local lsp = vim.lsp

local function virtual_text_document_handler(uri, res, client)
  if not res then
    return nil
  end

  local lines = vim.split(res.result, '\n')
  local bufnr = vim.uri_to_bufnr(uri)

  local current_buf = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
  if #current_buf ~= 0 then
    return nil
  end

  vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, lines)
  vim.api.nvim_set_option_value('readonly', true, { buf = bufnr })
  vim.api.nvim_set_option_value('modified', false, { buf = bufnr })
  vim.api.nvim_set_option_value('modifiable', false, { buf = bufnr })
  lsp.buf_attach_client(bufnr, client.id)
end

local function virtual_text_document(uri, client)
  local params = {
    textDocument = {
      uri = uri,
    },
  }
  local result = client:request_sync('deno/virtualTextDocument', params)
  virtual_text_document_handler(uri, result, client)
end

local function denols_handler(err, result, ctx, config)
  if not result or vim.tbl_isempty(result) then
    return nil
  end

  local client = vim.lsp.get_client_by_id(ctx.client_id)
  for _, res in pairs(result) do
    local uri = res.uri or res.targetUri
    if uri:match '^deno:' then
      if client then
        virtual_text_document(uri, client)
      end
      res['uri'] = uri
      res['targetUri'] = uri
    end
  end

  lsp.handlers[ctx.method](err, result, ctx, config)
end

local function buf_cache(bufnr, client)
  local params = {
    command = 'deno.cache',
    arguments = { {}, vim.uri_from_bufnr(bufnr) },
  }
  client:request('workspace/executeCommand', params, function(err, _result, ctx)
    if err then
      local uri = ctx.params.arguments[2]
      vim.notify('cache command failed for ' .. vim.uri_to_fname(uri), vim.log.levels.ERROR)
    end
  end, bufnr)
end

return {
  cmd = { 'deno', 'lsp' },
  cmd_env = { NO_COLOR = true },
  filetypes = {
    'javascript',
    'javascriptreact',
    'typescript',
    'typescriptreact',
    'json',
    'jsonc',
    'markdown',
  },
  root_markers = { 'deno.json', 'deno.jsonc' },
  workspace_required = true,
  settings = {
    deno = {
      enable = true,
      suggest = {
        imports = {
          hosts = {
            ['https://deno.land'] = true,
          },
        },
      },
    },
  },
  handlers = {
    ['textDocument/definition'] = denols_handler,
    ['textDocument/typeDefinition'] = denols_handler,
    ['textDocument/references'] = denols_handler,
  },
  on_attach = function(client, bufnr)
    local user_command = require 'std.user_command'
    user_command.buffer(bufnr).DenolsCache 'Cache a module and all of its dependencies.' { nargs = 0 } (function()
      local clients = vim.lsp.get_clients { bufnr = 0, name = 'denols' }
      if #clients > 0 then
        buf_cache(0, clients[#clients])
      end
    end)
  end,
  commands = {
    DenolsCache = {
      function()
        local clients = vim.lsp.get_clients { bufnr = 0, name = 'denols' }
        if #clients > 0 then
          buf_cache(0, clients[#clients])
        end
      end,
      description = 'Cache a module and all of its dependencies.',
    },
  },
  _test = {
    denols_handler = denols_handler,
    buf_cache = buf_cache,
  },
}