-- MIT License Copyright (c) 2021 Evgeni Chasnovski

-- Documentation ==============================================================

---@brief [[

--- Custom minimal and fast module for working with trailing whitespace.

---

--- Features:

--- - Highlighting is done only in modifiable buffer by default; only in Normal

--- mode; stops in Insert mode and when leaving window.

--- - Trim all trailing whitespace with |MiniTrailspace.trim()| function.

---

--- # Setup

---

--- This module needs a setup with `require('mini.trailspace').setup({})`

--- (replace `{}` with your `config` table). It will create global Lua table

--- `MiniTrailspace` which you can use for scripting or manually (with

--- `:lua MiniTrailspace.*`).

---

--- Default `config`:

--- <code>

--- {

--- -- Highlight only in normal buffers (ones with empty 'buftype'). This is

--- -- useful to not show trailing whitespace where it usually doesn't matter.

--- only_in_normal_buffers = true,

--- }

--- </code>

--- # Highlight groups

---

--- 1. `MiniTrailspace` - highlight group for trailing space.

---

--- To change any highlight group, modify it directly with |:highlight|.

---

--- # Disabling

---

--- To disable, set `g:minitrailspace_disable` (globally) or

--- `b:minitrailspace_disable` (for a buffer) to `v:true`. Note: after

--- disabling there might be highlighting left; it will be removed after next

--- highlighting update (see |events| and `MiniTrailspace` |augroup|).

---@brief ]]

---@tag MiniTrailspace mini.trailspace

-- Module definition ==========================================================

local MiniTrailspace = {}

local H = {}

--- Module setup

---

---@param config table: Module config table.

---@usage `require('mini.trailspace').setup({})` (replace `{}` with your `config` table)

function MiniTrailspace.setup(config)

-- Export module

_G.MiniTrailspace = MiniTrailspace

-- Setup config

config = H.setup_config(config)

-- Apply config

H.apply_config(config)

-- Module behavior

-- Use `defer_fn` for `MiniTrailspace.highlight` to ensure that

-- 'modifiable' option is set to its final value.

vim.api.nvim_exec(

[[augroup MiniTrailspace

au!

au WinEnter,BufEnter,InsertLeave * lua MiniTrailspace.highlight()

au WinLeave,BufLeave,InsertEnter * lua MiniTrailspace.unhighlight()

au FileType TelescopePrompt let b:minitrailspace_disable=v:true

augroup END]],

false

)

if config.only_in_normal_buffers then

-- Add tracking of 'buftype' changing because it can be set after events on

-- which highlighting is done. If not done, highlighting appears but

-- disappears if buffer is reentered.

vim.api.nvim_exec(

[[augroup MiniTrailspace

au OptionSet buftype lua MiniTrailspace.track_normal_buffer()

augroup END]],

false

)

end

-- Create highlighting

vim.api.nvim_exec([[hi default link MiniTrailspace Error]], false)

end

MiniTrailspace.config = {

-- Highlight only in normal buffers (ones with empty 'buftype'). This is

-- useful to not show trailing whitespace where it usually doesn't matter.

only_in_normal_buffers = true,

}

-- Module functionality =======================================================

--- Highlight trailing whitespace

function MiniTrailspace.highlight()

-- Highlight only in normal mode

if H.is_disabled() or vim.fn.mode() ~= 'n' then

MiniTrailspace.unhighlight()

return

end

if MiniTrailspace.config.only_in_normal_buffers and not H.is_buffer_normal() then

return

end

local win_id = vim.api.nvim_get_current_win()

if not vim.api.nvim_win_is_valid(win_id) then

return

end

-- Don't add match id on top of existing one

if H.window_matches[win_id] ~= nil then

return

end

local match_id = vim.fn.matchadd('MiniTrailspace', [[\s\+$]])

H.window_matches[win_id] = { id = match_id }

end

--- Unhighlight trailing whitespace

function MiniTrailspace.unhighlight()

-- Don't do anything if there is no valid information to act upon

local win_id = vim.api.nvim_get_current_win()

local win_match = H.window_matches[win_id]

if not vim.api.nvim_win_is_valid(win_id) or win_match == nil then

return

end

-- Use `pcall` because there is an error if match id is not present. It can

-- happen if something else called `clearmatches`.

pcall(vim.fn.matchdelete, win_match.id)

H.window_matches[win_id] = nil

end

--- Trim trailing whitespace

function MiniTrailspace.trim()

-- Save cursor position to later restore

local curpos = vim.api.nvim_win_get_cursor(0)

-- Search and replace trailing whitespace

vim.cmd([[keeppatterns %s/\s\+$//e]])

vim.api.nvim_win_set_cursor(0, curpos)

end

--- Track normal buffer

---

--- Designed to be used with |autocmd|. No need to use it directly.

function MiniTrailspace.track_normal_buffer()

if not MiniTrailspace.config.only_in_normal_buffers then

return

end

-- This should be used with 'OptionSet' event for 'buftype' option

-- Empty 'buftype' means "normal buffer"

if vim.v.option_new == '' then

MiniTrailspace.highlight()

else

MiniTrailspace.unhighlight()

end

end

-- Helper data ================================================================

-- Module default config

H.default_config = MiniTrailspace.config

-- Information about last match highlighting (stored *per window*):

-- - Key: windows' unique buffer identifiers.

-- - Value: table with `id` field for match id (from `vim.fn.matchadd()`).

H.window_matches = {}

-- Helper functionality =======================================================

-- Settings -------------------------------------------------------------------

function H.setup_config(config)

-- General idea: if some table elements are not present in user-supplied

-- `config`, take them from default config

vim.validate({ config = { config, 'table', true } })

config = vim.tbl_deep_extend('force', H.default_config, config or {})

vim.validate({ only_in_normal_buffers = { config.only_in_normal_buffers, 'boolean' } })

return config

end

function H.apply_config(config)

MiniTrailspace.config = config

end

function H.is_disabled()

return vim.g.minitrailspace_disable == true or vim.b.minitrailspace_disable == true

end

function H.is_buffer_normal(buf_id)

return vim.api.nvim_buf_get_option(buf_id or 0, 'buftype') == ''

end

return MiniTrailspace