local cmp = require("cmp")
-- local cmp_buffer = require("cmp_buffer")

-- https://github.com/zbirenbaum/copilot-cmp#tab-completion-configuration-highly-recommended
local has_words_before = function()
	if vim.api.nvim_buf_get_option(0, "buftype") == "prompt" then
		return false
	end
	local line, col = unpack(vim.api.nvim_win_get_cursor(0))
	return col ~= 0 and vim.api.nvim_buf_get_text(0, line - 1, 0, line - 1, col, {})[1]:match("^%s*$") == nil
end

cmp.setup({
	completion = {
		completeopt = "menu,menuone,noinsert,noselect",
	},
	snippet = {
		expand = function(args)
			vim.fn["vsnip#anonymous"](args.body)
		end,
	},
	preselect = cmp.PreselectMode.None,
	window = {
		completion = cmp.config.window.bordered(),
		documentation = cmp.config.window.bordered(),
	},
	mapping = cmp.mapping.preset.insert({
		["<C-u>"] = cmp.mapping.scroll_docs(-4),
		["<C-d>"] = cmp.mapping.scroll_docs(4),
		["<C-e>"] = cmp.mapping.close(),
		["C-y"] = cmp.mapping.confirm({ select = true, behaviour = cmp.ConfirmBehavior.Replace }),
		["<CR>"] = cmp.mapping.confirm({ select = true, behaviour = cmp.ConfirmBehavior.Replace }),
		-- https://github.com/hrsh7th/nvim-cmp/wiki/Example-mappings#super-tab-like-mapping
		["<C-Space>"] = cmp.mapping.confirm({
			behavior = cmp.ConfirmBehavior.Insert,
			select = true,
		}),
		["<Tab>"] = vim.schedule_wrap(function(fallback)
			if cmp.visible() and has_words_before() then
				cmp.select_next_item({ behavior = cmp.SelectBehavior.Select })
			else
				fallback()
			end
		end),
		["<S-Tab>"] = function(fallback)
			if not cmp.select_prev_item() then
				if vim.bo.buftype ~= "prompt" and has_words_before() then
					cmp.complete()
				else
					fallback()
				end
			end
		end,
	}),
	sources = cmp.config.sources({
		{ name = "copilot", keyword_length = 0 },
		{ name = "nvim_lsp", keyword_length = 3 },
		{
			name = "buffer",
			option = {
				get_bufnrs = function()
					return vim.api.nvim_list_bufs()
				end,
			},
		},
		{ name = "path" },
		{ name = "calc" },
	}),
	sorting = {
		comparators = {
			cmp.config.compare.exact,
			require("copilot_cmp.comparators").prioritize,
			cmp.config.compare.offset,
			cmp.config.compare.score,
			cmp.config.compare.recently_used,
			cmp.config.compare.locality,
			cmp.config.compare.kind,
			cmp.config.compare.sort_text,
			cmp.config.compare.length,
			cmp.config.compare.order,
		},
	},
	-- https://github.com/hrsh7th/nvim-cmp/wiki/Advanced-techniques#disabling-completion-in-certain-contexts-such-as-comments
	enabled = function()
		local context = require("cmp.config.context")
		if vim.api.nvim_get_mode().mode == "c" then
			return true
		end
		return not context.in_treesitter_capture("comment") and not context.in_syntax_group("Comment")
	end,
	formatting = {
		fields = { "kind", "abbr", "menu" },
	},
	experimental = {
		ghost_text = true,
	},
})