import functools
from collections import OrderedDict
from typing import Any, Callable, cast, Dict, List, Mapping, Sequence, Tuple, Union

import torch

from ignite.engine import Engine, EventEnum, Events
from ignite.handlers.timing import Timer


class BasicTimeProfiler:
    """
    BasicTimeProfiler can be used to profile the handlers,
    events, data loading and data processing times.

    Examples:
        .. code-block:: python

            from ignite.handlers import BasicTimeProfiler

            trainer = Engine(train_updater)

            # Create an object of the profiler and attach an engine to it
            profiler = BasicTimeProfiler()
            profiler.attach(trainer)

            @trainer.on(Events.EPOCH_COMPLETED)
            def log_intermediate_results():
                profiler.print_results(profiler.get_results())

            trainer.run(dataloader, max_epochs=3)

            profiler.write_results('path_to_dir/time_profiling.csv')

    .. versionadded:: 0.4.6
    """

    events_to_ignore = [
        Events.EXCEPTION_RAISED,
        Events.TERMINATE,
        Events.TERMINATE_SINGLE_EPOCH,
        Events.DATALOADER_STOP_ITERATION,
        Events.INTERRUPT,
    ]

    def __init__(self) -> None:
        self._dataflow_timer = Timer()
        self._processing_timer = Timer()
        self._event_handlers_timer = Timer()

        self.dataflow_times = torch.zeros(1)
        self.processing_times = torch.zeros(1)
        self.event_handlers_times: Dict[EventEnum, torch.Tensor] = {}

        self._events = [
            Events.EPOCH_STARTED,
            Events.EPOCH_COMPLETED,
            Events.ITERATION_STARTED,
            Events.ITERATION_COMPLETED,
            Events.GET_BATCH_STARTED,
            Events.GET_BATCH_COMPLETED,
            Events.COMPLETED,
        ]
        self._fmethods = [
            self._as_first_epoch_started,
            self._as_first_epoch_completed,
            self._as_first_iter_started,
            self._as_first_iter_completed,
            self._as_first_get_batch_started,
            self._as_first_get_batch_completed,
            self._as_first_completed,
        ]
        self._lmethods = [
            self._as_last_epoch_started,
            self._as_last_epoch_completed,
            self._as_last_iter_started,
            self._as_last_iter_completed,
            self._as_last_get_batch_started,
            self._as_last_get_batch_completed,
            self._as_last_completed,
        ]

    def _reset(self, num_epochs: int, total_num_iters: int) -> None:
        self.dataflow_times = torch.zeros(total_num_iters)
        self.processing_times = torch.zeros(total_num_iters)
        self.event_handlers_times = {
            Events.STARTED: torch.zeros(1),
            Events.COMPLETED: torch.zeros(1),
            Events.EPOCH_STARTED: torch.zeros(num_epochs),
            Events.EPOCH_COMPLETED: torch.zeros(num_epochs),
            Events.ITERATION_STARTED: torch.zeros(total_num_iters),
            Events.ITERATION_COMPLETED: torch.zeros(total_num_iters),
            Events.GET_BATCH_COMPLETED: torch.zeros(total_num_iters),
            Events.GET_BATCH_STARTED: torch.zeros(total_num_iters),
        }

    def _as_first_started(self, engine: Engine) -> None:
        if hasattr(engine.state.dataloader, "__len__"):
            num_iters_per_epoch = len(engine.state.dataloader)  # type: ignore[arg-type]
        else:
            if engine.state.epoch_length is None:
                raise ValueError(
                    "As epoch_length is not set, we can not use BasicTimeProfiler in this case."
                    "Please, set trainer.run(..., epoch_length=epoch_length) in order to fix this."
                )
            num_iters_per_epoch = engine.state.epoch_length

        self.max_epochs = cast(int, engine.state.max_epochs)
        self.total_num_iters = self.max_epochs * num_iters_per_epoch
        self._reset(self.max_epochs, self.total_num_iters)

        self.event_handlers_names = {
            e: [
                h.__qualname__ if hasattr(h, "__qualname__") else h.__class__.__name__
                for (h, _, _) in engine._event_handlers[e]
                if "BasicTimeProfiler." not in repr(h)  # avoid adding internal handlers into output
            ]
            for e in Events
            if e not in self.events_to_ignore
        }

        # Setup all other handlers:
        engine._event_handlers[Events.STARTED].append((self._as_last_started, (engine,), {}))

        for e, m in zip(self._events, self._fmethods):
            engine._event_handlers[e].insert(0, (m, (engine,), {}))

        for e, m in zip(self._events, self._lmethods):
            engine._event_handlers[e].append((m, (engine,), {}))

        # Let's go
        self._event_handlers_timer.reset()

    def _as_last_started(self, engine: Engine) -> None:
        self.event_handlers_times[Events.STARTED][0] = self._event_handlers_timer.value()

    def _as_first_epoch_started(self, engine: Engine) -> None:
        self._event_handlers_timer.reset()

    def _as_last_epoch_started(self, engine: Engine) -> None:
        t = self._event_handlers_timer.value()
        e = engine.state.epoch - 1
        self.event_handlers_times[Events.EPOCH_STARTED][e] = t

    def _as_first_get_batch_started(self, engine: Engine) -> None:
        self._event_handlers_timer.reset()
        self._dataflow_timer.reset()

    def _as_last_get_batch_started(self, engine: Engine) -> None:
        t = self._event_handlers_timer.value()
        i = engine.state.iteration - 1
        self.event_handlers_times[Events.GET_BATCH_STARTED][i] = t

    def _as_first_get_batch_completed(self, engine: Engine) -> None:
        self._event_handlers_timer.reset()

    def _as_last_get_batch_completed(self, engine: Engine) -> None:
        t = self._event_handlers_timer.value()
        i = engine.state.iteration - 1
        self.event_handlers_times[Events.GET_BATCH_COMPLETED][i] = t

        d = self._dataflow_timer.value()
        self.dataflow_times[i] = d

        self._dataflow_timer.reset()

    def _as_first_iter_started(self, engine: Engine) -> None:
        self._event_handlers_timer.reset()

    def _as_last_iter_started(self, engine: Engine) -> None:
        t = self._event_handlers_timer.value()
        i = engine.state.iteration - 1
        self.event_handlers_times[Events.ITERATION_STARTED][i] = t

        self._processing_timer.reset()

    def _as_first_iter_completed(self, engine: Engine) -> None:
        t = self._processing_timer.value()
        i = engine.state.iteration - 1
        self.processing_times[i] = t

        self._event_handlers_timer.reset()

    def _as_last_iter_completed(self, engine: Engine) -> None:
        t = self._event_handlers_timer.value()
        i = engine.state.iteration - 1
        self.event_handlers_times[Events.ITERATION_COMPLETED][i] = t

    def _as_first_epoch_completed(self, engine: Engine) -> None:
        self._event_handlers_timer.reset()

    def _as_last_epoch_completed(self, engine: Engine) -> None:
        t = self._event_handlers_timer.value()
        e = engine.state.epoch - 1
        self.event_handlers_times[Events.EPOCH_COMPLETED][e] = t

    def _as_first_completed(self, engine: Engine) -> None:
        self._event_handlers_timer.reset()

    def _as_last_completed(self, engine: Engine) -> None:
        self.event_handlers_times[Events.COMPLETED][0] = self._event_handlers_timer.value()

        # Remove added handlers:
        engine.remove_event_handler(self._as_last_started, Events.STARTED)

        for e, m in zip(self._events, self._fmethods):
            engine.remove_event_handler(m, e)

        for e, m in zip(self._events, self._lmethods):
            engine.remove_event_handler(m, e)

    def attach(self, engine: Engine) -> None:
        """Attach BasicTimeProfiler to the given engine.

        Args:
            engine: the instance of Engine to attach
        """
        if not isinstance(engine, Engine):
            raise TypeError(f"Argument engine should be ignite.engine.Engine, but given {type(engine)}")

        if not engine.has_event_handler(self._as_first_started):
            engine._event_handlers[Events.STARTED].insert(0, (self._as_first_started, (engine,), {}))

    @staticmethod
    def _compute_basic_stats(data: torch.Tensor) -> Dict[str, Union[str, float, Tuple[float, float]]]:
        # compute on non-zero data:
        data = data[data > 0]
        out: List[Tuple[str, Union[str, float, Tuple[float, float]]]] = [
            ("total", torch.sum(data).item() if len(data) > 0 else "not yet triggered")
        ]
        if len(data) > 1:
            out.extend(
                [
                    ("min/index", (torch.min(data).item(), torch.argmin(data).item())),
                    ("max/index", (torch.max(data).item(), torch.argmax(data).item())),
                    ("mean", torch.mean(data).item()),
                    ("std", torch.std(data).item()),
                ]
            )
        return OrderedDict(out)

    def get_results(self) -> Dict[str, Dict[str, Any]]:
        """
        Method to fetch the aggregated profiler results after the engine is run

        .. code-block:: python

            results = profiler.get_results()

        """
        total_eh_time: Union[int, torch.Tensor] = sum(
            [(self.event_handlers_times[e]).sum() for e in Events if e not in self.events_to_ignore]
        )
        event_handlers_stats = dict(
            [
                (str(e.name).replace(".", "_"), self._compute_basic_stats(self.event_handlers_times[e]))
                for e in Events
                if e not in self.events_to_ignore
            ]
            + [("total_time", total_eh_time)]
        )

        return OrderedDict(
            [
                ("processing_stats", self._compute_basic_stats(self.processing_times)),
                ("dataflow_stats", self._compute_basic_stats(self.dataflow_times)),
                ("event_handlers_stats", event_handlers_stats),
                (
                    "event_handlers_names",
                    {str(e.name).replace(".", "_") + "_names": v for e, v in self.event_handlers_names.items()},
                ),
            ]
        )

    def write_results(self, output_path: str) -> None:
        """
        Method to store the unaggregated profiling results to a csv file

        Args:
            output_path: file output path containing a filename

        .. code-block:: python

            profiler.write_results('path_to_dir/awesome_filename.csv')

        Examples:
            .. code-block:: text

                -----------------------------------------------------------------
                epoch iteration processing_stats dataflow_stats Event_STARTED ...
                1.0     1.0        0.00003         0.252387        0.125676
                1.0     2.0        0.00029         0.252342        0.125123

        """
        try:
            import pandas as pd
        except ImportError:
            raise ModuleNotFoundError("Need pandas to write results as files")

        iters_per_epoch = self.total_num_iters // self.max_epochs

        epochs = torch.arange(self.max_epochs, dtype=torch.float32).repeat_interleave(iters_per_epoch) + 1
        iterations = torch.arange(self.total_num_iters, dtype=torch.float32) + 1
        processing_stats = self.processing_times
        dataflow_stats = self.dataflow_times

        event_started = self.event_handlers_times[Events.STARTED].repeat_interleave(self.total_num_iters)
        event_completed = self.event_handlers_times[Events.COMPLETED].repeat_interleave(self.total_num_iters)
        event_epoch_started = self.event_handlers_times[Events.EPOCH_STARTED].repeat_interleave(iters_per_epoch)
        event_epoch_completed = self.event_handlers_times[Events.EPOCH_COMPLETED].repeat_interleave(iters_per_epoch)

        event_iter_started = self.event_handlers_times[Events.ITERATION_STARTED]
        event_iter_completed = self.event_handlers_times[Events.ITERATION_COMPLETED]
        event_batch_started = self.event_handlers_times[Events.GET_BATCH_STARTED]
        event_batch_completed = self.event_handlers_times[Events.GET_BATCH_COMPLETED]

        results_dump = torch.stack(
            [
                epochs,
                iterations,
                processing_stats,
                dataflow_stats,
                event_started,
                event_completed,
                event_epoch_started,
                event_epoch_completed,
                event_iter_started,
                event_iter_completed,
                event_batch_started,
                event_batch_completed,
            ],
            dim=1,
        ).numpy()

        results_df = pd.DataFrame(
            data=results_dump,
            columns=[
                "epoch",
                "iteration",
                "processing_stats",
                "dataflow_stats",
                "Event_STARTED",
                "Event_COMPLETED",
                "Event_EPOCH_STARTED",
                "Event_EPOCH_COMPLETED",
                "Event_ITERATION_STARTED",
                "Event_ITERATION_COMPLETED",
                "Event_GET_BATCH_STARTED",
                "Event_GET_BATCH_COMPLETED",
            ],
        )
        results_df.to_csv(output_path, index=False)

    @staticmethod
    def print_results(results: Dict) -> str:
        """
        Method to print the aggregated results from the profiler

        Args:
            results: the aggregated results from the profiler

        .. code-block:: python

            profiler.print_results(results)

        Examples:
            .. code-block:: text

                 ----------------------------------------------------
                | Time profiling stats (in seconds):                 |
                 ----------------------------------------------------
                total  |  min/index  |  max/index  |  mean  |  std

                Processing function:
                157.46292 | 0.01452/1501 | 0.26905/0 | 0.07730 | 0.01258

                Dataflow:
                6.11384 | 0.00008/1935 | 0.28461/1551 | 0.00300 | 0.02693

                Event handlers:
                2.82721

                - Events.STARTED: []
                0.00000

                - Events.EPOCH_STARTED: []
                0.00006 | 0.00000/0 | 0.00000/17 | 0.00000 | 0.00000

                - Events.ITERATION_STARTED: ['PiecewiseLinear']
                0.03482 | 0.00001/188 | 0.00018/679 | 0.00002 | 0.00001

                - Events.ITERATION_COMPLETED: ['TerminateOnNan']
                0.20037 | 0.00006/866 | 0.00089/1943 | 0.00010 | 0.00003

                - Events.EPOCH_COMPLETED: ['empty_cuda_cache', 'training.<locals>.log_elapsed_time', ]
                2.57860 | 0.11529/0 | 0.14977/13 | 0.12893 | 0.00790

                - Events.COMPLETED: []
                not yet triggered

        """

        def to_str(v: Union[str, tuple]) -> str:
            if isinstance(v, str):
                return v
            elif isinstance(v, tuple):
                return f"{v[0]:.5f}/{v[1]}"
            return f"{v:.5f}"

        def odict_to_str(d: Mapping) -> str:
            out = " | ".join([to_str(v) for v in d.values()])
            return out

        others = {
            k: odict_to_str(v) if isinstance(v, OrderedDict) else v for k, v in results["event_handlers_stats"].items()
        }

        others.update(results["event_handlers_names"])

        output_message = """
 ----------------------------------------------------
| Time profiling stats (in seconds):                 |
 ----------------------------------------------------
total  |  min/index  |  max/index  |  mean  |  std

Processing function:
{processing_stats}

Dataflow:
{dataflow_stats}

Event handlers:
{total_time:.5f}

- Events.STARTED: {STARTED_names}
{STARTED}

- Events.EPOCH_STARTED: {EPOCH_STARTED_names}
{EPOCH_STARTED}

- Events.ITERATION_STARTED: {ITERATION_STARTED_names}
{ITERATION_STARTED}

- Events.ITERATION_COMPLETED: {ITERATION_COMPLETED_names}
{ITERATION_COMPLETED}

- Events.EPOCH_COMPLETED: {EPOCH_COMPLETED_names}
{EPOCH_COMPLETED}

- Events.COMPLETED: {COMPLETED_names}
{COMPLETED}
""".format(
            processing_stats=odict_to_str(results["processing_stats"]),
            dataflow_stats=odict_to_str(results["dataflow_stats"]),
            **others,
        )
        print(output_message)
        return output_message


class HandlersTimeProfiler:
    """
    HandlersTimeProfiler can be used to profile the handlers,
    data loading and data processing times. Custom events are also
    profiled by this profiler

    Examples:
        .. code-block:: python

            from ignite.handlers import HandlersTimeProfiler

            trainer = Engine(train_updater)

            # Create an object of the profiler and attach an engine to it
            profiler = HandlersTimeProfiler()
            profiler.attach(trainer)

            @trainer.on(Events.EPOCH_COMPLETED)
            def log_intermediate_results():
                profiler.print_results(profiler.get_results())

            trainer.run(dataloader, max_epochs=3)

            profiler.write_results('path_to_dir/time_profiling.csv')

    .. versionadded:: 0.4.6
    """

    EVENT_FILTER_THESHOLD_TIME = 0.0001

    def __init__(self) -> None:
        self._dataflow_timer = Timer()
        self._processing_timer = Timer()
        self._event_handlers_timer = Timer()

        self.dataflow_times: List[float] = []
        self.processing_times: List[float] = []
        self.event_handlers_times: Dict[EventEnum, Dict[str, List[float]]] = {}

    @staticmethod
    def _get_callable_name(handler: Callable) -> str:
        # get name of the callable handler
        return getattr(handler, "__qualname__", handler.__class__.__name__)

    def _create_wrapped_handler(self, handler: Callable, event: EventEnum) -> Callable:
        @functools.wraps(handler)
        def _timeit_handler(*args: Any, **kwargs: Any) -> None:
            self._event_handlers_timer.reset()
            handler(*args, **kwargs)
            t = self._event_handlers_timer.value()
            hname = self._get_callable_name(handler)
            # filter profiled time if the handler was attached to event with event filter
            if not hasattr(handler, "_parent") or t >= self.EVENT_FILTER_THESHOLD_TIME:
                self.event_handlers_times[event][hname].append(t)

        # required to revert back to original handler after profiling
        setattr(_timeit_handler, "_profiler_original", handler)
        return _timeit_handler

    def _timeit_processing(self) -> None:
        # handler used for profiling processing times
        t = self._processing_timer.value()
        self.processing_times.append(t)

    def _timeit_dataflow(self) -> None:
        # handler used for profiling dataflow times
        t = self._dataflow_timer.value()
        self.dataflow_times.append(t)

    def _reset(self, event_handlers_names: Mapping[EventEnum, List[str]]) -> None:
        # reset the variables used for profiling
        self.dataflow_times = []
        self.processing_times = []

        self.event_handlers_times = {e: {h: [] for h in event_handlers_names[e]} for e in event_handlers_names}

    @staticmethod
    def _is_internal_handler(handler: Callable) -> bool:
        # checks whether the handler is internal
        return any(n in repr(handler) for n in ["HandlersTimeProfiler.", "Timer."])

    def _detach_profiler_handlers(self, engine: Engine) -> None:
        # reverts handlers to original handlers
        for e in engine._event_handlers:
            for i, (func, args, kwargs) in enumerate(engine._event_handlers[e]):
                if hasattr(func, "_profiler_original"):
                    engine._event_handlers[e][i] = (func._profiler_original, args, kwargs)

    def _as_first_started(self, engine: Engine) -> None:
        # wraps original handlers for profiling

        self.event_handlers_names = {
            e: [
                self._get_callable_name(h)
                for (h, _, _) in engine._event_handlers[e]
                if not self._is_internal_handler(h)
            ]
            for e in engine._allowed_events
        }

        self._reset(self.event_handlers_names)

        for e in engine._allowed_events:
            for i, (func, args, kwargs) in enumerate(engine._event_handlers[e]):
                if not self._is_internal_handler(func):
                    engine._event_handlers[e][i] = (self._create_wrapped_handler(func, e), args, kwargs)

        # processing timer
        engine.add_event_handler(Events.ITERATION_STARTED, self._processing_timer.reset)
        engine._event_handlers[Events.ITERATION_COMPLETED].insert(0, (self._timeit_processing, (), {}))

        # dataflow timer
        engine.add_event_handler(Events.GET_BATCH_STARTED, self._dataflow_timer.reset)
        engine._event_handlers[Events.GET_BATCH_COMPLETED].insert(0, (self._timeit_dataflow, (), {}))

        # revert back the wrapped handlers with original handlers at the end
        engine.add_event_handler(Events.COMPLETED, self._detach_profiler_handlers)

    def attach(self, engine: Engine) -> None:
        """Attach HandlersTimeProfiler to the given engine.

        Args:
            engine: the instance of Engine to attach
        """
        if not isinstance(engine, Engine):
            raise TypeError(f"Argument engine should be ignite.engine.Engine, but given {type(engine)}")

        if not engine.has_event_handler(self._as_first_started):
            engine._event_handlers[Events.STARTED].insert(0, (self._as_first_started, (engine,), {}))

    def get_results(self) -> List[List[Union[str, float, Tuple[Union[str, float], Union[str, float]]]]]:
        """
        Method to fetch the aggregated profiler results after the engine is run

        .. code-block:: python

            results = profiler.get_results()

        """
        total_eh_time = sum(
            [
                sum(self.event_handlers_times[e][h])
                for e in self.event_handlers_times
                for h in self.event_handlers_times[e]
            ]
        )
        total_eh_time = round(float(total_eh_time), 5)

        def compute_basic_stats(
            times: Union[Sequence, torch.Tensor]
        ) -> List[Union[str, float, Tuple[Union[str, float], Union[str, float]]]]:
            data = torch.as_tensor(times, dtype=torch.float32)
            # compute on non-zero data:
            data = data[data > 0]
            total: Union[str, float] = round(torch.sum(data).item(), 5) if len(data) > 0 else "not triggered"
            min_index: Tuple[Union[str, float], Union[str, float]] = ("None", "None")
            max_index: Tuple[Union[str, float], Union[str, float]] = ("None", "None")
            mean: Union[str, float] = "None"
            std: Union[str, float] = "None"
            if len(data) > 0:
                min_index = (round(torch.min(data).item(), 5), torch.argmin(data).item())
                max_index = (round(torch.max(data).item(), 5), torch.argmax(data).item())
                mean = round(torch.mean(data).item(), 5)
                if len(data) > 1:
                    std = round(torch.std(data).item(), 5)
            return [total, min_index, max_index, mean, std]

        event_handler_stats = [
            [
                h,
                getattr(e, "name", str(e)),
                *compute_basic_stats(torch.tensor(self.event_handlers_times[e][h], dtype=torch.float32)),
            ]
            for e in self.event_handlers_times
            for h in self.event_handlers_times[e]
        ]
        event_handler_stats.append(["Total", "", total_eh_time, "", "", "", ""])
        event_handler_stats.append(["Processing", "None", *compute_basic_stats(self.processing_times)])
        event_handler_stats.append(["Dataflow", "None", *compute_basic_stats(self.dataflow_times)])

        return event_handler_stats

    def write_results(self, output_path: str) -> None:
        """
        Method to store the unaggregated profiling results to a csv file

        Args:
            output_path: file output path containing a filename

        .. code-block:: python

            profiler.write_results('path_to_dir/awesome_filename.csv')

        Examples:
            .. code-block:: text

                -----------------------------------------------------------------
                # processing_stats dataflow_stats training.<locals>.log_elapsed_time (EPOCH_COMPLETED) ...
                1     0.00003         0.252387                          0.125676
                2     0.00029         0.252342                          0.125123

        """
        try:
            import pandas as pd
        except ImportError:
            raise ModuleNotFoundError("Need pandas to write results as files")

        processing_stats = torch.tensor(self.processing_times, dtype=torch.float32)
        dataflow_stats = torch.tensor(self.dataflow_times, dtype=torch.float32)

        cols = [processing_stats, dataflow_stats]
        headers = ["processing_stats", "dataflow_stats"]
        for e in self.event_handlers_times:
            for h in self.event_handlers_times[e]:
                headers.append(f"{h} ({getattr(e, 'name', str(e))})")
                cols.append(torch.tensor(self.event_handlers_times[e][h], dtype=torch.float32))
        # Determine maximum length
        max_len = max([x.numel() for x in cols])

        count_col = torch.arange(max_len, dtype=torch.float32) + 1
        cols.insert(0, count_col)
        headers.insert(0, "#")

        # pad all tensors to have same length
        cols = [torch.nn.functional.pad(x, pad=(0, max_len - x.numel()), mode="constant", value=0) for x in cols]

        results_dump = torch.stack(cols, dim=1).numpy()

        results_df = pd.DataFrame(data=results_dump, columns=headers)
        results_df.to_csv(output_path, index=False)

    @staticmethod
    def print_results(results: List[List[Union[str, float]]]) -> None:
        """
        Method to print the aggregated results from the profiler

        Args:
            results: the aggregated results from the profiler

        .. code-block:: python

            profiler.print_results(results)

        Examples:
            .. code-block:: text

                -----------------------------------------  -----------------------  -------------- ...
                Handler                                    Event Name                     Total(s)
                -----------------------------------------  -----------------------  --------------
                run.<locals>.log_training_results          EPOCH_COMPLETED                19.43245
                run.<locals>.log_validation_results        EPOCH_COMPLETED                 2.55271
                run.<locals>.log_time                      EPOCH_COMPLETED                 0.00049
                run.<locals>.log_intermediate_results      EPOCH_COMPLETED                 0.00106
                run.<locals>.log_training_loss             ITERATION_COMPLETED               0.059
                run.<locals>.log_time                      COMPLETED                 not triggered
                -----------------------------------------  -----------------------  --------------
                Total                                                                     22.04571
                -----------------------------------------  -----------------------  --------------
                Processing took total 11.29543s [min/index: 0.00393s/1875, max/index: 0.00784s/0,
                 mean: 0.00602s, std: 0.00034s]
                Dataflow took total 16.24365s [min/index: 0.00533s/1874, max/index: 0.01129s/937,
                 mean: 0.00866s, std: 0.00113s]

        """
        # adopted implementation of torch.autograd.profiler.build_table
        handler_column_width = max([len(item[0]) for item in results]) + 4  # type: ignore[arg-type]
        event_column_width = max([len(item[1]) for item in results]) + 4  # type: ignore[arg-type]

        DEFAULT_COLUMN_WIDTH = 14

        headers = [
            "Handler",
            "Event Name",
            "Total(s)",
            "Min(s)/IDX",
            "Max(s)/IDX",
            "Mean(s)",
            "Std(s)",
        ]

        # Have to use a list because nonlocal is Py3 only...
        SPACING_SIZE = 2
        row_format_lst = [""]
        header_sep_lst = [""]
        line_length_lst = [-SPACING_SIZE]

        def add_column(padding: int, text_dir: str = ">") -> None:
            row_format_lst[0] += "{: " + text_dir + str(padding) + "}" + (" " * SPACING_SIZE)
            header_sep_lst[0] += "-" * padding + (" " * SPACING_SIZE)
            line_length_lst[0] += padding + SPACING_SIZE

        add_column(handler_column_width, text_dir="<")
        add_column(event_column_width, text_dir="<")
        for _ in headers[2:]:
            add_column(DEFAULT_COLUMN_WIDTH)

        row_format = row_format_lst[0]
        header_sep = header_sep_lst[0]

        result = []

        def append(s: str) -> None:
            result.append(s)
            result.append("\n")

        result.append("\n")
        append(header_sep)
        append(row_format.format(*headers))
        append(header_sep)

        for row in results[:-3]:
            # format min/idx and max/idx
            row[3] = "{}/{}".format(*row[3])  # type: ignore[misc]
            row[4] = "{}/{}".format(*row[4])  # type: ignore[misc]

            append(row_format.format(*row))

        append(header_sep)
        # print total handlers time row
        append(row_format.format(*results[-3]))
        append(header_sep)

        summary_format = "{} took total {}s [min/index: {}, max/index: {}, mean: {}s, std: {}s]"
        for row in results[-2:]:
            row[3] = "{}s/{}".format(*row[3])  # type: ignore[misc]
            row[4] = "{}s/{}".format(*row[4])  # type: ignore[misc]
            del row[1]
            append(summary_format.format(*row))
        print("".join(result))