/**
 *  Copyright 2005-2015 Red Hat, Inc.
 *
 *  Red Hat licenses this file to you under the Apache License, version
 *  2.0 (the "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 *  implied.  See the License for the specific language governing
 *  permissions and limitations under the License.
 */
package io.fabric8.agent.resolver;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.felix.framework.wiring.BundleRequirementImpl;
import org.apache.felix.utils.version.VersionRange;
import org.osgi.framework.BundleException;
import org.osgi.framework.Constants;
import org.osgi.framework.Version;
import org.osgi.framework.namespace.ExecutionEnvironmentNamespace;
import org.osgi.framework.namespace.IdentityNamespace;
import org.osgi.framework.wiring.BundleRequirement;
import org.osgi.framework.wiring.BundleRevision;
import org.osgi.namespace.service.ServiceNamespace;
import org.osgi.resource.Capability;
import org.osgi.resource.Requirement;
import org.osgi.resource.Resource;
import org.osgi.service.repository.ContentNamespace;

public final class ResourceBuilder {

    public static final String RESOLUTION_DYNAMIC = "dynamic";

    private static final char EOF = (char) -1;

    private static final int CLAUSE_START = 0;
    private static final int PARAMETER_START = 1;
    private static final int KEY = 2;
    private static final int DIRECTIVE_OR_TYPEDATTRIBUTE = 4;
    private static final int ARGUMENT = 8;
    private static final int VALUE = 16;

    private static final int CHAR = 1;
    private static final int DELIMITER = 2;
    private static final int STARTQUOTE = 4;
    private static final int ENDQUOTE = 8;


    private ResourceBuilder() {
    }

    public static ResourceImpl build(String uri, Map<String, String> headerMap) throws BundleException {
        return build(new ResourceImpl(), uri, headerMap);
    }

    public static ResourceImpl build(ResourceImpl resource, String uri, Map<String, String> headerMap) throws BundleException {
        // Verify that only manifest version 2 is specified.
        String manifestVersion = getManifestVersion(headerMap);
        if (manifestVersion == null || !manifestVersion.equals("2")) {
            throw new BundleException("Unsupported 'Bundle-ManifestVersion' value: " + manifestVersion);
        }

        //
        // Parse bundle version.
        //

        Version bundleVersion = Version.emptyVersion;
        if (headerMap.get(Constants.BUNDLE_VERSION) != null) {
            bundleVersion = Version.parseVersion(headerMap.get(Constants.BUNDLE_VERSION));
        }

        //
        // Parse bundle symbolic name.
        //

        String bundleSymbolicName;
        ParsedHeaderClause bundleCap = parseBundleSymbolicName(headerMap);
        if (bundleCap == null) {
            throw new BundleException("Bundle manifest must include bundle symbolic name");
        }
        bundleSymbolicName = (String) bundleCap.attrs.get(BundleRevision.BUNDLE_NAMESPACE);

        // Now that we have symbolic name and version, create the resource
        String type = headerMap.get(Constants.FRAGMENT_HOST) == null ? IdentityNamespace.TYPE_BUNDLE : IdentityNamespace.TYPE_FRAGMENT;
        {
            Map<String, String> dirs = new HashMap<>();
            Map<String, Object> attrs = new HashMap<>();
            attrs.put(IdentityNamespace.IDENTITY_NAMESPACE, bundleSymbolicName);
            attrs.put(IdentityNamespace.CAPABILITY_TYPE_ATTRIBUTE, type);
            attrs.put(IdentityNamespace.CAPABILITY_VERSION_ATTRIBUTE, bundleVersion);
            CapabilityImpl identity = new CapabilityImpl(resource, IdentityNamespace.IDENTITY_NAMESPACE, dirs, attrs);
            resource.addCapability(identity);
        }
        if (uri != null) {
            Map<String, Object> attrs = new HashMap<>();
            attrs.put(ContentNamespace.CAPABILITY_URL_ATTRIBUTE, uri);
            resource.addCapability(new CapabilityImpl(resource, ContentNamespace.CONTENT_NAMESPACE, Collections.<String, String>emptyMap(), attrs));
        }

        // Add a bundle and host capability to all
        // non-fragment bundles. A host capability is the same
        // as a require capability, but with a different capability
        // namespace. Bundle capabilities resolve required-bundle
        // dependencies, while host capabilities resolve fragment-host
        // dependencies.
        if (headerMap.get(Constants.FRAGMENT_HOST) == null) {
            // All non-fragment bundles have bundle capability.
            resource.addCapability(new CapabilityImpl(resource, BundleRevision.BUNDLE_NAMESPACE, bundleCap.dirs, bundleCap.attrs));
            // A non-fragment bundle can choose to not have a host capability.
            String attachment = bundleCap.dirs.get(Constants.FRAGMENT_ATTACHMENT_DIRECTIVE);
            attachment = (attachment == null) ? Constants.FRAGMENT_ATTACHMENT_RESOLVETIME : attachment;
            if (!attachment.equalsIgnoreCase(Constants.FRAGMENT_ATTACHMENT_NEVER)) {
                Map<String, Object> hostAttrs = new HashMap<>(bundleCap.attrs);
                Object value = hostAttrs.remove(BundleRevision.BUNDLE_NAMESPACE);
                hostAttrs.put(BundleRevision.HOST_NAMESPACE, value);
                resource.addCapability(new CapabilityImpl(
                        resource, BundleRevision.HOST_NAMESPACE,
                        bundleCap.dirs,
                        hostAttrs));
            }
        }

        //
        // Parse Fragment-Host.
        //

        List<RequirementImpl> hostReqs = parseFragmentHost(resource, headerMap);

        //
        // Parse Require-Bundle
        //

        List<ParsedHeaderClause> rbClauses = parseStandardHeader(headerMap.get(Constants.REQUIRE_BUNDLE));
        rbClauses = normalizeRequireClauses(rbClauses);
        List<Requirement> rbReqs = convertRequires(rbClauses, resource);

        //
        // Parse Import-Package.
        //

        List<ParsedHeaderClause> importClauses = parseStandardHeader(headerMap.get(Constants.IMPORT_PACKAGE));
        importClauses = normalizeImportClauses(importClauses);
        List<Requirement> importReqs = convertImports(importClauses, resource);

        //
        // Parse DynamicImport-Package.
        //

        List<ParsedHeaderClause> dynamicClauses = parseStandardHeader(headerMap.get(Constants.DYNAMICIMPORT_PACKAGE));
        dynamicClauses = normalizeDynamicImportClauses(dynamicClauses);
        List<Requirement> dynamicReqs = convertImports(dynamicClauses, resource);

        //
        // Parse Require-Capability.
        //

        List<ParsedHeaderClause> requireClauses = parseStandardHeader(headerMap.get(Constants.REQUIRE_CAPABILITY));
        requireClauses = normalizeRequireCapabilityClauses(requireClauses);
        List<Requirement> requireReqs = convertRequireCapabilities(requireClauses, resource);

        //
        // Parse Bundle-RequiredExecutionEnvironment.
        //
        List<Requirement> breeReqs =
                parseBreeHeader((String) headerMap.get(Constants.BUNDLE_REQUIREDEXECUTIONENVIRONMENT), resource);

        //
        // Parse Export-Package.
        //

        List<ParsedHeaderClause> exportClauses = parseStandardHeader(headerMap.get(Constants.EXPORT_PACKAGE));
        exportClauses = normalizeExportClauses(exportClauses, bundleSymbolicName, bundleVersion);
        List<Capability> exportCaps = convertExports(exportClauses, resource);

        //
        // Parse Provide-Capability.
        //

        List<ParsedHeaderClause> provideClauses = parseStandardHeader(headerMap.get(Constants.PROVIDE_CAPABILITY));
        provideClauses = normalizeProvideCapabilityClauses(provideClauses);
        List<Capability> provideCaps = convertProvideCapabilities(provideClauses, resource);

        //
        // Parse Import-Service and Export-Service
        // if Require-Capability and Provide-Capability are not set for services
        //

        boolean hasServiceReferenceCapability = false;
        for (Capability cap : exportCaps) {
            hasServiceReferenceCapability |= ServiceNamespace.SERVICE_NAMESPACE.equals(cap.getNamespace());
        }
        if (!hasServiceReferenceCapability) {
            List<ParsedHeaderClause> exportServices = parseStandardHeader(headerMap.get(Constants.EXPORT_SERVICE));
            List<Capability> caps = convertExportService(exportServices, resource);
            provideCaps.addAll(caps);
        }

        boolean hasServiceReferenceRequirement = false;
        for (Requirement req : requireReqs) {
            hasServiceReferenceRequirement |= ServiceNamespace.SERVICE_NAMESPACE.equals(req.getNamespace());
        }
        if (!hasServiceReferenceRequirement) {
            List<ParsedHeaderClause> importServices = parseStandardHeader(headerMap.get(Constants.IMPORT_SERVICE));
            List<Requirement> reqs = convertImportService(importServices, resource);
            requireReqs.addAll(reqs);
        }

        // Combine all capabilities.
        resource.addCapabilities(exportCaps);
        resource.addCapabilities(provideCaps);

        // Combine all requirements.
        resource.addRequirements(hostReqs);
        resource.addRequirements(importReqs);
        resource.addRequirements(rbReqs);
        resource.addRequirements(requireReqs);
        resource.addRequirements(dynamicReqs);

        return resource;
    }

    public static List<Requirement> parseImport(Resource resource, String imports) throws BundleException {
        List<ParsedHeaderClause> importClauses = parseStandardHeader(imports);
        importClauses = normalizeImportClauses(importClauses);
        return convertImports(importClauses, resource);
    }

    public static List<Requirement> parseRequirement(Resource resource, String requirement) throws BundleException {
        List<ParsedHeaderClause> requireClauses = parseStandardHeader(requirement);
        requireClauses = normalizeRequireCapabilityClauses(requireClauses);
        return convertRequireCapabilities(requireClauses, resource);
    }

    public static List<Capability> parseExport(Resource resource, String bundleSymbolicName, Version bundleVersion, String exports) throws BundleException {
        List<ParsedHeaderClause> exportClauses = parseStandardHeader(exports);
        exportClauses = normalizeExportClauses(exportClauses, bundleSymbolicName, bundleVersion);
        return convertExports(exportClauses, resource);
    }

    public static List<Capability> parseCapability(Resource resource, String capability) throws BundleException {
        List<ParsedHeaderClause> provideClauses = parseStandardHeader(capability);
        provideClauses = normalizeProvideCapabilityClauses(provideClauses);
        return convertProvideCapabilities(provideClauses, resource);
    }

    @SuppressWarnings("deprecation")
    private static List<ParsedHeaderClause> normalizeImportClauses(List<ParsedHeaderClause> clauses) throws BundleException {
        // Verify that the values are equals if the package specifies
        // both version and specification-version attributes.
        Set<String> dupeSet = new HashSet<>();
        for (ParsedHeaderClause clause : clauses) {
            // Check for "version" and "specification-version" attributes
            // and verify they are the same if both are specified.
            Object v = clause.attrs.get(Constants.VERSION_ATTRIBUTE);
            Object sv = clause.attrs.get(Constants.PACKAGE_SPECIFICATION_VERSION);
            if ((v != null) && (sv != null)) {
                // Verify they are equal.
                if (!((String) v).trim().equals(((String) sv).trim())) {
                    throw new IllegalArgumentException(
                            "Both version and specification-version are specified, but they are not equal.");
                }
            }

            // Ensure that only the "version" attribute is used and convert
            // it to the VersionRange type.
            if ((v != null) || (sv != null)) {
                clause.attrs.remove(Constants.PACKAGE_SPECIFICATION_VERSION);
                v = (v == null) ? sv : v;
                clause.attrs.put(Constants.VERSION_ATTRIBUTE, VersionRange.parseVersionRange(v.toString()));
            }

            // If bundle version is specified, then convert its type to VersionRange.
            v = clause.attrs.get(Constants.BUNDLE_VERSION_ATTRIBUTE);
            if (v != null) {
                clause.attrs.put(Constants.BUNDLE_VERSION_ATTRIBUTE, VersionRange.parseVersionRange(v.toString()));
            }

            // Verify java.* is not imported, nor any duplicate imports.
            for (String pkgName : clause.paths) {
                if (!dupeSet.contains(pkgName)) {
                    // Verify that java.* packages are not imported.
                    if (pkgName.startsWith("java.")) {
                        throw new BundleException("Importing java.* packages not allowed: " + pkgName);
                        // The character "." has no meaning in the OSGi spec except
                        // when placed on the bundle class path. Some people, however,
                        // mistakenly think it means the default package when imported
                        // or exported. This is not correct. It is invalid.
                    } else if (pkgName.equals(".")) {
                        throw new BundleException("Importing '.' is invalid.");
                        // Make sure a package name was specified.
                    } else if (pkgName.length() == 0) {
                        throw new BundleException(
                                "Imported package names cannot be zero length.");
                    }
                    dupeSet.add(pkgName);
                } else {
                    throw new BundleException("Duplicate import: " + pkgName);
                }
            }
        }

        return clauses;
    }

    private static List<Capability> convertExportService(List<ParsedHeaderClause> clauses, Resource resource) {
        List<Capability> capList = new ArrayList<>();
        for (ParsedHeaderClause clause : clauses) {
            for (String path : clause.paths) {
                Map<String, String> dirs = new LinkedHashMap<>();
                dirs.put(ServiceNamespace.CAPABILITY_EFFECTIVE_DIRECTIVE, ServiceNamespace.EFFECTIVE_ACTIVE);
                Map<String, Object> attrs = new LinkedHashMap<>();
                attrs.put(Constants.OBJECTCLASS, path);
                attrs.putAll(clause.attrs);
                capList.add(new CapabilityImpl(
                        resource,
                        ServiceNamespace.SERVICE_NAMESPACE,
                        dirs,
                        attrs));
            }
        }
        return capList;
    }

    private static List<Requirement> convertImportService(List<ParsedHeaderClause> clauses, Resource resource) throws BundleException {
        try {
            List<Requirement> reqList = new ArrayList<>();
            for (ParsedHeaderClause clause : clauses) {
                for (String path : clause.paths) {
                    String multiple = clause.dirs.get("multiple");
                    String avail = clause.dirs.get("availability");
                    String filter = (String) clause.attrs.get("filter");
                    Map<String, String> dirs = new LinkedHashMap<>();
                    dirs.put(ServiceNamespace.REQUIREMENT_EFFECTIVE_DIRECTIVE, ServiceNamespace.EFFECTIVE_ACTIVE);
                    if ("optional".equals(avail)) {
                        dirs.put(ServiceNamespace.REQUIREMENT_RESOLUTION_DIRECTIVE, ServiceNamespace.RESOLUTION_OPTIONAL);
                    }
                    if ("true".equals(multiple)) {
                        dirs.put(ServiceNamespace.REQUIREMENT_CARDINALITY_DIRECTIVE, ServiceNamespace.CARDINALITY_MULTIPLE);
                    }
                    if (filter == null) {
                        filter = "(" + Constants.OBJECTCLASS + "=" + path + ")";
                    } else if (!filter.startsWith("(") && !filter.endsWith(")")) {
                        filter = "(&(" + Constants.OBJECTCLASS + "=" + path + ")(" + filter + "))";
                    } else {
                        filter = "(&(" + Constants.OBJECTCLASS + "=" + path + ")" + filter + ")";
                    }
                    dirs.put(ServiceNamespace.REQUIREMENT_FILTER_DIRECTIVE, filter);
                    reqList.add(new RequirementImpl(
                            resource,
                            ServiceNamespace.SERVICE_NAMESPACE,
                            dirs,
                            Collections.<String, Object>emptyMap(),
                            SimpleFilter.parse(filter)));
                }
            }
            return reqList;
        } catch (Exception ex) {
            throw new BundleException("Error creating requirement: " + ex, ex);
        }
    }

    private static List<Requirement> convertImports(List<ParsedHeaderClause> clauses, Resource resource) {
        // Now convert generic header clauses into requirements.
        List<Requirement> reqList = new ArrayList<>();
        for (ParsedHeaderClause clause : clauses) {
            for (String path : clause.paths) {
                // Prepend the package name to the array of attributes.
                Map<String, Object> attrs = clause.attrs;
                // Note that we use a linked hash map here to ensure the
                // package attribute is first, which will make indexing
                // more efficient.
                // TODO: OSGi R4.3 - This is ordering is kind of hacky.
                // Prepend the package name to the array of attributes.
                Map<String, Object> newAttrs = new LinkedHashMap<>(attrs.size() + 1);
                // We want this first from an indexing perspective.
                newAttrs.put(BundleRevision.PACKAGE_NAMESPACE, path);
                newAttrs.putAll(attrs);
                // But we need to put it again to make sure it wasn't overwritten.
                newAttrs.put(BundleRevision.PACKAGE_NAMESPACE, path);

                // Create filter now so we can inject filter directive.
                SimpleFilter sf = SimpleFilter.convert(newAttrs);

                // Inject filter directive.
                // TODO: OSGi R4.3 - Can we insert this on demand somehow?
                Map<String, String> dirs = clause.dirs;
                Map<String, String> newDirs = new HashMap<>(dirs.size() + 1);
                newDirs.putAll(dirs);
                newDirs.put(Constants.FILTER_DIRECTIVE, sf.toString());

                // Create package requirement and add to requirement list.
                reqList.add(
                        new RequirementImpl(
                                resource,
                                BundleRevision.PACKAGE_NAMESPACE,
                                newDirs,
                                Collections.<String, Object>emptyMap(),
                                sf)
                );
            }
        }

        return reqList;
    }

    @SuppressWarnings("deprecation")
    private static List<ParsedHeaderClause> normalizeDynamicImportClauses(List<ParsedHeaderClause> clauses) throws BundleException {
        // Verify that the values are equals if the package specifies
        // both version and specification-version attributes.
        for (ParsedHeaderClause clause : clauses) {
            // Add the resolution directive to indicate that these are
            // dynamic imports.
            clause.dirs.put(Constants.RESOLUTION_DIRECTIVE, RESOLUTION_DYNAMIC);

            // Check for "version" and "specification-version" attributes
            // and verify they are the same if both are specified.
            Object v = clause.attrs.get(Constants.VERSION_ATTRIBUTE);
            Object sv = clause.attrs.get(Constants.PACKAGE_SPECIFICATION_VERSION);
            if ((v != null) && (sv != null)) {
                // Verify they are equal.
                if (!((String) v).trim().equals(((String) sv).trim())) {
                    throw new IllegalArgumentException(
                            "Both version and specification-version are specified, but they are not equal.");
                }
            }

            // Ensure that only the "version" attribute is used and convert
            // it to the VersionRange type.
            if ((v != null) || (sv != null)) {
                clause.attrs.remove(Constants.PACKAGE_SPECIFICATION_VERSION);
                v = (v == null) ? sv : v;
                clause.attrs.put(Constants.VERSION_ATTRIBUTE, VersionRange.parseVersionRange(v.toString()));
            }

            // If bundle version is specified, then convert its type to VersionRange.
            v = clause.attrs.get(Constants.BUNDLE_VERSION_ATTRIBUTE);
            if (v != null) {
                clause.attrs.put(Constants.BUNDLE_VERSION_ATTRIBUTE, VersionRange.parseVersionRange(v.toString()));
            }

            // Dynamic imports can have duplicates, so verify that java.*
            // packages are not imported.
            for (String pkgName : clause.paths) {
                if (pkgName.startsWith("java.")) {
                    throw new BundleException("Dynamically importing java.* packages not allowed: " + pkgName);
                } else if (!pkgName.equals("*") && pkgName.endsWith("*") && !pkgName.endsWith(".*")) {
                    throw new BundleException("Partial package name wild carding is not allowed: " + pkgName);
                }
            }
        }

        return clauses;
    }

    private static List<ParsedHeaderClause> normalizeRequireCapabilityClauses(
            List<ParsedHeaderClause> clauses) throws BundleException {

        return clauses;
    }

    private static List<ParsedHeaderClause> normalizeProvideCapabilityClauses(
            List<ParsedHeaderClause> clauses) throws BundleException {

        // Convert attributes into specified types.
        for (ParsedHeaderClause clause : clauses) {
            for (Map.Entry<String, String> entry : clause.types.entrySet()) {
                String type = entry.getValue();
                if (!type.equals("String")) {
                    if (type.equals("Double")) {
                        clause.attrs.put(
                                entry.getKey(),
                                new Double(clause.attrs.get(entry.getKey()).toString().trim()));
                    } else if (type.equals("Version")) {
                        clause.attrs.put(
                                entry.getKey(),
                                new Version(clause.attrs.get(entry.getKey()).toString().trim()));
                    } else if (type.equals("Long")) {
                        clause.attrs.put(
                                entry.getKey(),
                                new Long(clause.attrs.get(entry.getKey()).toString().trim()));
                    } else if (type.startsWith("List")) {
                        int startIdx = type.indexOf('<');
                        int endIdx = type.indexOf('>');
                        if (((startIdx > 0) && (endIdx <= startIdx))
                                || ((startIdx < 0) && (endIdx > 0))) {
                            throw new BundleException(
                                    "Invalid Provide-Capability attribute list type for '"
                                            + entry.getKey()
                                            + "' : "
                                            + type
                            );
                        }

                        String listType = "String";
                        if (endIdx > startIdx) {
                            listType = type.substring(startIdx + 1, endIdx).trim();
                        }

                        List<String> tokens = parseDelimitedString(
                                clause.attrs.get(entry.getKey()).toString(), ",", false);
                        List<Object> values = new ArrayList<>(tokens.size());
                        for (String token : tokens) {
                            switch (listType) {
                            case "String":
                                values.add(token);
                                break;
                            case "Double":
                                values.add(new Double(token.trim()));
                                break;
                            case "Version":
                                values.add(new Version(token.trim()));
                                break;
                            case "Long":
                                values.add(new Long(token.trim()));
                                break;
                            default:
                                throw new BundleException(
                                        "Unknown Provide-Capability attribute list type for '"
                                                + entry.getKey()
                                                + "' : "
                                                + type
                                );
                            }
                        }
                        clause.attrs.put(
                                entry.getKey(),
                                values);
                    } else {
                        throw new BundleException(
                                "Unknown Provide-Capability attribute type for '"
                                        + entry.getKey()
                                        + "' : "
                                        + type
                        );
                    }
                }
            }
        }

        return clauses;
    }

    private static List<Requirement> convertRequireCapabilities(
            List<ParsedHeaderClause> clauses, Resource resource) throws BundleException {

        // Now convert generic header clauses into requirements.
        List<Requirement> reqList = new ArrayList<>();
        for (ParsedHeaderClause clause : clauses) {
            try {
                String filterStr = clause.dirs.get(Constants.FILTER_DIRECTIVE);
                SimpleFilter sf = (filterStr != null)
                        ? SimpleFilter.parse(filterStr)
                        : new SimpleFilter(null, null, SimpleFilter.MATCH_ALL);
                for (String path : clause.paths) {
                    // Create requirement and add to requirement list.
                    reqList.add(new RequirementImpl(
                            resource, path, clause.dirs, clause.attrs, sf));
                }
            } catch (Exception ex) {
                throw new BundleException("Error creating requirement: " + ex, ex);
            }
        }

        return reqList;
    }

    private static List<Capability> convertProvideCapabilities(
            List<ParsedHeaderClause> clauses, Resource resource) throws BundleException {

        List<Capability> capList = new ArrayList<>();
        for (ParsedHeaderClause clause : clauses) {
            for (String path : clause.paths) {
                if (path.startsWith("osgi.wiring.")) {
//                    throw new BundleException("Manifest cannot use Provide-Capability for '" + path + "' namespace.");
                }

                // Create package capability and add to capability list.
                capList.add(new CapabilityImpl(resource, path, clause.dirs, clause.attrs));
            }
        }

        return capList;
    }

    @SuppressWarnings("deprecation")
    private static List<ParsedHeaderClause> normalizeExportClauses(
            List<ParsedHeaderClause> clauses,
            String bsn, Version bv) throws BundleException {

        // Verify that "java.*" packages are not exported.
        for (ParsedHeaderClause clause : clauses) {
            // Verify that the named package has not already been declared.
            for (String pkgName : clause.paths) {
                // Verify that java.* packages are not exported.
                if (pkgName.startsWith("java.")) {
                    throw new BundleException("Exporting java.* packages not allowed: " + pkgName);
                    // The character "." has no meaning in the OSGi spec except
                    // when placed on the bundle class path. Some people, however,
                    // mistakenly think it means the default package when imported
                    // or exported. This is not correct. It is invalid.
                } else if (pkgName.equals(".")) {
                    throw new BundleException("Exporing '.' is invalid.");
                    // Make sure a package name was specified.
                } else if (pkgName.length() == 0) {
                    throw new BundleException("Exported package names cannot be zero length.");
                }
            }

            // Check for "version" and "specification-version" attributes
            // and verify they are the same if both are specified.
            Object v = clause.attrs.get(Constants.VERSION_ATTRIBUTE);
            Object sv = clause.attrs.get(Constants.PACKAGE_SPECIFICATION_VERSION);
            if ((v != null) && (sv != null)) {
                // Verify they are equal.
                if (!((String) v).trim().equals(((String) sv).trim())) {
                    throw new IllegalArgumentException("Both version and specification-version are specified, but they are not equal.");
                }
            }

            // Always add the default version if not specified.
            if ((v == null) && (sv == null)) {
                v = Version.emptyVersion;
            }

            // Ensure that only the "version" attribute is used and convert
            // it to the appropriate type.
            if ((v != null) || (sv != null)) {
                // Convert version attribute to type Version.
                clause.attrs.remove(Constants.PACKAGE_SPECIFICATION_VERSION);
                v = (v == null) ? sv : v;
                clause.attrs.put(Constants.VERSION_ATTRIBUTE, Version.parseVersion(v.toString()));
            }

            // Find symbolic name and version attribute, if present.
            if (clause.attrs.containsKey(Constants.BUNDLE_VERSION_ATTRIBUTE)
                    || clause.attrs.containsKey(Constants.BUNDLE_SYMBOLICNAME_ATTRIBUTE)) {
                throw new BundleException("Exports must not specify bundle symbolic name or bundle version.");
            }

            // Now that we know that there are no bundle symbolic name and version
            // attributes, add them since the spec says they are there implicitly.
            clause.attrs.put(Constants.BUNDLE_SYMBOLICNAME_ATTRIBUTE, bsn);
            clause.attrs.put(Constants.BUNDLE_VERSION_ATTRIBUTE, bv);
        }

        return clauses;
    }

    private static List<Capability> convertExports(List<ParsedHeaderClause> clauses, Resource resource) {
        List<Capability> capList = new ArrayList<>();
        for (ParsedHeaderClause clause : clauses) {
            for (String pkgName : clause.paths) {
                // Prepend the package name to the array of attributes.
                Map<String, Object> attrs = clause.attrs;
                Map<String, Object> newAttrs = new HashMap<>(attrs.size() + 1);
                newAttrs.putAll(attrs);
                newAttrs.put(BundleRevision.PACKAGE_NAMESPACE, pkgName);

                // Create package capability and add to capability list.
                capList.add(new CapabilityImpl(resource, BundleRevision.PACKAGE_NAMESPACE, clause.dirs, newAttrs));
            }
        }

        return capList;
    }

    private static String getManifestVersion(Map<String, String> headerMap) {
        String manifestVersion = headerMap.get(Constants.BUNDLE_MANIFESTVERSION);
        return (manifestVersion == null) ? "1" : manifestVersion.trim();
    }

    private static ParsedHeaderClause parseBundleSymbolicName(Map<String, String> headerMap) throws BundleException {
        List<ParsedHeaderClause> clauses = parseStandardHeader(headerMap.get(Constants.BUNDLE_SYMBOLICNAME));
        if (clauses.size() > 0) {
            if (clauses.size() > 1 || clauses.get(0).paths.size() > 1) {
                throw new BundleException("Cannot have multiple symbolic names: " + headerMap.get(Constants.BUNDLE_SYMBOLICNAME));
            }

            // Get bundle version.
            Version bundleVersion = Version.emptyVersion;
            if (headerMap.get(Constants.BUNDLE_VERSION) != null) {
                bundleVersion = Version.parseVersion(headerMap.get(Constants.BUNDLE_VERSION));
            }

            // Create a require capability and return it.
            ParsedHeaderClause clause = clauses.get(0);
            String symName = clause.paths.get(0);
            clause.attrs.put(BundleRevision.BUNDLE_NAMESPACE, symName);
            clause.attrs.put(Constants.BUNDLE_VERSION_ATTRIBUTE, bundleVersion);
            return clause;
        }

        return null;
    }

    private static List<RequirementImpl> parseFragmentHost(Resource resource, Map<String, String> headerMap) throws BundleException {
        List<RequirementImpl> reqs = new ArrayList<>();
        List<ParsedHeaderClause> clauses = parseStandardHeader(headerMap.get(Constants.FRAGMENT_HOST));
        if (clauses.size() > 0) {
            // Make sure that only one fragment host symbolic name is specified.
            if (clauses.size() > 1 || clauses.get(0).paths.size() > 1) {
                throw new BundleException("Fragments cannot have multiple hosts: " + headerMap.get(Constants.FRAGMENT_HOST));
            }

            // If the bundle-version attribute is specified, then convert
            // it to the proper type.
            Object value = clauses.get(0).attrs.get(Constants.BUNDLE_VERSION_ATTRIBUTE);
            value = (value == null) ? "0.0.0" : value;
            clauses.get(0).attrs.put(Constants.BUNDLE_VERSION_ATTRIBUTE, VersionRange.parseVersionRange(value.toString()));

            // Note that we use a linked hash map here to ensure the
            // host symbolic name is first, which will make indexing
            // more efficient.
            // TODO: OSGi R4.3 - This is ordering is kind of hacky.
            // Prepend the host symbolic name to the map of attributes.
            Map<String, Object> attrs = clauses.get(0).attrs;
            Map<String, Object> newAttrs = new LinkedHashMap<>(attrs.size() + 1);
            // We want this first from an indexing perspective.
            newAttrs.put(BundleRevision.HOST_NAMESPACE, clauses.get(0).paths.get(0));
            newAttrs.putAll(attrs);
            // But we need to put it again to make sure it wasn't overwritten.
            newAttrs.put(BundleRevision.HOST_NAMESPACE, clauses.get(0).paths.get(0));

            // Create filter now so we can inject filter directive.
            SimpleFilter sf = SimpleFilter.convert(newAttrs);

            // Inject filter directive.
            // TODO: OSGi R4.3 - Can we insert this on demand somehow?
            Map<String, String> dirs = clauses.get(0).dirs;
            Map<String, String> newDirs = new HashMap<>(dirs.size() + 1);
            newDirs.putAll(dirs);
            newDirs.put(Constants.FILTER_DIRECTIVE, sf.toString());

            reqs.add(new RequirementImpl(
                    resource, BundleRevision.HOST_NAMESPACE,
                    newDirs,
                    newAttrs));
        }

        return reqs;
    }

    private static List<Requirement> parseBreeHeader(String header, Resource resource) {
        List<String> filters = new ArrayList<String>();
        for (String entry : parseDelimitedString(header, ",")) {
            List<String> names = parseDelimitedString(entry, "/");
            List<String> left = parseDelimitedString(names.get(0), "-");

            String lName = left.get(0);
            Version lVer;
            try {
                lVer = Version.parseVersion(left.get(1));
            } catch (Exception ex) {
                // Version doesn't parse. Make it part of the name.
                lName = names.get(0);
                lVer = null;
            }

            String rName = null;
            Version rVer = null;
            if (names.size() > 1) {
                List<String> right = parseDelimitedString(names.get(1), "-");
                rName = right.get(0);
                try {
                    rVer = Version.parseVersion(right.get(1));
                } catch (Exception ex) {
                    rName = names.get(1);
                    rVer = null;
                }
            }

            String versionClause;
            if (lVer != null) {
                if ((rVer != null) && (!rVer.equals(lVer))) {
                    // Both versions are defined, but different. Make each of them part of the name
                    lName = names.get(0);
                    rName = names.get(1);
                    versionClause = null;
                } else {
                    versionClause = getBreeVersionClause(lVer);
                }
            } else {
                versionClause = getBreeVersionClause(rVer);
            }

            if ("J2SE".equals(lName)) {
                // J2SE is not used in the Capability variant of BREE, use JavaSE here
                // This can only happen with the lName part...
                lName = "JavaSE";
            }

            String nameClause;
            if (rName != null)
                nameClause = "(" + ExecutionEnvironmentNamespace.EXECUTION_ENVIRONMENT_NAMESPACE + "=" + lName + "/" + rName + ")";
            else
                nameClause = "(" + ExecutionEnvironmentNamespace.EXECUTION_ENVIRONMENT_NAMESPACE + "=" + lName + ")";

            String filter;
            if (versionClause != null)
                filter = "(&" + nameClause + versionClause + ")";
            else
                filter = nameClause;

            filters.add(filter);
        }

        if (filters.size() == 0) {
            return Collections.emptyList();
        } else {
            String reqFilter;
            if (filters.size() == 1) {
                reqFilter = filters.get(0);
            } else {
                // If there are more BREE filters, we need to or them together
                StringBuilder sb = new StringBuilder("(|");
                for (String f : filters) {
                    sb.append(f);
                }
                sb.append(")");
                reqFilter = sb.toString();
            }

            SimpleFilter sf = SimpleFilter.parse(reqFilter);
            return Collections.<Requirement>singletonList(new RequirementImpl(
                    resource,
                    ExecutionEnvironmentNamespace.EXECUTION_ENVIRONMENT_NAMESPACE,
                    Collections.singletonMap(ExecutionEnvironmentNamespace.REQUIREMENT_FILTER_DIRECTIVE, reqFilter),
                    Collections.<String, Object>emptyMap(),
                    sf));
        }
    }

    private static String getBreeVersionClause(Version ver) {
        if (ver == null)
            return null;

        return "(" + ExecutionEnvironmentNamespace.CAPABILITY_VERSION_ATTRIBUTE + "=" + ver + ")";
    }

    private static List<ParsedHeaderClause> normalizeRequireClauses(List<ParsedHeaderClause> clauses) {
        // Convert bundle version attribute to VersionRange type.
        for (ParsedHeaderClause clause : clauses) {
            Object value = clause.attrs.get(Constants.BUNDLE_VERSION_ATTRIBUTE);
            if (value != null) {
                clause.attrs.put(Constants.BUNDLE_VERSION_ATTRIBUTE, VersionRange.parseVersionRange(value.toString()));
            }
        }

        return clauses;
    }

    private static List<Requirement> convertRequires(List<ParsedHeaderClause> clauses, Resource resource) {
        List<Requirement> reqList = new ArrayList<>();
        for (ParsedHeaderClause clause : clauses) {
            for (String path : clause.paths) {
                // Prepend the bundle symbolic name to the array of attributes.
                Map<String, Object> attrs = clause.attrs;
                // Note that we use a linked hash map here to ensure the
                // symbolic name attribute is first, which will make indexing
                // more efficient.
                // TODO: OSGi R4.3 - This is ordering is kind of hacky.
                // Prepend the symbolic name to the array of attributes.
                Map<String, Object> newAttrs = new LinkedHashMap<>(attrs.size() + 1);
                // We want this first from an indexing perspective.
                newAttrs.put(BundleRevision.BUNDLE_NAMESPACE, path);
                newAttrs.putAll(attrs);
                // But we need to put it again to make sure it wasn't overwritten.
                newAttrs.put(BundleRevision.BUNDLE_NAMESPACE, path);

                // Create filter now so we can inject filter directive.
                SimpleFilter sf = SimpleFilter.convert(newAttrs);

                // Inject filter directive.
                // TODO: OSGi R4.3 - Can we insert this on demand somehow?
                Map<String, String> dirs = clause.dirs;
                Map<String, String> newDirs = new HashMap<>(dirs.size() + 1);
                newDirs.putAll(dirs);
                newDirs.put(Constants.FILTER_DIRECTIVE, sf.toString());

                // Create package requirement and add to requirement list.
                reqList.add(new RequirementImpl(resource, BundleRevision.BUNDLE_NAMESPACE, newDirs, newAttrs));
            }
        }

        return reqList;
    }

    private static char charAt(int pos, String headers, int length) {
        if (pos >= length) {
            return EOF;
        }
        return headers.charAt(pos);
    }

    @SuppressWarnings({"unchecked", "rawtypes"})
    private static List<ParsedHeaderClause> parseStandardHeader(String header) {
        List<ParsedHeaderClause> clauses = new ArrayList<>();
        if (header == null) {
            return clauses;
        }
        ParsedHeaderClause clause = null;
        String key = null;
        Map targetMap = null;
        int state = CLAUSE_START;
        int currentPosition = 0;
        int startPosition = 0;
        int length = header.length();
        boolean quoted = false;
        boolean escaped = false;

        char currentChar;
        do {
            currentChar = charAt(currentPosition, header, length);
            switch (state) {
            case CLAUSE_START:
                clause = new ParsedHeaderClause();
                clauses.add(clause);
                // Fall through
            case PARAMETER_START:
                startPosition = currentPosition;
                state = KEY;
                // Fall through
            case KEY:
                switch (currentChar) {
                case ':':
                case '=':
                    key = header.substring(startPosition, currentPosition).trim();
                    startPosition = currentPosition + 1;
                    targetMap = clause.attrs;
                    state = currentChar == ':' ? DIRECTIVE_OR_TYPEDATTRIBUTE : ARGUMENT;
                    break;
                case EOF:
                case ',':
                case ';':
                    clause.paths.add(header.substring(startPosition, currentPosition).trim());
                    state = currentChar == ',' ? CLAUSE_START : PARAMETER_START;
                    break;
                default:
                    break;
                }
                currentPosition++;
                break;
            case DIRECTIVE_OR_TYPEDATTRIBUTE:
                switch (currentChar) {
                case '=':
                    if (startPosition != currentPosition) {
                        clause.types.put(key, header.substring(startPosition, currentPosition).trim());
                    } else {
                        targetMap = clause.dirs;
                    }
                    state = ARGUMENT;
                    startPosition = currentPosition + 1;
                    break;
                default:
                    break;
                }
                currentPosition++;
                break;
            case ARGUMENT:
                if (currentChar == '\"') {
                    quoted = true;
                    currentPosition++;
                } else {
                    quoted = false;
                }
                if (!Character.isWhitespace(currentChar)) {
                    state = VALUE;
                } else {
                    currentPosition++;
                }
                break;
            case VALUE:
                if (escaped) {
                    escaped = false;
                } else {
                    if (currentChar == '\\') {
                        escaped = true;
                    } else if (quoted && currentChar == '\"') {
                        quoted = false;
                    } else if (!quoted) {
                        String value;
                        switch (currentChar) {
                        case EOF:
                        case ';':
                        case ',':
                            value = header.substring(startPosition, currentPosition).trim();
                            if (value.startsWith("\"") && value.endsWith("\"")) {
                                value = value.substring(1, value.length() - 1);
                            }
                            if (targetMap.put(key, value) != null) {
                                throw new IllegalArgumentException(
                                        "Duplicate '" + key + "' in: " + header);
                            }
                            state = currentChar == ';' ? PARAMETER_START : CLAUSE_START;
                            break;
                        default:
                            break;
                        }
                    }
                }
                currentPosition++;
                break;
            default:
                break;
            }
        } while (currentChar != EOF);

        if (state > PARAMETER_START) {
            throw new IllegalArgumentException("Unable to parse header: " + header);
        }
        return clauses;
    }

    public static List<String> parseDelimitedString(String value, String delim) {
        return parseDelimitedString(value, delim, true);
    }

    /**
     * Parses delimited string and returns an array containing the tokens. This
     * parser obeys quotes, so the delimiter character will be ignored if it is
     * inside of a quote. This method assumes that the quote character is not
     * included in the set of delimiter characters.
     *
     * @param value the delimited string to parse.
     * @param delim the characters delimiting the tokens.
     * @return a list of string or an empty list if there are none.
     */
    public static List<String> parseDelimitedString(String value, String delim, boolean trim) {
        if (value == null) {
            value = "";
        }

        List<String> list = new ArrayList<>();

        StringBuilder sb = new StringBuilder();

        int expecting = CHAR | DELIMITER | STARTQUOTE;

        boolean isEscaped = false;
        for (int i = 0; i < value.length(); i++) {
            char c = value.charAt(i);

            boolean isDelimiter = delim.indexOf(c) >= 0;

            if (!isEscaped && c == '\\') {
                isEscaped = true;
                continue;
            }

            if (isEscaped) {
                sb.append(c);
            } else if (isDelimiter && ((expecting & DELIMITER) > 0)) {
                if (trim) {
                    list.add(sb.toString().trim());
                } else {
                    list.add(sb.toString());
                }
                sb.delete(0, sb.length());
                expecting = CHAR | DELIMITER | STARTQUOTE;
            } else if ((c == '"') && (expecting & STARTQUOTE) > 0) {
                sb.append(c);
                expecting = CHAR | ENDQUOTE;
            } else if ((c == '"') && (expecting & ENDQUOTE) > 0) {
                sb.append(c);
                expecting = CHAR | STARTQUOTE | DELIMITER;
            } else if ((expecting & CHAR) > 0) {
                sb.append(c);
            } else {
                throw new IllegalArgumentException("Invalid delimited string: " + value);
            }

            isEscaped = false;
        }

        if (sb.length() > 0) {
            if (trim) {
                list.add(sb.toString().trim());
            } else {
                list.add(sb.toString());
            }
        }

        return list;
    }


    static class ParsedHeaderClause {
        public final List<String> paths = new ArrayList<>();
        public final Map<String, String> dirs = new LinkedHashMap<>();
        public final Map<String, Object> attrs = new LinkedHashMap<>();
        public final Map<String, String> types = new LinkedHashMap<>();
    }
}
