draft: initial implementation

lua/lz/n/handler/event.lua

@@ -0,0 +1,147 @@
+local loader = require('lz.n.loader')
+
+---@class LzEventOpts
+---@field event string
+---@field group? string
+---@field exclude? string[] augroups to exclude
+---@field data? unknown
+---@field buffer? number
+
+---@class LzEventHandler: LzHandler
+---@field events table<string,true>
+---@field group number
+
+---@type LzEventHandler
+local M = {
+  active = {},
+  managed = {},
+  type = 'event',
+}
+
+---@param spec LzEventSpec
+---@return LzEvent
+function M.parse(spec)
+  local ret
+  if type(spec) == 'string' then
+    local event, pattern = spec:match('^(%w+)%s+(.*)$')
+    event = event or spec
+    return { id = spec, event = event, pattern = pattern }
+  elseif vim.tbl_islist(spec) then
+    ret = { id = table.concat(spec, '|'), event = spec }
+  else
+    ret = spec --[[@as LzEvent]]
+    if not ret.id then
+      ---@diagnostic disable-next-line: assign-type-mismatch, param-type-mismatch
+      ret.id = type(ret.event) == 'string' and ret.event or table.concat(ret.event, '|')
+      if ret.pattern then
+        ---@diagnostic disable-next-line: assign-type-mismatch, param-type-mismatch
+        ret.id = ret.id .. ' ' .. (type(ret.pattern) == 'string' and ret.pattern or table.concat(ret.pattern, ', '))
+      end
+    end
+  end
+  return ret
+end
+
+-- Get all augroups for an event
+---@param event string
+local function get_augroups(event)
+  ---@type string[]
+  local groups = {}
+  for _, autocmd in ipairs(vim.api.nvim_get_autocmds { event = event }) do
+    if autocmd.group_name then
+      table.insert(groups, autocmd.group_name)
+    end
+  end
+  return groups
+end
+
+local event_triggers = {
+  FileType = 'BufReadPost',
+  BufReadPost = 'BufReadPre',
+}
+-- Get the current state of the event and all the events that will be fired
+---@param event string
+---@param buf integer
+---@param data unknown
+---@return LzEventOpts[]
+local function get_state(event, buf, data)
+  ---@type LzEventOpts[]
+  local state = {}
+  while event do
+    ---@type LzEventOpts
+    local event_opts = {
+      event = event,
+      exclude = event ~= 'FileType' and get_augroups(event) or nil,
+      buffer = buf,
+      data = data,
+    }
+    table.insert(state, 1, event_opts)
+    data = nil -- only pass the data to the first event
+    event = event_triggers[event]
+  end
+  return state
+end
+
+-- Trigger an event
+---@param opts LzEventOpts
+local function _trigger(opts)
+  xpcall(
+    function()
+      vim.api.nvim_exec_autocmds(opts.event, {
+        buffer = opts.buffer,
+        group = opts.group,
+        modeline = false,
+        data = opts.data,
+      })
+    end,
+    vim.schedule_wrap(function(err)
+      vim.notify(err, vim.log.levels.ERROR)
+    end)
+  )
+end
+
+-- Trigger an event. When a group is given, only the events in that group will be triggered.
+-- When exclude is set, the events in those groups will be skipped.
+---@param opts LzEventOpts
+local function trigger(opts)
+  if opts.group or opts.exclude == nil then
+    return _trigger(opts)
+  end
+  ---@type table<string,true>
+  local done = {}
+  for _, autocmd in ipairs(vim.api.nvim_get_autocmds { event = opts.event }) do
+    local id = autocmd.event .. ':' .. (autocmd.group or '') ---@type string
+    local skip = done[id] or (opts.exclude and vim.tbl_contains(opts.exclude, autocmd.group_name))
+    done[id] = true
+    if autocmd.group and not skip then
+      opts.group = autocmd.group_name
+      _trigger(opts)
+    end
+  end
+end
+
+---@param event LzEvent
+function M.add(event)
+  local done = false
+  vim.api.nvim_create_autocmd(event.event, {
+    group = M.group,
+    once = true,
+    pattern = event.pattern,
+    callback = function(ev)
+      if done or not M.active[event.id] then
+        return
+      end
+      -- HACK: work-around for https://github.com/neovim/neovim/issues/25526
+      done = true
+      local state = get_state(ev.event, ev.buf, ev.data)
+      -- load the plugins
+      loader.load(M.active[event.id])
+      -- check if any plugin created an event handler for this event and fire the group
+      for _, s in ipairs(state) do
+        trigger(s)
+      end
+    end,
+  })
+end
+
+return M