feat(debug,opt-in): temporarily highlight the search prefix (#95)

Issue
=====

It's hard to understand when exactly ripgrep is called to find matching
words in the project. This is an important concern because of
performance - ripgrep can take a long time to search through a large
project.

Solution
========

Temporarily highlight the search prefix when a new ripgrep search is
started. This will help users and maintainers understand the behavior of
the plugin.

To enable this feature, set `debug` to `true` in the configuration. It's
recommended to only enable this feature when debugging the plugin.

integration-tests/cypress/e2e/blink-ripgrep/basic_spec.cy.ts

@@ -308,6 +308,52 @@ describe("debug mode", () => {
       })
     })
   })
+
+  it("highlights the search word when a new ripgrep search is started", () => {
+    cy.visit("/")
+    cy.startNeovim({}).then(() => {
+      // wait until text on the start screen is visible
+      cy.contains("If you see this text, Neovim is ready!")
+      createFakeGitDirectoriesToLimitRipgrepScope()
+
+      // clear the current line and enter insert mode
+      cy.typeIntoTerminal("cc")
+
+      // debug mode should be on by default for all tests. Otherwise it doesn't
+      // make sense to test this, as nothing will be displayed.
+      cy.runLuaCode({
+        luaCode: `assert(require("blink-ripgrep").config.debug)`,
+      })
+
+      // this will match text from ../../../test-environment/other-file.lua
+      //
+      // If the plugin works, this text should show up as a suggestion.
+      cy.typeIntoTerminal("hip")
+      // the search should have been started for the prefix "hip"
+      cy.contains("hip").should(
+        "have.css",
+        "backgroundColor",
+        rgbify(flavors.macchiato.colors.flamingo.rgb),
+      )
+      //
+      // blink is now in the Fuzzy(3) stage, and additional keypresses must not
+      // start a new ripgrep search. They must be used for filtering the
+      // results instead.
+      // https://cmp.saghen.dev/development/architecture.html#architecture
+      cy.contains("Hippopotamus" + "234 (rg)") // wait for blink to show up
+      cy.typeIntoTerminal("234")
+
+      // wait for the highlight to disappear to test that too
+      cy.contains("hip").should(
+        "have.css",
+        "backgroundColor",
+        rgbify(flavors.macchiato.colors.base.rgb),
+      )
+
+      // TODO should programmatically check that only one search was started,
+      // this will not catch all cases
+    })
+  })
 })
 
 describe("using .gitignore files to exclude files from searching", () => {

integration-tests/test-environment/.config/nvim/init.lua

@@ -117,6 +117,12 @@ local plugins = {
         "BlinkRipgrepMatch",
         { fg = colors.base, bg = colors.mauve }
       )
+
+      vim.api.nvim_set_hl(
+        0,
+        "BlinkRipgrepSearchPrefix",
+        { fg = colors.base, bg = colors.flamingo }
+      )
     end,
   },
 

lua/blink-ripgrep/init.lua

@@ -176,6 +176,7 @@ function RgSource:get_completions(context, resolve)
 
     if RgSource.config.debug then
       command.debugify_for_shell(cmd)
+      require("blink-ripgrep.visualization").flash_search_prefix(prefix)
     end
   end
 

lua/blink-ripgrep/visualization.lua

@@ -0,0 +1,32 @@
+local visualization = {}
+
+local ns_id = vim.api.nvim_create_namespace("blink_ripgrep_debug")
+
+vim.api.nvim_set_hl(
+  0,
+  "BlinkRipgrepSearchPrefix",
+  { link = "Search", default = true }
+)
+
+---@param prefix string
+function visualization.flash_search_prefix(prefix)
+  vim.api.nvim_buf_clear_namespace(0, ns_id, 0, -1)
+  local cursor = vim.api.nvim_win_get_cursor(0)
+
+  local hlstart = cursor[2] - #prefix
+  local hlend = cursor[2]
+  vim.api.nvim_buf_add_highlight(
+    0,
+    ns_id,
+    "BlinkRipgrepSearchPrefix",
+    cursor[1] - 1,
+    hlstart,
+    hlend
+  )
+
+  vim.defer_fn(function()
+    vim.api.nvim_buf_clear_namespace(0, ns_id, 0, -1)
+  end, 500)
+end
+
+return visualization