ResourceController.java

package com.lmco.spectrum.systemnavigation3d.controller;

import com.amazonaws.services.s3.model.AmazonS3Exception;
import com.amazonaws.util.IOUtils;
import com.lmco.spectrum.systemnavigation3d.service.ResourceService;
import com.lmco.spectrum.systemnavigation3d.service.SmgService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.lang.Nullable;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

import java.io.IOException;
import java.io.InputStream;

@Controller
@RequestMapping("api/resources")
public class ResourceController {

    private final HttpHeaders PDF_HEADERS;

    @Autowired
    ResourceService resourceService;
    @Autowired
    SmgService smgService;

    public ResourceController() {
        this.PDF_HEADERS = new HttpHeaders();
        PDF_HEADERS.setContentType(MediaType.APPLICATION_PDF);
    }

    private HttpHeaders getAutoDownloadHeaders(String key) {
        HttpHeaders headers = new HttpHeaders();
        headers.setContentDispositionFormData(key, key);
        return headers;
    }

    private ResponseEntity<?> respondToException(Exception e) {
        if (e instanceof AmazonS3Exception) {
            AmazonS3Exception ex = (AmazonS3Exception)e;
            if (ex.getErrorCode().equals("NoSuchKey")) {
                return new ResponseEntity<>(ex.getErrorMessage(), HttpStatus.NOT_FOUND);
            } else {
                ex.printStackTrace();
                return new ResponseEntity<>(ex.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
            }
        } else if(e instanceof IOException) {
            e.printStackTrace();
            return new ResponseEntity<>(e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        }

        // Return 500 as default.
        return new ResponseEntity<>(e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
    }

    private ResponseEntity<?> fetchResponseFromS3(String key, @Nullable HttpHeaders headers) {
        try (InputStream is = resourceService.getFileAsStream(key)) {
            return new ResponseEntity<>(IOUtils.toByteArray(is), headers, HttpStatus.OK);
        } catch (Exception e) {
            return respondToException(e);
        }
    }

    @GetMapping("/pdf/{key}")
    public ResponseEntity<?> getResourcePDF(@PathVariable("key") String key){
        return fetchResponseFromS3(key, this.PDF_HEADERS);
    }

    @GetMapping("/{key}")
    public ResponseEntity<?> getResource(@PathVariable("key") String key){
        return fetchResponseFromS3(key, null);
    }

    // TODO what input data?
    @GetMapping("/smg/{key}")
    public ResponseEntity<?> getResourceSMG(@PathVariable("key") String key) {

        try(InputStream is = resourceService.getFileAsStream(String.format("smg/%s", key))) {

            byte[] data = IOUtils.toByteArray(is);

            byte[] processed = smgService.processSmg(data);
            if(processed == null) {
                // TODO failed to process, error?
                // TODO maybe return error list
                return new ResponseEntity<>("Failed to process SMG file.", HttpStatus.INTERNAL_SERVER_ERROR);
            } else {
                return new ResponseEntity<>(processed, getAutoDownloadHeaders(key), HttpStatus.OK);
            }

        } catch(Exception e) {
            return respondToException(e);
        }
    }

}