private boolean validateAndExecute()

in src/main/org/apache/tools/ant/taskdefs/Checksum.java [323:416]
90 lines of code
36 McCabe index (conditional complexity)

    private boolean validateAndExecute() throws BuildException {
        String savedFileExt = fileext;

        if (file == null && (resources == null || resources.size() == 0)) {
            throw new BuildException(
                "Specify at least one source - a file or a resource collection.");
        }
        if (resources != null && !resources.isFilesystemOnly()) {
            throw new BuildException("Can only calculate checksums for file-based resources.");
        }
        if (file != null && file.exists() && file.isDirectory()) {
            throw new BuildException("Checksum cannot be generated for directories");
        }
        if (file != null && totalproperty != null) {
            throw new BuildException("File and Totalproperty cannot co-exist.");
        }
        if (property != null && fileext != null) {
            throw new BuildException("Property and FileExt cannot co-exist.");
        }
        if (property != null) {
            if (forceOverwrite) {
                throw new BuildException(
                    "ForceOverwrite cannot be used when Property is specified");
            }
            int ct = 0;
            if (resources != null) {
                ct += resources.size();
            }
            if (file != null) {
                ct++;
            }
            if (ct > 1) {
                throw new BuildException(
                    "Multiple files cannot be used when Property is specified");
            }
        }
        if (verifyProperty != null) {
            isCondition = true;
        }
        if (verifyProperty != null && forceOverwrite) {
            throw new BuildException("VerifyProperty and ForceOverwrite cannot co-exist.");
        }
        if (isCondition && forceOverwrite) {
            throw new BuildException(
                "ForceOverwrite cannot be used when conditions are being used.");
        }
        messageDigest = null;
        if (provider != null) {
            try {
                messageDigest = MessageDigest.getInstance(algorithm, provider);
            } catch (NoSuchAlgorithmException | NoSuchProviderException noalgo) {
                throw new BuildException(noalgo, getLocation());
            }
        } else {
            try {
                messageDigest = MessageDigest.getInstance(algorithm);
            } catch (NoSuchAlgorithmException noalgo) {
                throw new BuildException(noalgo, getLocation());
            }
        }
        if (messageDigest == null) {
            throw new BuildException("Unable to create Message Digest", getLocation());
        }
        if (fileext == null) {
            fileext = "." + algorithm;
        } else if (fileext.trim().isEmpty()) {
            throw new BuildException("File extension when specified must not be an empty string");
        }
        try {
            if (resources != null) {
                for (Resource r : resources) {
                    File src = r.as(FileProvider.class).getFile();
                    if (totalproperty != null || todir != null) {
                        // Use '/' to calculate digest based on file name.
                        // This is required in order to get the same result
                        // on different platforms.
                        relativeFilePaths.put(src, r.getName().replace(File.separatorChar, '/'));
                    }
                    addToIncludeFileMap(src);
                }
            }
            if (file != null) {
                if (totalproperty != null || todir != null) {
                    relativeFilePaths.put(
                        file, file.getName().replace(File.separatorChar, '/'));
                }
                addToIncludeFileMap(file);
            }
            return generateChecksums();
        } finally {
            fileext = savedFileExt;
            includeFileMap.clear();
        }
    }