{ pkgs ? import <nixpkgs> {} }:
let
  odoo_version = "14.0";
  python_version = "3.7";
  pyproject = pkgs.writeText "pyproject.toml" ''
    [tool.poetry]
    name = "Odoo"
    version = "${odoo_version}"
    description = "Odoo is a suite of web based open source business apps."
    authors = ["Odoo SA"]

    [tool.poetry.dependencies]
    python = "^${python_version}"

    [tool.poetry.dev-dependencies]

    [build-system]
    requires = ["poetry-core>=1.0.0"]
    build-backend = "poetry.core.masonry.api"
  '';
  newPoetry = pkgs.poetry.override { python = pkgs.python36; };
in
pkgs.mkShell {
  buildInputs = [ pkgs.perl pkgs.gcc pkgs.libjpeg pkgs.libxslt pkgs.pkg-config pkgs.postgresql_11 pkgs.cyrus_sasl pkgs.openldap pkgs.zlib pkgs.file pkgs.libxml2 newPoetry ];
  shellHook = ''
    NIX_CFLAGS_COMPILE="$NIX_CFLAGS_COMPILE -isystem ${pkgs.cyrus_sasl.dev}/include/sasl -isystem ${pkgs.libxml2.dev}/include/libxml2/"
    check_valid() {
      expression="$1"
      expression=''${expression/sys_platform/\$sys_platform}
      expression=''${expression/python_version/\$python_version}
      expression=''${expression/"== '"/"eq '"}
      expression=''${expression/"!= '"/"ne '"}
      #echo "my \$python_version='${python_version}' ; my \$sys_platform='linux'; exit !($expression)"
      perl -e "my \$python_version='${python_version}' ; my \$sys_platform='linux'; exit !($expression)"
    }
    buildPoetry() {
      cat "${pyproject}" > pyproject.toml
      rm -f poetry.lock

      requirements=$(cat requirements.txt | grep -v "^#" | while read i; do
        if echo "$i" | grep -q ";"; then
          a="$(echo $i | sed -e "s/.*; *//")"
          check_valid "$a" && echo "$i" | sed -e "s/ *;.*//";
        else
          echo "$i"
        fi
      done)

      # Add mock -- since 14.0
      # add openupgradelib (for openupgrade)
      poetry add $requirements mock openupgradelib
    }
    '';
}