#!/usr/bin/env python
# -*- encoding: utf-8 -*-

import os
import os.path as osp

import torch
from typing import List
from decimal import Decimal
from colossalai.context import ParallelMode
from colossalai.core import global_context as gpc
from colossalai.registry import HOOKS
from colossalai.logging import DistributedLogger
from colossalai.utils import report_memory_usage, is_dp_rank_0, \
    is_tp_rank_0, is_no_pp_or_last_stage, MultiTimer
from ._base_hook import BaseHook


def _format_number(val, prec=5):
    if isinstance(val, float):
        return f'{val:.{prec}g}'
    elif torch.is_tensor(val) and torch.is_floating_point(val):
        return f'{val.item():.{prec}g}'
    return val


class LogByEpochHook(BaseHook):
    """Hook to log by epoch.

    Args:
        logger (:class:`colossalai.logging.DistributedLogger`): Logger for recording the log information.
        interval (int, optional): Interval of printing log information, defaults to 1.
        priority (int, optional): Priority in the printing, hooks with small priority will be printed in front,
            defaults to 1. If different hooks share same priority, the order of printing would
            depend on the hooks order in the hook list.
    """

    def __init__(self,
                 logger,
                 interval: int = 1,
                 priority: int = 1):
        super().__init__(priority)
        self.logger = logger
        self._interval = interval

    def _is_epoch_to_log(self, trainer):
        return trainer.cur_epoch % self._interval == 0


@HOOKS.register_module
class LogMetricByStepHook(BaseHook):
    """Hook to log metric by step.

    Args:
        priority (int, optional): Priority in the printing, hooks with small priority will be printed in front,
            defaults to 10. If different hooks share same priority, the order of printing would
            depend on the hooks order in the hook list.
    """

    def __init__(self, priority: int = 10):
        super().__init__(priority)

    def after_train_iter(self, trainer, *args):
        trainer.states['step_metrics'] = dict()
        for metric_name, metric_calculator in trainer.states['metrics']['train'].items():
            trainer.states['step_metrics'][metric_name.lower()] = \
                f'{_format_number(metric_calculator.get_last_step_value())}'

    def after_test_iter(self, trainer, *args):
        trainer.states['step_metrics'] = dict()
        for metric_name, metric_calculator in trainer.states['metrics']['test'].items():
            trainer.states['step_metrics'][metric_name.lower()] = \
                f'{_format_number(metric_calculator.get_last_step_value())}'


@HOOKS.register_module
class LogMetricByEpochHook(LogByEpochHook):
    """Specialized hook to record the metric to log.

    Args:
        logger (:class:`colossalai.logging.DistributedLogger`): Logger for recording the log information.
        interval (int, optional): Interval of printing log information, defaults to 1.
        priority (int, optional): Priority in the printing, hooks with small priority will be printed in front,
            defaults to 10. If different hooks share same priority, the order of printing would
            depend on the hooks order in the hook list.
    """

    def __init__(self,
                 logger,
                 interval: int = 1,
                 priority: int = 10) -> None:
        super().__init__(logger, interval, priority)
        self._is_rank_to_log = is_dp_rank_0() and is_tp_rank_0() and is_no_pp_or_last_stage()

    def _get_str(self, trainer, mode):
        msg = []
        for metric_name, metric_calculator in trainer.states['metrics'][mode].items():
            msg.append(
                f'{metric_name} = {_format_number(metric_calculator.get_accumulated_value())}')
        msg = ' | '.join(msg)
        return msg

    def after_train_epoch(self, trainer):
        if self._is_epoch_to_log(trainer):
            msg = self._get_str(trainer=trainer, mode='train')

            if self._is_rank_to_log:
                self.logger.info(f'[Epoch {trainer.cur_epoch} / Train]: {msg}')
                # f'Training - Epoch {trainer.cur_epoch} - {self.__class__.__name__}: {msg}')

    def after_test_epoch(self, trainer):
        if self._is_epoch_to_log(trainer):
            msg = self._get_str(trainer=trainer, mode='test')
            if self._is_rank_to_log:
                self.logger.info(f'[Epoch {trainer.cur_epoch} / Test]: {msg}')
                # f'Testing - Epoch {trainer.cur_epoch} - {self.__class__.__name__}: {msg}')


@HOOKS.register_module
class TensorboardHook(BaseHook):
    """Specialized hook to record the metric to Tensorboard.

    Args:
        log_dir (str): Directory of log.
        ranks (list): Ranks of processors.
        parallel_mode (:class:`colossalai.context.parallel_mode.ParallelMode`, optional): Parallel mode used in trainer,
            defaults to colossalai.context.parallel_mode.ParallelMode.GLOBAL.
        priority (int, optional): Priority in the printing, hooks with small priority will be printed in front,
            defaults to 10. If different hooks share same priority, the order of printing would
            depend on the hooks order in the hook list.
    """

    def __init__(self,
                 log_dir: str,
                 ranks: List = None,
                 parallel_mode: ParallelMode = ParallelMode.GLOBAL,
                 priority: int = 10,
                 ) -> None:
        super().__init__(priority=priority)
        from torch.utils.tensorboard import SummaryWriter

        # create log dir
        if not gpc.is_initialized(ParallelMode.GLOBAL) or gpc.get_global_rank() == 0:
            os.makedirs(log_dir, exist_ok=True)

        # determine the ranks to generate tensorboard logs
        self._is_valid_rank_to_log = False
        if not gpc.is_initialized(parallel_mode):
            self._is_valid_rank_to_log = True
        else:
            local_rank = gpc.get_local_rank(parallel_mode)

            if ranks is None or local_rank in ranks:
                self._is_valid_rank_to_log = True

        # check for
        if gpc.is_initialized(ParallelMode.PIPELINE) and \
                not gpc.is_last_rank(ParallelMode.PIPELINE) and self._is_valid_rank_to_log:
            raise ValueError("Tensorboard hook can only log on the last rank of pipeline process group")

        if self._is_valid_rank_to_log:
            # create workspace on only one rank
            if gpc.is_initialized(parallel_mode):
                rank = gpc.get_local_rank(parallel_mode)
            else:
                rank = 0

            # create workspace
            log_dir = osp.join(log_dir, f'{parallel_mode}_rank_{rank}')
            os.makedirs(log_dir, exist_ok=True)

            self.writer = SummaryWriter(log_dir=log_dir, filename_suffix=f'_rank_{rank}')

    def _log_by_iter(self, trainer, mode: str):
        for metric_name, metric_calculator in trainer.states['metrics'][mode].items():
            if metric_calculator.epoch_only:
                continue
            val = metric_calculator.get_last_step_value()

            if self._is_valid_rank_to_log:
                self.writer.add_scalar(f'{metric_name}/{mode}', val, trainer.cur_step)

    def _log_by_epoch(self, trainer, mode: str):
        for metric_name, metric_calculator in trainer.states['metrics'][mode].items():
            if metric_calculator.epoch_only:
                val = metric_calculator.get_accumulated_value()
                if self._is_valid_rank_to_log:
                    self.writer.add_scalar(f'{metric_name}/{mode}', val, trainer.cur_step)

    def after_test_iter(self, trainer, *args):
        self._log_by_iter(trainer, mode='test')

    def after_test_epoch(self, trainer):
        self._log_by_epoch(trainer, mode='test')

    def after_train_iter(self, trainer, *args):
        self._log_by_iter(trainer, mode='train')

    def after_train_epoch(self, trainer):
        self._log_by_epoch(trainer, mode='train')


@HOOKS.register_module
class LogTimingByEpochHook(LogByEpochHook):
    """Specialized hook to write timing record to log.

    Args:
        timer (:class:`colossalai.utils.MultiTimer`): Timer for the hook.
        logger (:class:`colossalai.logging.DistributedLogger`): Logger for recording the log information.
        interval (int, optional): Interval of printing log information, defaults to 1.
        priority (int, optional): Priority in the printing, hooks with small priority will be printed in front
            defaults to 10. If different hooks share same priority, the order of printing would
            depend on the hooks order in the hook list.
        log_eval (bool, optional): Whether writes in evaluation, defaults to True.
        ignore_num_train_steps (int, optional): Number of training steps to ignore, defaults to 0.
    """

    def __init__(self,
                 timer: MultiTimer,
                 logger: DistributedLogger,
                 interval: int = 1,
                 priority: int = 10,
                 log_eval: bool = True,
                 ignore_num_train_steps: int = 0) -> None:
        super().__init__(logger=logger, interval=interval, priority=priority)
        self._timer = timer
        self._log_eval = log_eval
        self._is_rank_to_log = is_dp_rank_0() and is_tp_rank_0() and is_no_pp_or_last_stage()

        # extra handling to avoid the unstable readings of the first
        # few training steps to affect the history mean time
        self._ignore_num_train_steps = ignore_num_train_steps
        self._is_train_step_history_trimmed = False

    def _get_message(self, mode):
        msg = []
        for timer_name, timer in self._timer:
            if timer_name.startswith(mode):
                last_elapsed_time = timer.get_elapsed_time()
                if timer.has_history:
                    if timer_name == 'Train-step' and not self._is_train_step_history_trimmed:
                        timer._history = timer._history[self._ignore_num_train_steps:]
                        self._is_train_step_history_trimmed = True
                    history_mean = timer.get_history_mean()
                    history_sum = timer.get_history_sum()
                    msg.append(
                        f'{timer_name}: last = {_format_number(last_elapsed_time)} s, mean = {_format_number(history_mean)} s'
                    )
                else:
                    msg.append(f'{timer_name}: last = {_format_number(last_elapsed_time)} s')

        msg = ' | '.join(msg)
        return msg

    def after_train_epoch(self, trainer):
        """Writes log after finishing a training epoch.
        """
        if self._is_epoch_to_log(trainer) and self._is_rank_to_log:
            msg = self._get_message('Train')
            self.logger.info(f'[Epoch {trainer.cur_epoch} / Train]: {msg} | #steps/epoch = {trainer.steps_per_epoch}')

    def after_test_epoch(self, trainer):
        """Writes log after finishing a testing epoch.
        """
        if self._is_epoch_to_log(trainer) and self._is_rank_to_log and self._log_eval:
            msg = self._get_message('Test')
            self.logger.info(f'[Epoch {trainer.cur_epoch} / Test]: {msg}')


@HOOKS.register_module
class LogMemoryByEpochHook(LogByEpochHook):
    """Specialized Hook to write memory usage record to log.

    Args:
        logger (:class:`colossalai.logging.DistributedLogger`): Logger for recording the log information.
        interval (int, optional): Interval of printing log information, defaults to 1.
        priority (int, optional): Priority in the printing, hooks with small priority will be printed in front
            defaults to 1. If different hooks share same priority, the order of printing would
            depend on the hooks order in the hook list.
        log_eval (bool, optional): Whether writes in evaluation, defaults to True.
    """

    def __init__(self,
                 logger: DistributedLogger,
                 interval: int = 1,
                 priority: int = 10,
                 log_eval: bool = True,
                 report_cpu: bool = False,  # no reference
                 ) -> None:
        super().__init__(logger=logger, interval=interval, priority=priority)
        self._log_eval = log_eval
        self._is_rank_to_log = is_dp_rank_0() and is_tp_rank_0()

    def before_train(self, trainer):
        """Resets before training.
        """
        if self._is_epoch_to_log(trainer) and self._is_rank_to_log:
            report_memory_usage('Before-train', self.logger)

    def after_train_epoch(self, trainer):
        """Writes log after finishing a training epoch.
        """
        if self._is_epoch_to_log(trainer) and self._is_rank_to_log:
            report_memory_usage(f'[Epoch {trainer.cur_epoch} / Train]', self.logger)

    def after_test(self, trainer):
        """Reports after testing.
        """
        if self._is_epoch_to_log(trainer) and self._is_rank_to_log and self._log_eval:
            report_memory_usage(f'[Epoch {trainer.cur_epoch} / Test]', self.logger)