#   Copyright (c) 2018 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 __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import os
if 'FLAGS_fraction_of_gpu_memory_to_use' not in os.environ:
    os.environ['FLAGS_fraction_of_gpu_memory_to_use'] = '0.98'
os.environ['FLAGS_enable_parallel_graph'] = '1'

import paddle
import paddle.fluid as fluid
import numpy as np
import argparse
from reader import CityscapeDataset
import reader
import models
import sys
import utility

parser = argparse.ArgumentParser()
add_arg = lambda *args: utility.add_arguments(*args, argparser=parser)

# yapf: disable
add_arg('total_step',           int,    -1,     "Number of the step to be evaluated, -1 for full evaluation.")
add_arg('init_weights_path',    str,    None,   "Path of the weights to evaluate.")
add_arg('dataset_path',         str,    None,   "Cityscape dataset path.")
add_arg('use_gpu',              bool,   True,   "Whether use GPU or CPU.")
add_arg('num_classes',          int,    19,     "Number of classes.")
add_arg('use_py_reader',        bool,   True,   "Use py_reader.")
add_arg('use_multiprocessing',  bool,   False, "Use multiprocessing.")
add_arg('norm_type',            str,    'bn',   "Normalization type, should be 'bn' or 'gn'.")
#yapf: enable


def mean_iou(pred, label):
    label = fluid.layers.elementwise_min(
        label, fluid.layers.assign(np.array(
            [num_classes], dtype=np.int32)))
    label_ignore = (label == num_classes).astype('int32')
    label_nignore = (label != num_classes).astype('int32')

    pred = pred * label_nignore + label_ignore * num_classes

    miou, wrong, correct = fluid.layers.mean_iou(pred, label, num_classes + 1)
    return miou, wrong, correct


def load_model():
    if os.path.isdir(args.init_weights_path):
        fluid.io.load_params(
            exe, dirname=args.init_weights_path, main_program=tp)
    else:
        fluid.io.load_params(
            exe, dirname="", filename=args.init_weights_path, main_program=tp)


CityscapeDataset = reader.CityscapeDataset

args = parser.parse_args()
utility.check_gpu(args.use_gpu)

models.clean()
models.is_train = False
models.default_norm_type = args.norm_type
deeplabv3p = models.deeplabv3p

image_shape = [1025, 2049]
eval_shape = [1024, 2048]

sp = fluid.Program()
tp = fluid.Program()
batch_size = 1
reader.default_config['crop_size'] = -1
reader.default_config['shuffle'] = False
num_classes = args.num_classes

with fluid.program_guard(tp, sp):
    if args.use_py_reader:
        py_reader = fluid.layers.py_reader(capacity=64,
                                        shapes=[[1, 3, 0, 0], [1] + eval_shape],
                                        dtypes=['float32', 'int32'])
        img, label = fluid.layers.read_file(py_reader)
    else:
        img = fluid.layers.data(name='img', shape=[3, 0, 0], dtype='float32')
        label = fluid.layers.data(name='label', shape=eval_shape, dtype='int32')

    img = fluid.layers.resize_bilinear(img, image_shape)
    logit = deeplabv3p(img)
    logit = fluid.layers.resize_bilinear(logit, eval_shape)
    pred = fluid.layers.argmax(logit, axis=1).astype('int32')
    miou, out_wrong, out_correct = mean_iou(pred, label)

tp = tp.clone(True)

place = fluid.CPUPlace()
if args.use_gpu:
    place = fluid.CUDAPlace(0)
exe = fluid.Executor(place)
exe.run(sp)

if args.init_weights_path:
    print("load from:", args.init_weights_path)
    load_model()

dataset = CityscapeDataset(args.dataset_path, 'val')
if args.total_step == -1:
    total_step = len(dataset.label_files)
else:
    total_step = args.total_step

batches = dataset.get_batch_generator(batch_size, total_step, use_multiprocessing=args.use_multiprocessing)
if args.use_py_reader:
    py_reader.decorate_tensor_provider(lambda :[ (yield b[0],b[1]) for b in batches])
    py_reader.start()

sum_iou = 0
all_correct = np.array([0], dtype=np.int64)
all_wrong = np.array([0], dtype=np.int64)

for i in range(total_step):
    if not args.use_py_reader:
        _, imgs, labels, names = next(batches)
        result = exe.run(tp,
                         feed={'img': imgs,
                               'label': labels},
                         fetch_list=[pred, miou, out_wrong, out_correct])
    else:
        result = exe.run(tp,
                         fetch_list=[pred, miou, out_wrong, out_correct])

    wrong = result[2][:-1] + all_wrong
    right = result[3][:-1] + all_correct
    all_wrong = wrong.copy()
    all_correct = right.copy()
    mp = (wrong + right) != 0
    miou2 = np.mean((right[mp] * 1.0 / (right[mp] + wrong[mp])))
    print('step: %s, mIoU: %s' % (i + 1, miou2))

print('eval done!')