local cmd = vim.cmd
local fn = vim.fn

local M = {}

-- check if a variable is not empty nor nil
M.isNotEmpty = function(s)
	return s ~= nil and s ~= ""
end

-- toggle quickfixlist
M.toggle_qf = function()
	local windows = fn.getwininfo()
	local qf_exists = false
	for _, win in pairs(windows) do
		if win["quickfix"] == 1 then
			qf_exists = true
		end
	end
	if qf_exists == true then
		cmd("cclose")
		return
	end
	if M.isNotEmpty(fn.getqflist()) then
		cmd("copen")
	end
end

M.gitui_toggle = function()
	local Terminal = require("toggleterm.terminal").Terminal
	local gitui = Terminal:new({ cmd = "gitui", direction = "float", hidden = true })
	gitui:toggle()
end

-- move over a closing element in insert mode
M.escapePair = function()
	local closers = { ")", "]", "}", ">", "'", '"', "`", "," }
	local line = vim.api.nvim_get_current_line()
	local row, col = unpack(vim.api.nvim_win_get_cursor(0))
	local after = line:sub(col + 1, -1)
	local closer_col = #after + 1
	local closer_i = nil
	for i, closer in ipairs(closers) do
		local cur_index, _ = after:find(closer)
		if cur_index and (cur_index < closer_col) then
			closer_col = cur_index
			closer_i = i
		end
	end
	if closer_i then
		vim.api.nvim_win_set_cursor(0, { row, col + closer_col })
	else
		vim.api.nvim_win_set_cursor(0, { row, col + 1 })
	end
end

diagnostics_active = true -- must be global since this function is called in which.lua
-- toggle diagnostics line
M.toggle_diagnostics = function()
	diagnostics_active = not diagnostics_active
	if diagnostics_active then
		vim.diagnostic.show()
	else
		vim.diagnostic.hide()
	end
end

--@author kikito
---@see https://codereview.stackexchange.com/questions/268130/get-list-of-buffers-from-current-neovim-instance
function M.get_listed_buffers()
	local buffers = {}
	local len = 0
	for buffer = 1, vim.fn.bufnr("$") do
		if vim.fn.buflisted(buffer) == 1 then
			len = len + 1
			buffers[len] = buffer
		end
	end

	return buffers
end

function M.bufdelete(bufnum)
	require("bufdelete").bufdelete(bufnum, true)
end

-- when there is no buffer left show Alpha dashboard
vim.api.nvim_create_augroup("alpha_on_empty", { clear = true })
vim.api.nvim_create_autocmd("User", {
	pattern = "BDeletePre",
	group = "alpha_on_empty",
	callback = function(event)
		local found_non_empty_buffer = false
		local buffers = M.get_listed_buffers()

		for _, bufnr in ipairs(buffers) do
			if not found_non_empty_buffer then
				local name = vim.api.nvim_buf_get_name(bufnr)
				local ft = vim.api.nvim_buf_get_option(bufnr, "filetype")

				if bufnr ~= event.buf and name ~= "" and ft ~= "Alpha" then
					found_non_empty_buffer = true
				end
			end
		end

		if not found_non_empty_buffer then
			vim.cmd([[:Alpha]])
		end
	end,
})

function M.custom_lsp_attach(client, bufnr)
	-- disable formatting for LSP clients as this is handled by null-ls
	client.server_capabilities.document_formatting = false
	client.server_capabilities.document_range_formatting = false
	-- enable illuminate to intelligently highlight
	require("illuminate").on_attach(client)
	-- enable navic for displaying current code context
	require("nvim-navic").attach(client, bufnr)
	-- add lsp-signature TODO: do I need this?
	-- require("lsp_signature").on_attach(require("config.lsp-signature").cfg)
	-- add LSP specific key mappings to which key
	local wk = require("which-key")
	local default_options = { silent = true }
	wk.register({
		l = {
			name = "LSP",
			D = { "<cmd>lua vim.lsp.buf.declaration()<cr>", "Go To Declaration" },
			I = {
				"<cmd>lua vim.lsp.buf.implementation()<cr>",
				"Show implementations",
			},
			R = { "<cmd>lua vim.lsp.buf.rename()<cr>", "Rename" },
			a = { "<cmd>lua vim.lsp.buf.code_action()<cr>", "Code Action" },
			d = { "<cmd>lua vim.lsp.buf.definition()<cr>", "Go To Definition" },
			e = { "<cmd>Telescope diagnostics bufnr=0<cr>", "Document Diagnostics" },
			-- f = { "<cmd>lua vim.lsp.buf.formatting()<cr>", "Format" },
			i = { "<cmd>LspInfo<cr>", "Connected Language Servers" },
			k = { "<cmd>lua vim.lsp.buf.hover()<cr>", "Hover Commands" },
			l = { "<cmd>lua vim.diagnostic.open_float()<CR>", "Line diagnostics" },
			n = { "<cmd>lua vim.diagnostic.goto_next()<cr>", "Next Diagnostic" },
			p = { "<cmd>lua vim.diagnostic.goto_prev()<cr>", "Prev Diagnostic" },
			q = { "<cmd>lua vim.diagnostic.setloclist()<cr>", "Quickfix" },
			r = { "<cmd>lua vim.lsp.buf.references()<cr>", "References" },
			s = { "<cmd>Telescope lsp_document_symbols<cr>", "Document Symbols" },
			t = { "<cmd>lua vim.lsp.buf.type_definition()<cr>", "Type Definition" },
			w = {
				name = "workspaces",
				a = {
					"<cmd>lua vim.lsp.buf.add_workspace_folder()<cr>",
					"Add Workspace Folder",
				},
				d = { "<cmd>Telescope diagnostics<cr>", "Workspace Diagnostics" },
				l = {
					"<cmd>lua print(vim.inspect(vim.lsp.buf.list_workspace_folders()))<cr>",
					"List Workspace Folders",
				},
				r = {
					"<cmd>lua vim.lsp.buf.remove_workspace_folder()<cr>",
					"Remove Workspace Folder",
				},
				s = {
					"<cmd>Telescope lsp_dynamic_workspace_symbols<cr>",
					"Workspace Symbols",
				},
			},
		},
	}, { prefix = "<leader>", mode = "n", default_options })
end

return M