#!/usr/bin/python3

import os
import numpy as np
from PIL import Image

import torch
from torch import nn
import torch.nn.init as initer


def step_learning_rate(base_lr, epoch, step_epoch, multiplier=0.1):
    """Sets the learning rate to the base LR decayed by 10 every step epochs"""
    lr = base_lr * (multiplier ** (epoch // step_epoch))
    return lr


def poly_learning_rate(base_lr, curr_iter, max_iter, power=0.9):
    """poly learning rate policy"""
    lr = base_lr * (1 - float(curr_iter) / max_iter) ** power
    return lr


def check_mkdir(dir_name):
    if not os.path.exists(dir_name):
        os.mkdir(dir_name)


def check_makedirs(dir_name):
    if not os.path.exists(dir_name):
        os.makedirs(dir_name)


def init_weights(model, conv='kaiming', batchnorm='normal', linear='kaiming', lstm='kaiming'):
    """
    :param model: Pytorch Model which is nn.Module
    :param conv:  'kaiming' or 'xavier'
    :param batchnorm: 'normal' or 'constant'
    :param linear: 'kaiming' or 'xavier'
    :param lstm: 'kaiming' or 'xavier'
    """
    for m in model.modules():
        if isinstance(m, (nn.modules.conv._ConvNd)):
            if conv == 'kaiming':
                initer.kaiming_normal_(m.weight)
            elif conv == 'xavier':
                initer.xavier_normal_(m.weight)
            else:
                raise ValueError("init type of conv error.\n")
            if m.bias is not None:
                initer.constant_(m.bias, 0)

        elif isinstance(m, (nn.modules.batchnorm._BatchNorm)):
            if batchnorm == 'normal':
                initer.normal_(m.weight, 1.0, 0.02)
            elif batchnorm == 'constant':
                initer.constant_(m.weight, 1.0)
            else:
                raise ValueError("init type of batchnorm error.\n")
            initer.constant_(m.bias, 0.0)

        elif isinstance(m, nn.Linear):
            if linear == 'kaiming':
                initer.kaiming_normal_(m.weight)
            elif linear == 'xavier':
                initer.xavier_normal_(m.weight)
            else:
                raise ValueError("init type of linear error.\n")
            if m.bias is not None:
                initer.constant_(m.bias, 0)

        elif isinstance(m, nn.LSTM):
            for name, param in m.named_parameters():
                if 'weight' in name:
                    if lstm == 'kaiming':
                        initer.kaiming_normal_(param)
                    elif lstm == 'xavier':
                        initer.xavier_normal_(param)
                    else:
                        raise ValueError("init type of lstm error.\n")
                elif 'bias' in name:
                    initer.constant_(param, 0)


def group_weight(weight_group, module, lr):
    group_decay = []
    group_no_decay = []
    for m in module.modules():
        if isinstance(m, nn.Linear):
            group_decay.append(m.weight)
            if m.bias is not None:
                group_no_decay.append(m.bias)
        elif isinstance(m, nn.modules.conv._ConvNd):
            group_decay.append(m.weight)
            if m.bias is not None:
                group_no_decay.append(m.bias)
        elif isinstance(m, nn.modules.batchnorm._BatchNorm):
            if m.weight is not None:
                group_no_decay.append(m.weight)
            if m.bias is not None:
                group_no_decay.append(m.bias)
    assert len(list(module.parameters())) == len(group_decay) + len(group_no_decay)
    weight_group.append(dict(params=group_decay, lr=lr))
    weight_group.append(dict(params=group_no_decay, weight_decay=.0, lr=lr))
    return weight_group


def colorize(gray, palette):
    # gray: numpy array of the label and 1*3N size list palette
    color = Image.fromarray(gray.astype(np.uint8)).convert('P')
    color.putpalette(palette)
    return color
