#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# Copyright 2016-2099 Ailemon.net
#
# This file is part of ASRT Speech Recognition Tool.
#
# ASRT is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# ASRT is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with ASRT.  If not, see <https://www.gnu.org/licenses/>.
# ============================================================================

"""
@author: nl8590687
若干声学模型模型的定义
"""

from tensorflow.keras.models import Model
from tensorflow.keras.layers import Dense, Dropout, Input, Reshape, BatchNormalization
from tensorflow.keras.layers import Lambda, Activation,Conv2D, MaxPooling2D
from tensorflow.keras import backend as K

class BaseModel:
    '''
    定义声学模型类型的接口基类
    '''
    def __init__(self):
        self.input_shape = None
        self.output_shape = None

    def get_model(self) -> tuple:
        raise Exception("method not implemented")

    def get_train_model(self) -> Model:
        raise Exception("method not implemented")

    def get_eval_model(self) -> Model:
        raise Exception("method not implemented")

    def load_weights(self, filename) -> None:
        raise Exception("method not implemented")

    def save_weights(self, filename) -> None:
        raise Exception("method not implemented")

    def get_model_name(self) -> str:
        raise Exception("method not implemented")
    
    def get_loss_function(self):
        raise Exception("method not implemented")

def ctc_lambda_func(args):
    y_pred, labels, input_length, label_length = args
    y_pred = y_pred[:, :, :]
    return K.ctc_batch_cost(labels, y_pred, input_length, label_length)

class SpeechModel251(BaseModel):
    '''
    定义CNN+CTC模型，使用函数式模型

    输入层：200维的特征值序列，一条语音数据的最大长度设为1600（大约16s）\\
    隐藏层：卷积池化层，卷积核大小为3x3，池化窗口大小为2 \\
    隐藏层：全连接层 \\
    输出层：全连接层，神经元数量为self.MS_OUTPUT_SIZE，使用softmax作为激活函数， \\
    CTC层：使用CTC的loss作为损失函数，实现连接性时序多输出

    参数： \\
        input_shape: tuple，默认值(1600, 200, 1) \\
        output_shape: tuple，默认值(200, 1428)
    '''
    def __init__(self, input_shape :tuple=(1600, 200, 1), output_shape :tuple=(200, 1428)) -> None:
        super().__init__()
        self.input_shape = input_shape
        self.output_shape = output_shape
        self._model_name = 'SpeechModel251'
        self.model, self.model_base = self._define_model(self.input_shape, self.output_shape[1])

    def _define_model(self, input_shape, output_size) -> tuple:
        label_max_string_length = 64

        input_data = Input(name='the_input', shape=input_shape)

        layer_h1 = Conv2D(32, (3,3), use_bias=False, activation='relu', padding='same', kernel_initializer='he_normal')(input_data) # 卷积层
        layer_h1 = Dropout(0.05)(layer_h1)
        layer_h2 = Conv2D(32, (3,3), use_bias=True, activation='relu', padding='same', kernel_initializer='he_normal')(layer_h1) # 卷积层
        layer_h3 = MaxPooling2D(pool_size=2, strides=None, padding="valid")(layer_h2) # 池化层
        #layer_h3 = Dropout(0.2)(layer_h2) # 随机中断部分神经网络连接，防止过拟合
        layer_h3 = Dropout(0.05)(layer_h3)
        layer_h4 = Conv2D(64, (3,3), use_bias=True, activation='relu', padding='same', kernel_initializer='he_normal')(layer_h3) # 卷积层
        layer_h4 = Dropout(0.1)(layer_h4)
        layer_h5 = Conv2D(64, (3,3), use_bias=True, activation='relu', padding='same', kernel_initializer='he_normal')(layer_h4) # 卷积层
        layer_h6 = MaxPooling2D(pool_size=2, strides=None, padding="valid")(layer_h5) # 池化层

        layer_h6 = Dropout(0.1)(layer_h6)
        layer_h7 = Conv2D(128, (3,3), use_bias=True, activation='relu', padding='same', kernel_initializer='he_normal')(layer_h6) # 卷积层
        layer_h7 = Dropout(0.15)(layer_h7)
        layer_h8 = Conv2D(128, (3,3), use_bias=True, activation='relu', padding='same', kernel_initializer='he_normal')(layer_h7) # 卷积层
        layer_h9 = MaxPooling2D(pool_size=2, strides=None, padding="valid")(layer_h8) # 池化层

        layer_h9 = Dropout(0.15)(layer_h9)
        layer_h10 = Conv2D(128, (3,3), use_bias=True, activation='relu', padding='same', kernel_initializer='he_normal')(layer_h9) # 卷积层
        layer_h10 = Dropout(0.2)(layer_h10)
        layer_h11 = Conv2D(128, (3,3), use_bias=True, activation='relu', padding='same', kernel_initializer='he_normal')(layer_h10) # 卷积层
        layer_h12 = MaxPooling2D(pool_size=1, strides=None, padding="valid")(layer_h11) # 池化层

        layer_h12 = Dropout(0.2)(layer_h12)
        layer_h13 = Conv2D(128, (3,3), use_bias=True, activation='relu', padding='same', kernel_initializer='he_normal')(layer_h12) # 卷积层
        layer_h13 = Dropout(0.2)(layer_h13)
        layer_h14 = Conv2D(128, (3,3), use_bias=True, activation='relu', padding='same', kernel_initializer='he_normal')(layer_h13) # 卷积层
        layer_h15 = MaxPooling2D(pool_size=1, strides=None, padding="valid")(layer_h14) # 池化层

        #test=Model(inputs = input_data, outputs = layer_h12)
        #test.summary()

        layer_h16 = Reshape((200, 3200))(layer_h15) #Reshape层
        #layer_h6 = Dropout(0.2)(layer_h5) # 随机中断部分神经网络连接，防止过拟合
        layer_h16 = Dropout(0.3)(layer_h16)
        layer_h17 = Dense(128, activation="relu", use_bias=True, kernel_initializer='he_normal')(layer_h16) # 全连接层
        layer_h17 = Dropout(0.3)(layer_h17)
        layer_h18 = Dense(output_size, use_bias=True, kernel_initializer='he_normal')(layer_h17) # 全连接层
        y_pred = Activation('softmax', name='Activation0')(layer_h18)

        model_base = Model(inputs = input_data, outputs = y_pred)
        #model_data.summary()

        labels = Input(name='the_labels', shape=[label_max_string_length], dtype='float32')
        input_length = Input(name='input_length', shape=[1], dtype='int64')
        label_length = Input(name='label_length', shape=[1], dtype='int64')
        # Keras doesn't currently support loss funcs with extra parameters
        # so CTC loss is implemented in a lambda layer
        loss_out = Lambda(ctc_lambda_func, output_shape=(1,), name='ctc')([y_pred, labels, input_length, label_length])

        model = Model(inputs=[input_data, labels, input_length, label_length], outputs=loss_out)

        return model, model_base

    def get_model(self) -> tuple:
        return self.model, self.model_base

    def get_train_model(self) -> Model:
        return self.model

    def get_eval_model(self) -> Model:
        return self.model_base

    def summary(self) -> None:
        self.model.summary()

    def get_model_name(self) -> str:
        return self._model_name

    def load_weights(self, filename :str) -> None:
        self.model.load_weights(filename)

    def save_weights(self, filename :str) -> None:
        self.model.save_weights(filename + '.model')
        self.model_base.save_weights(filename + '.model.base')
        # 需要安装 hdf5 模块
        self.model.save(filename + '.h5')
        self.model_base.save(filename + '.base.h5')
        f = open('epoch_'+self._model_name+'.txt','w')
        f.write(filename)
        f.close()

    def get_loss_function(self) -> dict:
        return {'ctc': lambda y_true, y_pred: y_pred}