/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozPersonalDictionary.h"
#include "nsIUnicharInputStream.h"
#include "nsReadableUtils.h"
#include "nsIFile.h"
#include "nsAppDirectoryServiceDefs.h"
#include "nsIObserverService.h"
#include "nsIPrefService.h"
#include "nsIPrefBranch.h"
#include "nsIWeakReference.h"
#include "nsCRT.h"
#include "nsNetUtil.h"
#include "nsNetCID.h"
#include "nsIInputStream.h"
#include "nsIOutputStream.h"
#include "nsISafeOutputStream.h"
#include "nsTArray.h"
#include "nsStringEnumerator.h"
#include "nsUnicharInputStream.h"
#include "nsIRunnable.h"
#include "nsThreadUtils.h"
#include "nsProxyRelease.h"
#include "prio.h"
#include "mozilla/Move.h"

#define MOZ_PERSONAL_DICT_NAME "persdict.dat"

/**
 * This is the most braindead implementation of a personal dictionary possible.
 * There is not much complexity needed, though.  It could be made much faster,
 *  and probably should, but I don't see much need for more in terms of interface.
 *
 * Allowing personal words to be associated with only certain dictionaries maybe.
 *
 * TODO:
 * Implement the suggestion record.
 */

NS_IMPL_CYCLE_COLLECTING_ADDREF(mozPersonalDictionary)
NS_IMPL_CYCLE_COLLECTING_RELEASE(mozPersonalDictionary)

NS_INTERFACE_MAP_BEGIN(mozPersonalDictionary)
  NS_INTERFACE_MAP_ENTRY(mozIPersonalDictionary)
  NS_INTERFACE_MAP_ENTRY(nsIObserver)
  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, mozIPersonalDictionary)
  NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(mozPersonalDictionary)
NS_INTERFACE_MAP_END

NS_IMPL_CYCLE_COLLECTION(mozPersonalDictionary, mEncoder)

class mozPersonalDictionaryLoader final : public mozilla::Runnable
{
public:
  explicit mozPersonalDictionaryLoader(mozPersonalDictionary *dict) : mDict(dict)
  {
  }

  NS_IMETHOD Run() override
  {
    mDict->SyncLoad();

    // Release the dictionary on the main thread
    NS_ReleaseOnMainThread(mDict.forget());

    return NS_OK;
  }

private:
  RefPtr<mozPersonalDictionary> mDict;
};

class mozPersonalDictionarySave final : public mozilla::Runnable
{
public:
  explicit mozPersonalDictionarySave(mozPersonalDictionary *aDict,
                                     nsCOMPtr<nsIFile> aFile,
                                     nsTArray<nsString> &&aDictWords)
    : mDictWords(aDictWords),
      mFile(aFile),
      mDict(aDict)
  {
  }

  NS_IMETHOD Run() override
  {
    nsresult res;

    MOZ_ASSERT(!NS_IsMainThread());

    {
      mozilla::MonitorAutoLock mon(mDict->mMonitorSave);

      nsCOMPtr<nsIOutputStream> outStream;
      NS_NewSafeLocalFileOutputStream(getter_AddRefs(outStream), mFile,
                                      PR_CREATE_FILE | PR_WRONLY | PR_TRUNCATE,
                                      0664);

      // Get a buffered output stream 4096 bytes big, to optimize writes.
      nsCOMPtr<nsIOutputStream> bufferedOutputStream;
      res = NS_NewBufferedOutputStream(getter_AddRefs(bufferedOutputStream),
                                       outStream, 4096);
      if (NS_FAILED(res)) {
        return res;
      }

      uint32_t bytesWritten;
      nsAutoCString utf8Key;
      for (uint32_t i = 0; i < mDictWords.Length(); ++i) {
        CopyUTF16toUTF8(mDictWords[i], utf8Key);

        bufferedOutputStream->Write(utf8Key.get(), utf8Key.Length(),
                                    &bytesWritten);
        bufferedOutputStream->Write("\n", 1, &bytesWritten);
      }
      nsCOMPtr<nsISafeOutputStream> safeStream =
        do_QueryInterface(bufferedOutputStream);
      NS_ASSERTION(safeStream, "expected a safe output stream!");
      if (safeStream) {
        res = safeStream->Finish();
        if (NS_FAILED(res)) {
          NS_WARNING("failed to save personal dictionary file! possible data loss");
        }
      }

      // Save is done, reset the state variable and notify those who are waiting.
      mDict->mSavePending = false;
      mon.Notify();

      // Leaving the block where 'mon' was declared will call the destructor
      // and unlock.
    }

    // Release the dictionary on the main thread.
    NS_ReleaseOnMainThread(mDict.forget());

    return NS_OK;
  }

private:
  nsTArray<nsString> mDictWords;
  nsCOMPtr<nsIFile> mFile;
  RefPtr<mozPersonalDictionary> mDict;
};

mozPersonalDictionary::mozPersonalDictionary()
 : mIsLoaded(false),
   mSavePending(false),
   mMonitor("mozPersonalDictionary::mMonitor"),
   mMonitorSave("mozPersonalDictionary::mMonitorSave")
{
}

mozPersonalDictionary::~mozPersonalDictionary()
{
}

nsresult mozPersonalDictionary::Init()
{
  nsCOMPtr<nsIObserverService> svc =
    do_GetService("@mozilla.org/observer-service;1");

  NS_ENSURE_STATE(svc);
  // we want to reload the dictionary if the profile switches
  nsresult rv = svc->AddObserver(this, "profile-do-change", true);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  rv = svc->AddObserver(this, "profile-before-change", true);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  Load();

  return NS_OK;
}

void mozPersonalDictionary::WaitForLoad()
{
  // If the dictionary is already loaded, we return straight away.
  if (mIsLoaded) {
    return;
  }

  // If the dictionary hasn't been loaded, we try to lock the same monitor
  // that the thread uses that does the load. This way the main thread will 
  // be suspended until the monitor becomes available.
  mozilla::MonitorAutoLock mon(mMonitor);

  // The monitor has become available. This can have two reasons:
  // 1: The thread that does the load has finished.
  // 2: The thread that does the load hasn't even started.
  //    In this case we need to wait.
  if (!mIsLoaded) {
    mon.Wait();
  }
}

nsresult mozPersonalDictionary::LoadInternal()
{
  nsresult rv;
  mozilla::MonitorAutoLock mon(mMonitor);

  if (mIsLoaded) {
    return NS_OK;
  }

  rv = NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR, getter_AddRefs(mFile));
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  if (!mFile) {
    return NS_ERROR_FAILURE;
  }

  rv = mFile->Append(NS_LITERAL_STRING(MOZ_PERSONAL_DICT_NAME));
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  nsCOMPtr<nsIEventTarget> target = do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID, &rv);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  nsCOMPtr<nsIRunnable> runnable = new mozPersonalDictionaryLoader(this);
  rv = target->Dispatch(runnable, NS_DISPATCH_NORMAL);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  return NS_OK;
}

NS_IMETHODIMP mozPersonalDictionary::Load()
{
  nsresult rv = LoadInternal();

  if (NS_FAILED(rv)) {
    mIsLoaded = true;
  }

  return rv;
}

void mozPersonalDictionary::SyncLoad()
{
  MOZ_ASSERT(!NS_IsMainThread());

  mozilla::MonitorAutoLock mon(mMonitor);

  if (mIsLoaded) {
    return;
  }

  SyncLoadInternal();
  mIsLoaded = true;
  mon.Notify();
}

void mozPersonalDictionary::SyncLoadInternal()
{
  MOZ_ASSERT(!NS_IsMainThread());

  //FIXME Deinst  -- get dictionary name from prefs;
  nsresult rv;
  bool dictExists;

  rv = mFile->Exists(&dictExists);
  if (NS_FAILED(rv)) {
    return;
  }

  if (!dictExists) {
    // Nothing is really wrong...
    return;
  }

  nsCOMPtr<nsIInputStream> inStream;
  NS_NewLocalFileInputStream(getter_AddRefs(inStream), mFile);

  nsCOMPtr<nsIUnicharInputStream> convStream;
  rv = NS_NewUnicharInputStream(inStream, getter_AddRefs(convStream));
  if (NS_FAILED(rv)) {
    return;
  }

  // we're rereading to get rid of the old data  -- we shouldn't have any, but...
  mDictionaryTable.Clear();

  char16_t c;
  uint32_t nRead;
  bool done = false;
  do{  // read each line of text into the string array.
    if( (NS_OK != convStream->Read(&c, 1, &nRead)) || (nRead != 1)) break;
    while(!done && ((c == '\n') || (c == '\r'))){
      if( (NS_OK != convStream->Read(&c, 1, &nRead)) || (nRead != 1)) done = true;
    }
    if (!done){ 
      nsAutoString word;
      while((c != '\n') && (c != '\r') && !done){
        word.Append(c);
        if( (NS_OK != convStream->Read(&c, 1, &nRead)) || (nRead != 1)) done = true;
      }
      mDictionaryTable.PutEntry(word.get());
    }
  } while(!done);
}

void mozPersonalDictionary::WaitForSave()
{
  // If no save is pending, we return straight away.
  if (!mSavePending) {
    return;
  }

  // If a save is pending, we try to lock the same monitor that the thread uses
  // that does the save. This way the main thread will be suspended until the
  // monitor becomes available.
  mozilla::MonitorAutoLock mon(mMonitorSave);

  // The monitor has become available. This can have two reasons:
  // 1: The thread that does the save has finished.
  // 2: The thread that does the save hasn't even started.
  //    In this case we need to wait.
  if (mSavePending) {
    mon.Wait();
  }
}

NS_IMETHODIMP mozPersonalDictionary::Save()
{
  nsCOMPtr<nsIFile> theFile;
  nsresult res;

  WaitForSave();

  mSavePending = true;

  //FIXME Deinst  -- get dictionary name from prefs;
  res = NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR, getter_AddRefs(theFile));
  if(NS_FAILED(res)) return res;
  if(!theFile)return NS_ERROR_FAILURE;
  res = theFile->Append(NS_LITERAL_STRING(MOZ_PERSONAL_DICT_NAME));
  if(NS_FAILED(res)) return res;

  nsCOMPtr<nsIEventTarget> target =
    do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID, &res);
  if (NS_WARN_IF(NS_FAILED(res))) {
    return res;
  }

  nsTArray<nsString> array;
  nsString* elems = array.AppendElements(mDictionaryTable.Count());
  for (auto iter = mDictionaryTable.Iter(); !iter.Done(); iter.Next()) {
    elems->Assign(iter.Get()->GetKey());
    elems++;
  }

  nsCOMPtr<nsIRunnable> runnable =
    new mozPersonalDictionarySave(this, theFile, mozilla::Move(array));
  res = target->Dispatch(runnable, NS_DISPATCH_NORMAL);
  if (NS_WARN_IF(NS_FAILED(res))) {
    return res;
  }
  return res;
}

NS_IMETHODIMP mozPersonalDictionary::GetWordList(nsIStringEnumerator **aWords)
{
  NS_ENSURE_ARG_POINTER(aWords);
  *aWords = nullptr;

  WaitForLoad();

  nsTArray<nsString> *array = new nsTArray<nsString>();
  nsString* elems = array->AppendElements(mDictionaryTable.Count());
  for (auto iter = mDictionaryTable.Iter(); !iter.Done(); iter.Next()) {
    elems->Assign(iter.Get()->GetKey());
    elems++;
  }

  array->Sort();

  return NS_NewAdoptingStringEnumerator(aWords, array);
}

NS_IMETHODIMP mozPersonalDictionary::Check(const char16_t *aWord, const char16_t *aLanguage, bool *aResult)
{
  NS_ENSURE_ARG_POINTER(aWord);
  NS_ENSURE_ARG_POINTER(aResult);

  WaitForLoad();

  *aResult = (mDictionaryTable.GetEntry(aWord) || mIgnoreTable.GetEntry(aWord));
  return NS_OK;
}

NS_IMETHODIMP mozPersonalDictionary::AddWord(const char16_t *aWord, const char16_t *aLang)
{
  nsresult res;
  WaitForLoad();

  mDictionaryTable.PutEntry(aWord);
  res = Save();
  return res;
}

NS_IMETHODIMP mozPersonalDictionary::RemoveWord(const char16_t *aWord, const char16_t *aLang)
{
  nsresult res;
  WaitForLoad();

  mDictionaryTable.RemoveEntry(aWord);
  res = Save();
  return res;
}

NS_IMETHODIMP mozPersonalDictionary::IgnoreWord(const char16_t *aWord)
{
  // avoid adding duplicate words to the ignore list
  if (aWord && !mIgnoreTable.GetEntry(aWord)) 
    mIgnoreTable.PutEntry(aWord);
  return NS_OK;
}

NS_IMETHODIMP mozPersonalDictionary::EndSession()
{
  WaitForLoad();

  WaitForSave();
  mIgnoreTable.Clear();
  return NS_OK;
}

NS_IMETHODIMP mozPersonalDictionary::AddCorrection(const char16_t *word, const char16_t *correction, const char16_t *lang)
{
    return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP mozPersonalDictionary::RemoveCorrection(const char16_t *word, const char16_t *correction, const char16_t *lang)
{
    return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP mozPersonalDictionary::GetCorrection(const char16_t *word, char16_t ***words, uint32_t *count)
{
    return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP mozPersonalDictionary::Observe(nsISupports *aSubject, const char *aTopic, const char16_t *aData)
{
  if (!nsCRT::strcmp(aTopic, "profile-do-change")) {
    // The observer is registered in Init() which calls Load and in turn
    // LoadInternal(); i.e. Observe() can't be called before Load().
    WaitForLoad();
    mIsLoaded = false;
    Load(); // load automatically clears out the existing dictionary table
  } else if (!nsCRT::strcmp(aTopic, "profile-before-change")) {
    WaitForSave();
  }

  return NS_OK;
}