feature: Add logger for debugging (#18)

README.md

@@ -111,11 +111,10 @@ EOF
   write_all_buffers = false, -- write all buffers when the current one meets `condition`
   debounce_delay = 1000, -- delay after which a pending save is executed
   callbacks = { -- functions to be executed at different intervals
-    enabling = nil, -- ran when enabling auto-save
-    disabling = nil, -- ran when disabling auto-save
     before_saving = nil, -- ran before doing the actual save
-    after_saving = nil -- ran after doing the actual save
-  }
+  },
+ -- log debug messages to 'auto-save.log' file in neovim cache directory, set to `true` to enable
+  debug = false,
 }
 ```
 

lua/auto-save/config.lua

@@ -22,11 +22,10 @@ Config = {
     write_all_buffers = false, -- write all buffers when the current one meets `condition`
     debounce_delay = 1000, -- delay after which a pending save is executed
     callbacks = { -- functions to be executed at different intervals
-      enabling = nil, -- ran when enabling auto-save
-      disabling = nil, -- ran when disabling auto-save
       before_saving = nil, -- ran before doing the actual save
-      after_saving = nil, -- ran after doing the actual save
     },
+    -- log debug messages to 'auto-save.log' file in neovim cache directory, set to `true` to enable
+    debug = false, -- print debug messages, set to `true` to enable
   },
 }
 

lua/auto-save/init.lua

@@ -4,6 +4,7 @@ local cnf = require("auto-save.config")
 local callback = require("auto-save.utils.data").do_callback
 local colors = require("auto-save.utils.colors")
 local echo = require("auto-save.utils.echo")
+local logger
 local autosave_running
 local api = vim.api
 local g = vim.g
@@ -25,6 +26,8 @@ local function cancel_timer(buf)
   if timer ~= nil then
     timer:close()
     timers_by_buffer[buf] = nil
+
+    logger.log(buf, "Timer canceled")
   end
 end
 
@@ -37,6 +40,8 @@ local function debounce(lfn, duration)
       timers_by_buffer[buf] = nil
     end, duration)
     timers_by_buffer[buf] = timer
+
+    logger.log(buf, "Timer started")
   end
   return inner_debounce
 end
@@ -64,11 +69,15 @@ local function should_be_saved(buf)
     return cnf.opts.condition(buf)
   end
 
+  logger.log(buf, "Should save buffer")
+
   return true
 end
 
 local function save(buf)
   if not api.nvim_buf_get_option(buf, "modified") then
+    logger.log(buf, "Abort saving buffer")
+
     return
   end
 
@@ -88,7 +97,7 @@ local function save(buf)
     end)
   end
 
-  callback("after_saving")
+  logger.log(buf, "Saved buffer")
 
   if cnf.opts.execution_message.enabled == true then
     echo_execution_message()
@@ -169,7 +178,6 @@ function M.on()
     group = "AutoSave",
   })
 
-  callback("enabling")
   autosave_running = true
 end
 
@@ -178,7 +186,6 @@ function M.off()
     clear = true,
   })
 
-  callback("disabling")
   autosave_running = false
 end
 
@@ -194,6 +201,7 @@ end
 
 function M.setup(custom_opts)
   cnf:set_options(custom_opts)
+  logger = require("auto-save.utils.logging").new(cnf:get_options())
 end
 
 return M

lua/auto-save/utils/logging.lua

@@ -0,0 +1,42 @@
+-- inspired from https://github.com/nvim-lua/plenary.nvim/blob/master/lua/plenary/log.lua
+
+local M = {}
+
+local outfile = string.format("%s/auto-save.log", vim.api.nvim_call_function("stdpath", { "cache" }))
+
+-- it could be that the directory of the file does not exist
+-- this would require further checks, see https://github.com/nvim-lua/plenary.nvim/blob/master/lua/plenary/log.lua#L138
+--- @param message string
+local write_to_outfile = function(message)
+  local f = assert(io.open(outfile, "a"))
+  f:write(message)
+  f:close()
+end
+
+M.new = function(options)
+  local enabled = options.debug
+
+  --- @param buf number | nil
+  --- @param message string
+  local log = function(buf, message)
+    if not enabled then
+      return
+    end
+
+    local log_message
+    if buf ~= nil then
+      local filename = vim.api.nvim_buf_get_name(buf)
+      log_message = string.format("[%s] [%s] - %s\n", os.date(), filename, message)
+    else
+      log_message = string.format("[%s] - %s\n", os.date(), message)
+    end
+
+    write_to_outfile(log_message)
+  end
+
+  return {
+    log = log,
+  }
+end
+
+return M