package com.designhub.controller;

import com.designhub.common.Result;
import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.tags.Tag;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import jakarta.annotation.PostConstruct;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.*;

/**
 * 文件上传Controller
 */
@Slf4j
@RestController
@RequestMapping("/api/upload")
@Tag(name = "文件上传", description = "文件上传相关API")
public class UploadController {

    @Value("${file.upload.path:./uploads}")
    private String uploadPath;

    @Value("${file.upload.max-size:52428800}")
    private long maxSize;

    @Value("${file.upload.allowed-extensions:.xls,.xlsx,.doc,.docx,.pdf,.zip}")
    private String allowedExtensions;

    private static final Set<String> ALLOWED_EXTENSIONS_SET = new HashSet<>();

    @PostConstruct
    public void init() {
        String[] extensions = allowedExtensions.split(",");
        for (String ext : extensions) {
            ALLOWED_EXTENSIONS_SET.add(ext.trim().toLowerCase());
        }
        
        // 确保上传目录存在
        try {
            Path path = Paths.get(uploadPath);
            if (!Files.exists(path)) {
                Files.createDirectories(path);
                log.info("创建上传目录: {}", uploadPath);
            }
        } catch (IOException e) {
            log.error("创建上传目录失败: {}", e.getMessage());
        }
    }

    /**
     * 上传文件
     */
    @PostMapping("/file")
    @Operation(summary = "上传文件", description = "支持Excel、Word、PDF、ZIP等格式")
    public Result<Map<String, Object>> uploadFile(@RequestParam("file") MultipartFile file) {
        try {
            // 验证文件
            if (file == null || file.isEmpty()) {
                return Result.error(400, "文件不能为空");
            }

            // 验证文件大小
            if (file.getSize() > maxSize) {
                return Result.error(400, String.format("文件大小不能超过 %d MB", maxSize / 1024 / 1024));
            }

            // 验证文件扩展名
            String originalFilename = file.getOriginalFilename();
            if (originalFilename == null || originalFilename.isEmpty()) {
                return Result.error(400, "文件名不能为空");
            }

            String extension = getFileExtension(originalFilename);
            if (!ALLOWED_EXTENSIONS_SET.contains(extension.toLowerCase())) {
                return Result.error(400, String.format("不支持的文件格式，支持的格式：%s", allowedExtensions));
            }

            // 生成文件存储路径
            String dateDir = LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyy/MM/dd"));
            String fileName = generateFileName(originalFilename);
            String relativePath = dateDir + "/" + fileName;
            String fullPath = uploadPath + "/" + relativePath;

            // 确保目录存在
            Path targetPath = Paths.get(fullPath);
            Files.createDirectories(targetPath.getParent());

            // 保存文件
            file.transferTo(targetPath.toFile());

            log.info("文件上传成功: originalName={}, savedPath={}, size={}", 
                    originalFilename, fullPath, file.getSize());

            // 构建返回数据
            Map<String, Object> data = new HashMap<>();
            data.put("fileName", originalFilename);
            data.put("filePath", relativePath);
            data.put("fileUrl", "/api/upload/download?path=" + relativePath);
            data.put("fileSize", file.getSize());
            data.put("fileType", extension);

            return Result.success(data);
        } catch (IOException e) {
            log.error("文件上传失败: {}", e.getMessage(), e);
            return Result.error(500, "文件上传失败: " + e.getMessage());
        } catch (Exception e) {
            log.error("文件上传异常: {}", e.getMessage(), e);
            return Result.error(500, "文件上传异常: " + e.getMessage());
        }
    }

    /**
     * 下载文件
     */
    @GetMapping("/download")
    @Operation(summary = "下载文件", description = "根据文件路径下载文件")
    public org.springframework.http.ResponseEntity<org.springframework.core.io.Resource> downloadFile(
            @RequestParam("path") String filePath) {
        try {
            String fullPath = uploadPath + "/" + filePath;
            Path path = Paths.get(fullPath);
            
            if (!Files.exists(path)) {
                return org.springframework.http.ResponseEntity.notFound().build();
            }

            org.springframework.core.io.Resource resource = 
                    new org.springframework.core.io.UrlResource(path.toUri());

            return org.springframework.http.ResponseEntity.ok()
                    .header(org.springframework.http.HttpHeaders.CONTENT_DISPOSITION,
                            "attachment; filename=\"" + resource.getFilename() + "\"")
                    .body(resource);
        } catch (Exception e) {
            log.error("文件下载失败: {}", e.getMessage(), e);
            return org.springframework.http.ResponseEntity.internalServerError().build();
        }
    }

    /**
     * 获取文件扩展名
     */
    private String getFileExtension(String filename) {
        int lastDotIndex = filename.lastIndexOf('.');
        if (lastDotIndex > 0 && lastDotIndex < filename.length() - 1) {
            return filename.substring(lastDotIndex);
        }
        return "";
    }

    /**
     * 生成唯一文件名
     */
    private String generateFileName(String originalFilename) {
        String extension = getFileExtension(originalFilename);
        String nameWithoutExt = originalFilename.substring(0, originalFilename.lastIndexOf('.'));
        String timestamp = String.valueOf(System.currentTimeMillis());
        String random = UUID.randomUUID().toString().substring(0, 8);
        return nameWithoutExt + "_" + timestamp + "_" + random + extension;
    }
}