# predict_server.py
import os
import json
import string
import socket
import traceback
from http.server import BaseHTTPRequestHandler, HTTPServer
from io import BytesIO
from collections import OrderedDict

# 深度学习依赖
import torch
from torch import nn
from torchvision import transforms
from PIL import Image

# ================= 定义模型结构 (保持不变) =================
class Model(nn.Module):
    def __init__(self, n_classes, input_shape=(3, 64, 128)):
        super(Model, self).__init__()
        self.input_shape = input_shape
        channels = [32, 64, 128, 256, 256]
        layers = [2, 2, 2, 2, 2]
        kernels = [3, 3, 3, 3, 3]
        pools = [2, 2, 2, 2, (2, 1)]
        modules = OrderedDict()
        
        def cba(name, in_channels, out_channels, kernel_size):
            modules[f'conv{name}'] = nn.Conv2d(in_channels, out_channels, kernel_size,
                                               padding=(1, 1) if kernel_size == 3 else 0)
            modules[f'bn{name}'] = nn.BatchNorm2d(out_channels)
            modules[f'relu{name}'] = nn.ReLU(inplace=True)
        
        last_channel = 3
        for block, (n_channel, n_layer, n_kernel, k_pool) in enumerate(zip(channels, layers, kernels, pools)):
            for layer in range(1, n_layer + 1):
                cba(f'{block+1}{layer}', last_channel, n_channel, n_kernel)
                last_channel = n_channel
            modules[f'pool{block + 1}'] = nn.MaxPool2d(k_pool)
        modules[f'dropout'] = nn.Dropout(0.25, inplace=True)
        
        self.cnn = nn.Sequential(modules)
        self.lstm = nn.LSTM(input_size=self.infer_features(), hidden_size=128, num_layers=2, bidirectional=True)
        self.fc = nn.Linear(in_features=256, out_features=n_classes)
    
    def infer_features(self):
        x = torch.zeros((1,)+self.input_shape)
        x = self.cnn(x)
        x = x.reshape(x.shape[0], -1, x.shape[-1])
        return x.shape[1]

    def forward(self, x):
        x = self.cnn(x)
        x = x.reshape(x.shape[0], -1, x.shape[-1])
        x = x.permute(2, 0, 1)
        x, _ = self.lstm(x)
        x = self.fc(x)
        return x

# ================= 推理类 =================
class DeployModel:
    def __init__(self, model_path):
        self.num_classes = 12
        self.characters = '-' + string.digits + '$'
        self.width = 150
        self.hight = 80
        self.model = Model(self.num_classes, input_shape=(3, self.hight, self.width))
        
        if os.path.exists(model_path):
            self.model.load_state_dict(torch.load(model_path, map_location=torch.device('cpu')))
            self.model.eval()
            print(f"Model loaded successfully from {model_path}")
        else:
            raise FileNotFoundError(f"Model file not found: {model_path}")

        self.transforms_func = transforms.Compose([
            transforms.Resize((self.hight, self.width)),
            transforms.ToTensor()
        ])
        
    def decode(self, sequence):
        a = ''.join([self.characters[x] for x in sequence])
        s = []
        last = None
        for x in a:
            if x != last:
                s.append(x)
                last = x
        s2 = ''.join([x for x in s if x != self.characters[0]])
        return s2
    
    def inference_bytes(self, image_bytes):
        try:
            image = Image.open(BytesIO(image_bytes))
            if image.mode == 'RGBA':
                image = image.convert('RGB')
            if self.transforms_func is not None:
                image = self.transforms_func(image)
            with torch.no_grad():
                output = self.model(image.unsqueeze(0).cpu())
                
            output_argmax = output.detach().permute(1, 0, 2).argmax(dim=-1)
            predict_label = self.decode(output_argmax[0])
            return predict_label
        except Exception as e:
            print(f"Inference error: {e}")
            return ""

# ================= HTTP 处理 =================
# 全局模型实例
deploy_model = None

class RequestHandler(BaseHTTPRequestHandler):
    
    def _send_response(self, status, content_type, content):
        self.send_response(status)
        self.send_header('Content-type', content_type)
        self.end_headers()
        self.wfile.write(content)

    def do_POST(self):
        if self.path == '/predict/vfcode':
            try:
                # 获取内容长度
                content_length = int(self.headers.get('Content-Length', 0))
                if content_length == 0:
                    self._send_response(400, 'application/json', json.dumps({'code': 400, 'msg': 'Empty body'}).encode())
                    return

                # 直接读取 Raw Binary 数据 (简化通信，避免 multipart 解析问题)
                file_content = self.rfile.read(content_length)

                # 推理
                result_string = deploy_model.inference_bytes(file_content)
                
                response = {
                    'data': result_string,
                    'msg': "success",
                    'code': 200
                }
                self._send_response(200, 'application/json', json.dumps(response).encode())
                print(f"Processed request. Result: {result_string}")

            except Exception as e:
                traceback.print_exc()
                response = {'data': '', 'msg': 'failed', 'code': 500}
                self._send_response(500, 'application/json', json.dumps(response).encode())
        else:
            self._send_response(404, 'text/plain', b'Not Found')

if __name__ == '__main__':
    # 配置区
    MODEL_PATH = 'data/ocr.pth'
    PORT = 8085
    
    # 启动
    if not os.path.exists(MODEL_PATH):
        print(f"[ERROR] 请确保模型文件存在: {MODEL_PATH}")
        exit(1)
        
    deploy_model = DeployModel(MODEL_PATH)
    
    server_address = ('0.0.0.0', PORT) # 监听所有接口
    httpd = HTTPServer(server_address, RequestHandler)
    print(f'OCR Server running on port {PORT}...')
    try:
        httpd.serve_forever()
    except KeyboardInterrupt:
        pass
    httpd.server_close()