private FileInfo readHeader()

in src/main/java/org/apache/commons/imaging/formats/pnm/PnmImageParser.java [186:319]
125 lines of code
35 McCabe index (conditional complexity)

    private FileInfo readHeader(final InputStream is) throws ImagingException,
            IOException {
        final byte identifier1 = readByte("Identifier1", is, "Not a Valid PNM File");
        final byte identifier2 = readByte("Identifier2", is, "Not a Valid PNM File");

        if (identifier1 != PnmConstants.PNM_PREFIX_BYTE) {
            throw new ImagingException("PNM file has invalid prefix byte 1");
        }

        final WhiteSpaceReader wsr = new WhiteSpaceReader(is);

        if (identifier2 == PnmConstants.PBM_TEXT_CODE
                || identifier2 == PnmConstants.PBM_RAW_CODE
                || identifier2 == PnmConstants.PGM_TEXT_CODE
                || identifier2 == PnmConstants.PGM_RAW_CODE
                || identifier2 == PnmConstants.PPM_TEXT_CODE
                || identifier2 == PnmConstants.PPM_RAW_CODE) {

            final int width;
            try {
              width = Integer.parseInt(wsr.readtoWhiteSpace());
            } catch (final NumberFormatException e) {
              throw new ImagingException("Invalid width specified." , e);
            }
            final int height;
            try {
              height = Integer.parseInt(wsr.readtoWhiteSpace());
            } catch (final NumberFormatException e) {
              throw new ImagingException("Invalid height specified." , e);
            }

            switch (identifier2) {
            case PnmConstants.PBM_TEXT_CODE:
                return new PbmFileInfo(width, height, false);
            case PnmConstants.PBM_RAW_CODE:
                return new PbmFileInfo(width, height, true);
            case PnmConstants.PGM_TEXT_CODE: {
                final int maxgray = Integer.parseInt(wsr.readtoWhiteSpace());
                return new PgmFileInfo(width, height, false, maxgray);
            }
            case PnmConstants.PGM_RAW_CODE: {
                final int maxgray = Integer.parseInt(wsr.readtoWhiteSpace());
                return new PgmFileInfo(width, height, true, maxgray);
            }
            case PnmConstants.PPM_TEXT_CODE: {
                final int max = Integer.parseInt(wsr.readtoWhiteSpace());
                return new PpmFileInfo(width, height, false, max);
            }
            case PnmConstants.PPM_RAW_CODE: {
                final int max = Integer.parseInt(wsr.readtoWhiteSpace());
                return new PpmFileInfo(width, height, true, max);
            }
            default:
                break;
            }
        } else if (identifier2 == PnmConstants.PAM_RAW_CODE) {
            int width = -1;
            boolean seenWidth = false;
            int height = -1;
            boolean seenHeight = false;
            int depth = -1;
            boolean seenDepth = false;
            int maxVal = -1;
            boolean seenMaxVal = false;
            final StringBuilder tupleType = new StringBuilder();
            boolean seenTupleType = false;

            // Advance to next line
            wsr.readLine();
            String line;
            while ((line = wsr.readLine()) != null) {
                line = line.trim();
                if (line.charAt(0) == '#') {
                    continue;
                }
                final StringTokenizer tokenizer = new StringTokenizer(line, " ", false);
                final String type = tokenizer.nextToken();
                if ("WIDTH".equals(type)) {
                    seenWidth = true;
                    if(!tokenizer.hasMoreTokens()) {
                        throw new ImagingException("PAM header has no WIDTH value");
                    }
                    width = Integer.parseInt(tokenizer.nextToken());
                } else if ("HEIGHT".equals(type)) {
                    seenHeight = true;
                    if(!tokenizer.hasMoreTokens()) {
                        throw new ImagingException("PAM header has no HEIGHT value");
                    }
                    height = Integer.parseInt(tokenizer.nextToken());
                } else if ("DEPTH".equals(type)) {
                    seenDepth = true;
                    if(!tokenizer.hasMoreTokens()) {
                        throw new ImagingException("PAM header has no DEPTH value");
                    }
                    depth = Integer.parseInt(tokenizer.nextToken());
                } else if ("MAXVAL".equals(type)) {
                    seenMaxVal = true;
                    if(!tokenizer.hasMoreTokens()) {
                        throw new ImagingException("PAM header has no MAXVAL value");
                    }
                    maxVal = Integer.parseInt(tokenizer.nextToken());
                } else if ("TUPLTYPE".equals(type)) {
                    seenTupleType = true;
                    if(!tokenizer.hasMoreTokens()) {
                        throw new ImagingException("PAM header has no TUPLTYPE value");
                    }
                    tupleType.append(tokenizer.nextToken());
                } else if ("ENDHDR".equals(type)) {
                    break;
                } else {
                    throw new ImagingException("Invalid PAM file header type " + type);
                }
            }

            if (!seenWidth) {
                throw new ImagingException("PAM header has no WIDTH");
            }
            if (!seenHeight) {
                throw new ImagingException("PAM header has no HEIGHT");
            }
            if (!seenDepth) {
                throw new ImagingException("PAM header has no DEPTH");
            }
            if (!seenMaxVal) {
                throw new ImagingException("PAM header has no MAXVAL");
            }
            if (!seenTupleType) {
                throw new ImagingException("PAM header has no TUPLTYPE");
            }

            return new PamFileInfo(width, height, depth, maxVal, tupleType.toString());
        }
        throw new ImagingException("PNM file has invalid prefix byte 2");
    }