{ pkgs, lib, ... }:
let
  models = [
    {
      name = "Qwen2.5-14B-Instruct-IQ4_XS.gguf";
      context_length = "32768";
      gen_length = "8192";
      source = pkgs.fetchurl {
        url = "https://huggingface.co/bartowski/Qwen2.5-14B-Instruct-GGUF/resolve/main/Qwen2.5-14B-Instruct-IQ4_XS.gguf?download=true";
        sha256 = "+AHt49no0qQ48MoNsqGJV4FeJ3Cf2hSZqTMjNUIHaO4=";
      };
    }
  ];

  # stolen from: https://stackoverflow.com/a/42398526
  optimizeWithFlags =
    pkg: flags:
    pkgs.lib.overrideDerivation pkg (
      old:
      let
        newflags = pkgs.lib.foldl' (acc: x: "${acc} ${x}") "" flags;
        oldflags = if (pkgs.lib.hasAttr "NIX_CFLAGS_COMPILE" old) then "${old.NIX_CFLAGS_COMPILE}" else "";
      in
      {
        NIX_CFLAGS_COMPILE = "${oldflags} ${newflags}";
        stdenv = pkgs.clangStdenv;
      }
    );

  gpt4all_package = (
    optimizeWithFlags
      (pkgs.gpt4all.overrideAttrs (old: {
        version = "3.4.0";
        src = pkgs.fetchFromGitHub {
          fetchSubmodules = true;
          owner = "nomic-ai";
          repo = "gpt4all";
          rev = "v3.4.0";
          sha256 = "yXp9MyezXQJWUyEvyXc6++/Ow/NNqs1cjLIpEuKDrn0=";
        };

        patches = old.patches ++ [
          ./gpt4all-HEAD-disable-settings-err.patch
        ];

      }))
      # compile flags
      [
        "-Ofast"
        "-march=native"
        "-mtune=native"
        "-fno-finite-math-only" # https://github.com/ggerganov/llama.cpp/pull/7154#issuecomment-2143844461
      ]
  );
in
{
  home.packages = [
    gpt4all_package
  ];

  home.file =
    lib.recursiveUpdate
      {
        ".config/nomic.ai/GPT4All.ini".text =
          let
            system_prompt = "You are an expert LLM who is thoughtful and works step-by-step from first principles derive an answer to the user's prompt. For each step, title the step and begin showing your work, then decide if your work is comprehensive and if you're ready to provide your final answer. Make sure to exhaust ALL POSSIBILITIES before answering. INTERNAL REASONING STEPS ARE NOT SHOWN TO THE USER, ONLY A \"Final Answer\" SECTION WILL BE SHOWN TO THE USER. USE AS MANY REASONING STEPS AS POSSIBLE. EXPLORE ALTERNATE ANSWERS AND CONSIDER THAT YOUR ANSWER OR ANY ASSUMPTIONS MAY BE WRONG. IDENTIFY POSSIBLE ERRORS IN YOUR REASONING AND WHERE SUCH ERRORS MAY BE. FULLY TEST ALL OTHER POSSIBILITIES. YOU CAN BE WRONG. SHOW YOUR WORK WHEN RE-EXAMINING.";
          in
          ''
            [General]
            chatTheme=Dark
            height=940
            suggestionMode=Off
            threadCount=8
            uniqueId=7096f2d2-448d-4272-a132-d37e77f8a781
            userDefaultModel=${
              # select the first element of `models` to be the default model
              (builtins.elemAt models 0).name
            }
            width=1472
            x=0
            y=0

            [download]
            lastVersionStarted=${gpt4all_package.version}
          ''
          + (lib.concatStrings (
            map (model: ''
              [model-${model.name}]
              contextLength=${model.context_length}
              filename=${model.name}
              maxLength=${model.gen_length}
              promptBatchSize=256
              promptTemplate=<|im_start|>user\n%1<|im_end|>\n<|im_start|>assistant\n
              systemPrompt="<|im_start|>system\n${
                # replace newlines with the string "\n" for gpt4all to properly parse
                builtins.replaceStrings [ "\n" ] [ "\\n" ] system_prompt
              }<|im_end|>
              \n"
            '') models
          ))
          + ''
            [network]
            isActive=true
            usageStatsActive=true
          '';
      }
      (
        builtins.listToAttrs (
          map (f: {
            name = ".local/share/nomic.ai/GPT4All/${f.name}";
            value.source = f.source;
          }) models
        )
      );
}