#!/bin/bash
set -e

DATA_DIR="/var/lib/postgresql/data"
OLD_VERSION_FILE="$DATA_DIR/PG_VERSION"
NEW_VERSION="16"

if [ -f "$OLD_VERSION_FILE" ]; then
    OLD_VERSION=$(cat "$OLD_VERSION_FILE")

    if [ "$OLD_VERSION" != "$NEW_VERSION" ]; then
        echo "Data version ($OLD_VERSION) differs from engine ($NEW_VERSION). Starting upgrade..."
        
        # 1. Move old data to a temporary folder
        mkdir -p $DATA_DIR/old_data
        mv $DATA_DIR/* $DATA_DIR/old_data/ || true
        
        # 2. Initialize new data directory
				mkdir $DATA_DIR/new_data
        initdb -D $DATA_DIR/new_data
        
        # 3. Run pg_upgrade
        # --link is used to avoid copying files (fast, but requires a backup!)
        pg_upgrade \
            -d $DATA_DIR/old_data \
            -D $DATA_DIR/new_data \
            -b /usr/bin/postgres-16 \
            -B /usr/local/bin \
            --link
            
        echo "Upgrade complete. Cleaning up..."
        rm -rf $DATA_DIR/old_data
				mv $DATA_DIR/new_data/* $DATA_DIR/
				rmdir $DATA_DIR/new_data
    fi
fi

exec $@