# flakelight -- Framework for simplifying flake setup
# Copyright (C) 2023 Archit Gupta <archit@accelbread.com>
# SPDX-License-Identifier: MIT

{ config, lib, flakelight, genSystems, moduleArgs, ... }:
let
  inherit (lib) filterAttrs functionArgs mapAttrs mkIf mkMerge mkOption;
  inherit (lib.types) attrs coercedTo functionTo lazyAttrsOf lines listOf
    package str submodule;
  inherit (flakelight) supportedSystem;
  inherit (flakelight.types) function nullable optCallWith optFunctionTo;

  devShellModule.options = {
    inputsFrom = mkOption {
      type = optFunctionTo (listOf package);
      default = [ ];
    };

    packages = mkOption {
      type = optFunctionTo (listOf package);
      default = [ ];
    };

    shellHook = mkOption {
      type = optFunctionTo lines;
      default = "";
    };

    env = mkOption {
      type = optFunctionTo (lazyAttrsOf str);
      default = { };
    };

    stdenv = mkOption {
      type = optFunctionTo package;
      default = pkgs: pkgs.stdenv;
    };

    overrideShell = mkOption {
      type = nullable package;
      internal = true;
      default = null;
    };
  };

  wrapFn = fn: pkgs:
    let val = pkgs.callPackage fn { }; in
    if (functionArgs fn == { }) || !(package.check val)
    then fn pkgs
    else { overrideShell = val; };

  devShellType = coercedTo function wrapFn
    (coercedTo attrs (x: _: x)
      (functionTo (submodule devShellModule)));

  genDevShell = pkgs: cfg:
    if cfg.overrideShell != null then cfg.overrideShell
    else
      let cfg' = mapAttrs (_: v: v pkgs) cfg; in
      pkgs.mkShell.override { inherit (cfg') stdenv; }
        (cfg'.env // { inherit (cfg') inputsFrom packages shellHook; });
in
{
  options = {
    devShell = mkOption {
      default = null;
      type = nullable devShellType;
    };

    devShells = mkOption {
      type = optCallWith moduleArgs (lazyAttrsOf devShellType);
      default = { };
    };
  };

  config = mkMerge [
    (mkIf (config.devShell != null) {
      devShells.default = config.devShell;
    })

    (mkIf (config.devShells != { }) {
      outputs.devShells = genSystems (pkgs:
        filterAttrs (_: supportedSystem pkgs)
          (mapAttrs (_: v: genDevShell pkgs (v pkgs)) config.devShells));
    })
  ];
}