From e04acb1459760af829ed08276cb51ebd0ea6a95c Mon Sep 17 00:00:00 2001
From: Sandeep Dilip <34922961+sanman1k98@users.noreply.github.com>
Date: Sat, 14 Jan 2023 10:34:55 -0500
Subject: [PATCH] feat(lua): `vim.autocmd` and `vim.augroup`

test(lua): `vim.autocmd` and `vim.augroup`

test: add describe blocks

Organize tests with `describe` blocks.

style: indentation
---
 runtime/lua/vim/_auto.lua          | 243 +++++++++++++++++++++++++++++
 runtime/lua/vim/_init_packages.lua |   3 +
 test/functional/lua/auto_spec.lua  | 230 +++++++++++++++++++++++++++
 3 files changed, 476 insertions(+)
 create mode 100644 runtime/lua/vim/_auto.lua
 create mode 100644 test/functional/lua/auto_spec.lua

diff --git a/runtime/lua/vim/_auto.lua b/runtime/lua/vim/_auto.lua
new file mode 100644
index 0000000000..847dfa41b0
--- /dev/null
+++ b/runtime/lua/vim/_auto.lua
@@ -0,0 +1,243 @@
+---@class EventContext
+---@field _group string|boolean
+---@field _buffer integer|boolean
+local EventContext = {}
+
+---@class Event
+---@field _ctx EventContext
+---@field _event string|string[]
+---@field _pattern? string|string[]
+local Event = {}
+
+---@class Augroup
+---@field _ctx EventContext
+---@field _group string
+local Augroup = {}
+
+local a, validate = vim.api, vim.validate
+
+---@param group? string|boolean
+---@param buffer? integer|boolean
+---@return EventContext
+---@private
+function EventContext._new(group, buffer)
+  -- use non-nil values to avoid triggering the `__index` metamethod when we access fields on self.
+  local self = {
+    _group = group or false,
+    _buffer = buffer or false,
+  }
+  return setmetatable(self, EventContext)
+end
+
+---@param opts? table API options
+---@return table opts
+function EventContext:_apply(opts)
+  opts = opts or {}
+  local g, b = self._group, self._buffer
+  b = b == true and 0 or b
+  opts.buffer = b or opts.buffer
+  opts.group = g or opts.group
+  return opts
+end
+
+---@param self EventContext
+---@param opts? table
+---@return table
+---@see |nvim_get_autocmds()|
+function EventContext:get(opts)
+  return a.nvim_get_autocmds(self:_apply(opts))
+end
+
+---@param self EventContext
+---@param opts? table
+---@see |nvim_clear_autocmds()|
+function EventContext:clear(opts)
+  a.nvim_clear_autocmds(self:_apply(opts))
+end
+
+---@param self EventContext
+---@private
+function EventContext:__index(k)
+  -- first, check methods
+  if EventContext[k] then
+    return EventContext[k]
+  end
+  -- then, check if we're trying to specify a buffer
+  if k == "buf" then
+    return self._buffer == false and EventContext._new(self._group, true) or nil
+  elseif type(k) == "number" then
+    return self._buffer == true and EventContext._new(self._group, k) or nil
+  end
+  -- nothing else to check; use k as event name
+  return Event._new(self, k)
+end
+
+---@param ctx EventContext
+---@param event string|string[]
+---@param pattern? string|string[]
+---@return Event
+---@private
+function Event._new(ctx, event, pattern)
+  local self = {
+    _ctx = ctx,
+    _event = event,
+    _pattern = pattern or false,
+  }
+  return setmetatable(self, Event)
+end
+
+---@param self Event
+---@param opts? table
+---@return table[]
+function Event:get(opts)
+  opts = self._ctx:_apply(opts)
+  opts.event = self._event
+  opts.pattern = self._pattern or opts.pattern
+  return a.nvim_get_autocmds(opts)
+end
+
+---@param self Event
+---@param opts? table
+function Event:exec(opts)
+  opts = self._ctx:_apply(opts)
+  opts.pattern = self._pattern or opts.pattern
+  a.nvim_exec_autocmds(self._event, opts)
+end
+
+---@param self Event
+---@param opts? table
+function Event:clear(opts)
+  opts = self._ctx:_apply(opts)
+  opts.event = self._event
+  opts.pattern = self._pattern or opts.pattern
+  a.nvim_clear_autocmds(opts)
+end
+
+--- Create an autocommand for this event
+---@param self Event
+---@param handler string|function
+---@param opts? table
+---@return integer
+function Event:__call(handler, opts)
+  validate {
+    handler = { handler, {"s", "f"} },
+    opts = { opts, "t", true },
+  }
+  opts = self._ctx:_apply(opts)
+  opts.pattern = self._pattern or opts.pattern
+  if type(handler) == "string" and handler:sub(1, 1) == ":" then
+    opts.command = handler:sub(2)
+  else
+    opts.callback = handler
+  end
+  return a.nvim_create_autocmd(self._event, opts)
+end
+
+---@param self Event
+---@return function|Event|nil
+function Event:__index(k)
+  if Event[k] then
+    return Event[k]
+  elseif not self._pattern and not self._ctx._buffer then
+    return Event._new(self._ctx, self._event, k)
+  else
+    return nil
+  end
+end
+
+Augroup.__index = Augroup
+
+---@param name string
+---@return Augroup
+function Augroup._new(name)
+  local self = {
+    _ctx = EventContext._new(name, nil),
+    _group = name,
+  }
+  return setmetatable(self, Augroup)
+end
+
+---@param self Augroup
+---@return integer id
+function Augroup:create()
+  return a.nvim_create_augroup(self._group, { clear = false })
+end
+
+---@param self Augroup
+---@param opts? table
+---@return integer? id
+function Augroup:clear(opts)
+  if not opts then
+    return a.nvim_create_augroup(self._group, { clear = true })
+  else
+    self._ctx:clear(opts)
+  end
+end
+
+---@param self Augroup
+function Augroup:del()
+  return a.nvim_del_augroup_by_name(self._group)
+end
+
+---@param self Augroup
+---@param opts? table
+---@return table[]?
+function Augroup:get(opts)
+  if not opts then
+    local exists, cmds = pcall(a.nvim_get_autocmds, { group = self._group })
+    return exists and cmds or nil
+  else
+    return self._ctx:get(opts)
+  end
+end
+
+---@param self Augroup
+---@param spec fun(au:EventContext):any
+---@return integer id 
+---@return any
+function Augroup:__call(spec)
+  local id = self:create()
+  local res = spec(self._ctx)
+  return id, res
+end
+
+--- Use `vim.autocmd` to manage autocommands. Index it by event names to create and execute them.
+---
+--- To create an autocommand, index `vim.autocmd` with an event name to return a callable table.
+--- Then call it with a handler (a Lua function, a Vimscript function name, or Ex command) and
+--- and optional table of options to pass to |nvim_create_autocmd()|.
+---
+--- <pre>lua
+---   -- prefix Ex commands with ":" to use as an event handler
+---   vim.autocmd.UIEnter(":echo 'Hello!'")
+---   -- a Lua callback as an event handler
+---   vim.autocmd.UIEnter(function()
+---     vim.cmd.echo 'Hello!'
+---   end)
+---   -- passing in additional options
+---   vim.autocmd.UIEnter(":echo 'Hello!'", {
+---     desc = "greeting",
+---     once = true,
+---   })
+---   -- specify multiple events
+---   vim.autocmd[{ "UIEnter", "TabEnter", "TermEnter" }](":echo 'Hello!'")
+--- </pre>
+---
+--- You may also specify a pattern by indexing the event.
+---
+--- <pre>lua
+---   vim.autocmd.FileType[{ "qf", "help", "man", }](function()
+---     vim.opt_local.number = false
+---     vim.opt_local.relativenumber = false
+---   end)
+--- </pre>
+---
+vim.autocmd = EventContext._new(nil, nil)
+
+vim.autocmd.buf = EventContext._new(nil, 0)
+
+--- Create, delete, and clear autocommand groups with `vim.augroup`.
+---
+vim.augroup = setmetatable({}, {
+  __index = function(_, k) return Augroup._new(k) end,
+})
diff --git a/runtime/lua/vim/_init_packages.lua b/runtime/lua/vim/_init_packages.lua
index 0c4ee8636d..bee7932864 100644
--- a/runtime/lua/vim/_init_packages.lua
+++ b/runtime/lua/vim/_init_packages.lua
@@ -59,6 +59,9 @@ setmetatable(vim, {
     elseif key == 'inspect_pos' or key == 'show_pos' then
       require('vim._inspector')
       return t[key]
+    elseif key == 'autocmd' or key == 'augroup' then
+      require('vim._auto')
+      return t[key]
     elseif vim.startswith(key, 'uri_') then
       local val = require('vim.uri')[key]
       if val ~= nil then
diff --git a/test/functional/lua/auto_spec.lua b/test/functional/lua/auto_spec.lua
new file mode 100644
index 0000000000..2fe8e304f1
--- /dev/null
+++ b/test/functional/lua/auto_spec.lua
@@ -0,0 +1,230 @@
+local helpers = require('test.functional.helpers')(after_each)
+local exec_lua = helpers.exec_lua
+local meths = helpers.meths
+local clear = helpers.clear
+local eq = helpers.eq
+
+before_each(clear)
+
+describe('vim.autocmd', function()
+  describe('vim.autocmd:get()', function()
+    pending('behaves like nvim_get_autocmds')
+  end)
+
+  describe('vim.autocmd:clear()', function()
+    pending('behaves like nvim_clear_autocmds')
+  end)
+
+  describe('vim.autocmd.buf', function()
+    pending('manages buflocal autocommands')
+
+    it('can create an autocommand for the current buffer', function()
+      exec_lua [[ vim.autocmd.buf.InsertEnter(':echo "Coding!"') ]]
+      eq(1, #meths.get_autocmds({ buffer = 0 }))
+    end)
+
+    it('can get all autocommands attached to the current buffer', function()
+      meths.create_autocmd('InsertEnter', {
+        buffer = 0,
+        command = 'echo "Coding!"'
+      })
+      meths.create_autocmd('InsertLeave', {
+        buffer = 0,
+        command = 'echo "Done!"'
+      })
+      local aus = exec_lua [[ return vim.autocmd.buf:get() ]]
+      eq(2, #aus)
+    end)
+
+    it('can clear all autocommands attached to the current buffer', function()
+      meths.create_autocmd('InsertEnter', {
+        buffer = 0,
+        command = 'echo "Coding!"'
+      })
+      meths.create_autocmd('InsertLeave', {
+        buffer = 0,
+        command = 'echo "Done!"'
+      })
+      eq(2, #meths.get_autocmds({ buffer = 0 }))
+      exec_lua [[ vim.autocmd.buf:clear() ]]
+      eq(0, #meths.get_autocmds({ buffer = 0 }))
+    end)
+
+    pending('can be indexed with a bufnr')
+  end)
+
+  it('can create an autocommand', function()
+    local id = exec_lua([[
+      return vim.autocmd.UIEnter(':echo "Hello!"')
+    ]])
+    assert.number(id)
+    local cmds = meths.get_autocmds({ event = 'UIEnter' })
+    eq(1, #cmds)
+    eq(id, cmds[1].id)
+    eq('echo "Hello!"', cmds[1].command)
+  end)
+
+  it('can create an autocommand with options', function()
+    local id = exec_lua([[
+      return vim.autocmd.UIEnter(':echo "Hello!"', {
+        desc = 'greeting',
+        once = true,
+      })
+    ]])
+    assert.number(id)
+    local cmds = meths.get_autocmds({ event = 'UIEnter' })
+    eq(id, cmds[1].id)
+    eq('greeting', cmds[1].desc)
+  end)
+
+  it('can create an autocommand for multiple events', function()
+    local id = exec_lua([[
+      return vim.autocmd[{ 'UIEnter', 'VimEnter', 'WinEnter' }](':echo "Hello!"')
+    ]])
+    assert.number(id)
+    eq(id, meths.get_autocmds({ event = 'UIEnter' })[1].id)
+    eq(id, meths.get_autocmds({ event = 'VimEnter' })[1].id)
+    eq(id, meths.get_autocmds({ event = 'WinEnter' })[1].id)
+  end)
+
+  it('can create an autocommand for an event and pattern', function()
+    local id = exec_lua([[
+      return vim.autocmd.User.CustomEvent(':echo "Hello!"')
+    ]])
+    assert.number(id)
+    eq(id, meths.get_autocmds({ event = 'User', pattern = 'CustomEvent' })[1].id)
+  end)
+
+  it('can create an autocommand and specify multiple patterns', function()
+    local id = exec_lua([[
+      return vim.autocmd.Filetype[{ 'lua', 'vim', 'sh' }](':echo "Hello!"')
+    ]])
+    assert.number(id)
+    eq(3, #meths.get_autocmds({ event = 'Filetype' }))
+  end)
+
+  it('can get autocommands for an event', function()
+    meths.create_autocmd('UIEnter', {
+      command = 'echo "Hello!"',
+    })
+    local cmds = exec_lua([[
+      return vim.autocmd.UIEnter:get()
+    ]])
+    eq(1, #cmds)
+  end)
+
+  it('can get autocommands for an event and pattern', function()
+    meths.create_autocmd('User', {
+      pattern = 'foo',
+      command = 'echo "Hello!"',
+    })
+    meths.create_autocmd('User', {
+      pattern = 'bar',
+      command = 'echo "Hello!"',
+    })
+    local cmds = exec_lua([[
+      return vim.autocmd.User.foo:get()
+    ]])
+    eq(1, #cmds)
+  end)
+
+  it('can clear autocommands for an event', function()
+    meths.create_autocmd('UIEnter', {
+      command = 'echo "Hello!"',
+    })
+    exec_lua([[
+      vim.autocmd.UIEnter:clear()
+    ]])
+    eq(0, #meths.get_autocmds({ event = 'UIEnter' }))
+  end)
+
+  it('can execute autocommands', function()
+    meths.set_var("some_condition", false)
+
+    exec_lua [[
+      vim.api.nvim_create_autocmd("User", {
+        pattern = "Test",
+        desc = "A test autocommand",
+        callback = function()
+          return vim.g.some_condition
+        end,
+      })
+    ]]
+
+    exec_lua [[ vim.autocmd.User.Test:exec() ]]
+
+    local aus = meths.get_autocmds({ event = 'User', pattern = 'Test' })
+    local first = aus[1]
+    eq(first.id, 1)
+
+    meths.set_var("some_condition", true)
+    exec_lua [[ vim.autocmd.User.Test:exec() ]]
+    eq({}, meths.get_autocmds({event = "User", pattern = "Test"}))
+  end)
+
+end)
+
+describe('vim.augroup', function()
+  it('can delete an existing group', function()
+    local id = meths.create_augroup('nvim_test_augroup', { clear = true })
+    meths.create_autocmd('User', {
+      group = id,
+      pattern = "Test",
+      desc = "A test autocommand",
+      command = 'echo "Test!"',
+    })
+    local aus = meths.get_autocmds({ group = 'nvim_test_augroup' })
+    eq(1, #aus)
+    exec_lua [[ vim.augroup.nvim_test_augroup:del() ]]
+    local success = exec_lua [[
+      return pcall(vim.api.nvim_get_autocmds, { group = 'nvim_test_augroup' })
+    ]]
+    eq(false, success)
+  end)
+
+  describe('Augroup:create()', function()
+    it('can create a group and return its id', function()
+      local id = exec_lua [[ return vim.augroup.nvim_test_augroup:create() ]]
+      meths.create_autocmd('User', {
+        group = id,
+        pattern = "Test",
+        desc = "A test autocommand",
+        command = 'echo "Test!"',
+      })
+      local aus = meths.get_autocmds({ group = id })
+      eq(1, #aus)
+    end)
+
+    pending('can return the id of an existing group')
+    pending('does not clear an existing group')
+  end)
+
+  describe('Augroup:clear()', function()
+    pending('clears autocommands in the group')
+    pending('can be called with a dictionary of autocommand options')
+    pending('can create the group when called without arguments')
+  end)
+
+  describe('Augroup:get()', function()
+    pending('can return a list of autocommands in the group')
+    pending('can be called with a dictionary of autocommand options')
+    pending('returns nil when called without arguments on a nonexistant group')
+  end)
+
+  describe('Augroup:__call()', function()
+    it('can create a group and define its autocommands', function()
+      exec_lua [[
+        vim.augroup.nvim_test_augroup(function(au)
+          au.UIEnter(":echo 'Hello!'")
+          au.User.Test(":echo 'Test!'")
+          au.InsertEnter['*'](":echo 'Test!'")
+        end)
+      ]]
+      local aus = meths.get_autocmds({ group = 'nvim_test_augroup' })
+      eq(3, #aus)
+    end)
+
+    pending('can add autocommands to an existing group')
+    pending('returns the group id and any values returned from the function')
+  end)
+end)