Repository: neovim/neovim
File: runtime/lua/vim/net.lua (Lua)

Code before:
local M = {}

--- Makes an HTTP GET request to the given URL.
--- Can either return the body or save it to a file.
---
--- @param url string The URL to fetch.
--- @param opts? table Optional parameters:
---   - verbose (boolean|nil): Enables curl verbose output.
---   - retry   (integer|nil): Number of retries on transient failures (default: 3).
---   - output  (string|nil): If set, path to save response body instead of returning it.
--- @param on_exit? fun(err?: string, content?: string)
---   - Async mode if provided: always called as
---       - on_exit(err)           on failure
---       - on_exit(nil, content)  on success; if `opts.output` is set, `content` is nil
---   - Sync mode if omitted: returns
---       - (nil, err)             on failure
---       - (true, nil)            on success when `opts.output` is set
---       - (content, nil)         on success when returning the body
function M.request(url, opts, on_exit)
  vim.validate({
    url = { url, 'string' },
    opts = { opts, 'table', true },
    on_exit = { on_exit, 'function', true },
  })

  opts = opts or {}
  local retry = opts.retry or 3

  -- Build curl command
  local args = { 'curl' }
  if opts.verbose then
    table.insert(args, '--verbose')
  else
    vim.list_extend(args, { '--silent', '--show-error', '--fail' })
  end
  table.insert(args, '--location')
  table.insert(args, '--retry')
  table.insert(args, tostring(retry))

  if opts.output then
    table.insert(args, '--output')
    table.insert(args, opts.output)
  end

Review comment (suggestion):
need a `@return` tag. maybe helpful to look at `vim.system` example https://github.com/neovim/neovim/blob/e518666f1db110abcfc899e1227da949998cdd82/runtime/lua/vim/_editor.lua#L130

Code after:
local M = {}

--- Makes an HTTP GET request to the given URL (asynchronous).
---
--- This function operates in one mode:
---   - Asynchronous (non-blocking): Returns immediately and passes the response object to the
---   provided `on_response` handler on completetion.
---
--- @param url string The URL for the request.
--- @param opts? table Optional parameters:
---   - `verbose` (boolean|nil): Enables verbose output.
---   - `retry`   (integer|nil): Number of retries on transient failures (default: 3).
---   - `outpath`  (string|nil): File path to save the response body to. If set, the `body` value in the Response Object will be `true` instead of the response body.
--- @param on_response fun(err?: string, response?: { body: string|boolean }) Callback invoked on request
--- completetion. The `body` field in the response object contains the raw response data (text or binary).
--- Called with (err, nil) on failure, or (nil, { body = string|boolean }) on success.
function M.request(url, opts, on_response)
  vim.validate({
    url = { url, 'string' },
    opts = { opts, 'table', true },
    on_response = { on_response, 'function' },
  })

  opts = opts or {}
  local retry = opts.retry or 3

  -- Build curl command
  local args = { 'curl' }
  if opts.verbose then
    table.insert(args, '--verbose')
  else
    vim.list_extend(args, { '--silent', '--show-error', '--fail' })
  end
  vim.list_extend(args, { '--location', '--retry', tostring(retry) })

  if opts.outpath then
    vim.list_extend(args, { '--output', opts.outpath })
  end

  table.insert(args, url)

  local function on_exit(res)
    local err_msg = nil