import html/dom
import html/tags
import js/javascript
import types/blob
import types/formdata
import utils/twtstr

proc constructEntryList*(form: HTMLFormElement, submitter: Element = nil,
    encoding: string = ""): Option[seq[FormDataEntry]]

proc newFormData*(form: HTMLFormElement = nil,
    submitter: HTMLElement = nil): FormData {.jserr, jsctor.} =
  let this = FormData()
  if form != nil:
    if submitter != nil:
      if not submitter.isSubmitButton():
        JS_ERR JS_TypeError, "Submitter must be a submit button"
      if FormAssociatedElement(submitter).form != form:
        #TODO should be DOMException
        JS_ERR JS_TypeError, "InvalidStateError"
    this.entries = constructEntryList(form, submitter).get(@[])
  return this

#TODO as jsfunc
proc append*(this: FormData, name: string, svalue: string, filename = "") =
  this.entries.add(FormDataEntry(
    name: name,
    isstr: true,
    svalue: svalue,
    filename: filename
  ))

proc append*(this: FormData, name: string, value: Blob,
    filename = "blob") =
  this.entries.add(FormDataEntry(
    name: name,
    isstr: false,
    value: value,
    filename: filename
  ))

#TODO hack
proc append(ctx: JSContext, this: FormData, name: string, value: JSValue,
    filename = none(string)) {.jsfunc.} =
  let blob = fromJS[Blob](ctx, value)
  if blob.isSome:
    let filename = if filename.isSome:
      filename.get
    elif blob.get of WebFile:
      WebFile(blob.get).name
    else:
      "blob"
    this.append(name, blob.get, filename)
  else:
    let s = fromJS[string](ctx, value)
    # toString should never fail (?)
    this.append(name, s.get, filename.get(""))

proc delete(this: FormData, name: string) {.jsfunc.} =
  for i in countdown(this.entries.high, 0):
    if this.entries[i].name == name:
      this.entries.delete(i)

proc get(ctx: JSContext, this: FormData, name: string): JSValue {.jsfunc.} =
  for entry in this.entries:
    if entry.name == name:
      if entry.isstr:
        return toJS(ctx, entry.svalue)
      else:
        return toJS(ctx, entry.value)
  return JS_NULL

proc getAll(this: FormData, name: string): seq[Blob] {.jsfunc.} =
  for entry in this.entries:
    if entry.name == name:
      result.add(entry.value) # may be null

proc add(list: var seq[FormDataEntry], entry: tuple[name, value: string]) =
  list.add(FormDataEntry(
    name: entry.name,
    isstr: true,
    svalue: entry.value
  ))

func toNameValuePairs*(list: seq[FormDataEntry]):
    seq[tuple[name, value: string]] =
  for entry in list:
    if entry.isstr:
      result.add((entry.name, entry.svalue))
    else:
      result.add((entry.name, entry.name))

# https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#constructing-the-form-data-set
proc constructEntryList*(form: HTMLFormElement, submitter: Element = nil,
    encoding: string = ""): Option[seq[FormDataEntry]] =
  if form.constructingentrylist:
    return
  form.constructingentrylist = true

  var entrylist: seq[FormDataEntry]
  for field in form.controls:
    if field.findAncestor({TAG_DATALIST}) != nil or
        field.attrb("disabled") or
        field.isButton() and Element(field) != submitter:
      continue

    if field.tagType == TAG_INPUT:
      let field = HTMLInputElement(field)
      if field.inputType == INPUT_IMAGE:
        let name = if field.attr("name") != "":
          field.attr("name") & '.'
        else:
          ""
        entrylist.add((name & 'x', $field.xcoord))
        entrylist.add((name & 'y', $field.ycoord))
        continue

    #TODO custom elements

    let name = field.attr("name")

    if name == "":
      continue

    if field.tagType == TAG_SELECT:
      let field = HTMLSelectElement(field)
      for option in field.options:
        if option.selected or option.disabled:
          entrylist.add((name, option.value))
    elif field.tagType == TAG_INPUT and HTMLInputElement(field).inputType in {INPUT_CHECKBOX, INPUT_RADIO}:
      let value = if field.attr("value") != "":
        field.attr("value")
      else:
        "on"
      entrylist.add((name, value))
    elif field.tagType == TAG_INPUT and HTMLInputElement(field).inputType == INPUT_FILE:
      #TODO file
      discard
    elif field.tagType == TAG_INPUT and HTMLInputElement(field).inputType == INPUT_HIDDEN and name.equalsIgnoreCase("_charset_"):
      let charset = if encoding != "":
        encoding
      else:
        "UTF-8"
      entrylist.add((name, charset))
    else:
      case field.tagType
      of TAG_INPUT:
        entrylist.add((name, HTMLInputElement(field).value))
      of TAG_BUTTON:
        entrylist.add((name, HTMLButtonElement(field).value))
      of TAG_TEXTAREA:
        entrylist.add((name, HTMLTextAreaElement(field).value))
      else: assert false, "Tag type " & $field.tagType & " not accounted for in constructEntryList"
    if field.tagType == TAG_TEXTAREA or
        field.tagType == TAG_INPUT and HTMLInputElement(field).inputType in {INPUT_TEXT, INPUT_SEARCH}:
      if field.attr("dirname") != "":
        let dirname = field.attr("dirname")
        let dir = "ltr" #TODO bidi
        entrylist.add((dirname, dir))

  form.constructingentrylist = false
  return some(entrylist)

proc addFormDataModule*(ctx: JSContext) =
  ctx.registerType(FormData)