#!/bin/bash

RED='\033[0;31m'
GREEN='\033[0;32m'
NC='\033[0m' # No Color

echo "=========================================="
echo "   GitLab Dynamic Resource Auto-Tuner     "
echo "=========================================="

CORES=$(nproc 2>/dev/null || echo 2)
RAM_MB=$(free -m | awk '/^Mem:/{print $2}')
RAM_GB=$(awk '/MemTotal/ {printf "%.0f", $2/1024/1024}' /proc/meminfo)

echo "Detected Hardware: $CORES CPU Cores, ${RAM_GB}GB RAM (${RAM_MB}MB)"

# PUMA WORKERS: 1 per CPU core (Minimum 2)
PUMA_WORKERS=$CORES
if [ "$PUMA_WORKERS" -lt 2 ]; then PUMA_WORKERS=2; fi

# PUMA THREADS: Usually optimal at 4
PUMA_THREADS=4

# SIDEKIQ CONCURRENCY: 5 background jobs per CPU core (Min 10)
SIDEKIQ_CONCURRENCY=$((CORES * 5))
if [ "$SIDEKIQ_CONCURRENCY" -lt 10 ]; then SIDEKIQ_CONCURRENCY=10; fi

# POSTGRES WORKERS: Match CPU cores
POSTGRES_WORKERS=$CORES

# POSTGRES SHARED BUFFERS: ~12.5% of total RAM in MB (Min 256MB)
POSTGRES_SHARED_BUFFERS=$((RAM_MB / 8))
if [ "$POSTGRES_SHARED_BUFFERS" -lt 256 ]; then POSTGRES_SHARED_BUFFERS=256; fi

update_env() {
    local key=$1
    local val=$2
    local env_file=".env"
    
    if [ ! -f "$env_file" ]; then
        if ! touch "$env_file" 2>/dev/null; then
            echo -e "\n${RED}[ERROR] Permission denied: Cannot create $env_file.${NC}"
            echo -e "${RED}The script failed. Try running it with sudo.${NC}"
            exit 1
        fi
    fi

    if grep -q "^${key}=" "$env_file"; then
        if ! sed -i "s/^${key}=.*/${key}=${val}/" "$env_file" 2>/dev/null; then
            echo -e "\n${RED}[ERROR] Permission denied: sed cannot modify $env_file.${NC}"
            echo -e "${RED}The script failed. This usually happens if .env is owned by root. Try running the script with sudo.${NC}"
            exit 1
        fi
    else
        if ! echo "${key}=${val}" >> "$env_file" 2>/dev/null; then
            echo -e "\n${RED}[ERROR] Permission denied: Cannot append to $env_file.${NC}"
            echo -e "${RED}The script failed. Try running it with sudo.${NC}"
            exit 1
        fi
    fi
}

echo ""
echo "=========================================="
echo " Calculated Optimal Settings:"
echo "=========================================="
echo " PUMA_WORKERS=${PUMA_WORKERS}"
echo " PUMA_THREADS=${PUMA_THREADS}"
echo " SIDEKIQ_CONCURRENCY=${SIDEKIQ_CONCURRENCY}"
echo " POSTGRES_WORKERS=${POSTGRES_WORKERS}"
echo " POSTGRES_SHARED_BUFFERS=${POSTGRES_SHARED_BUFFERS}"
echo "=========================================="
echo ""
read -p "Do you want to apply these settings to your .env file? (y/n): " CONFIRM_ENV

if [[ "$CONFIRM_ENV" =~ ^[Yy]$ ]]; then
    echo "Updating variables in .env file..."

    update_env "PUMA_WORKERS" "$PUMA_WORKERS"
    update_env "PUMA_THREADS" "$PUMA_THREADS"
    update_env "SIDEKIQ_CONCURRENCY" "$SIDEKIQ_CONCURRENCY"
    update_env "POSTGRES_WORKERS" "$POSTGRES_WORKERS"
    update_env "POSTGRES_SHARED_BUFFERS" "$POSTGRES_SHARED_BUFFERS"
    
    echo -e "${GREEN}-> Success: .env file updated successfully.${NC}"
else
    echo "-> Skipped: No changes were made to the .env file."
fi

echo ""
read -p "Do you want to start/update the Docker containers now? (y/n): " CONFIRM_DOCKER

if [[ "$CONFIRM_DOCKER" =~ ^[Yy]$ ]]; then
    echo "Starting containers with 'docker compose up -d'..."
    docker compose up -d

    echo ""
    echo "=========================================="
    echo " GitLab is now applying the configuration."
    echo "=========================================="
else
    echo "-> Skipped: Containers were not started/updated."
    echo "-> Note: You can apply these changes later by running: docker compose up -d"
fi