package emissary.output.filter;
   
   import emissary.config.ConfigUtil;
   import emissary.config.Configurator;
   import emissary.core.EmissaryRuntimeException;
   import emissary.core.IBaseDataObject;
   import emissary.output.DropOffUtil;
   import emissary.util.JavaCharSet;
   
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.UnsupportedEncodingException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Set;
  import java.util.regex.Pattern;
  import javax.annotation.Nullable;
  
  /**
   * Provides the base mechanism for a drop off filter
   */
  public abstract class AbstractFilter implements IDropOffFilter {
      /** A static convenience logger */
      protected static final Logger slogger = LoggerFactory.getLogger(AbstractFilter.class);
  
      /** get a logger configured on the impl's classname */
      protected Logger logger = LoggerFactory.getLogger(this.getClass().getName());
  
      /** hold onto the parent configurator */
      protected Configurator configG;
  
      /** hold onto the specific filter configurator */
      protected Configurator filterConfig;
  
      /** hold onto the filter name, impl should set this */
      protected String filterName = "Abstract";
  
      /** hold the output specification, if any, for this filter */
      protected String outputSpec;
  
      /** hold the error specification, if any, for this filter */
      protected String errorSpec;
  
      /** hold the filter condition specification, if any, for this filter */
      protected String filterConditionSpec;
  
      /** hold the filter condition, if any, for this filter */
      private IFilterCondition filterCondition;
  
      /**
       * A set of FileType and FileTYpe.ViewName strings controlling what can be output by this filter
       */
      protected Set<String> outputTypes = Collections.emptySet();
  
      /** String to use when dealing with the primary view specifically */
      public static final String PRIMARY_VIEW_NAME = "PrimaryView";
      public static final String PRIMARY_VIEW = "." + PRIMARY_VIEW_NAME;
  
      /** Primary view wildcard string */
      public static final String ALL_PRIMARY_VIEWS = "*" + PRIMARY_VIEW;
  
      /** String to use when dealing with a language in a view */
      public static final String LANGUAGE_VIEW_NAME = "Language";
      public static final String LANGUAGE_VIEW = "." + LANGUAGE_VIEW_NAME;
  
      /** Language wildcard string */
      public static final String ALL_LANGUAGE_VIEWS = "*" + LANGUAGE_VIEW;
  
      /** Alternate view wildcard string */
      public static final String ALL_ALT_VIEWS = "*.AlternateView";
  
      /** Metadata view name */
      public static final String METADATA_VIEW_NAME = "Metadata";
      public static final String METADATA_VIEW = "." + METADATA_VIEW_NAME;
  
      /* alternate views to NOT output if only a file type/form is specified */
      protected Set<String> denylist = new HashSet<>();
      protected Set<String> wildCardDenylist = new HashSet<>();
  
      @Nullable
      protected DropOffUtil dropOffUtil = null;
  
      protected String denylistAllowedNameChars = "a-zA-Z0-9_\\-";
      protected String denylistFiletypeFormat = "^[%s]+$";
      protected Pattern denylistFiletypeFormatPattern;
      protected String denylistViewNameFormat = "^[%s]+(\\.[%s]+)?\\*?$";
      protected Pattern denylistViewNameFormatPattern;
  
      /**
       * Initialization phase hook for the filter with default preferences for the runtime configuration of the filter
      */
     @Override
     public void initialize(final Configurator theConfigG, final String filterName) {
         loadFilterConfiguration(null);
         initialize(theConfigG, filterName, this.filterConfig);
     }
 
     /**
      * Initialization phase hook for the filter with provided filter configuration
      * 
      * @param theConfigG passed in configuration object, usually DropOff's config
      * @param filterName the configured name of this filter or null for the default
      * @param theFilterConfig the configuration for the specific filter
      */
     @Override
     public void initialize(final Configurator theConfigG, @Nullable final String filterName,
             final Configurator theFilterConfig) {
         this.configG = theConfigG;
         if (filterName != null) {
             setFilterName(filterName);
         }
         loadFilterConfiguration(theFilterConfig);
         loadFilterCondition(theConfigG);
         loadOutputSpec(theConfigG);
         this.dropOffUtil = new DropOffUtil(theConfigG);
         initializeOutputTypes(this.filterConfig);
     }
 
     private void loadFilterCondition(final Configurator parentConfig) {
         this.filterConditionSpec = parentConfig.findStringEntry("FILTER_CONDITION_" + getFilterName(), null);
 
         // format FILTER_CONDITION_<filtername> = profilename:clazz just like dropoff filter config
         if (!StringUtils.isEmpty(filterConditionSpec)) {
             final String name;
             final String clazz;
             Configurator filterConfig = null;
             final int colpos = filterConditionSpec.indexOf(':');
             if (colpos > -1) {
                 name = filterConditionSpec.substring(0, colpos);
                 clazz = filterConditionSpec.substring(colpos + 1);
                 final String filterConfigName = parentConfig.findStringEntry(name);
                 if (filterConfigName != null) {
                     try {
                         filterConfig = ConfigUtil.getConfigInfo(filterConfigName);
                     } catch (IOException configError) {
                         logger.warn("Specified filter configuration {} cannot be loaded", filterConfigName);
                         return;
                     }
                 }
             } else {
                 clazz = filterConditionSpec;
             }
 
             try {
                 final Object filterConditionObj = emissary.core.Factory.create(clazz);
 
                 if (filterConditionObj != null && filterConditionObj instanceof IFilterCondition) {
                     this.filterCondition = (IFilterCondition) filterConditionObj;
                     // initialize using the config
                     filterCondition.initialize(filterConfig);
                 } else {
                     logger.warn("Failed to initialize filter condition {}. Filter does not implement IFilterCondition", getFilterName());
                 }
             } catch (Throwable t) {
                 // failed to initialize
                 logger.error("Failed in initialize filter condition {} with argument {} and message {}", getFilterName(), filterConditionSpec,
                         t.getMessage(), t);
             }
 
         }
     }
 
     /**
      * Run custom configuration
      * 
      * @param config the filter specific configurator
      */
     protected void initializeOutputTypes(@Nullable final Configurator config) {
         if (config != null) {
             this.loadNameValidationPatterns(config);
             this.outputTypes = config.findEntriesAsSet("OUTPUT_TYPE");
             this.logger.debug("Loaded {} output types for filter {}", this.outputTypes.size(), this.outputTypes);
             this.initializeDenylist(config);
         } else {
             this.logger.debug("InitializeCustom has null filter config");
         }
     }
 
     protected void loadNameValidationPatterns(final Configurator config) {
         denylistAllowedNameChars = config.findStringEntry("DENYLIST_ALLOWED_NAME_CHARS", denylistAllowedNameChars);
         denylistFiletypeFormat = config.findStringEntry("DENYLIST_FILETYPE_FORMAT", denylistFiletypeFormat);
         denylistFiletypeFormatPattern = Pattern.compile(denylistFiletypeFormat.replace("%s", denylistAllowedNameChars));
         denylistViewNameFormat = config.findStringEntry("DENYLIST_VIEW_NAME_FORMAT", denylistViewNameFormat);
         denylistViewNameFormatPattern = Pattern.compile(denylistViewNameFormat.replace("%s", denylistAllowedNameChars));
     }
 
     protected void initializeDenylist(final Configurator config) {
         for (String entry : config.findEntriesAsSet("DENYLIST")) {
             String viewName = validateAndRemoveDenylistFiletype(entry);
             if (matchesDenylistViewNameFormatPattern(viewName)) {
                 if (viewName.chars().filter(ch -> ch == '.').count() > 0) {
                     logger.warn("`DENYLIST = \"{}\"` viewName `{}` should not contain any `.` characters", entry, viewName);
                 }
 
                 if (viewName.endsWith("*")) {
                     String strippedEntry = entry.substring(0, entry.length() - 1);
                     this.wildCardDenylist.add(strippedEntry);
                 } else {
                     this.denylist.add(entry);
                 }
 
             } else {
                 throw new EmissaryRuntimeException(String.format(
                         "Invalid filter configuration: `DENYLIST = \"%s\"` " +
                                 "entry `%s` must match pattern `%s`.",
                         entry, entry, getDenylistViewNameFormat()));
             }
         }
 
         this.logger.debug("Loaded {} ignorelist types for filter {}", this.denylist.size(), this.denylist);
         this.logger.debug("Loaded {} wildcard suffix ignorelist types for filter {}", this.wildCardDenylist.size(), this.wildCardDenylist);
     }
 
     protected String validateAndRemoveDenylistFiletype(final String entry) {
         String[] names = entry.split("\\.", 2);
 
         if (names.length > 1) {
             String filetype = names[0];
             String viewName = names[1];
 
             if (filetype.equals("*")) { // DENYLIST = "*.<viewName>" not allowed
                 throw new EmissaryRuntimeException(String.format(
                         "Invalid filter configuration: `DENYLIST = \"%s\"` " +
                                 "wildcarded filetypes not allowed in denylist - Did you mean `DENYLIST = \"%s\"`?",
                         entry, viewName));
             } else if (!matchesDenylistFiletypeFormatPattern(filetype)) {
                 throw new EmissaryRuntimeException(String.format(
                         "Invalid filter configuration: `DENYLIST = \"%s\"` " +
                                 "filetype `%s` must match pattern `%s`",
                         entry, filetype, getDenylistFiletypeFormat()));
             }
             return viewName;
         }
         return entry;
     }
 
     /**
      * Return the name of this filter
      * 
      * @return the string name of the filter
      */
     @Override
     public String getFilterName() {
         return this.filterName;
     }
 
     /**
      * Set the filter name
      * 
      * @param s the new name to use for this filter instance
      */
     @Override
     public void setFilterName(final String s) {
         this.filterName = s;
     }
 
     /**
      * Load the filter configuration with precendence of provided, named, default Preference order for loading
      * configurations
      * <ol>
      * <li>[filter-package].FILTER_NAME.cfg</li>
      * <li>[filter-package].[filter-class]-FILTER_NAME.cfg</li>
      * <li>[filter-package].[filter-class].cfg</li>
      * </ol>
      * 
      * @param suppliedFilterConfig configuration to use when not null
      */
     protected void loadFilterConfiguration(@Nullable final Configurator suppliedFilterConfig) {
         if (suppliedFilterConfig != null) {
             this.filterConfig = suppliedFilterConfig;
             return;
         }
 
         final List<String> configPreferences = new ArrayList<>();
 
         if (getFilterName() != null) {
             configPreferences.add(this.getClass().getPackage().getName() + "." + getFilterName() + ConfigUtil.CONFIG_FILE_ENDING);
             configPreferences.add(this.getClass().getName() + "-" + getFilterName() + ConfigUtil.CONFIG_FILE_ENDING);
         }
         configPreferences.add(this.getClass().getName() + ConfigUtil.CONFIG_FILE_ENDING);
 
         this.logger.debug("Looking for filter configuration preferences {}", configPreferences);
         try {
             this.filterConfig = ConfigUtil.getConfigInfo(configPreferences);
         } catch (IOException iox) {
             this.logger.debug("Could not find filter configuration for {}", getFilterName(), iox);
         }
     }
 
     /**
      * Run the filter for a set of documents
      * 
      * @param list collection of IBaseDataObject to run the filter on
      * @param params map of params
      * @return status value
      */
     @Override
     public int filter(final List<IBaseDataObject> list, final Map<String, Object> params) {
         // Important to process them in order, if not already sorted
 
         int status = 0;
         for (final IBaseDataObject d : list) {
             status = filter(d, params);
         }
         return status;
     }
 
     /**
      * Run the filter for a set of documents
      * 
      * @param list collection of IBaseDataObject to run the filter on
      * @param params map of params
      * @param output the output stream
      * @return status value
      */
     @Override
     public int filter(final List<IBaseDataObject> list, final Map<String, Object> params, final OutputStream output) {
 
         int status = 0;
         for (final IBaseDataObject d : list) {
             status = filter(d, params, output);
         }
         return status;
     }
 
     /**
      * The method that all filter have to provide for stream based output
      */
     @Override
     public int filter(final IBaseDataObject payload, final Map<String, Object> params, final OutputStream output) {
         throw new IllegalArgumentException("Not supported, override to support");
     }
 
     @Override
     public boolean isOutputtable(final IBaseDataObject d) {
         return filterCondition == null || filterCondition.accept(d);
     }
 
     @Override
     public boolean isOutputtable(final List<IBaseDataObject> list) {
         return filterCondition == null || filterCondition.accept(list);
     }
 
     /**
      * Determine if the payload is outputtable by the filter
      * 
      * @param d the document
      * @param params map of params
      * @return true if the filter wants a crack at outputting this payload
      */
     @Override
     public boolean isOutputtable(final IBaseDataObject d, final Map<String, Object> params) {
         return true;
     }
 
     /**
      * Determine if the payload list is outputtable by the filter
      * 
      * @param list collection of IBaseDataObject to check for outputtability
      * @param params map of params
      * @return true if the filter wants a crack at outputting this payload
      */
     @Override
     public boolean isOutputtable(final List<IBaseDataObject> list, final Map<String, Object> params) {
         return true;
     }
 
     /**
      * Determine is this payload should be output by this filter Usually by the primary view or one of the alternate views
      * being on the outputTypes list from the run-time type configuration stream for the filter in questin.
      *
      * @param type of the data
      */
     protected boolean isOutputtable(final String type) {
         return this.outputTypes.contains("*") || this.outputTypes.contains(type);
     }
 
     /**
      * Determine is this payload should be output by this filter Usually by the primary view or one of the alternate views
      * being on the outputTypes list from the run-time type configuration stream for the filter in question.
      *
      * @param types types to check
      * @return true if any one of the types is outputtable
      */
     protected boolean isOutputtable(final Collection<String> types) {
         if (this.outputTypes.contains("*")) {
             this.logger.debug("Outputtable due to wildcard in output types");
             return true;
         }
 
         final boolean canOutput = !Collections.disjoint(this.outputTypes, types);
         if (canOutput && this.logger.isDebugEnabled()) {
             final Set<String> outputFor = new HashSet<>();
             for (final String s : this.outputTypes) {
                 if (types.contains(s)) {
                     outputFor.add(s);
                 }
             }
             this.logger.debug("Outputtable due to non-disjoint sets: {}", outputFor);
         }
         return canOutput;
     }
 
     /**
      * Close the filter
      */
     @Override
     public void close() {
         // nothing to do
     }
 
     /*
      * Extract my Output Spec from the supplied config info and save it
      */
     protected void loadOutputSpec(final Configurator theConfigG) {
         this.outputSpec = theConfigG.findStringEntry("OUTPUT_SPEC_" + getFilterName(), null);
         this.errorSpec = theConfigG.findStringEntry("ERROR_SPEC_" + getFilterName(), null);
         this.logger.debug("Output spec for {} is {}", getFilterName(), this.outputSpec);
     }
 
     /**
      * Get bytes as UTF-8 converted from specified charset
      * 
      * @param value the contents
      * @param charset the charset of the bytes in value
      */
     protected String normalizeBytes(final byte[] value, final String charset) {
         return normalizeBytes(value, 0, value.length, charset);
     }
 
     /**
      * Get bytes as UTF-8 converted from specified charset
      * 
      * @param value the contents
      * @param start position to start subarray
      * @param len length of subarray
      * @param charset the charset of the bytes in value
      */
     protected String normalizeBytes(final byte[] value, final int start, final int len, @Nullable final String charset) {
         String s = null;
 
         if (charset != null) {
             try {
                 s = new String(value, start, len, charset);
             } catch (UnsupportedEncodingException ex) {
                 this.logger.debug("Error encoding string", ex);
             }
         }
 
         if (s == null) {
             // from exception or no charset
             s = new String(value, start, len);
         }
 
         return s;
     }
 
     /**
      * Extract the charset from the payload or defaultCharset
      * 
      * @param d the payload
      * @param defaultCharset the default
      * @return the charset or defualtCharset if none
      */
     protected String getCharset(final IBaseDataObject d, final String defaultCharset) {
         String lang = d.getFontEncoding();
         if (lang == null || lang.toUpperCase(Locale.getDefault()).contains("ASCII") || lang.toUpperCase(Locale.getDefault()).contains("8859-1")) {
             final String s = d.getStringParameter("HTML_CHARSET");
             if (s != null) {
                 lang = s;
             }
         }
         if (lang == null || lang.toUpperCase(Locale.getDefault()).contains("ASCII") || lang.toUpperCase(Locale.getDefault()).contains("8859-1")) {
             final String s = d.getStringParameter("MIME_CHARSET");
             if (s != null) {
                 lang = s;
             }
         }
         if (lang == null) {
             return defaultCharset;
         } else {
             return JavaCharSet.get(lang);
         }
     }
 
     /**
      * Makes a set of the file type, current form with and without the .PrimaryView qualifier and all the alternate view
      * names Result set can be passed to {@link #isOutputtable(Collection)} for checking
      *
      * @param d the payload
      */
     protected Set<String> getTypesToCheck(final IBaseDataObject d) {
         final Set<String> checkTypes = getPrimaryTypesToCheck(d);
         for (final String viewName : d.getAlternateViewNames()) {
             checkTypes.addAll(getTypesToCheckForNamedView(d, viewName));
         }
         checkTypes.addAll(getTypesToCheckForNamedView(d, METADATA_VIEW_NAME));
         checkTypes.add(ALL_ALT_VIEWS);
         return checkTypes;
     }
 
     protected Set<String> getTypesToCheckForNamedView(final IBaseDataObject d, final String viewName) {
         final Set<String> checkTypes = new HashSet<>();
         final String lang = this.dropOffUtil.getLanguage(d);
         final String fileType = DropOffUtil.getFileType(d);
         final String currentForm = d.currentForm();
 
         // skip over denylisted alt views
         if (denyListContains(fileType, viewName)) {
             return checkTypes;
         }
 
         checkTypes.add(fileType);
         checkTypes.add(fileType + "." + viewName);
         checkTypes.add("*." + viewName);
 
         if (!"NONE".equals(lang)) {
             checkTypes.add(lang);
             checkTypes.add(lang + "." + viewName);
             checkTypes.add(lang + "." + fileType);
             checkTypes.add(lang + "." + fileType + "." + viewName);
         }
 
         if (currentForm != null && !fileType.equals(currentForm)) {
             checkTypes.add(currentForm);
             checkTypes.add(currentForm + "." + viewName);
             if (!"NONE".equals(lang)) {
                 checkTypes.add(lang + "." + currentForm);
                 checkTypes.add(lang + "." + currentForm + "." + viewName);
             }
         }
         this.logger.debug("Types to be checked for named view {}: {}", viewName, checkTypes);
         return checkTypes;
     }
 
     protected boolean denyListContains(final String fileType, final String viewName) {
         String fullName = fileType + "." + viewName;
         if (this.denylist.contains(viewName) || this.denylist.contains(fullName)) {
             return true;
         }
         return this.wildCardDenylist.stream().anyMatch(i -> viewName.startsWith(i) || fullName.startsWith(i));
     }
 
     /**
      * Makes a set of the file type, current form with and without the .PrimaryView qualifier. Result set can be passed to
      * {@link #isOutputtable(Collection)} for checking whether the primary view should be output
      *
      * @param d the payload
      */
     protected Set<String> getPrimaryTypesToCheck(final IBaseDataObject d) {
         final Set<String> checkTypes = getTypesToCheckForNamedView(d, PRIMARY_VIEW_NAME);
         final String lang = this.dropOffUtil.getLanguage(d);
         checkTypes.add(lang + LANGUAGE_VIEW);
         checkTypes.add(ALL_LANGUAGE_VIEWS);
         checkTypes.add(ALL_PRIMARY_VIEWS);
         return checkTypes;
     }
 
     @Override
     public String getOutputSpec() {
         return this.outputSpec;
     }
 
     @Override
     public String getErrorSpec() {
         return this.errorSpec;
     }
 
     @Override
     public Collection<String> getOutputTypes() {
         return new HashSet<>(this.outputTypes);
     }
 
     public boolean matchesDenylistFiletypeFormatPattern(String str) {
         return denylistFiletypeFormatPattern.matcher(str).matches();
     }
 
     public String getDenylistFiletypeFormat() {
         return denylistFiletypeFormatPattern.pattern();
     }
 
     public boolean matchesDenylistViewNameFormatPattern(String str) {
         return denylistViewNameFormatPattern.matcher(str).matches();
     }
 
     public String getDenylistViewNameFormat() {
         return denylistViewNameFormatPattern.pattern();
     }
 }