// Copyright (c) 2011 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 "chrome/browser/ui/webui/screenshot_source.h"

#include "base/bind.h"
#include "base/callback.h"
#include "base/file_util.h"
#include "base/memory/ref_counted_memory.h"
#include "base/message_loop.h"
#include "base/path_service.h"
#include "base/task.h"
#include "chrome/common/chrome_paths.h"
#include "chrome/common/url_constants.h"

#if defined(OS_CHROMEOS)
#include "content/public/browser/browser_thread.h"
#endif

static const char kCurrentScreenshotFilename[] = "current";
#if defined(OS_CHROMEOS)
static const char kSavedScreenshotsBasePath[] = "saved/";
#endif

ScreenshotSource::ScreenshotSource(
    std::vector<unsigned char>* current_screenshot)
    : DataSource(chrome::kChromeUIScreenshotPath, MessageLoop::current()) {
  // Setup the last screenshot taken.
  if (current_screenshot)
    current_screenshot_.reset(new ScreenshotData(*current_screenshot));
  else
    current_screenshot_.reset(new ScreenshotData());
}

ScreenshotSource::~ScreenshotSource() {}

void ScreenshotSource::StartDataRequest(const std::string& path, bool,
                                        int request_id) {
  SendScreenshot(path, request_id);
}

std::string ScreenshotSource::GetMimeType(const std::string&) const {
  // We need to explicitly return a mime type, otherwise if the user tries to
  // drag the image they get no extension.
  return "image/png";
}

ScreenshotDataPtr ScreenshotSource::GetCachedScreenshot(
    const std::string& screenshot_path) {
  std::map<std::string, ScreenshotDataPtr>::iterator pos;
  std::string path = screenshot_path.substr(
      0, screenshot_path.find_first_of("?"));
  if ((pos = cached_screenshots_.find(path)) != cached_screenshots_.end()) {
    return pos->second;
  } else {
    return ScreenshotDataPtr(new ScreenshotData);
  }
}

void ScreenshotSource::SendScreenshot(const std::string& screenshot_path,
                                      int request_id) {
  // Strip the query param value - we only use it as a hack to ensure our
  // image gets reloaded instead of being pulled from the browser cache
  std::string path = screenshot_path.substr(
      0, screenshot_path.find_first_of("?"));
  if (path == kCurrentScreenshotFilename) {
    CacheAndSendScreenshot(path, request_id, current_screenshot_);
#if defined(OS_CHROMEOS)
  } else if (path.compare(0, strlen(kSavedScreenshotsBasePath),
                          kSavedScreenshotsBasePath) == 0) {
    using content::BrowserThread;
    BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
                            base::Bind(&ScreenshotSource::SendSavedScreenshot,
                                       base::Unretained(this), path,
                                       request_id));
#endif
  } else {
    CacheAndSendScreenshot(
        path, request_id, ScreenshotDataPtr(new ScreenshotData()));
  }
}

#if defined(OS_CHROMEOS)
void ScreenshotSource::SendSavedScreenshot(const std::string& screenshot_path,
                                           int request_id) {
  ScreenshotDataPtr read_bytes(new ScreenshotData);
  std::string filename = screenshot_path.substr(
      strlen(kSavedScreenshotsBasePath));

  FilePath fileshelf_path;
  if (!PathService::Get(chrome::DIR_DEFAULT_DOWNLOADS, &fileshelf_path)) {
    CacheAndSendScreenshot(screenshot_path, request_id, read_bytes);
    return;
  }

  int64 file_size = 0;
  FilePath file = fileshelf_path.Append(filename);
  if (!file_util::GetFileSize(file, &file_size)) {
    CacheAndSendScreenshot(screenshot_path, request_id, read_bytes);
    return;
  }

  read_bytes->resize(file_size);
  if (!file_util::ReadFile(file, reinterpret_cast<char*>(&read_bytes->front()),
                           static_cast<int>(file_size)))
    read_bytes->clear();

  CacheAndSendScreenshot(screenshot_path, request_id, read_bytes);
}
#endif

void ScreenshotSource::CacheAndSendScreenshot(
    const std::string& screenshot_path,
    int request_id,
    ScreenshotDataPtr bytes) {
  cached_screenshots_[screenshot_path] = bytes;
  SendResponse(request_id, new RefCountedBytes(*bytes));
}