#!/usr/bin/env python
# Copyright 2015 The PDFium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import distutils.spawn
import itertools
import os
import shutil
import sys

# pylint: disable=relative-import
import common


class NotFoundError(Exception):
  """Raised when file doesn't exist"""
  pass


class PNGDiffer():

  def __init__(self, finder, reverse_byte_order):
    self.pdfium_diff_path = finder.ExecutablePath('pdfium_diff')
    self.os_name = finder.os_name
    self.reverse_byte_order = reverse_byte_order

  def CheckMissingTools(self, regenerate_expected):
    if (regenerate_expected and self.os_name == 'linux' and
        not distutils.spawn.find_executable('optipng')):
      return 'Please install "optipng" to regenerate expected images.'
    return None

  def GetActualFiles(self, input_filename, source_dir, working_dir):
    actual_paths = []
    path_templates = PathTemplates(input_filename, source_dir, working_dir)

    for page in itertools.count():
      actual_path = path_templates.GetActualPath(page)
      expected_path = path_templates.GetExpectedPath(page)
      platform_expected_path = path_templates.GetPlatformExpectedPath(
          self.os_name, page)
      if os.path.exists(platform_expected_path):
        expected_path = platform_expected_path
      elif not os.path.exists(expected_path):
        break
      actual_paths.append(actual_path)

    return actual_paths

  def _RunImageDiffCommand(self, expected_path, actual_path):
    if not os.path.exists(expected_path):
      return NotFoundError('%s does not exist.' % expected_path)

    cmd = [self.pdfium_diff_path]
    if self.reverse_byte_order:
      cmd.append('--reverse-byte-order')
    cmd.extend([expected_path, actual_path])
    return common.RunCommand(cmd)

  def HasDifferences(self, input_filename, source_dir, working_dir):
    path_templates = PathTemplates(input_filename, source_dir, working_dir)

    for page in itertools.count():
      actual_path = path_templates.GetActualPath(page)
      expected_path = path_templates.GetExpectedPath(page)
      # PDFium tests should be platform independent. Platform based results are
      # used to capture platform dependent implementations.
      platform_expected_path = path_templates.GetPlatformExpectedPath(
          self.os_name, page)
      if (not os.path.exists(expected_path) and
          not os.path.exists(platform_expected_path)):
        if page == 0:
          print "WARNING: no expected results files for " + input_filename
        if os.path.exists(actual_path):
          print('FAILURE: Missing expected result for 0-based page %d of %s' %
                (page, input_filename))
          return True
        break
      print "Checking " + actual_path
      sys.stdout.flush()

      error = self._RunImageDiffCommand(expected_path, actual_path)
      if error:
        # When failed, we check against platform based results.
        platform_error = self._RunImageDiffCommand(platform_expected_path,
                                                   actual_path)
        if platform_error:
          if not isinstance(platform_error, NotFoundError):
            error = platform_error
          print "FAILURE: " + input_filename + "; " + str(error)
          return True

    return False

  def Regenerate(self, input_filename, source_dir, working_dir, platform_only):
    path_templates = PathTemplates(input_filename, source_dir, working_dir)

    for page in itertools.count():
      # Loop through the generated page images. Stop when there is a page
      # missing a png, which means the document ended.
      actual_path = path_templates.GetActualPath(page)
      if not os.path.isfile(actual_path):
        break

      platform_expected_path = path_templates.GetPlatformExpectedPath(
          self.os_name, page)

      # If there is a platform expected png, we will overwrite it. Otherwise,
      # overwrite the generic png in "all" mode, or do nothing in "platform"
      # mode.
      if os.path.exists(platform_expected_path):
        expected_path = platform_expected_path
      elif not platform_only:
        expected_path = path_templates.GetExpectedPath(page)
      else:
        continue

      shutil.copyfile(actual_path, expected_path)
      common.RunCommand(['optipng', expected_path])


ACTUAL_TEMPLATE = '.pdf.%d.png'
EXPECTED_TEMPLATE = '_expected' + ACTUAL_TEMPLATE
PLATFORM_EXPECTED_TEMPLATE = '_expected_%s' + ACTUAL_TEMPLATE


class PathTemplates(object):

  def __init__(self, input_filename, source_dir, working_dir):
    input_root, _ = os.path.splitext(input_filename)
    self.actual_path_template = os.path.join(working_dir,
                                             input_root + ACTUAL_TEMPLATE)
    self.expected_path = os.path.join(source_dir,
                                      input_root + EXPECTED_TEMPLATE)
    self.platform_expected_path = os.path.join(
        source_dir, input_root + PLATFORM_EXPECTED_TEMPLATE)

  def GetActualPath(self, page):
    return self.actual_path_template % page

  def GetExpectedPath(self, page):
    return self.expected_path % page

  def GetPlatformExpectedPath(self, platform, page):
    return self.platform_expected_path % (platform, page)