treewide: begin restructuring the module tree

modules/plugins/languages/bash/config.nix

@@ -0,0 +1,83 @@
+{
+  pkgs,
+  config,
+  lib,
+  ...
+}: let
+  inherit (lib.lists) isList;
+  inherit (lib.modules) mkIf mkMerge;
+  inherit (lib.nvim.lua) expToLua;
+  inherit (lib.nvim.languages) diagnosticsToLua;
+
+  cfg = config.vim.languages.bash;
+  diagnosticsProviders = {
+    shellcheck = {
+      package = pkgs.shellcheck;
+      nullConfig = pkg: ''
+        table.insert(
+          ls_sources,
+          null_ls.builtins.diagnostics.shellcheck.with({
+            command = "${pkg}/bin/shellcheck",
+          })
+        )
+      '';
+    };
+  };
+
+  formats = {
+    shfmt = {
+      package = pkgs.shfmt;
+      nullConfig = ''
+        table.insert(
+          ls_sources,
+          null_ls.builtins.formatting.shfmt.with({
+            command = "${pkgs.shfmt}/bin/shfmt",
+          })
+        )
+      '';
+    };
+  };
+
+  servers = {
+    bash-ls = {
+      package = pkgs.nodePackages.bash-language-server;
+      lspConfig = ''
+        lspconfig.bashls.setup{
+          capabilities = capabilities;
+          on_attach = default_on_attach;
+          cmd = ${
+          if isList cfg.lsp.package
+          then expToLua cfg.lsp.package
+          else ''{"${cfg.lsp.package}/bin/bash-language-server",  "start"}''
+        };
+        }
+      '';
+    };
+  };
+in {
+  config = mkIf cfg.enable (mkMerge [
+    (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.bash-lsp = servers.${cfg.lsp.server}.lspConfig;
+    })
+
+    (mkIf cfg.format.enable {
+      vim.lsp.null-ls.enable = true;
+      vim.lsp.null-ls.sources.bash-format = formats.${cfg.format.type}.nullConfig;
+    })
+
+    (mkIf cfg.extraDiagnostics.enable {
+      vim.lsp.null-ls.enable = true;
+      vim.lsp.null-ls.sources = diagnosticsToLua {
+        lang = "bash";
+        config = cfg.extraDiagnostics.types;
+        inherit diagnosticsProviders;
+      };
+    })
+  ]);
+}