#!/usr/bin/env python3
# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved

"""
DensePose Training Script.

This script is similar to the training script in detectron2/tools.

It is an example of how a user might use detectron2 for a new project.
"""

import logging
import os
from collections import OrderedDict
from fvcore.common.file_io import PathManager

import detectron2.utils.comm as comm
from detectron2.checkpoint import DetectionCheckpointer
from detectron2.config import CfgNode, get_cfg
from detectron2.engine import DefaultTrainer, default_argument_parser, default_setup, hooks, launch
from detectron2.evaluation import COCOEvaluator, DatasetEvaluators, verify_results
from detectron2.modeling import DatasetMapperTTA
from detectron2.utils.logger import setup_logger

from densepose import (
    DensePoseCOCOEvaluator,
    DensePoseGeneralizedRCNNWithTTA,
    add_dataset_category_config,
    add_densepose_config,
    load_from_cfg,
)
from densepose.data import DatasetMapper, build_detection_test_loader, build_detection_train_loader


class Trainer(DefaultTrainer):
    @classmethod
    def build_evaluator(cls, cfg: CfgNode, dataset_name, output_folder=None):
        if output_folder is None:
            output_folder = os.path.join(cfg.OUTPUT_DIR, "inference")
        evaluators = [COCOEvaluator(dataset_name, cfg, True, output_folder)]
        if cfg.MODEL.DENSEPOSE_ON:
            evaluators.append(DensePoseCOCOEvaluator(dataset_name, True, output_folder))
        return DatasetEvaluators(evaluators)

    @classmethod
    def build_test_loader(cls, cfg: CfgNode, dataset_name):
        return build_detection_test_loader(cfg, dataset_name, mapper=DatasetMapper(cfg, False))

    @classmethod
    def build_train_loader(cls, cfg: CfgNode):
        return build_detection_train_loader(cfg, mapper=DatasetMapper(cfg, True))

    @classmethod
    def test_with_TTA(cls, cfg: CfgNode, model):
        logger = logging.getLogger("detectron2.trainer")
        # In the end of training, run an evaluation with TTA
        # Only support some R-CNN models.
        logger.info("Running inference with test-time augmentation ...")
        transform_data = load_from_cfg(cfg)
        model = DensePoseGeneralizedRCNNWithTTA(cfg, model, transform_data, DatasetMapperTTA(cfg))
        evaluators = [
            cls.build_evaluator(
                cfg, name, output_folder=os.path.join(cfg.OUTPUT_DIR, "inference_TTA")
            )
            for name in cfg.DATASETS.TEST
        ]
        res = cls.test(cfg, model, evaluators)
        res = OrderedDict({k + "_TTA": v for k, v in res.items()})
        return res


def setup(args):
    cfg = get_cfg()
    add_dataset_category_config(cfg)
    add_densepose_config(cfg)
    cfg.merge_from_file(args.config_file)
    cfg.merge_from_list(args.opts)
    cfg.freeze()
    default_setup(cfg, args)
    # Setup logger for "densepose" module
    setup_logger(output=cfg.OUTPUT_DIR, distributed_rank=comm.get_rank(), name="densepose")
    return cfg


def main(args):
    cfg = setup(args)
    # disable strict kwargs checking: allow one to specify path handle
    # hints through kwargs, like timeout in DP evaluation
    PathManager.set_strict_kwargs_checking(False)

    if args.eval_only:
        model = Trainer.build_model(cfg)
        DetectionCheckpointer(model, save_dir=cfg.OUTPUT_DIR).resume_or_load(
            cfg.MODEL.WEIGHTS, resume=args.resume
        )
        res = Trainer.test(cfg, model)
        if cfg.TEST.AUG.ENABLED:
            res.update(Trainer.test_with_TTA(cfg, model))
        if comm.is_main_process():
            verify_results(cfg, res)
        return res

    trainer = Trainer(cfg)
    trainer.resume_or_load(resume=args.resume)
    if cfg.TEST.AUG.ENABLED:
        trainer.register_hooks(
            [hooks.EvalHook(0, lambda: trainer.test_with_TTA(cfg, trainer.model))]
        )
    return trainer.train()


if __name__ == "__main__":
    args = default_argument_parser().parse_args()
    print("Command Line Args:", args)
    launch(
        main,
        args.num_gpus,
        num_machines=args.num_machines,
        machine_rank=args.machine_rank,
        dist_url=args.dist_url,
        args=(args,),
    )