update completions logic

config/plugins/cmp/cmp.nix

@@ -6,47 +6,76 @@
 
     # Options provided to the require('cmp').setup function.
     settings = {
+      # Disable autocompletion by default
+      completion.autocomplete = false;
+
       # The sources to use
       sources = [
-        { # Language Server Protocol
-          name = "nvim_lsp";
-        }      
+        # Language Server Protocol
+        { name = "nvim_lsp"; }      
 
-        { # Buffer Words
-          name = "buffer";
-        }       
+        # Buffer Words
+        { name = "buffer"; }       
 
-        { # Filesystem paths
-          name = "path";
-        }
+        # Filesystem paths
+        { name = "path"; }
 
-        { # Markdown
-          name = "render_markdown";
-        }
+        # Markdown
+        { name = "render_markdown"; }
 
-        { # VimTex
-          name = "vimtex";
-        }
+        # VimTex
+        { name = "vimtex"; }
 
-        { # Neorg
-          name = "neorg";
-        }
+        # Neorg
+        { name = "neorg"; }
       ];
 
       # Key mappings for the completion menu.
       mapping = {
-        "<esc>" =
-          # Lua
-          "cmp.mapping.close()";
-        "<Down>" =
-          # Lua
-          "cmp.mapping(cmp.mapping.select_next_item({behavior = cmp.SelectBehavior.Select}), {'i', 's'})";
-        "<Up>" =
-          # Lua
-          "cmp.mapping(cmp.mapping.select_prev_item({behavior = cmp.SelectBehavior.Select}), {'i', 's'})";
-        "<cr>" =
-          # Lua
-          "cmp.mapping.confirm({ select = true })";
+        # Confirm candidate on TAB immediately when there's only one completion entry
+        "<Tab>" = /* lua */ ''
+          cmp.mapping(function(fallback)
+            local line, col = unpack(vim.api.nvim_win_get_cursor(0))
+
+            -- When the selection menu is open select the next item
+            if cmp.visible() then
+              cmp.select_next_item({behavior = cmp.SelectBehavior.Select})
+            -- Ensure we are mid word
+            elseif col ~= 0 and vim.api.nvim_buf_get_lines(0, line - 1, line, true)[1]:sub(col, col):match("%s") == nil then
+              -- Open the selection menu
+              cmp.complete()
+              -- Autocomplete when there is only 1 selection available
+              if #cmp.get_entries() == 1 then
+                cmp.confirm({ select = true })
+              end
+              -- Select the firt item
+              cmp.select_next_item({behavior = cmp.SelectBehavior.Select})
+            -- Keep regular functionality of tab
+            else
+              fallback()
+            end
+          end, {'i', 's'})
+        '';
+
+        # Confirm selection
+        "<CR>" = /* lua */ ''
+          cmp.mapping.confirm({ select = true })
+        '';
+
+        # Select the next item in the menu
+        "<Down>" = /* lua */ ''
+          cmp.mapping(cmp.mapping.select_next_item({behavior = cmp.SelectBehavior.Select}), {'i', 's'})
+        '';
+
+        # Select the prev item in the menu
+        "<Up>" = /* lua */ ''
+          cmp.mapping(cmp.mapping.select_prev_item({behavior = cmp.SelectBehavior.Select}), {'i', 's'})
+        '';
+
+        # Exit the completion menu
+        "<esc>" = /* lua */ ''
+          cmp.mapping.close()
+        '';
       };
     };
   };