#!/usr/bin/env python
# Copyright (c) 2012 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.

'''Support for formatting a data pack file used for platform agnostic resource
files.
'''

import exceptions
import os
import struct
import sys
if __name__ == '__main__':
  sys.path[0] = os.path.abspath(os.path.join(sys.path[0], '../..'))

from grit import util
from grit.format import interface
from grit.node import include
from grit.node import message
from grit.node import structure
from grit.node import misc


PACK_FILE_VERSION = 4
HEADER_LENGTH = 2 * 4 + 1  # Two uint32s. (file version, number of entries) and
                           # one uint8 (encoding of text resources)
BINARY, UTF8, UTF16 = range(3)

class WrongFileVersion(Exception):
  pass

class DataPackContents:
  def __init__(self, resources, encoding):
    self.resources = resources
    self.encoding = encoding

class DataPack(interface.ItemFormatter):
  '''Writes out the data pack file format (platform agnostic resource file).'''
  def Format(self, item, lang='en', output_dir='.'):
    assert isinstance(item, misc.ReleaseNode)

    nodes = DataPack.GetDataNodes(item)
    data = {}
    for node in nodes:
      id, value = node.GetDataPackPair(lang, UTF8)
      if value is not None:
        data[id] = value
    return DataPack.WriteDataPackToString(data, UTF8)

  @staticmethod
  def GetDataNodes(item):
    '''Returns a list of nodes that can be packed into the data pack file.'''
    nodes = []
    if (isinstance(item, misc.IfNode) and not item.IsConditionSatisfied()):
      return nodes
    if (isinstance(item, include.IncludeNode) or
        isinstance(item, message.MessageNode) or
        isinstance(item, structure.StructureNode)):
      # Include this node if it wasn't marked as skipped by a whitelist.
      if not item.WhitelistMarkedAsSkip():
        return [item]
      return nodes
    for child in item.children:
      nodes.extend(DataPack.GetDataNodes(child))
    return nodes

  @staticmethod
  def ReadDataPack(input_file):
    """Reads a data pack file and returns a dictionary."""
    data = util.ReadFile(input_file, util.BINARY)
    original_data = data

    # Read the header.
    version, num_entries, encoding = struct.unpack("<IIB",
                                                   data[:HEADER_LENGTH])
    if version != PACK_FILE_VERSION:
      print "Wrong file version in ", input_file
      raise WrongFileVersion

    resources = {}
    if num_entries == 0:
      return DataPackContents(resources, encoding)

    # Read the index and data.
    data = data[HEADER_LENGTH:]
    kIndexEntrySize = 2 + 4  # Each entry is a uint16 and a uint32.
    for _ in range(num_entries):
      id, offset = struct.unpack("<HI", data[:kIndexEntrySize])
      data = data[kIndexEntrySize:]
      next_id, next_offset = struct.unpack("<HI", data[:kIndexEntrySize])
      resources[id] = original_data[offset:next_offset]

    return DataPackContents(resources, encoding)

  @staticmethod
  def WriteDataPackToString(resources, encoding):
    """Write a map of id=>data into a string in the data pack format and return
    it."""
    ids = sorted(resources.keys())
    ret = []

    # Write file header.
    ret.append(struct.pack("<IIB", PACK_FILE_VERSION, len(ids), encoding))
    HEADER_LENGTH = 2 * 4 + 1            # Two uint32s and one uint8.

    # Each entry is a uint16 + a uint32s. We have one extra entry for the last
    # item.
    index_length = (len(ids) + 1) * (2 + 4)

    # Write index.
    data_offset = HEADER_LENGTH + index_length
    for id in ids:
      ret.append(struct.pack("<HI", id, data_offset))
      data_offset += len(resources[id])

    ret.append(struct.pack("<HI", 0, data_offset))

    # Write data.
    for id in ids:
      ret.append(resources[id])
    return ''.join(ret)

  @staticmethod
  def WriteDataPack(resources, output_file, encoding):
    """Write a map of id=>data into output_file as a data pack."""
    content = DataPack.WriteDataPackToString(resources, encoding)
    with open(output_file, "wb") as file:
      file.write(content)

  @staticmethod
  def RePack(output_file, input_files):
    """Write a new data pack to |output_file| based on a list of filenames
    (|input_files|)"""
    resources = {}
    encoding = None
    for filename in input_files:
      new_content = DataPack.ReadDataPack(filename)

      # Make sure we have no dups.
      duplicate_keys = set(new_content.resources.keys()) & set(resources.keys())
      if len(duplicate_keys) != 0:
        raise exceptions.KeyError("Duplicate keys: " +
                                  str(list(duplicate_keys)))

      # Make sure encoding is consistent.
      if encoding in (None, BINARY):
        encoding = new_content.encoding
      elif new_content.encoding not in (BINARY, encoding):
          raise exceptions.KeyError("Inconsistent encodings: " +
                                    str(encoding) + " vs " +
                                    str(new_content.encoding))

      resources.update(new_content.resources)

    # Encoding is 0 for BINARY, 1 for UTF8 and 2 for UTF16
    if encoding is None:
      encoding = BINARY
    DataPack.WriteDataPack(resources, output_file, encoding)

def main():
  if len(sys.argv) > 1:
    # When an argument is given, read and explode the file to text
    # format, for easier diffing.
    data = DataPack.ReadDataPack(sys.argv[1])
    print data.encoding
    for (resource_id, text) in data.resources.iteritems():
      print "%s: %s" % (resource_id, text)
  else:
    # Just write a simple file.
    data = { 1: "", 4: "this is id 4", 6: "this is id 6", 10: "" }
    DataPack.WriteDataPack(data, "datapack1.pak", UTF8)
    data2 = { 1000: "test", 5: "five" }
    DataPack.WriteDataPack(data2, "datapack2.pak", UTF8)
    print "wrote datapack1 and datapack2 to current directory."

if __name__ == '__main__':
  main()
