# %%
import numpy as np
import pandas as pd
import csv
import torch.nn as nn
from torch.optim.lr_scheduler import ReduceLROnPlateau
from torch.utils.data import TensorDataset, DataLoader
from transformers import BertTokenizer,BertConfig,AdamW
from sklearn.metrics import accuracy_score
from sklearn.metrics import classification_report
from tqdm import tqdm
import torch
import transformers
from torch.utils.data import Dataset, DataLoader

# %%

class MyDataSet(Dataset):
    def __init__(self, loaded_data):
        self.data = loaded_data
    
    def __len__(self):
        return len(self.data)
    
    def __getitem__(self, idx):
        return self.data[idx]
 
Data_path = "/kaggle/input/inference/train.csv"
Totle_data = pd.read_csv(Data_path)
Totle_data = Totle_data.sample(frac=0.1)
Totle_data = Totle_data.dropna(axis=0,subset = ["2"])
custom_dataset = MyDataSet(Totle_data)
#按照比例划分
train_size = int(len(custom_dataset) * 0.6)
validate_size = int(len(custom_dataset) * 0.1)
test_size = len(custom_dataset) - validate_size - train_size
train_dataset, validate_dataset, test_dataset = torch.utils.data.random_split(custom_dataset, [train_size, validate_size, test_size])
 
#设置保存路径
train_data_path="Bert_Try.csv"
dev_data_path = "Bert_Dev.csv" 
test_data_path="Bert_Test.csv"

train_dataset = Totle_data.iloc[train_dataset.indices]
validate_dataset = Totle_data.iloc[validate_dataset.indices]
test_dataset = Totle_data.iloc[test_dataset.indices]

#index参数设置为False表示不保存行索引,header设置为False表示不保存列索引
train_dataset.to_csv(train_data_path,index=False,header=True)
validate_dataset.to_csv(dev_data_path ,index=False,header=True)
test_dataset.to_csv(test_data_path,index=False,header=True)

# %%
data = pd.read_csv(train_data_path)
data.head

# %%

class BertClassificationModel(nn.Module):
    def __init__(self):
        super(BertClassificationModel, self).__init__()   
        #加载预训练模型
        pretrained_weights="bert-base-chinese"
        self.bert = transformers.BertModel.from_pretrained(pretrained_weights)
        for param in self.bert.parameters():
            param.requires_grad = True
        #定义线性函数      
        self.dense = nn.Linear(768, 3)
        
    def forward(self, input_ids,token_type_ids,attention_mask):
        #得到bert_output
        bert_output = self.bert(input_ids=input_ids,token_type_ids=token_type_ids, attention_mask=attention_mask)
        #获得预训练模型的输出
        bert_cls_hidden_state = bert_output[1]
        #将768维的向量输入到线性层映射为二维向量
        linear_output = self.dense(bert_cls_hidden_state)
        return  linear_output

# %%

def encoder(max_len,vocab_path,text_list):
    #将text_list embedding成bert模型可用的输入形式
    #加载分词模型
    tokenizer = BertTokenizer.from_pretrained("bert-base-chinese")
    tokenizer = tokenizer(
        text_list,
        padding = True,
        truncation = True,
        max_length = max_len,
        return_tensors='pt'  # 返回的类型为pytorch tensor
        )
    input_ids = tokenizer['input_ids']
    token_type_ids = tokenizer['token_type_ids']
    attention_mask = tokenizer['attention_mask']
    return input_ids,token_type_ids,attention_mask

# %%
labels2dict = {"neutral":0,"entailment":1,"contradiction":2}
def load_data(path):
    csvFileObj = open(path)
    readerObj = csv.reader(csvFileObj)
    text_list = []
    labels = []
    for row in readerObj:
        #跳过表头
        if readerObj.line_num == 1:
            continue
        #label在什么位置就改成对应的index
        label = int(labels2dict[row[0]])
        text = row[1]
        text_list.append(text)
        labels.append(label)
    #调用encoder函数，获得预训练模型的三种输入形式
    input_ids,token_type_ids,attention_mask = encoder(max_len=150,vocab_path="/root/Bert/bert-base-chinese/vocab.txt",text_list=text_list)
    labels = torch.tensor(labels)
    #将encoder的返回值以及label封装为Tensor的形式
    data = TensorDataset(input_ids,token_type_ids,attention_mask,labels)
    return data

# %%
#设定batch_size
batch_size = 16
#引入数据路径
train_data_path="Bert_Try.csv"
dev_data_path="Bert_Dev.csv"
test_data_path="Bert_Test.csv"
#调用load_data函数，将数据加载为Tensor形式
train_data = load_data(train_data_path)
dev_data = load_data(dev_data_path)
test_data = load_data(test_data_path)
#将训练数据和测试数据进行DataLoader实例化
train_loader = DataLoader(dataset=train_data, batch_size=batch_size, shuffle=True)
dev_loader = DataLoader(dataset=dev_data, batch_size=batch_size, shuffle=True)
test_loader = DataLoader(dataset=test_data, batch_size=batch_size, shuffle=False)

# %%
def dev(model,dev_loader):
    model.to(device)

    model.eval()

    with torch.no_grad():
        correct = 0
        total = 0
        for step, (input_ids,token_type_ids,attention_mask,labels) in tqdm(enumerate(dev_loader),desc='Dev Itreation:'):                
            input_ids,token_type_ids,attention_mask,labels=input_ids.to(device),token_type_ids.to(device),attention_mask.to(device),labels.to(device)
            out_put = model(input_ids,token_type_ids,attention_mask)
            _, predict = torch.max(out_put.data, 1)
            correct += (predict==labels).sum().item()
            total += labels.size(0)
        res = correct / total
    return res

# %%

device = torch.device('cuda:0' if torch.cuda.is_available() else 'cpu')
def train(model,train_loader,dev_loader) :

    model.to(device)
    model.train()
    criterion = nn.CrossEntropyLoss()
    param_optimizer = list(model.named_parameters())
    no_decay = ['bias', 'LayerNorm.bias', 'LayerNorm.weight']

    optimizer_grouped_parameters = [
        {'params': [p for n, p in param_optimizer if not any(nd in n for nd in no_decay)],
         'weight_decay': 0.01},
        {'params': [p for n, p in param_optimizer if any(nd in n for nd in no_decay)], 'weight_decay': 0.0}
    ]

    optimizer_params = {'lr': 1e-5, 'eps': 1e-6, 'correct_bias': False}
    optimizer = AdamW(optimizer_grouped_parameters, **optimizer_params)
    scheduler = ReduceLROnPlateau(optimizer,mode='max',factor=0.5,min_lr=1e-7, patience=5,verbose= True, threshold=0.0001, eps=1e-08)
    t_total = len(train_loader)

    total_epochs = 10
    bestAcc = 0
    correct = 0
    total = 0
    print('Training and verification begin!')
    for epoch in range(total_epochs): 
        for step, (input_ids,token_type_ids,attention_mask,labels) in enumerate(train_loader):

            optimizer.zero_grad()
            input_ids,token_type_ids,attention_mask,labels=input_ids.to(device),token_type_ids.to(device),attention_mask.to(device),labels.to(device)
            out_put =  model(input_ids,token_type_ids,attention_mask)
            loss = criterion(out_put, labels)
            _, predict = torch.max(out_put.data, 1)
            correct += (predict == labels).sum().item()
            total += labels.size(0)
            loss.backward()
            optimizer.step()
             #每两步进行一次打印
            if (step + 1) % 10 == 0:
                train_acc = correct / total
                print("Train Epoch[{}/{}],step[{}/{}],tra_acc{:.6f} %,loss:{:.6f}".format(epoch + 1, total_epochs, step + 1, len(train_loader),train_acc*100,loss.item()))
            #每五十次进行一次验证
            if (step + 1) % 200 == 0:
                train_acc = correct / total
                #调用验证函数dev对模型进行验证，并将有效果提升的模型进行保存
                acc = dev(model, dev_loader)
                if bestAcc < acc:
                    bestAcc = acc
                    #模型保存路径
                    path = 'bert_model.pkl'
                    torch.save(model, path)
                print("DEV Epoch[{}/{}],step[{}/{}],tra_acc{:.6f} %,bestAcc{:.6f}%,dev_acc{:.6f} %,loss:{:.6f}".format(epoch + 1, total_epochs, step + 1, len(train_loader),train_acc*100,bestAcc*100,acc*100,loss.item()))
        scheduler.step(bestAcc)

# %%

path = '/kaggle/input/inference/bert_model.pkl'
# model = torch.load(path)
#实例化模型
model = BertClassificationModel()
#调用训练函数进行训练与验证
train(model,train_loader,dev_loader)