#!/usr/bin/env sh
set -eu

OUTPUT_FILE="${1:-}"
if [ -z "$OUTPUT_FILE" ]; then
  echo "用法: scripts/docker-limits.sh <output-compose-override.yml>" >&2
  exit 1
fi

detect_cpus() {
  if command -v nproc >/dev/null 2>&1; then
    nproc
    return
  fi
  if command -v getconf >/dev/null 2>&1; then
    getconf _NPROCESSORS_ONLN
    return
  fi
  if command -v sysctl >/dev/null 2>&1; then
    sysctl -n hw.ncpu
    return
  fi
  echo 2
}

detect_memory_mb() {
  if [ -r /proc/meminfo ]; then
    awk '/MemTotal/ { printf "%d\n", $2 / 1024 }' /proc/meminfo
    return
  fi
  if command -v sysctl >/dev/null 2>&1; then
    sysctl -n hw.memsize | awk '{ printf "%d\n", $1 / 1024 / 1024 }'
    return
  fi
  echo 4096
}

cpu_value() {
  awk -v total="$1" -v share="$2" 'BEGIN {
    value = total * 0.80 * share / 100;
    if (value < 0.10) value = 0.10;
    printf "%.2f", value;
  }'
}

memory_value() {
  awk -v total="$1" -v share="$2" 'BEGIN {
    value = int(total * 0.50 * share / 100);
    if (value < 96) value = 96;
    printf "%dm", value;
  }'
}

integer_at_least_one() {
  awk -v value="$1" 'BEGIN {
    n = int(value);
    if (n < 1) n = 1;
    printf "%d", n;
  }'
}

CPUS="$(detect_cpus)"
MEMORY_MB="$(detect_memory_mb)"
BUILD_CPUS="$(integer_at_least_one "$(awk -v total="$CPUS" 'BEGIN { print total * 0.80 }')")"
NODE_OLD_SPACE_MB="$(awk -v total="$MEMORY_MB" 'BEGIN {
  value = int(total * 0.50 * 0.25);
  if (value < 512) value = 512;
  printf "%d", value;
}')"

mkdir -p "$(dirname "$OUTPUT_FILE")"
cat > "$OUTPUT_FILE" <<EOF
services:
  postgres:
    cpus: "$(cpu_value "$CPUS" 20)"
    mem_limit: "$(memory_value "$MEMORY_MB" 25)"
    memswap_limit: "$(memory_value "$MEMORY_MB" 25)"
    pids_limit: 512

  redis:
    cpus: "$(cpu_value "$CPUS" 5)"
    mem_limit: "$(memory_value "$MEMORY_MB" 5)"
    memswap_limit: "$(memory_value "$MEMORY_MB" 5)"
    pids_limit: 256

  rabbitmq:
    cpus: "$(cpu_value "$CPUS" 15)"
    mem_limit: "$(memory_value "$MEMORY_MB" 15)"
    memswap_limit: "$(memory_value "$MEMORY_MB" 15)"
    pids_limit: 512

  backend:
    cpus: "$(cpu_value "$CPUS" 50)"
    mem_limit: "$(memory_value "$MEMORY_MB" 45)"
    memswap_limit: "$(memory_value "$MEMORY_MB" 45)"
    pids_limit: 1024
    build:
      args:
        MAVEN_OPTS: "-XX:ActiveProcessorCount=$BUILD_CPUS -XX:MaxRAMPercentage=50 -Djava.awt.headless=true"
    environment:
      JAVA_TOOL_OPTIONS: "-XX:MaxRAMPercentage=50"

  frontend:
    cpus: "$(cpu_value "$CPUS" 10)"
    mem_limit: "$(memory_value "$MEMORY_MB" 10)"
    memswap_limit: "$(memory_value "$MEMORY_MB" 10)"
    pids_limit: 256
    build:
      args:
        NODE_OPTIONS: "--max-old-space-size=$NODE_OLD_SPACE_MB"
EOF

echo "已生成 Docker 资源限制: $OUTPUT_FILE"
echo "宿主机 CPU: $CPUS, Docker CPU 总预算: 80%"
echo "宿主机内存: ${MEMORY_MB}MB, Docker 内存总预算: 50%"