nvf/modules/plugins/languages/nix.nix

{
  config,
  pkgs,
  lib,
  inputs,
  ...
}: let
  inherit (builtins) attrNames;
  inherit (lib) concatStringsSep mkLuaInline;
  inherit (lib.meta) getExe;
  inherit (lib.options) mkEnableOption mkOption;
  inherit (lib.modules) mkIf mkMerge;
  inherit (lib.lists) isList;
  inherit (lib.strings) optionalString;
  inherit
    (lib.types)
    anything
    attrsOf
    enum
    either
    listOf
    nullOr
    package
    str
    ;
  inherit (lib.nvim.types) mkGrammarOption diagnostics;
  inherit (lib.nvim.lua) expToLua toLuaObject;

  cfg = config.vim.languages.nix;

  useFormat = "on_attach = default_on_attach";
  noFormat = "on_attach = attach_keymaps";

  defaultServer = "nil";
  packageToCmd = package: defaultCmd:
    if isList package
    then expToLua package
    else ''{"${package}/bin/${defaultCmd}"}'';
  servers = {
    nil = {
      package = inputs.nil.packages.${pkgs.stdenv.system}.nil;
      internalFormatter = true;
      lspConfig = ''lspconfig.nil_ls.setup ${
          toLuaObject {
            capabilities = mkLuaInline "capabilities";
            on_attach =
              if cfg.format.enable
              then mkLuaInline "default_on_attach"
              else "attach_keymaps";
            cmd = mkLuaInline (packageToCmd cfg.lsp.package "nil");
            settings.nil =
              {
                formatting.command =
                  if cfg.format.enable
                  then
                    if cfg.format.type == "alejandra"
                    then mkLuaInline ''{"${cfg.format.package}/bin/alejandra", "--quiet"}''
                    else if cfg.format.type == "nixfmt"
                    then mkLuaInline ''{"${cfg.format.package}/bin/nixfmt"}''
                    else null
                  else null;
              }
              // cfg.lsp.options;
          }
        }'';
    };

    nixd = {
      package = pkgs.nixd;
      internalFormatter = true;
      lspConfig = ''
        lspconfig.nixd.setup{
          capabilities = capabilities,
        ${
          if cfg.format.enable
          then useFormat
          else noFormat
        },
          cmd = ${packageToCmd cfg.lsp.package "nixd"},
        ${optionalString cfg.format.enable ''
          settings = {
            nixd = {
          ${optionalString (cfg.format.type == "alejandra") ''
            formatting = {
              command = {"${cfg.format.package}/bin/alejandra", "--quiet"},
            },
          ''}
          ${optionalString (cfg.format.type == "nixfmt") ''
            formatting = {
              command = {"${cfg.format.package}/bin/nixfmt"},
            },
          ''}
            nix = ${toLuaObject cfg.lsp.options},
            },
          },
        ''}
        }
      '';
    };
  };

  defaultFormat = "alejandra";
  formats = {
    alejandra = {
      package = pkgs.alejandra;
    };

    nixfmt = {
      package = pkgs.nixfmt-rfc-style;
    };
  };

  defaultDiagnosticsProvider = [
    "statix"
    "deadnix"
  ];
  diagnosticsProviders = {
    statix = {
      package = pkgs.statix;
      nullConfig = pkg: ''
        table.insert(
          ls_sources,
          null_ls.builtins.diagnostics.statix.with({
            command = "${pkg}/bin/statix",
          })
        )
      '';
    };

    deadnix = {
      package = pkgs.deadnix;
      nullConfig = pkg: ''
        table.insert(
          ls_sources,
          null_ls.builtins.diagnostics.deadnix.with({
            command = "${pkg}/bin/deadnix",
          })
        )
      '';
    };
  };
in {
  options.vim.languages.nix = {
    enable = mkEnableOption "Nix language support";

    treesitter = {
      enable =
        mkEnableOption "Nix treesitter"
        // {
          default = config.vim.languages.enableTreesitter;
        };
      package = mkGrammarOption pkgs "nix";
    };

    lsp = {
      enable =
        mkEnableOption "Nix LSP support"
        // {
          default = config.vim.lsp.enable;
        };
      server = mkOption {
        description = "Nix LSP server to use";
        type = enum (attrNames servers);
        default = defaultServer;
      };

      package = mkOption {
        description = "Nix LSP server package, or the command to run as a list of strings";
        example = ''[lib.getExe pkgs.jdt-language-server "-data" "~/.cache/jdtls/workspace"]'';
        type = either package (listOf str);
        default = servers.${cfg.lsp.server}.package;
      };

      options = mkOption {
        type = nullOr (attrsOf anything);
        default = null;
        description = "Options to pass to nixd LSP server";
      };
    };

    format = {
      enable =
        mkEnableOption "Nix formatting"
        // {
          default = config.vim.languages.enableFormat;
        };

      type = mkOption {
        description = "Nix formatter to use";
        type = enum (attrNames formats);
        default = defaultFormat;
      };

      package = mkOption {
        description = "Nix formatter package";
        type = package;
        default = formats.${cfg.format.type}.package;
      };
    };

    extraDiagnostics = {
      enable =
        mkEnableOption "extra Nix diagnostics"
        // {
          default = config.vim.languages.enableExtraDiagnostics;
        };

      types = diagnostics {
        langDesc = "Nix";
        inherit diagnosticsProviders;
        inherit defaultDiagnosticsProvider;
      };
    };
  };

  config = mkIf cfg.enable (mkMerge [
    {
      assertions = [
        {
          assertion = cfg.format.type != "nixpkgs-fmt";
          message = ''
            nixpkgs-fmt has been archived upstream. Please use one of the following available formatters:
            ${concatStringsSep ", " (attrNames formats)}
          '';
        }
        {
          assertion = cfg.lsp.server != "rnix";
          message = ''
            rnix-lsp has been archived upstream. Please use one of the following available language servers:
            ${concatStringsSep ", " (attrNames servers)}
          '';
        }
      ];
    }

    (mkIf cfg.treesitter.enable {
      vim.treesitter.enable = true;
      vim.treesitter.grammars = [cfg.treesitter.package];
    })

    (mkIf cfg.lsp.enable {
      vim.lsp.lspconfig.enable = true;
      vim.lsp.lspconfig.sources.nix-lsp = servers.${cfg.lsp.server}.lspConfig;
    })

    (mkIf (cfg.format.enable && (!cfg.lsp.enable || !servers.${cfg.lsp.server}.internalFormatter)) {
      vim.formatter.conform-nvim = {
        enable = true;
        setupOpts.formatters_by_ft.nix = [cfg.format.type];
        setupOpts.formatters.${cfg.format.type} = {
          command = getExe cfg.format.package;
        };
      };
    })

    (mkIf cfg.extraDiagnostics.enable {
      vim.diagnostics.nvim-lint = {
        enable = true;
        linters_by_ft.nix = cfg.extraDiagnostics.types;
        linters = mkMerge (
          map (name: {
            ${name}.cmd = getExe diagnosticsProviders.${name}.package;
          })
          cfg.extraDiagnostics.types
        );
      };
    })
  ]);
}