feat: add agenda plugin

Import the package from my dotfiles.

lua/agenda.lua

@@ -0,0 +1,132 @@
+local api = vim.api
+local fn = vim.fn
+
+---Wrapper for using my `agenda` script from within neovim.
+local M = {}
+
+function M.on_attach(buf)
+  vim.bo[buf].bufhidden = 'delete'
+end
+
+---@return string
+function M.dir()
+  if vim.env.AGENDA_DIR then
+    return vim.env.AGENDA_DIR
+  end
+
+  if vim.env.XDG_DATA_HOME then
+    return string.format('%/agenda', vim.env.XDG_DATA_HOME)
+  end
+
+  return string.format('%/.local/share/agenda', vim.env.HOME)
+end
+
+---Gets the first window with an agenda note buffer in a tabpage.
+---@param tabpage integer Tabpage handle, or 0 for the current tabpage.
+---@param opts {dir: string?}?
+---@return integer? win Window handle
+function M.tabpage_get_win(tabpage, opts)
+  local agenda_dir = opts and opts.dir or M.dir()
+
+  for _, win in ipairs(api.nvim_tabpage_list_wins(tabpage)) do
+    local buf = api.nvim_win_get_buf(win)
+    -- Better to look at the name (file path), since that state is always there
+    -- (e.g. after restoring a session).
+    local name = api.nvim_buf_get_name(buf)
+    if vim.startswith(name, agenda_dir) then
+      return win
+    end
+  end
+end
+
+---@class agenda.Opts
+---@field backlog string? Set the -b flag.
+---@field create boolean? Set the -c flag.
+---@field dir string? Set this as AGENDA_DIR value.
+---@field extension string? Set this as -e option value.
+---@field name string? Set this as -t option value.
+
+---Open an agenda note.
+---@param date string Either the date or backlog name.
+---@param opts agenda.Opts?
+function M.open(date, opts)
+  local filepath, err = M.agenda(date, opts)
+
+  if not filepath or fn.filereadable(filepath) < 1 then
+    if not err then
+      err = string.format("agenda: file '%s' is not readable", filepath)
+    end
+    vim.notify(err, vim.log.levels.WARN)
+    return
+  end
+
+  local win = M.tabpage_get_win(0)
+  if win then
+    vim.api.nvim_set_current_win(win)
+    vim.cmd.edit(filepath)
+  else
+    vim.cmd.split(filepath)
+  end
+
+  M.on_attach(0)
+end
+
+---Query an agenda note's file path.
+---@param date string Either the date or backlog name.
+---@param opts agenda.Opts?
+---@return string? filepath
+---@return string? err
+function M.agenda(date, opts)
+  local env = {
+    -- An empty environment table is invalid.
+    AGENDA_DIR = vim.env.AGENDA_DIR
+  }
+  local cmd = { 'agenda', '-E' }
+
+  if opts then
+    if opts.dir then
+      env.AGENDA_DIR = opts.dir
+    end
+
+    if opts.backlog then
+      cmd[#cmd + 1] = '-b'
+    end
+
+    if opts.create then
+      cmd[#cmd + 1] = '-c'
+    end
+
+    if opts.extension then
+      cmd[#cmd + 1] = '-e'
+      cmd[#cmd + 1] = opts.extension
+    end
+
+    if opts.name then
+      cmd[#cmd + 1] = '-t'
+      cmd[#cmd + 1] = opts.name
+    end
+  end
+
+  cmd[#cmd + 1] = date
+
+  local filepath = ''
+  local err = ''
+  local pid = fn.jobstart(cmd, {
+    env = env,
+    on_stdout = function(_, data)
+      filepath = filepath .. data[1]
+    end,
+    on_stderr = function(_, data)
+      err = err .. data[1]
+    end,
+  })
+
+  local code = unpack(fn.jobwait { pid })
+  if code > 0 then
+    return nil, err
+  end
+
+  return filepath
+end
+
+return M