{
  description = "Progressive LLM Training for 松尾研LLMコンペ2025";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs {
          inherit system;
          config = {
            allowUnfree = true;
            cudaSupport = true;
          };
          overlays = [
            (final: prev: {
              python311 = prev.python311.override {
                packageOverrides = python-self: python-super: {
                  # Disable tests for problematic packages
                  pytest-doctestplus = python-super.pytest-doctestplus.overrideAttrs (oldAttrs: {
                    doCheck = false;
                    doInstallCheck = false;
                    pytestCheckPhase = "echo 'Skipping tests'";
                  });
                  # Also disable tests for jupyter-related packages if they cause issues
                  jupyter = python-super.jupyter.overrideAttrs (oldAttrs: {
                    doCheck = false;
                    doInstallCheck = false;
                  });
                  notebook = python-super.notebook.overrideAttrs (oldAttrs: {
                    doCheck = false;
                    doInstallCheck = false;
                  });
                  # Disable tests for psycopg and psycopg2
                  psycopg = python-super.psycopg.overrideAttrs (oldAttrs: {
                    doCheck = false;
                    doInstallCheck = false;
                    pytestCheckPhase = "echo 'Skipping tests'";
                    pythonImportsCheck = [];  # Disable import checks
                  });
                  psycopg2 = python-super.psycopg2.overrideAttrs (oldAttrs: {
                    doCheck = false;
                    doInstallCheck = false;
                    pytestCheckPhase = "echo 'Skipping tests'";
                    pythonImportsCheck = [];  # Disable import checks
                  });
                  # Disable tests for sqlframe
                  sqlframe = python-super.sqlframe.overrideAttrs (oldAttrs: {
                    doCheck = false;
                    doInstallCheck = false;
                    pytestCheckPhase = "echo 'Skipping tests'";
                    pythonImportsCheck = [];  # Disable import checks
                  });
                  # Disable tests for accelerate
                  accelerate = python-super.accelerate.overrideAttrs (oldAttrs: {
                    doCheck = false;
                    doInstallCheck = false;
                    pytestCheckPhase = "echo 'Skipping tests'";
                    pythonImportsCheck = [];  # Disable import checks
                  });
                };
              };
            })
          ];
        };
        
        # Python 3.11 for better compatibility
        python = pkgs.python311;
        
        # Python packages
        pythonWithPackages = python.withPackages (ps: with ps; [
          # Core ML packages
          torch
          torchvision
          torchaudio
          transformers
          accelerate
          datasets
          tokenizers
          scikit-learn
          
          # Required dependencies from requirements.txt
          pyyaml
          jsonlines
          sentencepiece
          protobuf
          
          # Additional useful packages
          numpy
          scipy
          matplotlib
          jupyter
          notebook
          ipython
          pandas
          rich  # For TUI
          
          # Development tools
          black
          flake8
          pytest
          mypy
          
          # Build tools
          pip
          setuptools
          wheel
          
          # LLM specific packages
          peft
          trl
          bitsandbytes
          wandb
        ]);
        
      in
      {
        devShells.default = pkgs.mkShell {
          buildInputs = with pkgs; [
            # Python with packages
            pythonWithPackages
            
            # Build tools
            gcc
            cmake
            ninja
            pkg-config
            
            # Git
            git
            git-lfs
            
            # Development tools
            htop
            tmux
            vim
            
            # Libraries needed for Python packages
            openssl
            zlib
            glib
            stdenv.cc.cc.lib
            
            # CUDA support
            cudaPackages.cudatoolkit
            cudaPackages.cudnn
          ];
          
          shellHook = ''
            echo "🚀 Progressive LLM Training Environment"
            echo "Python version: $(python --version)"
            echo "PyTorch version: $(python -c 'import torch; print(torch.__version__)')"
            echo "CUDA available: $(python -c 'import torch; print(torch.cuda.is_available())')"
            
            # Set up CUDA environment
            export CUDA_HOME=${pkgs.cudaPackages.cudatoolkit}
            export CUDA_PATH=${pkgs.cudaPackages.cudatoolkit}
            export LD_LIBRARY_PATH=${pkgs.cudaPackages.cudatoolkit}/lib:${pkgs.cudaPackages.cudnn}/lib:${pkgs.stdenv.cc.cc.lib}/lib:$LD_LIBRARY_PATH
            
            # Set Python path
            export PYTHONPATH=$PWD/src:$PYTHONPATH
            
            echo ""
            echo "Available commands:"
            echo "  python scripts/train_progressive.py  # Start training"
            echo "  python scripts/evaluate.py          # Evaluate model"
            echo "  jupyter notebook                     # Start Jupyter"
            echo ""
            
            # Create data directory if not exists
            mkdir -p data
            
            # Prepare sample data if not exists
            if [ ! -f "data/basic_cot/train.jsonl" ]; then
              echo "Preparing sample datasets..."
              python -c "from src.data_utils import prepare_sample_datasets; prepare_sample_datasets()" || echo "Sample data preparation skipped"
            fi
            
            # Note about flash-attn
            echo "Note: flash-attn is not included in nixpkgs. If needed, install manually with:"
            echo "  pip install flash-attn --no-build-isolation"
          '';
          
          # Environment variables
          CUDA_HOME = "${pkgs.cudaPackages.cudatoolkit}";
          CUDA_PATH = "${pkgs.cudaPackages.cudatoolkit}";
          NIX_SHELL_PRESERVE_PROMPT = 1;
          LOCALE_ARCHIVE = "${pkgs.glibcLocales}/lib/locale/locale-archive";
          LC_ALL = "en_US.UTF-8";
        };
      });
}