB}"
}

function cleanup_incomplete_db_backup {
    info "Cleaning up DB backup created as part of failed/incomplete backup"
    rm -r "${CONFLUENCE_BACKUP_DB_TMP}"
}

function cleanup_old_db_backups {
    # Not required as old backups with this strategy are typically cleaned up in the archiving strategy.
    no_op
}

function perform_rsync_compress_db {
    [ -d "${CONFLUENCE_BACKUP_DB}" ] && rm -r "${CONFLUENCE_BACKUP_DB}"
    mkdir -p "${CONFLUENCE_BACKUP_DB}"
    rsync  --remove-source-files -h $CONFLUENCE_BACKUP_DB_TMP/* $CONFLUENCE_BACKUP_DB/
}