local M = {}

local cnf = require("auto-save.config")
local callback = require("auto-save.utils.data").do_callback
local colors = require("auto-save.utils.colors")
local echo = require("auto-save.utils.echo")
local autosave_running
local api = vim.api
local g = vim.g
local fn = vim.fn
local cmd = vim.cmd
local o = vim.o
local AUTO_SAVE_COLOR = "MsgArea"
local BLACK = "#000000"
local WHITE = "#ffffff"

api.nvim_create_augroup("AutoSave", {
	clear = true,
})

local global_vars = {}

local function set_buf_var(buf, name, value)
	if buf == nil then
		global_vars[name] = value
	else
		if api.nvim_buf_is_valid(buf) then
			api.nvim_buf_set_var(buf, "autosave_" .. name, value)
		end
	end
end

local function get_buf_var(buf, name)
	if buf == nil then
		return global_vars[name]
	end
	local success, mod = pcall(api.nvim_buf_get_var, buf, "autosave_" .. name)
	return success and mod or nil
end

local function debounce(lfn, duration)
	local function inner_debounce()
		local buf = api.nvim_get_current_buf()
		if not get_buf_var(buf, "queued") then
			vim.defer_fn(function()
				set_buf_var(buf, "queued", false)
				lfn(buf)
			end, duration)
			set_buf_var(buf, "queued", true)
		end
	end

	return inner_debounce
end

function M.save(buf)
	buf = buf or api.nvim_get_current_buf()

	callback("before_asserting_save")

	if cnf.opts.condition(buf) == false then
		return
	end

	if not api.nvim_buf_get_option(buf, "modified") then
		return
	end

	callback("before_saving")

	if g.auto_save_abort == true then
		return
	end

	if cnf.opts.write_all_buffers then
		cmd("silent! wall")
	else
		api.nvim_buf_call(buf, function()
			cmd("silent! write")
		end)
	end

	callback("after_saving")

	if cnf.opts.execution_message.enabled == true then
		echo_execution_message()
	end
end

local function echo_execution_message()
	local msg = type(cnf.opts.execution_message.message) == "function" and cnf.opts.execution_message.message()
		or cnf.opts.execution_message.message
	api.nvim_echo({ { msg, AUTO_SAVE_COLOR } }, true, {})
	if cnf.opts.execution_message.cleaning_interval > 0 then
		fn.timer_start(cnf.opts.execution_message.cleaning_interval, function()
			cmd([[echon '']])
		end)
	end
end

local save_func = nil

local function perform_save()
	g.auto_save_abort = false
	if save_func == nil then
		save_func = (cnf.opts.debounce_delay > 0 and debounce(M.save, cnf.opts.debounce_delay) or M.save)
	end
	save_func()
end

function M.on()
	api.nvim_create_autocmd(cnf.opts.trigger_events, {
		callback = function()
			perform_save()
		end,
		pattern = "*",
		group = "AutoSave",
	})

	api.nvim_create_autocmd({ "VimEnter", "ColorScheme", "UIEnter" }, {
		callback = function()
			vim.schedule(function()
				if cnf.opts.execution_message.dim > 0 then
					MSG_AREA = colors.get_hl("MsgArea")
					if MSG_AREA.foreground ~= nil then
						MSG_AREA.background = (MSG_AREA.background or colors.get_hl("Normal")["background"])
						local foreground = (
							o.background == "dark"
								and colors.darken(
									(MSG_AREA.background or BLACK),
									cnf.opts.execution_message.dim,
									MSG_AREA.foreground or BLACK
								)
							or colors.lighten(
								(MSG_AREA.background or WHITE),
								cnf.opts.execution_message.dim,
								MSG_AREA.foreground or WHITE
							)
						)

						colors.highlight("AutoSaveText", { fg = foreground })
						AUTO_SAVE_COLOR = "AutoSaveText"
					end
				end
			end)
		end,
		pattern = "*",
		group = "AutoSave",
	})

	callback("enabling")
	autosave_running = true
end

function M.off()
	api.nvim_create_augroup("AutoSave", {
		clear = true,
	})

	callback("disabling")
	autosave_running = false
end

function M.toggle()
	if autosave_running then
		M.off()
		echo("off")
	else
		M.on()
		echo("on")
	end
end

function M.setup(custom_opts)
	cnf:set_options(custom_opts)
end

return M