let s:supports_vt = exists('*nvim_buf_set_virtual_text')
let s:enabled = 0
let s:severity_sign_names_mapping = {
    \ 1: 'LspError',
    \ 2: 'LspWarning',
    \ 3: 'LspInformation',
    \ 4: 'LspHint',
    \ }

if !hlexists('LspErrorText')
    highlight link LspErrorText Error
endif

if !hlexists('LspWarningText')
    highlight link LspWarningText Todo
endif

if !hlexists('LspInformationText')
    highlight link LspInformationText Normal
endif

if !hlexists('LspHintText')
    highlight link LspHintText Normal
endif

function! lsp#ui#vim#virtual#enable() abort
    if !s:supports_vt
        call lsp#log('vim-lsp virtual text requires neovim')
        return
    endif
    if !s:enabled
        let s:enabled = 1
        call lsp#log('vim-lsp virtual text enabled')
    endif
endfunction

function! lsp#ui#vim#virtual#disable() abort
    if s:enabled
        for l:ns in keys(nvim_get_namespaces())
            call s:clear_all_virtual(l:ns)
        endfor

        let s:enabled = 0
        call lsp#log('vim-lsp virtual text disabled')
    endif
endfunction

function! s:get_virtual_group(name) abort
    return nvim_create_namespace('vim_lsp_'.a:name)
endfunction

function! s:clear_all_virtual(ns) abort
    if a:ns =~# '^vim_lsp_'
        let l:ns = s:get_virtual_group(a:ns)
        for l:bufnr in nvim_list_bufs()
            call nvim_buf_clear_namespace(l:bufnr, l:ns, 0, -1)
        endfor
    endif
endfunction

function! s:clear_virtual(server_name, path) abort
    if !s:supports_vt | return | endif
    if !s:enabled | return | endif

    let l:ns = s:get_virtual_group(a:server_name)
    let l:bufnr = bufnr(a:path)

    call nvim_buf_clear_namespace(l:bufnr, l:ns, 0, -1)
endfunction

function! s:place_virtual(server_name, path, diagnostics) abort
    if !s:supports_vt | return | endif
    if !s:enabled | return | endif

    let l:ns = s:get_virtual_group(a:server_name)
    let l:bufnr = bufnr(a:path)

    if !empty(a:diagnostics) && bufnr(a:path) >= 0
        for l:item in a:diagnostics
            let l:line = l:item['range']['start']['line']

            let l:name = get(s:severity_sign_names_mapping, l:item['severity'], 'LspError')
            let l:hl_name = l:name . 'Text'
            call nvim_buf_set_virtual_text(l:bufnr, l:ns, l:line,
                        \ [[g:lsp_virtual_text_prefix . l:item['message'], l:hl_name]], {})
        endfor
    endif
endfunction

function! lsp#ui#vim#virtual#set(server_name, data) abort
    if !s:supports_vt | return | endif
    if !s:enabled | return | endif

    if lsp#client#is_error(a:data['response'])
        return
    endif

    let l:uri = a:data['response']['params']['uri']
    let l:diagnostics = a:data['response']['params']['diagnostics']

    let l:path = lsp#utils#uri_to_path(l:uri)

    " will always replace existing set
    call s:clear_virtual(a:server_name, l:path)
    call s:place_virtual(a:server_name, l:path, l:diagnostics)
endfunction