local utils = require('codemp.utils')

---@type table<integer, string>
local id_buffer_map = {}
---@type table<string, integer>
local buffer_id_map = {}
---@type table<string, string>
local user_buffer_name = {}
local ticks = {}

---@param name string name of buffer to attach to
---@param buffer? integer buffer to use for attaching (will clear content)
---@param content? string if provided, set this content after attaching
---@param nowait? boolean skip waiting for initial content sync
local function attach(name, buffer, content, nowait)
	if vim.fn.bufexists(name) then
		error("buffer '" .. name .. "' already exists!")
	end

	if buffer_id_map[name] ~= nil then
		error("already attached to buffer " .. name)
	end

	if buffer == nil then
		buffer = vim.api.nvim_get_current_buf()
	end

	vim.api.nvim_set_option_value('fileformat', 'unix', { buf = buffer })
	vim.api.nvim_buf_set_name(buffer, name)
	CODEMP.workspace:attach(name):and_then(function (controller)
		-- TODO disgusting! but poll blocks forever on empty buffers...
		if not nowait then
			local promise = controller:poll()
			for i=1, 20, 1 do
				if promise.ready then break end
				vim.uv.sleep(100)
			end
		end

		-- TODO map name to uuid

		id_buffer_map[buffer] = name
		buffer_id_map[name] = buffer
		ticks[buffer] = 0

		-- hook serverbound callbacks
		-- TODO breaks when deleting whole lines at buffer end
		vim.api.nvim_buf_attach(buffer, false, {
			on_bytes = function(_, buf, tick, start_row, start_col, start_offset, old_end_row, old_end_col, old_end_byte_len, new_end_row, new_end_col, new_byte_len)
				if tick <= ticks[buf] then return end
				if id_buffer_map[buf] == nil then return true end -- unregister callback handler
				if CODEMP.config.debug then print(string.format(
					"start(row:%s, col:%s) offset:%s end(row:%s, col:%s new(row:%s, col:%s)) len(old:%s, new:%s)",
					start_row, start_col, start_offset, old_end_row, old_end_col, new_end_row, new_end_col, old_end_byte_len, new_byte_len
				)) end
				local end_offset = start_offset + old_end_byte_len
				local change_content = ""
				local len = utils.buffer.len(buf)
				if start_offset + new_byte_len + 1 > len then
					-- i dont know why but we may go out of bounds when doing 'dd' at the end of buffer??
					local delta = (start_offset + new_byte_len + 1) - len
					if CODEMP.config.debug then print("/!\\ bytes out of bounds by " .. delta .. ", adjusting") end
					end_offset = end_offset - delta
					start_offset = start_offset - delta
				end
				if new_byte_len > 0 then
					local actual_end_col = new_end_col
					if new_end_row == 0 then actual_end_col = new_end_col + start_col end
					local actual_end_row = start_row + new_end_row
					-- -- when bulk inserting at the end we go out of bounds, so we probably need to clamp?
					-- --  issue: row=x+1 col=0 and row=x col=0 may be very far apart! we need to get last col of row x, ughh..
					-- -- also, this doesn't work so it will stay commented out for a while longer
					-- if new_end_row ~= old_end_row and new_end_col == 0 then
					-- 	-- we may be dealing with the last line of the buffer, get_text could error because out-of-bounds
					-- 	local row_count = vim.api.nvim_buf_line_count(buf)
					-- 	if actual_end_row + 1 > row_count then
					-- 		local delta = (actual_end_row + 1) - row_count
					-- 		if CODEMP.config.debug then print("/!\\ row out of bounds by " .. delta .. ", adjusting") end
					-- 		actual_end_row = actual_end_row - delta
					-- 		actual_end_col = len - vim.api.nvim_buf_get_offset(buf, row_count)
					-- 	end
					-- end
					local lines = vim.api.nvim_buf_get_text(buf, start_row, start_col, actual_end_row, actual_end_col, {})
					change_content = table.concat(lines, '\n')
				end
				if CODEMP.config.debug then
					print(string.format("sending: %s..%s '%s'", start_offset, start_offset + old_end_byte_len, change_content))
				end
				controller:send({
					start = start_offset, finish = end_offset, content = change_content
				}):await()
			end,
		})

		local async = vim.loop.new_async(vim.schedule_wrap(function ()
			while true do
				local event = controller:try_recv():await()
				if event == nil then break end
				ticks[buffer] = vim.api.nvim_buf_get_changedtick(buffer)
				CODEMP.ignore_following_action = true
				if CODEMP.config.debug then
					print(" ~~ applying change ~~ " .. event.start .. ".." .. event.finish .. "::[" .. event.content .. "]")
				end
				utils.buffer.set_content(buffer, event.content, event.start, event.finish)
				if event.hash ~= nil then
					if CODEMP.native.hash(utils.buffer.get_content(buffer)) ~= event.hash then
						-- OUT OF SYNC!
						-- TODO this may be destructive! we should probably prompt the user before doing this
						print(" /!\\ out of sync, resynching...")
						utils.buffer.set_content(buffer, controller:content():await())
						return
					end
				end
			end
		end))

		local remote_content = controller:content():await()
		if content ~= nil then
			-- TODO this may happen too soon!!
			local _ = controller:send({
				start = 0, finish = #remote_content, content = content
			}) -- no need to await
		else
			local current_content = utils.buffer.get_content(buffer)
			if current_content ~= remote_content then
				ticks[buffer] = vim.api.nvim_buf_get_changedtick(buffer)
				utils.buffer.set_content(buffer, remote_content)
			end
		end

		controller:callback(function (_) async:send() end)
		vim.defer_fn(function() async:send() end, 500) -- force a try_recv after 500ms

		local filetype = vim.filetype.match({ buf = buffer })
		vim.api.nvim_set_option_value("filetype", filetype, { buf = buffer })
		print(" ++ attached to buffer " .. name)
		require('codemp.window').update()
	end)
end

---@param name string
--TODO this should happen at the level above (Workspace) but accesses tables on this level, badly designed!
local function detach(name)
	local buffer = buffer_id_map[name]
	id_buffer_map[buffer] = nil
	buffer_id_map[name] = nil
	CODEMP.workspace:detach(name)

	print(" -- detached from buffer " .. name)
	require('codemp.window').update()
end

---@param buffer? integer if provided, sync given buffer id, otherwise sync current buf
local function sync(buffer)
	if buffer == nil then
		buffer = vim.api.nvim_get_current_buf()
	end
	local name = id_buffer_map[buffer]
	if name ~= nil then
		local controller = CODEMP.workspace:get_buffer(name)
		if controller ~= nil then
			local real_content = controller:content():await()
			local my_content = utils.buffer.get_content(buffer)
			if real_content ~= my_content then
				ticks[buffer] = vim.api.nvim_buf_get_changedtick(buffer)
				utils.buffer.set_content(buffer, real_content)
				print(" !! re-synched buffer " .. name)
			else
				print(" :: buffer " .. name .. " is in sync")
			end
			return
		end
	end

	print(" !! buffer not managed")
end

local function create(buffer)
	if buffer == nil then
		buffer = vim.fn.expand("%p")
	end
	if CODEMP.workspace == nil then
		error("join a workspace first")
	end
	CODEMP.workspace:create(buffer):and_then(function ()
		print(" ++  created buffer " .. buffer)
		require('codemp.window').update()
	end)
end

return {
	sync = sync,
	attach = attach,
	detach = detach,
	create = create,
	map = id_buffer_map,
	map_rev = buffer_id_map,
	ticks = ticks,
	users = user_buffer_name,
}