Help with cmp completion + context input

[paulodiovani]

Since v3 does not include the [cmp integration])https://github.com/CopilotC-Nvim/CopilotChat.nvim/blob/v2.16.0/lua/CopilotChat/integrations/cmp.lua anymore, I created my own complete source as below, but I also wanted to use the same <C-Space> mapping to autocomplete or prompt #context options.

e.g.

#files:<C-Space>

Setting <C-Space> in the mappings does not work, neither does <C-@>.
e.g.

copilot_chat.setup({
  chat_autocomplete = false,
  mappings = {
    complete = {
      insert = '<C-Space>',
    },
 -- ...

It would be nice to be able to use cmp for some of the contexts, such as #buffers:, but I didn't managed to do that either.

CMP Complete source for CopilotChat

-- disable original autocomplete
copilot_chat.setup({
  chat_autocomplete = false,
})

local copilot_chat = require('CopilotChat')
local cmp = require('cmp')

-- Configure cmp completion
local source = {}

function source:get_trigger_characters()
  local info = copilot_chat.complete_info()
  return info['triggers']
end

function source:get_keyword_pattern()
  local info = copilot_chat.complete_info()
  return info['pattern']
end

function source:complete(_, callback)
  local items = copilot_chat.complete_items() or {}
  local completion_kinds = vim.lsp.protocol.CompletionItemKind

  local mapped_items = vim.tbl_map(function(item)
    return {
      label = item.word,
      kind = completion_kinds[item.kind] or completion_kinds.Text,
      detail = item.info,
      documentation = item.menu,
    }
  end, items)

  callback(mapped_items)
end

function source:execute(completion_item, callback)
  callback(completion_item)
end

cmp.register_source('copilot_chat', source)

cmp.setup.filetype('copilot-chat', {
  completion = {
    autocomplete = false,
    completeopt = table.concat(vim.opt.completeopt:get(), ","),
  },
  sources = {
    { name = 'copilot_chat' },
  },
})

Note: this works for current main branch, more precisely for commit f84727f, but will not work for the v3.9.1 or older, because the complete_items() changed from receiving a callback to returning the list of items. If someone intend to copy these and use with a released version, you'll need to update the code. I'm using main because the version with the callback was much slower.