Plug 'prabirshrestha/asyncomplete.vim'

inoremap <expr> <Tab>   pumvisible() ? "\<C-n>" : "\<Tab>"
inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"
inoremap <expr> <cr>    pumvisible() ? asyncomplete#close_popup() : "\<cr>"

inoremap <expr> <cr> pumvisible() ? asyncomplete#close_popup() . "\<cr>" : "\<cr>"

imap <c-space> <Plug>(asyncomplete_force_refresh)
" For Vim 8 (<c-@> corresponds to <c-space>):
" imap <c-@> <Plug>(asyncomplete_force_refresh)

let g:asyncomplete_auto_popup = 0

let g:asyncomplete_auto_popup = 0

function! s:check_back_space() abort
    let col = col('.') - 1
    return !col || getline('.')[col - 1]  =~ '\s'
endfunction

inoremap <silent><expr> <TAB>
  \ pumvisible() ? "\<C-n>" :
  \ <SID>check_back_space() ? "\<TAB>" :
  \ asyncomplete#force_refresh()
inoremap <expr><S-TAB> pumvisible() ? "\<C-p>" : "\<C-h>"

" allow modifying the completeopt variable, or it will
" be overridden all the time
let g:asyncomplete_auto_completeopt = 0

set completeopt=menuone,noinsert,noselect,preview

autocmd! CompleteDone * if pumvisible() == 0 | pclose | endif

Plug 'prabirshrestha/asyncomplete.vim'
Plug 'prabirshrestha/vim-lsp'
Plug 'prabirshrestha/asyncomplete-lsp.vim'

if executable('pyls')
    " pip install python-language-server
    au User lsp_setup call lsp#register_server({
        \ 'name': 'pyls',
        \ 'cmd': {server_info->['pyls']},
        \ 'allowlist': ['python'],
        \ })
endif

function s:completor(opt, ctx)
  call mylanguage#get_async_completions({candidates, startcol -> asyncomplete#complete(a:opt['name'], a:ctx, startcol, candidates) })
endfunction

au User asyncomplete_setup call asyncomplete#register_source({
    \ 'name': 'mylanguage',
    \ 'allowlist': ['*'],
    \ 'completor': function('s:completor'),
    \ })

function! s:js_completor(opt, ctx) abort
    let l:col = a:ctx['col']
    let l:typed = a:ctx['typed']

    let l:kw = matchstr(l:typed, '\v\S $')
    let l:kwlen = len(l:kw)

    let l:startcol = l:col - l:kwlen

    let l:matches = [
        \ "do", "if", "in", "for", "let", "new", "try", "var", "case", "else", "enum", "eval", "null", "this", "true",
        \ "void", "with", "await", "break", "catch", "class", "const", "false", "super", "throw", "while", "yield",
        \ "delete", "export", "import", "public", "return", "static", "switch", "typeof", "default", "extends",
        \ "finally", "package", "private", "continue", "debugger", "function", "arguments", "interface", "protected",
        \ "implements", "instanceof"
        \ ]

    call asyncomplete#complete(a:opt['name'], a:ctx, l:startcol, l:matches)
endfunction

au User asyncomplete_setup call asyncomplete#register_source({
    \ 'name': 'javascript',
    \ 'allowlist': ['javascript'],
    \ 'completor': function('s:js_completor'),
    \ })

call timer_start(2000, {timer-> asyncomplete#complete(a:opt['name'], a:ctx, l:startcol, l:matches)})

call asyncomplete#complete(a:opt['name'], a:ctx, l:startcol, l:matches, 1)