package com.example.demo.barcode;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.ByteArrayResource;
import org.springframework.http.*;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.client.HttpStatusCodeException;
import org.springframework.web.multipart.MultipartFile;

import java.io.IOException;
import java.time.Duration;

@RestController
@RequestMapping("/api/barcode")
public class BarcodeProxyController {

    private final PythonBarcodeProperties properties;
    private final RestTemplate restTemplate;
    private static final Logger log = LoggerFactory.getLogger(BarcodeProxyController.class);

    public BarcodeProxyController(PythonBarcodeProperties properties) {
        this.properties = properties;
        SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
        factory.setConnectTimeout((int) Duration.ofSeconds(2).toMillis());
        factory.setReadTimeout((int) Duration.ofSeconds(8).toMillis());
        this.restTemplate = new RestTemplate(factory);
    }

    @PostMapping(value = "/scan", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public ResponseEntity<String> scan(@RequestPart("file") MultipartFile file) throws IOException {
        if (file == null || file.isEmpty()) {
            return ResponseEntity.badRequest().body("{\"success\":false,\"message\":\"文件为空\"}");
        }
        long maxBytes = (long) properties.getMaxUploadMb() * 1024L * 1024L;
        if (file.getSize() > maxBytes) {
            return ResponseEntity.status(HttpStatus.PAYLOAD_TOO_LARGE)
                    .body(String.format("{\"success\":false,\"message\":\"文件过大(> %dMB)\"}", properties.getMaxUploadMb()));
        }
        String url = String.format("http://%s:%d/api/barcode/scan", properties.getHost(), properties.getPort());
        if (log.isDebugEnabled()) {
            log.debug("转发条码识别请求: url={} filename={} size={}B", url, file.getOriginalFilename(), file.getSize());
        }

        // 构建 multipart/form-data 请求转发
        MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
        HttpHeaders fileHeaders = new HttpHeaders();
        String contentType = file.getContentType();
        MediaType mediaType = MediaType.APPLICATION_OCTET_STREAM;
        if (contentType != null && !contentType.isBlank()) {
            try {
                mediaType = MediaType.parseMediaType(contentType);
            } catch (Exception ignored) {
                mediaType = MediaType.APPLICATION_OCTET_STREAM;
            }
        }
        fileHeaders.setContentType(mediaType);
        String originalName = file.getOriginalFilename();
        if (originalName == null || originalName.isBlank()) {
            originalName = file.getName();
        }
        if (originalName == null || originalName.isBlank()) {
            originalName = "upload.bin";
        }
        fileHeaders.setContentDisposition(ContentDisposition.builder("form-data")
                .name("file")
                .filename(originalName)
                .build());
        final String finalFilename = originalName;
        ByteArrayResource resource = new ByteArrayResource(file.getBytes()) {
            @Override
            public String getFilename() {
                return finalFilename;
            }
        };
        HttpEntity<ByteArrayResource> fileEntity = new HttpEntity<>(resource, fileHeaders);
        body.add("file", fileEntity);

        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.MULTIPART_FORM_DATA);
        HttpEntity<MultiValueMap<String, Object>> req = new HttpEntity<>(body, headers);

        try {
            long t0 = System.currentTimeMillis();
            ResponseEntity<String> resp = restTemplate.postForEntity(url, req, String.class);
            long cost = System.currentTimeMillis() - t0;
            if (log.isDebugEnabled()) {
                String bodyStr = resp.getBody();
                if (bodyStr != null && bodyStr.length() > 500) {
                    bodyStr = bodyStr.substring(0, 500) + "...";
                }
                log.debug("转发完成: status={} cost={}ms resp={}", resp.getStatusCodeValue(), cost, bodyStr);
            }
            return ResponseEntity.status(resp.getStatusCode())
                    .contentType(MediaType.APPLICATION_JSON)
                    .body(resp.getBody());
        } catch (HttpStatusCodeException ex) {
            String bodyStr = ex.getResponseBodyAsString();
            if (bodyStr != null && bodyStr.length() > 500) {
                bodyStr = bodyStr.substring(0, 500) + "...";
            }
            log.warn("Python 服务返回非 2xx: status={} body={}", ex.getStatusCode(), bodyStr);
            MediaType respType = ex.getResponseHeaders() != null
                    ? ex.getResponseHeaders().getContentType()
                    : MediaType.APPLICATION_JSON;
            if (respType == null) {
                respType = MediaType.APPLICATION_JSON;
            }
            return ResponseEntity.status(ex.getStatusCode())
                    .contentType(respType)
                    .body(ex.getResponseBodyAsString());
        } catch (Exception ex) {
            // Python 服务不可用或超时等异常
            log.warn("转发到 Python 服务失败: {}:{} path=/api/barcode/scan, err={}", properties.getHost(), properties.getPort(), ex.toString());
            return ResponseEntity.status(HttpStatus.SERVICE_UNAVAILABLE)
                    .contentType(MediaType.APPLICATION_JSON)
                    .body("{\"success\":false,\"message\":\"识别服务不可用，请稍后重试\"}");
        }
    }
}