# coding:utf-8
# Copyright (c) 2019  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
import contextlib
import time
import copy
import logging
import paddle.fluid as fluid
from tb_paddle import SummaryWriter

import paddlehub as hub
from paddlehub.common.paddle_helper import dtype_map, clone_program
from paddlehub.common.utils import mkdir, to_list
from paddlehub.common.logger import logger
from paddlehub.finetune.checkpoint import load_checkpoint, save_checkpoint
from paddlehub.finetune.config import RunConfig


class RunState(object):
    def __init__(self, length):
        self.run_time_begin = time.time()
        self.run_step = 0
        self.run_examples = 0
        self.run_results = [0] * length
        self.run_time_used = 0
        self.run_speed = 0.0

    def __add__(self, other):
        self.run_step += other.run_step
        self.run_examples += other.run_examples
        for index in range(len(self.run_results)):
            self.run_results[index] += other.run_results[index]
        return self

    def update(self):
        self.run_time_used = time.time() - self.run_time_begin
        self.run_speed = self.run_step / self.run_time_used
        return self


class RunEnv(object):
    def __init__(self):
        self.current_epoch = 0
        self.current_step = 0
        self.main_program = None
        self.start_program = None
        self.main_program_compiled = None
        self.py_reader = None
        self.reader = None
        self.loss = None
        self.labels = None
        self.metrics = None
        self.is_inititalized = False
        self.UNG = copy.deepcopy(fluid.unique_name.generator)

    def __setattr__(self, key, value):
        self.__dict__[key] = value

    def __getattr__(self, key):
        return self.__dict__[key]


class BasicTask(object):
    def __init__(self,
                 feed_list,
                 data_reader,
                 main_program=None,
                 startup_program=None,
                 config=None,
                 metrics_choices="default"):

        # base item
        self._base_data_reader = data_reader
        self._base_feed_list = feed_list

        # metrics item
        self.best_score = -999
        if metrics_choices == "default":
            metrics_choices = ["acc"]
        elif metrics_choices == None:
            metrics_choices = []
        if isinstance(metrics_choices, list):
            self.metrics_choices = metrics_choices
        else:
            self.metrics_choices = [metrics_choices]

        if main_program is None:
            self._base_main_program = clone_program(
                fluid.default_main_program(), for_test=False)

        else:
            self._base_main_program = clone_program(
                main_program, for_test=False)
        if startup_program is None:
            self._base_startup_program = clone_program(
                fluid.default_startup_program(), for_test=False)
        else:
            self._base_startup_program = clone_program(
                startup_program, for_test=False)
        self.is_checkpoint_loaded = False
        self._base_compiled_program = None

        # run config
        self.config = config if config else RunConfig()
        self.place = self.places[0]
        self.device_count = len(self.places)

        if self.config.use_data_parallel:
            if not self.config.use_pyreader and self.config.batch_size < self.device_count:
                logger.warning(
                    "Batch size({}) is less than the count of devices({}), which is not allowed in current Paddle versions"
                    .format(self.config.batch_size, self.device_count))
                logger.warning("Batch size automatically adjusted to {}".format(
                    self.device_count))
                self.config._batch_size = self.device_count

        self.exe = fluid.Executor(place=self.place)
        self.build_strategy = fluid.BuildStrategy()
        if self.config.enable_memory_optim:
            self.build_strategy.memory_optimize = True
        else:
            self.build_strategy.memory_optimize = False

        # log item
        if not os.path.exists(self.config.checkpoint_dir):
            mkdir(self.config.checkpoint_dir)
        tb_log_dir = os.path.join(self.config.checkpoint_dir, "visualization")
        self.tb_writer = SummaryWriter(tb_log_dir)

        # run environment
        self._phases = []
        self._envs = {}
        self._predict_data = None

        # accelerate predict
        self.is_best_model_loaded = False

        # set default phase
        self.enter_phase("train")

    @contextlib.contextmanager
    def phase_guard(self, phase):
        self.enter_phase(phase)
        yield
        self.exit_phase()

    def enter_phase(self, phase):
        if phase not in ["train", "val", "dev", "test", "predict", "inference"]:
            raise RuntimeError()
        self._phases.append(phase)

    def exit_phase(self):
        self._phases = self._phases[:-1]

    def init_if_necessary(self):
        if not self.is_checkpoint_loaded:
            if not self.load_checkpoint():
                self.exe.run(self._base_startup_program)
            self.is_checkpoint_loaded = True
            self.is_best_model_loaded = False

    def init_if_load_best_model(self):
        if not self.is_best_model_loaded:
            best_model_path = os.path.join(self.config.checkpoint_dir,
                                           "best_model")
            logger.info("Load the best model from %s" % best_model_path)
            if os.path.exists(best_model_path):
                self.load_parameters(best_model_path)
                self.is_checkpoint_loaded = False
                self.is_best_model_loaded = True
            else:
                self.init_if_necessary()
        else:
            logger.info("The best model has been loaded")

    def _build_env(self):
        if self.env.is_inititalized:
            return

        self._build_env_start_event()
        self.env.is_inititalized = True
        self.env.main_program = clone_program(
            self._base_main_program, for_test=False)

        self.env.startup_program = fluid.Program()
        with fluid.program_guard(self.env.main_program,
                                 self._base_startup_program):
            with fluid.unique_name.guard(self.env.UNG):
                self.env.outputs = self._build_net()
                if self.is_train_phase or self.is_test_phase:
                    self.env.labels = self._add_label()
                    self.env.loss = self._add_loss()
                    self.env.metrics = self._add_metrics()

        if self.is_predict_phase or self.is_test_phase:
            self.env.main_program = clone_program(
                self.env.main_program, for_test=True)
            hub.common.paddle_helper.set_op_attr(
                self.env.main_program, is_test=True)

        if self.config.use_pyreader:
            t_program = fluid.Program()
            with fluid.program_guard(t_program, self.env.startup_program):
                self.env.py_reader = fluid.layers.py_reader(
                    capacity=64,
                    shapes=[var.shape for var in self.feed_var_list],
                    dtypes=[dtype_map[var.dtype] for var in self.feed_var_list],
                    lod_levels=[var.lod_level for var in self.feed_var_list],
                    use_double_buffer=False)

                feed_var_list = self.feed_var_list
                py_vars = fluid.layers.read_file(self.env.py_reader)
                py_vars = to_list(py_vars)
                input_dict = {
                    feed_var_list[index].name: py_var
                    for index, py_var in enumerate(py_vars)
                }

                hub.connect_program(
                    pre_program=t_program,
                    next_program=self.env.main_program,
                    input_dict=input_dict,
                    need_log=False)

            self.env.main_program = t_program
            if not self.is_predict_phase:
                self.env.loss = self.env.main_program.global_block().vars[
                    self.env.loss.name]
                metrics_name = [var.name for var in self.env.metrics]
                self.env.metrics = [
                    self.env.main_program.global_block().vars[name]
                    for name in metrics_name
                ]

            outputs_name = [var.name for var in self.env.outputs]
            self.env.outputs = [
                self.env.main_program.global_block().vars[name]
                for name in outputs_name
            ]

        if self.config.enable_memory_optim:
            for var_name in self.fetch_list:
                var = self.env.main_program.global_block().vars[var_name]
                var.persistable = True

        if self.is_train_phase:
            with fluid.program_guard(self.env.main_program,
                                     self._base_startup_program):
                with fluid.unique_name.guard(self.env.UNG):
                    self.scheduled_lr, self.max_train_steps = self.config.strategy.execute(
                        self.loss, self._base_data_reader, self.config,
                        self.device_count)

        if self.is_train_phase:
            loss_name = self.env.loss.name
        else:
            loss_name = None

        share_vars_from = self._base_compiled_program

        if not self.config.use_data_parallel:
            if self.config.enable_memory_optim:
                fluid.memory_optimize(self.env.main_program)
            self.env.main_program_compiled = None
        else:
            self.env.main_program_compiled = fluid.CompiledProgram(
                self.env.main_program).with_data_parallel(
                    loss_name=loss_name,
                    share_vars_from=share_vars_from,
                    build_strategy=self.build_strategy)

        self.exe.run(self.env.startup_program)

        # to avoid to print logger two times in result of the logger usage of paddle-fluid
        for handler in logging.root.handlers[:]:
            logging.root.removeHandler(handler)

        self._build_env_end_event()

    @property
    def places(self):
        if self.config.use_cuda:
            _places = fluid.framework.cuda_places()
        else:
            _places = fluid.framework.cpu_places()

        if not self.config.use_data_parallel:
            return [_places[0]]
        return _places

    @property
    def is_train_phase(self):
        return self.phase in ["train"]

    @property
    def is_test_phase(self):
        return self.phase in ["val", "dev", "test"]

    @property
    def is_predict_phase(self):
        return self.phase in ["predict", "inference"]

    @property
    def phase(self):
        return self._phases[-1]

    @property
    def env(self):
        phase = self.phase
        if phase in ["val", "dev", "test"]:
            phase = "val"
        if not phase in self._envs:
            self._envs[phase] = RunEnv()
        return self._envs[phase]

    @property
    def py_reader(self):
        if not self.env.is_inititalized:
            self._build_env()
        return self.env.py_reader

    @property
    def current_step(self):
        if not self.env.is_inititalized:
            self._build_env()
        return self.env.current_step

    @property
    def current_epoch(self):
        if not self.env.is_inititalized:
            self._build_env()
        return self.env.current_epoch

    @property
    def main_program(self):
        if not self.env.is_inititalized:
            self._build_env()
        return self.env.main_program

    @property
    def startup_program(self):
        if not self.env.is_inititalized:
            self._build_env()
        return self.env.startup_program

    @property
    def main_program_compiled(self):
        if not self.env.is_inititalized:
            self._build_env()
        return self.env.main_program_compiled

    @property
    def main_program_to_be_run(self):
        if self.config.use_data_parallel:
            if self._base_compiled_program is None:
                self._base_compiled_program = self.env.main_program_compiled
            return self.main_program_compiled
        return self.main_program

    @property
    def reader(self):
        if self.is_predict_phase:
            data = self._predict_data
        else:
            data = None
        self.env.reader = self._base_data_reader.data_generator(
            batch_size=self.config.batch_size, phase=self.phase, data=data)
        return self.env.reader

    @property
    def loss(self):
        if self.is_predict_phase:
            raise RuntimeError()

        if not self.env.is_inititalized:
            self._build_env()
        return self.env.loss

    @property
    def labels(self):
        if self.is_predict_phase:
            raise RuntimeError()

        if not self.env.is_inititalized:
            self._build_env()
        return self.env.labels

    @property
    def outputs(self):
        if not self.env.is_inititalized:
            self._build_env()
        return self.env.outputs

    @property
    def metrics(self):
        if self.is_predict_phase:
            raise RuntimeError()

        if not self.env.is_inititalized:
            self._build_env()
        return self.env.metrics

    @property
    def unique_name_generator(self):
        return self.env.UNG

    @property
    def feed_list(self):
        feed_list = [varname for varname in self._base_feed_list]
        if self.is_train_phase or self.is_test_phase:
            feed_list += [label.name for label in self.labels]
        return feed_list

    @property
    def feed_var_list(self):
        vars = self.main_program.global_block().vars
        return [vars[varname] for varname in self.feed_list]

    @property
    def fetch_list(self):
        if self.is_train_phase or self.is_test_phase:
            return [metric.name for metric in self.metrics] + [self.loss.name]
        return [output.name for output in self.outputs]

    def _build_env_start_event(self):
        pass

    def _build_env_end_event(self):
        if not self.is_predict_phase:
            self.env.score_scalar = {}

    def _finetune_start_event(self):
        logger.info("PaddleHub finetune start")

    def _finetune_end_event(self, run_states):
        logger.info("PaddleHub finetune finished.")

    def _predict_start_event(self):
        logger.info("PaddleHub predict start")

    def _predict_end_event(self, run_states):
        logger.info("PaddleHub predict finished.")

    def _eval_start_event(self):
        logger.info("Evaluation on {} dataset start".format(self.phase))

    def _eval_end_event(self, run_states):
        eval_scores, eval_loss, run_speed = self._calculate_metrics(run_states)
        self.tb_writer.add_scalar(
            tag="Loss_{}".format(self.phase),
            scalar_value=eval_loss,
            global_step=self._envs['train'].current_step)

        log_scores = ""
        for metric in eval_scores:
            self.tb_writer.add_scalar(
                tag="{}_{}".format(metric, self.phase),
                scalar_value=eval_scores[metric],
                global_step=self._envs['train'].current_step)

            log_scores += "%s=%.5f " % (metric, eval_scores[metric])
        logger.info(
            "[%s dataset evaluation result] loss=%.5f %s[step/sec: %.2f]" %
            (self.phase, eval_loss, log_scores, run_speed))

        eval_scores_items = eval_scores.items()
        if len(eval_scores_items):
            # The first metric will be chose to eval
            main_metric, main_value = list(eval_scores_items)[0]
        else:
            logger.warning(
                "None of metrics has been implemented, loss will be used to evaluate."
            )
            # The larger, the better
            main_metric, main_value = "negative loss", -eval_loss
        if self.phase in ["dev", "val"] and main_value > self.best_score:
            self.best_score = main_value
            model_saved_dir = os.path.join(self.config.checkpoint_dir,
                                           "best_model")
            logger.info("best model saved to %s [best %s=%.5f]" %
                        (model_saved_dir, main_metric, main_value))
            save_result = fluid.io.save_persistables(
                executor=self.exe,
                dirname=model_saved_dir,
                main_program=self.main_program)

    def _log_interval_event(self, run_states):
        scores, avg_loss, run_speed = self._calculate_metrics(run_states)
        self.tb_writer.add_scalar(
            tag="Loss_{}".format(self.phase),
            scalar_value=avg_loss,
            global_step=self._envs['train'].current_step)
        log_scores = ""
        for metric in scores:
            self.tb_writer.add_scalar(
                tag="{}_{}".format(metric, self.phase),
                scalar_value=scores[metric],
                global_step=self._envs['train'].current_step)
            log_scores += "%s=%.5f " % (metric, scores[metric])
        logger.info("step %d / %d: loss=%.5f %s[step/sec: %.2f]" %
                    (self.current_step, self.max_train_steps, avg_loss,
                     log_scores, run_speed))

    def _save_ckpt_interval_event(self):
        self.save_checkpoint()

    def _eval_interval_event(self):
        self.eval(phase="dev")

    def _run_step_event(self, run_state):
        if self.is_predict_phase:
            yield run_state.run_results

    def _build_net(self):
        raise NotImplementedError

    def _add_loss(self):
        raise NotImplementedError

    def _add_label(self):
        raise NotImplementedError

    def _add_metrics(self):
        # Some metrics like acc, auc can be calculated by fluid.layers
        # The others can be calculated in _calculate_metrics function
        raise NotImplementedError

    def _calculate_metrics(self, run_states):
        # NOTE: if you want to customize the metrics
        # you should make sure that the first parameter returned is a dict
        # The first key will be used as main metrics to update the best model
        raise NotImplementedError

    # NOTE: current saved checkpoint machanism is not completed,
    # it can't restore dataset training status
    def save_checkpoint(self):
        save_checkpoint(
            checkpoint_dir=self.config.checkpoint_dir,
            current_epoch=self.current_epoch,
            global_step=self.current_step,
            best_score=self.best_score,
            exe=self.exe,
            main_program=self.main_program)

    def load_checkpoint(self):
        is_load_successful, self.env.current_epoch, self.env.current_step, self.best_score = load_checkpoint(
            self.config.checkpoint_dir,
            self.exe,
            main_program=self.main_program)

        return is_load_successful

    def load_parameters(self, dirname):
        def if_exist(var):
            path = os.path.join(dirname, var.name)
            return os.path.exists(path)

        fluid.io.load_vars(
            self.exe, dirname, self.main_program, predicate=if_exist)

    def save_parameters(self, dirname):
        fluid.io.save_params(
            self.exe, dirname=dirname, main_program=self.main_program)

    def finetune_and_eval(self):
        return self.finetune(do_eval=True)

    def finetune(self, do_eval=False):
        # Start to finetune
        with self.phase_guard(phase="train"):
            self.init_if_necessary()
            self._finetune_start_event()
            run_states = []
            if self.current_epoch <= self.config.num_epoch:
                while self.current_epoch <= self.config.num_epoch:
                    self.config.strategy.step()
                    run_states = self._run(do_eval=do_eval)
                    self.env.current_epoch += 1

                # Final evaluation
                if self._base_data_reader.get_dev_examples() != []:
                    self.eval(phase="dev")
                if self._base_data_reader.get_test_examples() != []:
                    self.eval(phase="test", load_best_model=True)
                # Save checkpoint after finetune
                self.save_checkpoint()

            self._finetune_end_event(run_states)
            return run_states

    def eval(self, phase="dev", load_best_model=False):
        # Warning: DO NOT use eval(load_best_model=True) in finetune_and_eval
        # It will cause trainer unable to continue training from checkpoint after eval
        # More important, The model should evaluate current performance during training.
        with self.phase_guard(phase=phase):
            if load_best_model:
                self.init_if_load_best_model()
            else:
                self.init_if_necessary()
            self._eval_start_event()
            run_states = self._run()
            self._eval_end_event(run_states)
            return run_states

    def predict(self, data, load_best_model=True):
        with self.phase_guard(phase="predict"):
            if load_best_model:
                self.init_if_load_best_model()
            else:
                self.init_if_necessary()
            self._predict_data = data
            self._predict_start_event()
            run_states = self._run()
            self._predict_end_event(run_states)
            self._predict_data = None
        return run_states

    def _run(self, do_eval=False):
        with fluid.program_guard(self.main_program, self.startup_program):
            if self.config.use_pyreader:
                return self._run_with_py_reader(do_eval=do_eval)
            return self._run_with_data_feeder(do_eval=do_eval)

    def _run_with_data_feeder(self, do_eval=False):

        data_feeder = fluid.DataFeeder(
            feed_list=self.feed_list, place=self.place)

        global_run_states = []
        period_run_states = []

        for run_step, batch in enumerate(self.reader(), start=1):
            if self.config.use_data_parallel and len(batch) < self.device_count:
                continue
            step_run_state = RunState(len(self.fetch_list))
            step_run_state.run_step = 1
            num_batch_examples = len(batch)

            fetch_result = self.exe.run(
                self.main_program_to_be_run,
                feed=data_feeder.feed(batch),
                fetch_list=self.fetch_list)

            for index, result in enumerate(fetch_result):
                step_run_state.run_results[index] = result
            step_run_state.run_examples += num_batch_examples
            step_run_state.update()
            period_run_states += [step_run_state]
            self.env.current_step += 1
            if self.is_train_phase:
                if self.current_step % self.config.log_interval == 0:
                    self._log_interval_event(period_run_states)
                    global_run_states += period_run_states
                    period_run_states = []

                if self.config.save_ckpt_interval and self.current_step % self.config.save_ckpt_interval == 0:
                    self._save_ckpt_interval_event()

                if do_eval and self.current_step % self.config.eval_interval == 0:
                    self._eval_interval_event()

            self._run_step_event(step_run_state)

        global_run_states += period_run_states
        return global_run_states

    def _run_with_py_reader(self, do_eval=False):
        flag = False
        use_data_parallel_backup = self.config.use_data_parallel
        while True:
            global_run_states = []
            period_run_states = []
            self.py_reader.decorate_paddle_reader(self.reader)
            self.py_reader.start()
            try:
                while True:
                    num_batch_examples = self.config.batch_size * self.device_count
                    step_run_state = RunState(len(self.fetch_list))
                    step_run_state.run_step = 1
                    fetch_result = self.exe.run(
                        self.main_program_to_be_run, fetch_list=self.fetch_list)

                    for index, result in enumerate(fetch_result):
                        step_run_state.run_results[index] = result
                    step_run_state.run_examples += num_batch_examples
                    step_run_state.update()
                    period_run_states += [step_run_state]
                    self.env.current_step += 1
                    if self.is_train_phase:
                        if self.current_step % self.config.log_interval == 0:
                            self._log_interval_event(period_run_states)
                            global_run_states += period_run_states
                            period_run_states = []

                        if self.config.save_ckpt_interval and self.current_step % self.config.save_ckpt_interval == 0:
                            self._save_ckpt_interval_event()

                        if do_eval and self.current_step % self.config.eval_interval == 0:
                            self._eval_interval_event()

                    self._run_step_event(step_run_state)
            except fluid.core.EOFException:
                global_run_states += period_run_states
                self.py_reader.reset()
                '''
                When opening use_data_parallel and use_pyreader, if the amount of data is too small,
                the reader will have thrown EOF Exception when not fetching to the running result.
                In this case, temporarily close the use_data_parallel to get the result.
                '''
                if flag:
                    self.config._use_data_parallel = use_data_parallel_backup
                elif len(global_run_states) == 0:
                    flag = True
                    self.config._use_data_parallel = False
                    continue
                break

        return global_run_states
