Add module jsfetch (#12531)

* Add module jsfetch for fetch support for JavaScript target https://developer.mozilla.org/docs/Web/API/Fetch_API

* Update lib/std/jsheaders.nim

* Update lib/std/jsformdata.nim

* Update lib/std/jsfetch.nim

Co-authored-by: Timothee Cour <timothee.cour2@gmail.com>
Co-authored-by: flywind <xzsflywind@gmail.com>

1 files changed, 198 insertions, 0 deletions

diff --git a/lib/std/jsfetch.nim b/lib/std/jsfetch.nim
new file mode 100644
index 000000000..2ff894985
--- /dev/null
+++ b/lib/std/jsfetch.nim
@@ -0,0 +1,198 @@
+## - Fetch for the JavaScript target: https://developer.mozilla.org/docs/Web/API/Fetch_API
+## .. Note:: jsfetch is Experimental. jsfetch module requires `-d:nimExperimentalJsfetch`
+when not defined(js):
+  {.fatal: "Module jsfetch is designed to be used with the JavaScript backend.".}
+
+when defined(nimExperimentalJsfetch) or defined(nimdoc):
+  import std/[asyncjs, jsheaders, jsformdata]
+  from std/httpcore import HttpMethod
+  from std/jsffi import JsObject
+
+  type
+    FetchOptions* = ref object of JsRoot  ## Options for Fetch API.
+      keepalive*: bool
+      metod* {.importjs: "method".}: cstring
+      body*, integrity*, referrer*, mode*, credentials*, cache*, redirect*, referrerPolicy*: cstring
+
+    FetchModes* = enum  ## Mode options.
+      fmCors = "cors"
+      fmNoCors = "no-cors"
+      fmSameOrigin = "same-origin"
+
+    FetchCredentials* = enum  ## Credential options. See https://developer.mozilla.org/en-US/docs/Web/API/Request/credentials
+      fcInclude = "include"
+      fcSameOrigin = "same-origin"
+      fcOmit = "omit"
+
+    FetchCaches* = enum  ## https://developer.mozilla.org/docs/Web/API/Request/cache
+      fchDefault = "default"
+      fchNoStore = "no-store"
+      fchReload = "reload"
+      fchNoCache = "no-cache"
+      fchForceCache = "force-cache"
+
+    FetchRedirects* = enum  ## Redirects options.
+      frFollow = "follow"
+      frError = "error"
+      frManual = "manual"
+
+    FetchReferrerPolicies* = enum  ## Referrer Policy options.
+      frpNoReferrer = "no-referrer"
+      frpNoReferrerWhenDowngrade = "no-referrer-when-downgrade"
+      frpOrigin = "origin"
+      frpOriginWhenCrossOrigin = "origin-when-cross-origin"
+      frpUnsafeUrl = "unsafe-url"
+
+    Body* = ref object of JsRoot  ## https://developer.mozilla.org/en-US/docs/Web/API/Body
+      bodyUsed*: bool
+
+    Response* = ref object of JsRoot  ## https://developer.mozilla.org/en-US/docs/Web/API/Response
+      bodyUsed*, ok*, redirected*: bool
+      typ* {.importjs: "type".}: cstring
+      url*, statusText*: cstring
+      status*: cint
+      headers*: Headers
+      body*: Body
+
+    Request* = ref object of JsRoot  ## https://developer.mozilla.org/en-US/docs/Web/API/Request
+      bodyUsed*, ok*, redirected*: bool
+      typ* {.importjs: "type".}: cstring
+      url*, statusText*: cstring
+      status*: cint
+      headers*: Headers
+      body*: Body
+
+
+  func newResponse*(body: cstring | FormData): Response {.importjs: "(new Response(#))".}
+    ## Constructor for `Response`. This does *not* call `fetch()`. Same as `new Response()`.
+
+  func newRequest*(url: cstring): Request {.importjs: "(new Request(#))".}
+    ## Constructor for `Request`. This does *not* call `fetch()`. Same as `new Request()`.
+
+  func clone*(self: Response | Request): Response {.importjs: "#.$1()".}
+    ## https://developer.mozilla.org/en-US/docs/Web/API/Response/clone
+
+  proc text*(self: Response): Future[cstring] {.importjs: "#.$1()".}
+    ## https://developer.mozilla.org/en-US/docs/Web/API/Body/text
+
+  proc json*(self: Response): Future[JsObject] {.importjs: "#.$1()".}
+    ## https://developer.mozilla.org/en-US/docs/Web/API/Body/json
+
+  proc formData*(self: Body): Future[FormData] {.importjs: "#.$1()".}
+    ## https://developer.mozilla.org/en-US/docs/Web/API/Body/formData
+
+  proc unsafeNewFetchOptions*(metod, body, mode, credentials, cache, referrerPolicy: cstring;
+      keepalive: bool; redirect = "follow".cstring; referrer = "client".cstring; integrity = "".cstring): FetchOptions {.importjs:
+      "{method: #, body: #, mode: #, credentials: #, cache: #, referrerPolicy: #, keepalive: #, redirect: #, referrer: #, integrity: #}".}
+    ## .. Warning:: Unsafe `newfetchOptions`.
+
+  func newfetchOptions*(metod: HttpMethod; body: cstring;
+      mode: FetchModes; credentials: FetchCredentials; cache: FetchCaches; referrerPolicy: FetchReferrerPolicies;
+      keepalive: bool; redirect = frFollow; referrer = "client".cstring; integrity = "".cstring): FetchOptions =
+    ## Constructor for `FetchOptions`.
+    result = FetchOptions(
+      body: body, mode: $mode, credentials: $credentials, cache: $cache, referrerPolicy: $referrerPolicy,
+      keepalive: keepalive, redirect: $redirect, referrer: referrer, integrity: integrity,
+      metod: (case metod
+        of HttpHead:   "HEAD".cstring
+        of HttpGet:    "GET".cstring
+        of HttpPost:   "POST".cstring
+        of HttpPut:    "PUT".cstring
+        of HttpDelete: "DELETE".cstring
+        of HttpPatch:  "PATCH".cstring
+        else:          "GET".cstring
+      )
+    )
+
+  proc fetch*(url: cstring | Request): Future[Response] {.importjs: "$1(#)".}
+    ## `fetch()` API, simple `GET` only, returns a `Future[Response]`.
+
+  proc fetch*(url: cstring | Request; options: FetchOptions): Future[Response] {.importjs: "$1(#, #)".}
+    ## `fetch()` API that takes a `FetchOptions`, returns a `Future[Response]`.
+
+  func toCstring*(self: Request | Response | Body | FetchOptions): cstring {.importjs: "JSON.stringify(#)".}
+
+  func `$`*(self: Request | Response | Body | FetchOptions): string = $toCstring(self)
+
+
+runnableExamples("-d:nimExperimentalJsfetch -r:off"):
+  import std/[asyncjs, jsconsole, jsheaders, jsformdata]
+  from std/httpcore import HttpMethod
+  from std/jsffi import JsObject
+  from std/sugar import `=>`
+
+  block:
+    let options0: FetchOptions = unsafeNewFetchOptions(
+      metod = "POST".cstring,
+      body = """{"key": "value"}""".cstring,
+      mode = "no-cors".cstring,
+      credentials = "omit".cstring,
+      cache = "no-cache".cstring,
+      referrerPolicy = "no-referrer".cstring,
+      keepalive = false,
+      redirect = "follow".cstring,
+      referrer = "client".cstring,
+      integrity = "".cstring
+    )
+    assert options0.keepalive == false
+    assert options0.metod == "POST".cstring
+    assert options0.body == """{"key": "value"}""".cstring
+    assert options0.mode == "no-cors".cstring
+    assert options0.credentials == "omit".cstring
+    assert options0.cache == "no-cache".cstring
+    assert options0.referrerPolicy == "no-referrer".cstring
+    assert options0.redirect == "follow".cstring
+    assert options0.referrer == "client".cstring
+    assert options0.integrity == "".cstring
+
+  block:
+    let options1: FetchOptions = newFetchOptions(
+      metod =  HttpPost,
+      body = """{"key": "value"}""".cstring,
+      mode = fmNoCors,
+      credentials = fcOmit,
+      cache = fchNoCache,
+      referrerPolicy = frpNoReferrer,
+      keepalive = false,
+      redirect = frFollow,
+      referrer = "client".cstring,
+      integrity = "".cstring
+    )
+    assert options1.keepalive == false
+    assert options1.metod == $HttpPost
+    assert options1.body == """{"key": "value"}""".cstring
+    assert options1.mode == $fmNoCors
+    assert options1.credentials == $fcOmit
+    assert options1.cache == $fchNoCache
+    assert options1.referrerPolicy == $frpNoReferrer
+    assert options1.redirect == $frFollow
+    assert options1.referrer == "client".cstring
+    assert options1.integrity == "".cstring
+
+  block:
+    let response: Response = newResponse(body = "-. .. --".cstring)
+    let request: Request = newRequest(url = "http://nim-lang.org".cstring)
+
+  if not defined(nodejs):
+    block:
+      proc doFetch(): Future[Response] {.async.} =
+        fetch "https://httpbin.org/get".cstring
+
+      proc example() {.async.} =
+        let response: Response = await doFetch()
+        assert response.ok
+        assert response.status == 200.cint
+        assert response.headers is Headers
+        assert response.body is Body
+
+      discard example()
+
+    when defined(nimExperimentalAsyncjsThen):
+      block:
+        proc example2 {.async.} =
+          await fetch("https://api.github.com/users/torvalds".cstring)
+            .then((response: Response) => response.json())
+            .then((json: JsObject) => console.log(json))
+            .catch((err: Error) => console.log("Request Failed", err))
+
+        discard example2()