Add remember last cursor position indicators & jump functionality (#52)

* feat: Add last cursor position

* fix

* feat: Add last cursor position config option

* feat: Add command to jump to last position

* fix: Update last position on mode change

* feat: Add support for enter and leave for last position

* feat: Export get_last_positions for other plugins

* feat: Add support for multiple buffers

* refactor: Outsource last_positions into its own module

* refactor: Improve formatting

* refactor: Improve formatting

* docs: Add last position info to README.md

* fix: Get correct buffer

* chore: Apply stylua

README.md

@@ -95,6 +95,11 @@ require('smoothcursor').setup({
     disable_float_win = false,  -- Disable in floating windows
     enabled_filetypes = nil,    -- Enable only for specific file types, e.g., { "lua", "vim" }
     disabled_filetypes = nil,   -- Disable for these file types, ignored if enabled_filetypes is set. e.g., { "TelescopePrompt", "NvimTree" }
+    -- Show the position of the latest input mode positions. 
+    -- A value of "enter" means the position will be updated when entering the mode.
+    -- A value of "leave" means the position will be updated when leaving the mode.
+    -- `nil` = disabled
+    show_last_positions = nil,  
 })
 ```
 
@@ -119,6 +124,7 @@ https://github.com/gen740/SmoothCursor.nvim/assets/54583542/ba3f90b1-e9ff-4729-b
 | :SmoothCursorFancyOn           | Turn on fancy mode                               |
 | :SmoothCursorFancyOff          | Turn off fancy mode                              |
 | :SmoothCursorDeleteSigns       | Delete all signs if exist                        |
+| :SmoothCursorJump <mode>       | Jump to the given <mode>'s last position         |
 
 ## FAQs
 
@@ -155,3 +161,19 @@ autocmd({ 'ModeChanged' }, {
 
 https://user-images.githubusercontent.com/54583542/220056425-a7698013-7173-4247-9d40-d468b24df47a.mov
 
+
+### How do I add icons (signs) for mode's last positions?
+
+You can decide which modes should be added. 
+Define the `smoothcursor_<mode>` sign group and set your icon.
+Each `<mode>` is a lowercase letter, e.g., `n` for normal mode, `i` for insert mode, etc.
+
+**example**
+```lua
+vim.fn.sign_define('smoothcursor_v', { text = ' ' })
+vim.fn.sign_define('smoothcursor_V', { text = '' })
+vim.fn.sign_define('smoothcursor_i', { text = '' })
+vim.fn.sign_define('smoothcursor_�', { text = '' })
+vim.fn.sign_define('smoothcursor_R', { text = '󰊄' })
+```
+

lua/smoothcursor/callbacks/default.lua

@@ -2,13 +2,15 @@ local callback = require('smoothcursor.callbacks')
 local buffer = callback.buffer
 
 local config = require('smoothcursor.config')
+local last_positions = require('smoothcursor.last_positions')
 local debug_callback = require('smoothcursor.debug').debug_callback
 
--- Default corsor callback. buffer["prev"] is always integer
+-- Default cursor callback. buffer["prev"] is always integer
 local function sc_default()
   if not callback.is_enabled() then
     return
   end
+
   buffer['.'] = vim.fn.line('.')
   if buffer['prev'] == nil then
     buffer['prev'] = buffer['.']
@@ -17,6 +19,7 @@ local function sc_default()
   buffer['diff'] = math.min(buffer['diff'], vim.fn.winheight(0) * 2)
   buffer['w0'] = vim.fn.line('w0')
   buffer['w$'] = vim.fn.line('w$')
+
   if math.abs(buffer['diff']) > config.value.threshold then
     local counter = 1
     callback.sc_timer:post(function()
@@ -54,10 +57,21 @@ local function sc_default()
   else
     buffer['prev'] = buffer['.']
     buffer:all(buffer['.'])
+
     callback.unplace_signs()
+
     if callback.fancy_head_exists() then
       callback.place_sign(buffer['prev'], 'smoothcursor')
+
+      local current_buf = vim.api.nvim_get_current_buf()
+
+      for name, pos in pairs(last_positions.get_positions(current_buf)) do
+        local line = pos[1]
+
+        callback.place_sign(line, 'smoothcursor_' .. name)
+      end
     end
+
     debug_callback(buffer, { 'Jump: False' })
   end
 end

lua/smoothcursor/callbacks/init.lua

@@ -21,7 +21,6 @@ local function buffer_set_all(value)
   buffer['prev'] = value
   buffer:all(value)
 
-  -- Debug
   sc_debug.debug_callback(buffer, { 'Buffer Reset' }, function()
     sc_debug.reset_counter = sc_debug.reset_counter + 1
   end)
@@ -45,7 +44,11 @@ local function place_sign(position, name, priority)
   if position < buffer['w0'] or position > buffer['w$'] then
     return
   end
-  if name ~= nil then
+
+  -- if len == 0, then sign is undefined
+  local is_sign_defined = #vim.fn.sign_getdefined(name) > 0
+
+  if is_sign_defined and name ~= nil then
     vim.fn.sign_place(
       0,
       'SmoothCursor',

lua/smoothcursor/config.lua

@@ -60,5 +60,6 @@ return {
     disable_float_win = false,
     disabled_filetypes = nil,
     enabled_filetypes = nil,
+    show_last_positions = 'leave',
   },
 }

lua/smoothcursor/init.lua

@@ -57,6 +57,15 @@ local config = require('smoothcursor.config')
 ---@field disable_float_win boolean
 ---@field disabled_filetypes string[]|nil
 ---@field enabled_filetypes string[]|nil
+---@field show_last_positions string|nil -- "enter" | "leave"
+
+-- Used for debugging, doesn't contain all the actual fields.
+-- More meant to be used as an example.
+---@class LastPositionsInfo
+---@field i number[]
+---@field n number[]
+---@field V number[]
+---@field v number[]
 
 -- local function define_signs(name, cursor, texthl,  )
 

lua/smoothcursor/last_positions.lua

@@ -0,0 +1,48 @@
+local last_positions = {}
+
+---Format a buffer for saving it
+---@param buffer number
+---@return string
+local function format_buf(buffer)
+  return tostring(buffer)
+end
+
+---Set the last position of the cursor for a buffer
+---@param buffer number
+---@param mode string
+---@param pos number[]
+local function set_position(buffer, mode, pos)
+  if last_positions[format_buf(buffer)] == nil then
+    return
+  end
+
+  last_positions[format_buf(buffer)][mode] = pos
+end
+
+---Get the last positions for a buffer.
+---Returns an empty table if the buffer is not found.
+---@param buffer number
+---@return LastPositionsInfo
+local function get_positions(buffer)
+  return last_positions[format_buf(buffer)] or {}
+end
+
+---Register a buffer to be tracked
+---We explicitly register buffers to avoid tracking buffers that shouldn't save
+---last positions (such as floating windows for example).
+---@param buffer any
+local function register_buffer(buffer)
+  last_positions[format_buf(buffer)] = {}
+end
+
+local function unregister_buffer(buffer)
+  last_positions[format_buf(buffer)] = nil
+end
+
+return {
+  last_positions = last_positions,
+  set_position = set_position,
+  get_positions = get_positions,
+  register_buffer = register_buffer,
+  unregister_buffer = unregister_buffer,
+}

lua/smoothcursor/utils.lua

@@ -3,6 +3,7 @@ local smoothcursor_started = false
 local callback = require('smoothcursor.callbacks')
 local config = require('smoothcursor.config')
 local init = require('smoothcursor.init')
+local last_positions = require('smoothcursor.last_positions')
 local buffer_leaved = false
 
 --@param init_fire boolean
@@ -54,6 +55,64 @@ sc.smoothcursor_start = function(init_fire)
     end,
   })
 
+  local last_pos_config = config.value.show_last_positions
+
+  if last_pos_config ~= nil then
+    -- Please note that casting the buffer numbers to strings is necessary, otherwise
+    -- lua will interpret the buffer numbers as array indices
+    -- Add / Remove buffers to `last_positions` table
+    vim.api.nvim_create_autocmd({ 'BufAdd' }, {
+      group = 'SmoothCursor',
+      callback = function()
+        local buffer = vim.fn.bufnr('$')
+
+        last_positions.register_buffer(buffer)
+      end,
+    })
+    vim.api.nvim_create_autocmd({ 'BufDelete' }, {
+      group = 'SmoothCursor',
+      callback = function()
+        local buffer = vim.fn.bufnr('$')
+
+        last_positions.unregister_buffer(buffer)
+      end,
+    })
+    -- If starting into a buffer, the BufEnter event is not fired, but `VimEnter` is.
+    vim.api.nvim_create_autocmd({ 'VimEnter' }, {
+      group = 'SmoothCursor',
+      callback = function()
+        local buffer = vim.api.nvim_get_current_buf()
+
+        last_positions.register_buffer(buffer)
+      end,
+    })
+
+    -- Neovim always starts with normal mode, doesn't it?
+    local current_mode = 'n'
+
+    vim.api.nvim_create_autocmd({ 'ModeChanged' }, {
+      group = 'SmoothCursor',
+      callback = function()
+        local buffer = vim.api.nvim_get_current_buf()
+        local mode = vim.api.nvim_get_mode().mode
+
+        local last_pos = last_positions.get_positions(buffer)
+
+        -- if is nil, the current buffer is not a text file (could be floating window for example)
+        -- we don't want to set the last position in this case
+        if last_pos ~= nil then
+          if last_pos_config == 'enter' then
+            last_positions.set_position(buffer, mode, vim.api.nvim_win_get_cursor(0))
+          else
+            last_positions.set_position(buffer, current_mode, vim.api.nvim_win_get_cursor(0))
+
+            current_mode = vim.api.nvim_get_mode().mode
+          end
+        end
+      end,
+    })
+  end
+
   smoothcursor_started = true
   if init_fire then
     callback.sc_callback()

plugin/smoothcursor.lua

@@ -1,5 +1,6 @@
 -- Define Commands
 local utils = require('smoothcursor.utils')
+local last_positions = require('smoothcursor.last_positions')
 
 vim.api.nvim_create_user_command('SmoothCursorStart', utils.smoothcursor_start, {})
 
@@ -37,3 +38,24 @@ end, {})
 vim.api.nvim_create_user_command('SmoothCursorDeleteSigns', utils.smoothcursor_delete_signs, {})
 
 vim.api.nvim_create_user_command('SmoothCursorDebug', require('smoothcursor.debug').debug, {})
+
+-- Jump to last positions
+-- TODO: Add autocomplete
+vim.api.nvim_create_user_command('SmoothCursorJump', function(opt)
+  -- Get identifier from args
+  local identifier = opt.fargs[1]
+
+  local buffer = vim.api.nvim_get_current_buf()
+  local last_position = last_positions.get_positions(buffer)[identifier]
+
+  if last_position == nil then
+    vim.notify(string.format('No last position for identifier %s', identifier))
+    return
+  end
+
+  -- Jump to last position
+  vim.api.nvim_win_set_cursor(0, last_position)
+end, {
+  nargs = 1,
+  desc = 'Jump to last position of identifier <identifier>',
+})