// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/autofill/content/renderer/form_cache.h"

#include "base/logging.h"
#include "base/strings/utf_string_conversions.h"
#include "components/autofill/content/renderer/form_autofill_util.h"
#include "components/autofill/core/common/autofill_constants.h"
#include "components/autofill/core/common/form_data.h"
#include "components/autofill/core/common/form_data_predictions.h"
#include "components/autofill/core/common/form_field_data.h"
#include "components/autofill/core/common/form_field_data_predictions.h"
#include "grit/component_strings.h"
#include "third_party/WebKit/public/platform/WebString.h"
#include "third_party/WebKit/public/platform/WebVector.h"
#include "third_party/WebKit/public/web/WebDocument.h"
#include "third_party/WebKit/public/web/WebFormControlElement.h"
#include "third_party/WebKit/public/web/WebFormElement.h"
#include "third_party/WebKit/public/web/WebFrame.h"
#include "third_party/WebKit/public/web/WebInputElement.h"
#include "third_party/WebKit/public/web/WebSelectElement.h"
#include "third_party/WebKit/public/web/WebTextAreaElement.h"
#include "ui/base/l10n/l10n_util.h"

using blink::WebDocument;
using blink::WebFormControlElement;
using blink::WebFormElement;
using blink::WebFrame;
using blink::WebInputElement;
using blink::WebSelectElement;
using blink::WebTextAreaElement;
using blink::WebString;
using blink::WebVector;

namespace autofill {

// Helper function to discard state of various WebFormElements when they go out
// of web frame's scope. This is done to release memory that we no longer need
// to hold.
// K should inherit from WebFormControlElement as the function looks to extract
// WebFormElement for K.form().
template <class K, class V>
void RemoveOldElements(const WebFrame& frame, std::map<const K, V>* states) {
  std::vector<K> to_remove;
  for (typename std::map<const K, V>::const_iterator it = states->begin();
       it != states->end(); ++it) {
    WebFormElement form_element = it->first.form();
    if (form_element.isNull()) {
      to_remove.push_back(it->first);
    } else {
      const WebFrame* element_frame = form_element.document().frame();
      if (!element_frame || element_frame == &frame)
        to_remove.push_back(it->first);
    }
  }

  for (typename std::vector<K>::const_iterator it = to_remove.begin();
       it != to_remove.end(); ++it) {
    states->erase(*it);
  }
}

FormCache::FormCache() {
}

FormCache::~FormCache() {
}

void FormCache::ExtractForms(const WebFrame& frame,
                             std::vector<FormData>* forms) {
  ExtractFormsAndFormElements(frame, kRequiredAutofillFields, forms, NULL);
}

bool FormCache::ExtractFormsAndFormElements(
    const WebFrame& frame,
    size_t minimum_required_fields,
    std::vector<FormData>* forms,
    std::vector<WebFormElement>* web_form_elements) {
  // Reset the cache for this frame.
  ResetFrame(frame);

  WebDocument document = frame.document();
  if (document.isNull())
    return false;

  web_documents_.insert(document);

  WebVector<WebFormElement> web_forms;
  document.forms(web_forms);

  size_t num_fields_seen = 0;
  bool has_skipped_forms = false;
  for (size_t i = 0; i < web_forms.size(); ++i) {
    WebFormElement form_element = web_forms[i];

    std::vector<WebFormControlElement> control_elements;
    ExtractAutofillableElements(form_element, autofill::REQUIRE_NONE,
                                &control_elements);

    size_t num_editable_elements = 0;
    for (size_t j = 0; j < control_elements.size(); ++j) {
      WebFormControlElement element = control_elements[j];

      // Save original values of <select> elements so we can restore them
      // when |ClearFormWithNode()| is invoked.
      if (IsSelectElement(element)) {
        const WebSelectElement select_element =
            element.toConst<WebSelectElement>();
        initial_select_values_.insert(std::make_pair(select_element,
                                                     select_element.value()));
        ++num_editable_elements;
      } else if (IsTextAreaElement(element)) {
        ++num_editable_elements;
      } else {
        const WebInputElement input_element =
            element.toConst<WebInputElement>();
        if (IsCheckableElement(&input_element)) {
          initial_checked_state_.insert(
              std::make_pair(input_element, input_element.isChecked()));
        } else {
          ++num_editable_elements;
        }
      }
    }

    // To avoid overly expensive computation, we impose a minimum number of
    // allowable fields.  The corresponding maximum number of allowable fields
    // is imposed by WebFormElementToFormData().
    if (num_editable_elements < minimum_required_fields &&
        control_elements.size() > 0) {
      has_skipped_forms = true;
      continue;
    }

    FormData form;
    ExtractMask extract_mask =
      static_cast<ExtractMask>(EXTRACT_VALUE | EXTRACT_OPTIONS);

    if (!WebFormElementToFormData(form_element, WebFormControlElement(),
                                  REQUIRE_NONE, extract_mask, &form, NULL)) {
      continue;
    }

    num_fields_seen += form.fields.size();
    if (num_fields_seen > kMaxParseableFields)
      break;

    if (form.fields.size() >= minimum_required_fields) {
      forms->push_back(form);
      if (web_form_elements)
        web_form_elements->push_back(form_element);
    } else {
      has_skipped_forms = true;
    }
  }

  // Return true if there are any WebFormElements skipped, else false.
  return has_skipped_forms;
}

void FormCache::ResetFrame(const WebFrame& frame) {
  std::vector<WebDocument> documents_to_delete;
  for (std::set<WebDocument>::const_iterator it = web_documents_.begin();
       it != web_documents_.end(); ++it) {
    const WebFrame* document_frame = it->frame();
    if (!document_frame || document_frame == &frame)
      documents_to_delete.push_back(*it);
  }

  for (std::vector<WebDocument>::const_iterator it =
           documents_to_delete.begin();
       it != documents_to_delete.end(); ++it) {
    web_documents_.erase(*it);
  }

  RemoveOldElements(frame, &initial_select_values_);
  RemoveOldElements(frame, &initial_checked_state_);
}

bool FormCache::ClearFormWithElement(const WebInputElement& element) {
  WebFormElement form_element = element.form();
  if (form_element.isNull())
    return false;

  std::vector<WebFormControlElement> control_elements;
  ExtractAutofillableElements(form_element, autofill::REQUIRE_NONE,
                              &control_elements);
  for (size_t i = 0; i < control_elements.size(); ++i) {
    WebFormControlElement control_element = control_elements[i];
    // Don't modify the value of disabled fields.
    if (!control_element.isEnabled())
      continue;

    control_element.setAutofilled(false);

    WebInputElement* input_element = toWebInputElement(&control_element);
    if (IsTextInput(input_element) || IsMonthInput(input_element)) {
      input_element->setValue(base::string16(), true);

      // Clearing the value in the focused node (above) can cause selection
      // to be lost. We force selection range to restore the text cursor.
      if (element == *input_element) {
        int length = input_element->value().length();
        input_element->setSelectionRange(length, length);
      }
    } else if (IsTextAreaElement(control_element)) {
      WebTextAreaElement text_area = control_element.to<WebTextAreaElement>();
      text_area.setValue(base::string16());
      text_area.dispatchFormControlChangeEvent();
    } else if (IsSelectElement(control_element)) {
      WebSelectElement select_element = control_element.to<WebSelectElement>();

      std::map<const WebSelectElement, base::string16>::const_iterator
          initial_value_iter = initial_select_values_.find(select_element);
      if (initial_value_iter != initial_select_values_.end() &&
          select_element.value() != initial_value_iter->second) {
        select_element.setValue(initial_value_iter->second);
        select_element.dispatchFormControlChangeEvent();
      }
    } else {
      WebInputElement input_element = control_element.to<WebInputElement>();
      DCHECK(IsCheckableElement(&input_element));
      std::map<const WebInputElement, bool>::const_iterator it =
          initial_checked_state_.find(input_element);
      if (it != initial_checked_state_.end() &&
          input_element.isChecked() != it->second) {
        input_element.setChecked(it->second, true);
      }
    }
  }

  return true;
}

bool FormCache::ShowPredictions(const FormDataPredictions& form) {
  DCHECK_EQ(form.data.fields.size(), form.fields.size());

  // Find the form.
  bool found_form = false;
  WebFormElement form_element;
  for (std::set<WebDocument>::const_iterator it = web_documents_.begin();
       it != web_documents_.end() && !found_form; ++it) {
    WebVector<WebFormElement> web_forms;
    it->forms(web_forms);

    for (size_t i = 0; i < web_forms.size(); ++i) {
      form_element = web_forms[i];

      // Note: matching on the form name here which is not guaranteed to be
      // unique for the page, nor is it guaranteed to be non-empty.  Ideally, we
      // would have a way to uniquely identify the form cross-process.  For now,
      // we'll check form name and form action for identity.
      // Also note that WebString() == WebString(string16()) does not evaluate
      // to |true| -- WebKit distinguishes between a "null" string (lhs) and an
      // "empty" string (rhs).  We don't want that distinction, so forcing to
      // string16.
      base::string16 element_name = GetFormIdentifier(form_element);
      GURL action(form_element.document().completeURL(form_element.action()));
      if (element_name == form.data.name && action == form.data.action) {
        found_form = true;
        break;
      }
    }
  }

  if (!found_form)
    return false;

  std::vector<WebFormControlElement> control_elements;
  ExtractAutofillableElements(form_element, autofill::REQUIRE_NONE,
                              &control_elements);
  if (control_elements.size() != form.fields.size()) {
    // Keep things simple.  Don't show predictions for forms that were modified
    // between page load and the server's response to our query.
    return false;
  }

  for (size_t i = 0; i < control_elements.size(); ++i) {
    WebFormControlElement* element = &control_elements[i];

    if (base::string16(element->nameForAutofill()) !=
        form.data.fields[i].name) {
      // Keep things simple.  Don't show predictions for elements whose names
      // were modified between page load and the server's response to our query.
      continue;
    }

    std::string placeholder = form.fields[i].overall_type;
    base::string16 title = l10n_util::GetStringFUTF16(
        IDS_AUTOFILL_SHOW_PREDICTIONS_TITLE,
        UTF8ToUTF16(form.fields[i].heuristic_type),
        UTF8ToUTF16(form.fields[i].server_type),
        UTF8ToUTF16(form.fields[i].signature),
        UTF8ToUTF16(form.signature),
        UTF8ToUTF16(form.experiment_id));
    if (!element->hasAttribute("placeholder"))
      element->setAttribute("placeholder", WebString(UTF8ToUTF16(placeholder)));
    element->setAttribute("title", WebString(title));
  }

  return true;
}

}  // namespace autofill