#!/bin/sh

set -eo pipefail

get_max_mem(){
  if [ -e /sys/fs/cgroup/memory.max ]; then
    # Read /sys/fs/cgroup/memory.max
    MAX=$(cat /sys/fs/cgroup/memory.max)
    # If it's "max", then the container has no limit, and we must detect the available RAM
    if [ "${MAX}" = "max" ]; then
      echo $(($(cat /proc/meminfo | grep MemTotal | sed -E 's/MemTotal:\s+([0-9]+)\s+kB/\1/')/1024))
    else
      echo $(($(cat /sys/fs/cgroup/memory.max)/1024/1024))
    fi
  else
    echo $(($(cat /proc/meminfo | grep MemTotal | sed -E 's/MemTotal:\s+([0-9]+)\s+kB/\1/')/1024))
  fi
}

if mount | grep -q ' /etc/my.cnf '; then
  echo "/etc/my.cnf is mounted, skiping config from env vars"
else
  echo "Configuring from env vars"
  for VAR in $(printenv | grep -E '^MYSQL_CONF_' | sed -E 's/MYSQL_CONF_([^=]+)=.*/\1/' | sort -V); do
    DIRECTIVE=$(echo ${VAR} | sed -E 's/^[0-9]+_//')
    VALUE=$(printenv MYSQL_CONF_${VAR})

    if [ "${DIRECTIVE}" = "section" ]; then
      echo "[${VALUE}]" >> /etc/my.cnf.d/env.cnf
    else

      # Allow some memory related settings to be expressed as a %
      if echo ${DIRECTIVE} | grep -q -E "^(innodb_buffer_pool_size)$"; then
        if echo ${VALUE} | grep -q -E "[0-9]+%$"; then
          PERCENT=$(echo $VALUE | sed -E 's|%$||')
          MAX_MEM=$(get_max_mem)
          VALUE=$((${MAX_MEM}*${PERCENT}/100))MB
        fi
      fi
      echo "Adding ${DIRECTIVE} = ${VALUE} in /etc/my.cnf.d/env.cnf"
      echo "${DIRECTIVE} = ${VALUE}" >> /etc/my.cnf.d/env.cnf
    fi
  done
fi