// Copyright (c) 2014 GitHub, Inc.
// Use of this source code is governed by the MIT license that can be
// found in the LICENSE file.

#include "atom/renderer/api/atom_api_spell_check_client.h"

#include <algorithm>
#include <vector>

#include "atom/common/native_mate_converters/string16_converter.h"
#include "base/logging.h"
#include "base/threading/thread_task_runner_handle.h"
#include "chrome/renderer/spellchecker/spellcheck_worditerator.h"
#include "native_mate/converter.h"
#include "native_mate/dictionary.h"
#include "third_party/WebKit/public/web/WebTextCheckingCompletion.h"
#include "third_party/WebKit/public/web/WebTextCheckingResult.h"
#include "third_party/icu/source/common/unicode/uscript.h"

namespace atom {

namespace api {

namespace {

bool HasWordCharacters(const base::string16& text, int index) {
  const base::char16* data = text.data();
  int length = text.length();
  while (index < length) {
    uint32_t code = 0;
    U16_NEXT(data, index, length, code);
    UErrorCode error = U_ZERO_ERROR;
    if (uscript_getScript(code, &error) != USCRIPT_COMMON)
      return true;
  }
  return false;
}

}  // namespace

class SpellCheckClient::SpellcheckRequest {
 public:
  SpellcheckRequest(const base::string16& text,
                    blink::WebTextCheckingCompletion* completion)
      : text_(text), completion_(completion) {
    DCHECK(completion);
  }
  ~SpellcheckRequest() {}

  base::string16 text() { return text_; }
  blink::WebTextCheckingCompletion* completion() { return completion_; }

 private:
  base::string16 text_;  // Text to be checked in this task.

  // The interface to send the misspelled ranges to WebKit.
  blink::WebTextCheckingCompletion* completion_;

  DISALLOW_COPY_AND_ASSIGN(SpellcheckRequest);
};

SpellCheckClient::SpellCheckClient(const std::string& language,
                                   bool auto_spell_correct_turned_on,
                                   v8::Isolate* isolate,
                                   v8::Local<v8::Object> provider)
    : isolate_(isolate),
      context_(isolate, isolate->GetCurrentContext()),
      provider_(isolate, provider) {
  DCHECK(!context_.IsEmpty());

  character_attributes_.SetDefaultLanguage(language);

  // Persistent the method.
  mate::Dictionary dict(isolate, provider);
  dict.Get("spellCheck", &spell_check_);
}

SpellCheckClient::~SpellCheckClient() {
  context_.Reset();
}

void SpellCheckClient::CheckSpelling(
    const blink::WebString& text,
    int& misspelling_start,
    int& misspelling_len,
    blink::WebVector<blink::WebString>* optional_suggestions) {
  std::vector<blink::WebTextCheckingResult> results;
  SpellCheckText(text.Utf16(), true, &results);
  if (results.size() == 1) {
    misspelling_start = results[0].location;
    misspelling_len = results[0].length;
  }
}

void SpellCheckClient::RequestCheckingOfText(
    const blink::WebString& textToCheck,
    blink::WebTextCheckingCompletion* completionCallback) {
  base::string16 text(textToCheck.Utf16());
  // Ignore invalid requests.
  if (text.empty() || !HasWordCharacters(text, 0)) {
    completionCallback->DidCancelCheckingText();
    return;
  }

  // Clean up the previous request before starting a new request.
  if (pending_request_param_.get()) {
    pending_request_param_->completion()->DidCancelCheckingText();
  }

  pending_request_param_.reset(new SpellcheckRequest(text, completionCallback));

  base::ThreadTaskRunnerHandle::Get()->PostTask(
      FROM_HERE,
      base::BindOnce(&SpellCheckClient::PerformSpellCheck, AsWeakPtr(),
                     base::Owned(pending_request_param_.release())));
}

void SpellCheckClient::ShowSpellingUI(bool show) {}

bool SpellCheckClient::IsShowingSpellingUI() {
  return false;
}

void SpellCheckClient::UpdateSpellingUIWithMisspelledWord(
    const blink::WebString& word) {}

void SpellCheckClient::SpellCheckText(
    const base::string16& text,
    bool stop_at_first_result,
    std::vector<blink::WebTextCheckingResult>* results) {
  if (text.empty() || spell_check_.IsEmpty())
    return;

  if (!text_iterator_.IsInitialized() &&
      !text_iterator_.Initialize(&character_attributes_, true)) {
    // We failed to initialize text_iterator_, return as spelled correctly.
    VLOG(1) << "Failed to initialize SpellcheckWordIterator";
    return;
  }

  if (!contraction_iterator_.IsInitialized() &&
      !contraction_iterator_.Initialize(&character_attributes_, false)) {
    // We failed to initialize the word iterator, return as spelled correctly.
    VLOG(1) << "Failed to initialize contraction_iterator_";
    return;
  }

  text_iterator_.SetText(text.c_str(), text.size());

  SpellCheckScope scope(*this);
  base::string16 word;
  int word_start;
  int word_length;
  for (auto status =
           text_iterator_.GetNextWord(&word, &word_start, &word_length);
       status != SpellcheckWordIterator::IS_END_OF_TEXT;
       status = text_iterator_.GetNextWord(&word, &word_start, &word_length)) {
    if (status == SpellcheckWordIterator::IS_SKIPPABLE)
      continue;

    // Found a word (or a contraction) that the spellchecker can check the
    // spelling of.
    if (SpellCheckWord(scope, word))
      continue;

    // If the given word is a concatenated word of two or more valid words
    // (e.g. "hello:hello"), we should treat it as a valid word.
    if (IsValidContraction(scope, word))
      continue;

    blink::WebTextCheckingResult result;
    result.location = word_start;
    result.length = word_length;
    results->push_back(result);

    if (stop_at_first_result)
      return;
  }
}

bool SpellCheckClient::SpellCheckWord(
    const SpellCheckScope& scope,
    const base::string16& word_to_check) const {
  DCHECK(!scope.spell_check_.IsEmpty());

  v8::Local<v8::Value> word = mate::ConvertToV8(isolate_, word_to_check);
  v8::Local<v8::Value> result =
      scope.spell_check_->Call(scope.provider_, 1, &word);

  if (!result.IsEmpty() && result->IsBoolean())
    return result->BooleanValue();
  else
    return true;
}

// Returns whether or not the given string is a valid contraction.
// This function is a fall-back when the SpellcheckWordIterator class
// returns a concatenated word which is not in the selected dictionary
// (e.g. "in'n'out") but each word is valid.
bool SpellCheckClient::IsValidContraction(const SpellCheckScope& scope,
                                          const base::string16& contraction) {
  DCHECK(contraction_iterator_.IsInitialized());

  contraction_iterator_.SetText(contraction.c_str(), contraction.length());

  base::string16 word;
  int word_start;
  int word_length;

  for (auto status =
           contraction_iterator_.GetNextWord(&word, &word_start, &word_length);
       status != SpellcheckWordIterator::IS_END_OF_TEXT;
       status = contraction_iterator_.GetNextWord(&word, &word_start,
                                                  &word_length)) {
    if (status == SpellcheckWordIterator::IS_SKIPPABLE)
      continue;

    if (!SpellCheckWord(scope, word))
      return false;
  }
  return true;
}

void SpellCheckClient::PerformSpellCheck(SpellcheckRequest* param) {
  DCHECK(param);

  std::vector<blink::WebTextCheckingResult> results;
  SpellCheckText(param->text(), false, &results);
  param->completion()->DidFinishCheckingText(results);
}

SpellCheckClient::SpellCheckScope::SpellCheckScope(
    const SpellCheckClient& client)
    : handle_scope_(client.isolate_),
      context_scope_(
          v8::Local<v8::Context>::New(client.isolate_, client.context_)),
      provider_(client.provider_.NewHandle()),
      spell_check_(client.spell_check_.NewHandle()) {}

SpellCheckClient::SpellCheckScope::~SpellCheckScope() = default;

}  // namespace api

}  // namespace atom