Implement functionality to extract smgXml file from SMG, edit it, and…

… repackage it.

The input SMG file is not a zip archive, for some reason it is an SFX zip. Added a filter input stream to ignore the local headers, enabling us to read the file. The entries are cached and bundled into a fresh zip once the transformations are complete.

src/main/java/com/lmco/spectrum/systemnavigation3d/controller/ResourceController.java

@@ -3,16 +3,17 @@
 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 org.springframework.web.bind.annotation.RequestMethod;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -21,36 +22,80 @@
 @RequestMapping("api/resources")
 public class ResourceController {
 
+    private final HttpHeaders PDF_HEADERS;
+
     @Autowired
     ResourceService resourceService;
+    @Autowired
+    SmgService smgService;
 
-    private ResponseEntity<?> handleS3Input(String key, @Nullable HttpHeaders headers) {
-        try (InputStream is = resourceService.getFileAsStream(key)) {
-            return new ResponseEntity<>(IOUtils.toByteArray(is), headers, HttpStatus.OK);
-        } catch (AmazonS3Exception e) {
-            if(e.getErrorCode().equals("NoSuchKey")) {
-                return new ResponseEntity<>(e.getErrorMessage(), HttpStatus.NOT_FOUND);
+    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 {
-                e.printStackTrace();
-                return new ResponseEntity<>(e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
+                ex.printStackTrace();
+                return new ResponseEntity<>(ex.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
             }
-        } catch (IOException e) {
+        } 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);
     }
 
-    @RequestMapping(value = "/pdf/{key}", method = RequestMethod.GET)
+    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){
-        HttpHeaders headers = new HttpHeaders();
-        headers.setContentType(MediaType.APPLICATION_PDF);
-        // headers.setContentDispositionFormData(key, key); // Auto download
-        return handleS3Input(key, headers);
+        return fetchResponseFromS3(key, this.PDF_HEADERS);
     }
 
-    @RequestMapping(value = "/{key}", method = RequestMethod.GET)
+    @GetMapping("/{key}")
     public ResponseEntity<?> getResource(@PathVariable("key") String key){
-        return handleS3Input(key, null);
+        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);
+        }
     }
 
 }

src/main/java/com/lmco/spectrum/systemnavigation3d/service/SmgService.java

@@ -0,0 +1,83 @@
+package com.lmco.spectrum.systemnavigation3d.service;
+
+import com.amazonaws.util.IOUtils;
+import com.lmco.spectrum.systemnavigation3d.util.io.SfxZipInputStream;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Service;
+
+import javax.annotation.Nullable;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipInputStream;
+import java.util.zip.ZipOutputStream;
+
+@Service
+public class SmgService {
+
+    private static final Logger log = LoggerFactory.getLogger(SmgService.class);
+    private static final String PRODUCT_XML = "product.smgXml";
+
+    // Max capacity is 2^31-1 bytes or ~2GB.
+    @Nullable
+    public byte[] processSmg(byte[] data){
+        Map<String, byte[]> entryMap = getSmgXmlEntry(data);
+        byte[] smgXmlData = entryMap.get(PRODUCT_XML);
+        if(smgXmlData != null) {
+            String smgXml = new String(smgXmlData);
+            // TODO transform
+
+            // Update XML entry.
+            entryMap.put(PRODUCT_XML, smgXml.getBytes());
+            return repackageSmg(entryMap);
+        } else {
+            return null;
+        }
+    }
+
+    public Map<String, byte[]> getSmgXmlEntry(byte[] data) {
+
+        Map<String, byte[]> entryMap = new HashMap<>();
+
+        try(ZipInputStream zis = new ZipInputStream(new SfxZipInputStream(new ByteArrayInputStream(data)))) {
+
+            ZipEntry entry;
+            while((entry = zis.getNextEntry()) != null) {
+                entryMap.put(entry.getName(), IOUtils.toByteArray(zis));
+                zis.closeEntry();
+            }
+            return entryMap;
+
+        } catch (IOException e) {
+            log.error("Failed to read .smgXml entry!");
+            e.printStackTrace();
+        }
+
+        return entryMap;
+    }
+
+    @Nullable
+    public byte[] repackageSmg(Map<String, byte[]> entryMap) {
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        try (ZipOutputStream zos = new ZipOutputStream(bos)) {
+            for(Map.Entry<String, byte[]> entry : entryMap.entrySet()) {
+                ZipEntry zipEntry = new ZipEntry(entry.getKey());
+                zos.putNextEntry(zipEntry);
+                zos.write(entry.getValue());
+                zos.closeEntry();
+            }
+        } catch (IOException e) {
+            log.error("Failed to repackage smg file");
+            e.printStackTrace();
+            return null;
+        }
+
+        return bos.toByteArray();
+
+    }
+
+}

src/main/java/com/lmco/spectrum/systemnavigation3d/util/io/SfxZipInputStream.java

@@ -0,0 +1,46 @@
+package com.lmco.spectrum.systemnavigation3d.util.io;
+
+import javax.annotation.Nonnull;
+import java.io.FilterInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+// Credit
+// https://stackoverflow.com/questions/7924895/how-can-i-read-from-a-winzip-self-extracting-exe-zip-file-in-java
+public class SfxZipInputStream extends FilterInputStream {
+
+    // https://en.wikipedia.org/wiki/Zip_(file_format)#Local_file_header
+    public static final byte[] ZIP_LOCAL = { 0x50, 0x4b, 0x03, 0x04 };
+    protected int ip;
+    protected int op;
+
+    public SfxZipInputStream(InputStream is) {
+        super(is);
+    }
+
+    @Override
+    public int read() throws IOException {
+        while(ip < ZIP_LOCAL.length) {
+            int c = super.read();
+            if (c == ZIP_LOCAL[ip]) {
+                ip++;
+            }
+            else ip = 0;
+        }
+
+        if (op < ZIP_LOCAL.length)
+            return ZIP_LOCAL[op++];
+        else
+            return super.read();
+    }
+
+    @Override
+    public int read(@Nonnull byte[] b, int off, int len) throws IOException {
+        if (op == ZIP_LOCAL.length) return super.read(b, off, len);
+        int l = 0;
+        while (l < Math.min(len, ZIP_LOCAL.length)) {
+            b[l++] = (byte)read();
+        }
+        return l;
+    }
+}