SoloVim/lua/user/cmp_gh_source.lua

local plenary_status_ok, plenary = pcall(require, "plenary.job")
if not plenary_status_ok then
	return
end

local source = {}

local enabled = true

source.new = function()
	local self = setmetatable({ cache = {} }, { __index = source })

	return self
end

source.complete = function(self, _, callback)
	if not enabled then
		return
	end

	local bufnr = vim.api.nvim_get_current_buf()

	-- This just makes sure that we only hit the GH API once per session.
	--
	-- You could remove this if you wanted, but this just makes it so we're
	-- good programming citizens.
	if not self.cache[bufnr] then
		plenary
			:new({
				-- Uses `gh` executable to request the issues from the remote repository.
				"gh",
				"issue",
				"list",
				"--limit",
				"1000",
				"--json",
				"title,number,body",
				on_exit = function(job)
					local result = job:result()
					local parser_status_ok, parsed = pcall(vim.json.decode, table.concat(result, ""))
					if not parser_status_ok then
						enabled = false
						return
					end

					local items = {}
					for _, gh_item in ipairs(parsed) do
						gh_item.body = string.gsub(gh_item.body or "", "\r", "")

						table.insert(items, {
							label = string.format("#%s", gh_item.number),
							documentation = {
								kind = "markdown",
								value = string.format("# %s\n\n%s", gh_item.title, gh_item.body),
							},
						})
					end

					callback({ items = items, isIncomplete = false })
					self.cache[bufnr] = items
				end,
			})
			:start()
	else
		callback({ items = self.cache[bufnr], isIncomplete = false })
	end
end

source.get_trigger_characters = function()
	return { "#" }
end

source.is_available = function()
	return vim.bo.filetype == "gitcommit"
end

require("cmp").register_source("gh_issues", source.new())