Preserve cursor presentation state

2 files changed, 126 insertions, 0 deletions

diff --git a/lua/clever_f/host_adapter.lua b/lua/clever_f/host_adapter.lua
index ab3467c..51591a9 100644
--- a/lua/clever_f/host_adapter.lua
+++ b/lua/clever_f/host_adapter.lua
@@ -45,6 +45,7 @@ function HostAdapter.new(options)
     next_identity = 1,
     highlights = {},
     timers = {},
+    cursor_presentations = {},
     events = {},
     event_order = {},
     augroup = nil,
@@ -417,6 +418,77 @@ function HostAdapter:commit_action_transition(token)
   return adapter_records[self].event_queue:commit_transition(token)
 end
 
+local function terminal_cursor_option(runtime)
+  return runtime.fn.eval("&t_ve")
+end
+
+local function set_terminal_cursor_option(runtime, value)
+  runtime.api.nvim_cmd({
+    cmd = "let",
+    args = { "&t_ve", "=", runtime.fn.string(value) },
+  }, {})
+end
+
+function HostAdapter:supports_cursor_presentation()
+  local runtime = self:runtime()
+  return type(runtime.api.nvim_get_option_value) == "function"
+    and type(runtime.api.nvim_set_option_value) == "function"
+    and type(runtime.api.nvim_cmd) == "function"
+    and type(runtime.fn) == "table"
+    and type(runtime.fn.exists) == "function"
+    and runtime.fn.exists("+t_ve") == 1
+    and type(runtime.fn.eval) == "function"
+    and type(runtime.fn.string) == "function"
+end
+
+function HostAdapter:suppress_cursor_presentation()
+  if not self:supports_cursor_presentation() then
+    return nil
+  end
+  local record = adapter_records[self]
+  local runtime = record.runtime
+  local identity = next_identity(self, "cursor-presentation")
+  local saved = {
+    guicursor = runtime.api.nvim_get_option_value(
+      "guicursor",
+      { scope = "global" }
+    ),
+    terminal_cursor = terminal_cursor_option(runtime),
+  }
+  runtime.api.nvim_set_option_value(
+    "guicursor",
+    "a:ver1",
+    { scope = "global" }
+  )
+  local ok, failure = pcall(set_terminal_cursor_option, runtime, "")
+  if not ok then
+    runtime.api.nvim_set_option_value(
+      "guicursor",
+      saved.guicursor,
+      { scope = "global" }
+    )
+    error(failure, 0)
+  end
+  record.cursor_presentations[identity] = saved
+  return identity
+end
+
+function HostAdapter:restore_cursor_presentation(identity)
+  local record = adapter_records[self]
+  local saved = record.cursor_presentations[identity]
+  if saved == nil then
+    return false
+  end
+  record.cursor_presentations[identity] = nil
+  record.runtime.api.nvim_set_option_value(
+    "guicursor",
+    saved.guicursor,
+    { scope = "global" }
+  )
+  set_terminal_cursor_option(record.runtime, saved.terminal_cursor)
+  return true
+end
+
 local function escape_key(runtime)
   if type(runtime.keycode) == "function" then
     return runtime.keycode("<Esc>")
diff --git a/tests/run.lua b/tests/run.lua
index e0c9b0c..5ca4f34 100644
--- a/tests/run.lua
+++ b/tests/run.lua
@@ -361,6 +361,60 @@ test("ActionOutcome and DotPayload retain resolved result data", function()
   same("problem", domain.ActionOutcome.error(destination, "problem").diagnostic)
 end)
 
+test("Host adapter restores exact cursor presentation values", function()
+  local options = {
+    guicursor = "n:block,i:ver37-blinkon123",
+    t_ve = "terminal-visible-sequence",
+  }
+  local writes = {}
+  local runtime = {
+    api = {
+      nvim_get_option_value = function(name, request)
+        same("global", request.scope)
+        return options[name]
+      end,
+      nvim_set_option_value = function(name, value, request)
+        same("global", request.scope)
+        options[name] = value
+        writes[#writes + 1] = { name = name, value = value }
+      end,
+      nvim_cmd = function(command)
+        same("let", command.cmd)
+        same("&t_ve", command.args[1])
+        same("=", command.args[2])
+        options.t_ve = command.args[3]
+        writes[#writes + 1] = { name = "t_ve", value = command.args[3] }
+      end,
+    },
+    fn = {
+      exists = function(name)
+        same("+t_ve", name)
+        return 1
+      end,
+      eval = function(name)
+        same("&t_ve", name)
+        return options.t_ve
+      end,
+      string = function(value)
+        return value
+      end,
+    },
+  }
+  local adapter = host_adapter.new({ runtime = runtime })
+  truthy(adapter:supports_cursor_presentation())
+
+  local lease = adapter:suppress_cursor_presentation()
+  truthy(lease ~= nil)
+  same("a:ver1", options.guicursor)
+  same("", options.t_ve)
+
+  truthy(adapter:restore_cursor_presentation(lease))
+  same("n:block,i:ver37-blinkon123", options.guicursor)
+  same("terminal-visible-sequence", options.t_ve)
+  falsy(adapter:restore_cursor_presentation(lease))
+  same(4, #writes)
+end)
+
 test("Host adapter owns Nvim timers and event registrations", function()
   local timer_callbacks = {}
   local stopped_timers = {}