From b3f2d03674574910157f175bb714deba90001fb8 Mon Sep 17 00:00:00 2001
From: Fernando Schauenburg <dev@schauenburg.me>
Date: Sun, 6 Aug 2023 23:35:45 +0200
Subject: [PATCH] vim: better window resizing

---
 config/nvim/lua/user/keymap.lua | 11 ++++---
 config/nvim/lua/user/util.lua   | 58 ++++++++++++++++++++++++++++++++-
 2 files changed, 63 insertions(+), 6 deletions(-)

diff --git a/config/nvim/lua/user/keymap.lua b/config/nvim/lua/user/keymap.lua
index 63574a9..597abe4 100644
--- a/config/nvim/lua/user/keymap.lua
+++ b/config/nvim/lua/user/keymap.lua
@@ -1,4 +1,5 @@
-local partial = require('user.util').partial
+local util = require('user.util')
+local partial = util.partial
 local nmap = partial(vim.keymap.set, 'n')
 local imap = partial(vim.keymap.set, 'i')
 local vmap = partial(vim.keymap.set, 'v')
@@ -33,10 +34,10 @@ nmap('<c-h>', '<c-w>h')
 nmap('<c-l>', '<c-w>l')
 
 -- window resizing
-nmap('<s-Up>', '<cmd>resize +1<cr>')
-nmap('<s-Down>', '<cmd>resize -1<cr>')
-nmap('<s-Left>', '<cmd>vertical resize -1<cr>')
-nmap('<s-Right>', '<cmd>vertical resize +1<cr>')
+nmap('<s-Up>',       util.win_resize_up(2), { desc = 'Resize window upward' })
+nmap('<s-Down>',   util.win_resize_down(2), { desc = 'Resize window downward' })
+nmap('<s-Left>',   util.win_resize_left(2), { desc = 'Resize window leftward' })
+nmap('<s-Right>', util.win_resize_right(2), { desc = 'Resize window rightward' })
 
 -- easy tab navigation
 nmap('<Right>', '<cmd>tabnext<cr>', { silent = true })
diff --git a/config/nvim/lua/user/util.lua b/config/nvim/lua/user/util.lua
index f5c79eb..0380435 100644
--- a/config/nvim/lua/user/util.lua
+++ b/config/nvim/lua/user/util.lua
@@ -37,6 +37,17 @@ M.partial = function(f, ...)
   end
 end
 
+--- Delayed function execution.
+---@param f function: function whose evaluation will be delayed.
+---@param ... any: arguments to `f`.
+---@return function: a new function that calls f with provided arguments.
+M.thunk = function(f, ...)
+  local args = {...}
+  return function()
+    return f(unpack(args))
+  end
+end
+
 -- Perform `func` (which can freely use register `reg`) and make sure `reg`
 -- is restored afterwards.
 M.with_saved_register = function(reg, func)
@@ -73,8 +84,53 @@ M.goto_prev_diagnostic = function(opts)
   vim.diagnostic.goto_prev(vim.tbl_extend('keep', opts or {}, diag_opts))
 end
 
-M.use_local = function()
+--- Whether the current window is the last in a given direction.
+---@param direction string: one of 'h', 'j', 'k', or 'l'
+local win_is_last = function(direction)
+  local current = vim.api.nvim_get_current_win()
+  vim.cmd('wincmd ' .. direction)
+  local next = vim.api.nvim_get_current_win()
+
+  local is_last = current == next
+  if not is_last then vim.cmd('wincmd p') end
+
+  return is_last
 end
 
+--- Resize current window in a given direction.
+---@param dir string: one of 'h', 'j', 'k', or 'l'
+---@param size integer: how much to resize
+local win_resize = function(dir, size)
+  if dir ~= 'h' and dir ~= 'j' and dir ~= 'k' and dir ~= 'l' then return end
+
+  size = math.abs(size)
+  local is_height = dir == 'j' or dir == 'k'
+  local is_positive = dir == 'j' or dir == 'l'
+
+  if win_is_last(is_height and 'j' or 'l') then
+    is_positive = not is_positive
+  end
+
+  local delta = string.format('%s%d', is_positive and '+' or '-', size)
+  local prefix = is_height and '' or 'vertical '
+  vim.cmd(prefix .. 'resize ' .. delta .. '<cr>')
+end
+
+--- Resize current window upwards.
+---@param size integer: how much to resize
+M.win_resize_up    = function(size) return M.thunk(win_resize, 'k', size) end
+
+--- Resize current window downwards.
+---@param size integer: how much to resize
+M.win_resize_down  = function(size) return M.thunk(win_resize, 'j', size) end
+
+--- Resize current window leftwards.
+---@param size integer: how much to resize
+M.win_resize_left  = function(size) return M.thunk(win_resize, 'h', size) end
+
+--- Resize current window rightwards.
+---@param size integer: how much to resize
+M.win_resize_right = function(size) return M.thunk(win_resize, 'l', size) end
+
 return M