import argparse
import glob
import json
import logging
import os
import pickle
import sys
import time

import numpy as np
import torch
import torch.backends.cudnn as cudnn
import torch.nn as nn
import torch.utils
import torchvision.datasets as dset

from nasbench_analysis import eval_darts_one_shot_model_in_nasbench as naseval
from nasbench_analysis.search_spaces.search_space_1 import SearchSpace1
from nasbench_analysis.search_spaces.search_space_2 import SearchSpace2
from nasbench_analysis.search_spaces.search_space_3 import SearchSpace3
from optimizers.darts import utils
from optimizers.darts.architect import Architect
from optimizers.darts.model_search import Network

parser = argparse.ArgumentParser("cifar")
parser.add_argument('--data', type=str, default='../data', help='location of the darts corpus')
parser.add_argument('--batch_size', type=int, default=96, help='batch size')
parser.add_argument('--learning_rate', type=float, default=0.025, help='init learning rate')
parser.add_argument('--learning_rate_min', type=float, default=0.001, help='min learning rate')
parser.add_argument('--momentum', type=float, default=0.9, help='momentum')
parser.add_argument('--weight_decay', type=float, default=3e-4, help='weight decay')
parser.add_argument('--report_freq', type=float, default=50, help='report frequency')
parser.add_argument('--gpu', type=int, default=0, help='gpu device id')
parser.add_argument('--epochs', type=int, default=50, help='num of training epochs')
parser.add_argument('--init_channels', type=int, default=16, help='num of init channels')
parser.add_argument('--layers', type=int, default=9, help='total number of layers')
parser.add_argument('--model_path', type=str, default='saved_models', help='path to save the model')
parser.add_argument('--cutout', action='store_true', default=False, help='use cutout')
parser.add_argument('--cutout_length', type=int, default=16, help='cutout length')
parser.add_argument('--cutout_prob', type=float, default=1.0, help='cutout probability')
parser.add_argument('--drop_path_prob', type=float, default=0.3, help='drop path probability')
parser.add_argument('--save', type=str, default='EXP', help='experiment name')
parser.add_argument('--seed', type=int, default=2, help='random_ws seed')
parser.add_argument('--grad_clip', type=float, default=5, help='gradient clipping')
parser.add_argument('--train_portion', type=float, default=0.5, help='portion of training darts')
parser.add_argument('--unrolled', action='store_true', default=False, help='use one-step unrolled validation loss')
parser.add_argument('--arch_learning_rate', type=float, default=3e-4, help='learning rate for arch encoding')
parser.add_argument('--arch_weight_decay', type=float, default=1e-3, help='weight decay for arch encoding')
parser.add_argument('--output_weights', type=bool, default=True, help='Whether to use weights on the output nodes')
parser.add_argument('--search_space', choices=['1', '2', '3'], default='1')
parser.add_argument('--debug', action='store_true', default=False, help='run only for some batches')
parser.add_argument('--warm_start_epochs', type=int, default=0,
                    help='Warm start one-shot model before starting architecture updates.')
args = parser.parse_args()

args.save = 'experiments/darts/search_space_{}/search-{}-{}-{}-{}'.format(args.search_space, args.save,
                                                                          time.strftime("%Y%m%d-%H%M%S"), args.seed,
                                                                          args.search_space)
utils.create_exp_dir(args.save, scripts_to_save=glob.glob('*.py'))

# Dump the config of the run
with open(os.path.join(args.save, 'config.json'), 'w') as fp:
    json.dump(args.__dict__, fp)

for handler in logging.root.handlers[:]:
    logging.root.removeHandler(handler)

log_format = '%(asctime)s %(message)s'
logging.basicConfig(stream=sys.stdout, level=logging.INFO,
                    format=log_format, datefmt='%m/%d %I:%M:%S %p')
fh = logging.FileHandler(os.path.join(args.save, 'log.txt'))
fh.setFormatter(logging.Formatter(log_format))
logging.getLogger().addHandler(fh)

CIFAR_CLASSES = 10


def main():
    # Select the search space to search in
    if args.search_space == '1':
        search_space = SearchSpace1()
    elif args.search_space == '2':
        search_space = SearchSpace2()
    elif args.search_space == '3':
        search_space = SearchSpace3()
    else:
        raise ValueError('Unknown search space')

    if not torch.cuda.is_available():
        logging.info('no gpu device available')
        sys.exit(1)

    np.random.seed(args.seed)
    torch.cuda.set_device(args.gpu)
    cudnn.benchmark = True
    torch.manual_seed(args.seed)
    cudnn.enabled = True
    torch.cuda.manual_seed(args.seed)
    logging.info('gpu device = %d' % args.gpu)
    logging.info("args = %s", args)

    criterion = nn.CrossEntropyLoss()
    criterion = criterion.cuda()
    model = Network(args.init_channels, CIFAR_CLASSES, args.layers, criterion, output_weights=args.output_weights,
                    steps=search_space.num_intermediate_nodes, search_space=search_space)
    model = model.cuda()
    logging.info("param size = %fMB", utils.count_parameters_in_MB(model))

    optimizer = torch.optim.SGD(
        model.parameters(),
        args.learning_rate,
        momentum=args.momentum,
        weight_decay=args.weight_decay)

    train_transform, valid_transform = utils._data_transforms_cifar10(args)
    train_data = dset.CIFAR10(root=args.data, train=True, download=True, transform=train_transform)

    num_train = len(train_data)
    indices = list(range(num_train))
    split = int(np.floor(args.train_portion * num_train))

    train_queue = torch.utils.data.DataLoader(
        train_data, batch_size=args.batch_size,
        sampler=torch.utils.data.sampler.SubsetRandomSampler(indices[:split]),
        pin_memory=True)

    valid_queue = torch.utils.data.DataLoader(
        train_data, batch_size=args.batch_size,
        sampler=torch.utils.data.sampler.SubsetRandomSampler(indices[split:num_train]),
        pin_memory=True)

    scheduler = torch.optim.lr_scheduler.CosineAnnealingLR(
        optimizer, float(args.epochs), eta_min=args.learning_rate_min)

    architect = Architect(model, args)

    for epoch in range(args.epochs):
        scheduler.step()
        lr = scheduler.get_lr()[0]
        # increase the cutout probability linearly throughout search
        train_transform.transforms[-1].cutout_prob = args.cutout_prob * epoch / (args.epochs - 1)
        logging.info('epoch %d lr %e cutout_prob %e', epoch, lr,
                     train_transform.transforms[-1].cutout_prob)

        # Save the one shot model architecture weights for later analysis
        arch_filename = os.path.join(args.save, 'one_shot_architecture_{}.obj'.format(epoch))
        with open(arch_filename, 'wb') as filehandler:
            numpy_tensor_list = []
            for tensor in model.arch_parameters():
                numpy_tensor_list.append(tensor.detach().cpu().numpy())
            pickle.dump(numpy_tensor_list, filehandler)

        # Save the entire one-shot-model
        filepath = os.path.join(args.save, 'one_shot_model_{}.obj'.format(epoch))
        torch.save(model.state_dict(), filepath)

        logging.info('architecture', numpy_tensor_list)

        # training
        train_acc, train_obj = train(train_queue, valid_queue, model, architect, criterion, optimizer, lr, epoch)
        logging.info('train_acc %f', train_acc)

        # validation
        valid_acc, valid_obj = infer(valid_queue, model, criterion)
        logging.info('valid_acc %f', valid_acc)

        utils.save(model, os.path.join(args.save, 'weights.pt'))

    logging.info('STARTING EVALUATION')
    test, valid, runtime, params = naseval.eval_one_shot_model(config=args.__dict__,
                                                               model=arch_filename)
    index = np.random.choice(list(range(3)))
    logging.info('TEST ERROR: %.3f | VALID ERROR: %.3f | RUNTIME: %f | PARAMS: %d'
                 % (test[index],
                    valid[index],
                    runtime[index],
                    params[index])
                 )


def train(train_queue, valid_queue, model, architect, criterion, optimizer, lr, epoch):
    objs = utils.AvgrageMeter()
    top1 = utils.AvgrageMeter()
    top5 = utils.AvgrageMeter()

    for step, (input, target) in enumerate(train_queue):
        model.train()
        n = input.size(0)

        input = input.cuda()
        target = target.cuda(non_blocking=True)

        # get a minibatch from the search queue with replacement
        try:
            input_search, target_search = next(valid_queue_iter)
        except:
            valid_queue_iter = iter(valid_queue)
            input_search, target_search = next(valid_queue_iter)

        input_search = input_search.cuda()
        target_search = target_search.cuda(non_blocking=True)

        # Allow for warm starting of the one-shot model for more reliable architecture updates.
        if epoch >= args.warm_start_epochs:
            architect.step(input, target, input_search, target_search, lr, optimizer, unrolled=args.unrolled)

        optimizer.zero_grad()
        logits = model(input)
        loss = criterion(logits, target)

        loss.backward()
        nn.utils.clip_grad_norm_(model.parameters(), args.grad_clip)
        optimizer.step()

        prec1, prec5 = utils.accuracy(logits, target, topk=(1, 5))
        objs.update(loss.data.item(), n)
        top1.update(prec1.data.item(), n)
        top5.update(prec5.data.item(), n)

        if step % args.report_freq == 0:
            logging.info('train %03d %e %f %f', step, objs.avg, top1.avg, top5.avg)
            if args.debug:
                break

    return top1.avg, objs.avg


def infer(valid_queue, model, criterion):
    objs = utils.AvgrageMeter()
    top1 = utils.AvgrageMeter()
    top5 = utils.AvgrageMeter()
    model.eval()

    for step, (input, target) in enumerate(valid_queue):
        input = input.cuda()
        target = target.cuda(non_blocking=True)

        logits = model(input)
        loss = criterion(logits, target)

        prec1, prec5 = utils.accuracy(logits, target, topk=(1, 5))
        n = input.size(0)
        objs.update(loss.data.item(), n)
        top1.update(prec1.data.item(), n)
        top5.update(prec5.data.item(), n)

        if step % args.report_freq == 0:
            logging.info('valid %03d %e %f %f', step, objs.avg, top1.avg, top5.avg)
            if args.debug:
                break

    return top1.avg, objs.avg


if __name__ == '__main__':
    main()