From 09835e2a1a5404b4ee4b80fb8e3fa84ccbddfec4 Mon Sep 17 00:00:00 2001
From: Shadman <shadmansaleh3@gmail.com>
Date: Wed, 20 Jan 2021 16:19:10 +0600
Subject: [PATCH] Insted of calling git branch is read from HEAD (#68)

Co-authored-by: hoob3rt <pelczarskihubert@gmail.com>
---
 lua/lualine/async.lua             | 75 -------------------------
 lua/lualine/components/branch.lua | 91 ++++++++++++++++++++++---------
 2 files changed, 65 insertions(+), 101 deletions(-)
 delete mode 100644 lua/lualine/async.lua

diff --git a/lua/lualine/async.lua b/lua/lualine/async.lua
deleted file mode 100644
index fba27f6..0000000
--- a/lua/lualine/async.lua
+++ /dev/null
@@ -1,75 +0,0 @@
-local M = {}
-
-function M:new(args)
-  args = args or {}
-  for index, arg in pairs(args) do
-    self[index] = arg
-  end
-  setmetatable(args, self)
-  self.__index = self
-  return args
-end
-
-local function close_pipe(pipe)
-  if pipe ~= nil and not pipe:is_closing() then
-      pipe:close()
-  end
-end
-
-function M.close_all()
-  close_pipe(M.stdin)
-  close_pipe(M.stderr)
-  close_pipe(M.stdout)
-  close_pipe(M.handle)
-end
-
-function M.init_options()
-  local options = {}
-  local args  = vim.fn.split(M.cmd, ' ')
-  M.stdin = vim.loop.new_pipe(false)
-  M.stdout = vim.loop.new_pipe(false)
-  M.stderr = vim.loop.new_pipe(false)
-  options.command = table.remove(args, 1)
-  options.args = args
-  options.stdio = {
-    M.stdin,
-    M.stdout,
-    M.stderr
-  }
-  if M.cwd then
-    options.cwd = M.cwd
-  end
-  if M.env then
-    options.env = M.env
-  end
-  if M.detach then
-    options.detach = M.detach
-  end
-  return options
-end
-
-function M.start()
-  local options = M.init_options()
-  M.handle = vim.loop.spawn(options.command, options, vim.schedule_wrap(M.stop))
-  if M.on_stdout then
-      M.stdout:read_start(vim.schedule_wrap(M.on_stdout))
-  end
-  if M.on_stderr then
-      M.stderr:read_start(vim.schedule_wrap(M.on_stderr))
-  end
-end
-
-function M.stop(code, signal)
-  if M.on_exit then
-    M.on_exit(code, signal)
-  end
-  if M.on_stdout then
-      M.stdout:read_stop()
-  end
-  if M.on_stderr then
-      M.stderr:read_stop()
-  end
-  M.close_all()
-end
-
-return M
diff --git a/lua/lualine/components/branch.lua b/lua/lualine/components/branch.lua
index a687137..b589dbe 100644
--- a/lua/lualine/components/branch.lua
+++ b/lua/lualine/components/branch.lua
@@ -1,34 +1,65 @@
-local async = require('lualine.async')
-
 local git_branch
 
-local get_git_branch = async:new({
-  cmd = 'git branch --show-current',
-  on_stdout = function(_, data)
-    if data then
-      git_branch = data:gsub('\n', '')
-    end
-  end,
-  on_stderr = function (_, data)
-    if data then
-      if data:find("fatal: not a git repository") then
-        git_branch = ''
-      end
-    end
-  end,
-})
+-- os specific path separator
+local sep = package.config:sub(1,1)
 
-local timer = vim.loop.new_timer()
-timer:start(0, 1000, vim.schedule_wrap(function()
-  local cur_dir = vim.fn.getcwd()
-  local buffer_working_directory = vim.fn.expand("%:p:h")
-  local status, _ = pcall(vim.api.nvim_set_current_dir, buffer_working_directory)
-  if status == true then
-    get_git_branch:start()
-    vim.api.nvim_set_current_dir(cur_dir)
+-- returns full path to git directory for current directory
+local function find_git_dir()
+  -- get file dir so we can search from that dir
+  local file_dir = vim.fn.expand('%:p:h') .. ';'
+  -- find .git/ folder genaral case
+  local git_dir = vim.fn.finddir('.git', file_dir)
+  -- find .git file in case of submodules or any other case git dir is in
+  -- any other place than .git/
+  local git_file = vim.fn.findfile('.git', file_dir)
+  -- for some weird reason findfile gives relative path so expand it to fullpath
+  if #git_file > 0 then git_file = vim.fn.fnamemodify(git_file, ':p') end
+  if #git_file > #git_dir then
+    -- separate git-dir or submodule is used
+    local file = io.open(git_file)
+    git_dir = file:read()
+    git_dir = git_dir:match("gitdir: (.+)$")
+    file:close()
+    -- submodule / relative file path
+    if git_dir:sub(1,1) ~= sep and not git_dir:match('^%a:.*$') then
+      git_dir = git_file:match('(.*).git')..git_dir
+    end
   end
-end))
+  return git_dir
+end
 
+-- sets git_branch veriable to branch name or commit hash if not on branch
+local function get_git_head(head_file)
+  local f_head = io.open(head_file)
+  if f_head then
+    local HEAD = f_head:read()
+    f_head:close()
+    local branch = HEAD:match('ref: refs/heads/(.+)$')
+    if branch then git_branch = branch
+    else git_branch =  HEAD:sub(1,6) end
+  end
+  return nil
+end
+
+-- event watcher to watch head file
+local file_changed = vim.loop.new_fs_event()
+local function watch_head()
+  file_changed:stop()
+  local git_dir = find_git_dir()
+  if #git_dir > 0 then
+    local head_file = git_dir..sep..'HEAD'
+    get_git_head(head_file)
+    file_changed:start(head_file, {}, vim.schedule_wrap(function()
+      -- reset file-watch
+      watch_head()
+    end))
+  else
+    -- set to nil when git dir was not found
+    git_branch = nil
+  end
+end
+
+-- returns the git_branch value to be shown on statusline
 local function branch()
   if not git_branch or #git_branch == 0 then return '' end
   local ok,devicons = pcall(require,'nvim-web-devicons')
@@ -47,4 +78,12 @@ local function branch()
   return git_branch
 end
 
+-- run watch head on load so branch is present when component is loaded
+watch_head()
+
+-- TODO Don't export as a global function
+_G.lualine_branch_update = watch_head
+-- update branch state of BufEnter as different Buffer may be on different repos
+vim.cmd[[autocmd BufEnter * call v:lua.lualine_branch_update()]]
+
 return branch