local utils = require('codemp.utils')
local buffers = require('codemp.buffers')

---@class UserHighlight
---@field ns integer namespace to use for this user
---@field hi string color for user to use
---@field pos [integer, integer] cursor start position of this user

---@type table<string, UserHighlight>
local user_hl = {}

local function fetch_workspaces_list()
	local new_list = {}
	CODEMP.client:list_workspaces(true, false):and_then(function (owned)
		for _, ws in pairs(owned) do
			table.insert(new_list, {
				name = ws,
				owned = true,
			})
		end
		CODEMP.client:list_workspaces(false, true):and_then(function (invited)
			for _, ws in pairs(invited) do
				table.insert(new_list, {
					name = ws,
					owned = false,
				})
			end
			CODEMP.available = new_list
			require('codemp.window').update()
		end)
	end)
end

---@param ws Workspace
local function register_cursor_callback(ws)
	local controller = ws.cursor
	local once = true
	vim.api.nvim_create_autocmd({"CursorMoved", "CursorMovedI", "ModeChanged"}, {
		group = vim.api.nvim_create_augroup("codemp-workspace-" .. ws.name, { clear = true }),
		callback = function (_)
			local cur = utils.cursor.position()
			local buf = vim.api.nvim_get_current_buf()
			if buffers.map[buf] ~= nil then
				once = true
				local _ = controller:send({
					buffer = buffers.map[buf],
					start = cur[1],
					finish = cur[2],
				}) -- no need to await here
			else -- set ourselves "away" only once
				if once then
					local _ = controller:send({
						buffer = "",
						start = { 0, 0 },
						finish = { 0, 0 },
					}) -- no need to await here
				end
				once = false
			end
		end
	})
end

---@param ws Workspace
local function register_cursor_handler(ws)
	local controller = ws.cursor
	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
			local user = event.user -- do it on separate line so language server understands that it wont be nil
			if user ~= nil then
				if user_hl[user] == nil then
					user_hl[user] = {
						ns = vim.api.nvim_create_namespace("codemp-cursor-" .. event.user),
						hi = utils.color(event.user),
						pos = { 0, 0 },
					}
				end
				user_hl[user].pos = event.start
				local old_buffer = buffers.users[event.user]
				if old_buffer ~= nil then
					local old_buffer_id = buffers.map_rev[old_buffer]
					if old_buffer_id ~= nil then
						vim.api.nvim_buf_clear_namespace(old_buffer_id, user_hl[event.user].ns, 0, -1)
					end
				end
				buffers.users[event.user] = event.buffer
				local buffer_id = buffers.map_rev[event.buffer]
				if buffer_id ~= nil then
					vim.api.nvim_buf_set_extmark(
						buffer_id,
						user_hl[event.user].ns,
						event.start[1],
						event.start[2],
						{
							end_col = event.finish[1],
							end_row = event.finish[2],
							hl_group = user_hl[event.user].hi,
							hl_eol = true,
							virt_text_pos = "overlay",
							virt_text = {
								{ event.user, "InlayHint" }
							},
						}
					)
					utils.multiline_highlight(
						buffer_id,
						user_hl[event.user].ns,
						user_hl[event.user].hi,
						event.start,
						event.finish
					)
				end
				if old_buffer ~= event.buffer then
					require('codemp.window').update() -- redraw user positions
				end
			end
		end
	end))
	controller:callback(function (_controller) async:send() end)
end

---@param workspace string workspace name to join
---join a workspace and register event handlers
local function join(workspace)
	print(" <> joining workspace " .. workspace .. " ...")
	CODEMP.client:join_workspace(workspace):and_then(function (ws)
		print(" >< joined workspace " .. ws.name)
		register_cursor_callback(ws)
		register_cursor_handler(ws)
		CODEMP.workspace = ws
		require('codemp.window').update()
		utils.poller(
			function() return ws:event() end,
			function(event)
				if event.type == "leave" then
					if buffers.users[event.value] ~= nil then
						local buf_name = buffers.users[event.value]
						local buf_id = buffers.map_rev[buf_name]
						if buf_id ~= nil then
							vim.api.nvim_buf_clear_namespace(buf_id, user_hl[event.value].ns, 0, -1)
						end
						buffers.users[event.value] = nil
						user_hl[event.value] = nil
					end
				elseif event.type == "join" then
					buffers.users[event.value] = ""
					user_hl[event.value] = {
						ns = vim.api.nvim_create_namespace("codemp-cursor-" .. event.value),
						hi = utils.color(event.value),
						pos = { 0, 0 },
					}
				end
				require('codemp.window').update()
			end
		)
	end)
end

local function leave()
	CODEMP.client:leave_workspace(CODEMP.workspace.name)
	print(" -- left workspace")
	CODEMP.workspace = nil
	require('codemp.window').update()
end

return {
	join = join,
	leave = leave,
	map = user_hl,
	list = fetch_workspaces_list,
}