# Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from paddle.trainer.PyDataProvider2 import *
from common_utils import meta_to_header


def __list_to_map__(lst):
    ret_val = dict()
    for each in lst:
        k, v = each
        ret_val[k] = v
    return ret_val


def hook(settings, meta, **kwargs):
    """
    Init hook is invoked before process data. It will set obj.slots and store
    data meta.

    :param obj: global object. It will passed to process routine.
    :type obj: object
    :param meta: the meta file object, which passed from trainer_config. Meta
                 file record movie/user features.
    :param kwargs: unused other arguments.
    """

    # Header define slots that used for paddle.
    #    first part is movie features.
    #    second part is user features.
    #    final part is rating score.
    # header is a list of [USE_SEQ_OR_NOT?, SlotType]
    movie_headers = list(meta_to_header(meta, 'movie'))
    settings.movie_names = [h[0] for h in movie_headers]
    headers = movie_headers
    user_headers = list(meta_to_header(meta, 'user'))
    settings.user_names = [h[0] for h in user_headers]
    headers.extend(user_headers)
    headers.append(("rating", dense_vector(1)))  # Score

    # slot types.
    settings.input_types = __list_to_map__(headers)
    settings.meta = meta


@provider(init_hook=hook, cache=CacheType.CACHE_PASS_IN_MEM)
def process(settings, filename):
    with open(filename, 'r') as f:
        for line in f:
            # Get a rating from file.
            user_id, movie_id, score = map(int, line.split('::')[:-1])

            # Scale score to [-2, +2]
            score = float(score - 3)

            # Get movie/user features by movie_id, user_id
            movie_meta = settings.meta['movie'][movie_id]
            user_meta = settings.meta['user'][user_id]

            outputs = [('movie_id', movie_id - 1)]

            # Then add movie features
            for i, each_meta in enumerate(movie_meta):
                outputs.append((settings.movie_names[i + 1], each_meta))

            # Then add user id.
            outputs.append(('user_id', user_id - 1))

            # Then add user features.
            for i, each_meta in enumerate(user_meta):
                outputs.append((settings.user_names[i + 1], each_meta))

            # Finally, add score
            outputs.append(('rating', [score]))
            # Return data to paddle
            yield __list_to_map__(outputs)