/*
    * Copyright (C) 2002-2003,2017-2023 Dipl.-Inform. Kai Hofmann. All rights reserved!
    */
   package de.powerstat.phplib.templateengine.intern;
   
   
   import java.io.BufferedReader;
   import java.io.File;
   import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Files;
  import java.nio.file.StandardOpenOption;
  import java.util.Map;
  import java.util.Objects;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  
  
  /**
   * Template file manager.
   */
  public final class FileManager
   {
    /**
     * Logger.
     */
    private static final Logger LOGGER = LogManager.getLogger(FileManager.class);
  
    /**
     * Maximum template size.
     */
    private static final int MAX_TEMPLATE_SIZE = 1048576;
  
    /**
     * File path separator.
     */
    private static final String FILEPATH_SEPARATOR = "/"; //$NON-NLS-1$
  
    /**
     * Variable manager reference.
     */
    private final VariableManager variableManager;
  
    /**
     * File name map.
     */
    private final Map<String, File> files = new ConcurrentHashMap<>();
  
  
    /**
     * Copy constructor.
     *
     * @param vManager Variable manager
     * @param fManager File manager to copy from
     * @throws NullPointerException If vManager or fManager is null
     */
    @SuppressFBWarnings("EI_EXPOSE_REP2")
    public FileManager(final VariableManager vManager, final FileManager fManager)
     {
      super();
      Objects.requireNonNull(vManager, "vManager"); //$NON-NLS-1$
      Objects.requireNonNull(fManager, "fManager"); //$NON-NLS-1$
      this.variableManager = vManager;
      for (final Map.Entry<String, File> entry : fManager.files.entrySet())
       {
        this.files.put(entry.getKey(), entry.getValue());
       }
     }
  
  
    /**
     * Constructor.
     *
     * @param vManager Variable manager
     */
    @SuppressFBWarnings("EI_EXPOSE_REP2")
    public FileManager(final VariableManager vManager)
     {
      super();
      this.variableManager = vManager;
     }
  
  
    /**
     * Add template file for variable.
     *
     * @param newVarname Variable that should hold the template
     * @param newFile Template file UTF-8 encoded
     * @return true when successful (file exists) otherwise false
     * @throws NullPointerException If newVarname or newFile is null
     * @throws IllegalArgumentException If newVarname is empty
     */
   @SuppressWarnings({"PMD.LinguisticNaming", "java:S3457"})
   public boolean addFile(final String newVarname, final File newFile)
    {
     // asserts
     boolean exists = newFile.exists();
     if (exists)
      {
       if (newFile.length() > FileManager.MAX_TEMPLATE_SIZE)
        {
         throw new IllegalArgumentException("newFile to large"); //$NON-NLS-1$
        }
       this.files.put(newVarname, newFile);
      }
     else
      {
       try (InputStream stream = this.getClass().getResourceAsStream(FileManager.FILEPATH_SEPARATOR + newFile.getName()))
        {
         if (stream != null)
          {
           exists = true;
           this.files.put(newVarname, newFile);
          }
        }
       catch (final IOException ignored)
        {
         // exists is already false
         FileManager.LOGGER.warn("File does not exist: " + newFile.getAbsolutePath(), ignored); //$NON-NLS-1$
        }
      }
     return exists;
    }
 
 
   /**
    * Exists file for varname.
    *
    * @param varname Variable to read from file
    * @return true if file exists, false otherwise
    */
   public boolean existsFile(final String varname)
    {
     final var file = this.files.get(varname);
     return (file != null);
    }
 
 
   /**
    * Load template file (UTF-8 encoded) if required.
    *
    * @param varname Variable to read from file
    * @return true if successful otherwise false
    * @throws FileNotFoundException File not found
    * @throws IOException IO exception
    */
   @SuppressWarnings("PMD.CloseResource")
   public boolean loadFile(final String varname) throws IOException
    {
     // assert (varname != null) && !varname.isEmpty() && (varname.length() <= TemplateEngine.MAX_VARNAME_SIZE);
     if (this.variableManager.existsVar(varname)) // Already loaded?
      {
       return true;
      }
     final var file = this.files.get(varname);
     if (file == null)
      {
       return false;
      }
     InputStream istream = this.getClass().getResourceAsStream(FileManager.FILEPATH_SEPARATOR + file.getName()); // Read from classpath/jar
     if (istream == null)
      {
       istream = Files.newInputStream(this.files.get(varname).toPath(), StandardOpenOption.READ); // Read from filesystem
      }
     final var fileBuffer = new StringBuilder();
     try (var reader = new BufferedReader(new InputStreamReader(istream, StandardCharsets.UTF_8)))
      {
       String line = reader.readLine();
       while (line != null)
        {
         fileBuffer.append(line);
         fileBuffer.append('\n');
         line = reader.readLine();
        }
      }
     if (fileBuffer.length() == 0)
      {
       return false;
      }
     this.variableManager.setVar(varname, fileBuffer.toString());
     return true;
    }
 
 
   /**
    * Returns the string representation of this FileManager.
    *
    * The exact details of this representation are unspecified and subject to change, but the following may be regarded as typical:
    *
    * "FileManager[files=[name, ...]]"
    *
    * @return String representation of this FileManager.
    * @see java.lang.Object#toString()
    */
   @Override
   public String toString()
    {
     return new StringBuilder().append("FileManager[").append("files=").append(this.files.values().stream().map(File::getName).reduce((s1, s2) -> s1 + ", " + s2)).append(']').toString(); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
    }
 
 
   /**
    * Calculate hash code.
    *
    * @return Hash
    * @see java.lang.Object#hashCode()
    */
   @Override
   public int hashCode()
    {
     return Objects.hash(this.files);
    }
 
 
   /**
    * Is equal with another object.
    *
    * @param obj Object
    * @return true when equal, false otherwise
    * @see java.lang.Object#equals(java.lang.Object)
    */
   @Override
   public boolean equals(final Object obj)
    {
     if (this == obj)
      {
       return true;
      }
     if (!(obj instanceof FileManager))
      {
       return false;
      }
     final FileManager other = (FileManager)obj;
     return this.files.equals(other.files) && this.variableManager.equals(other.variableManager);
    }
 
  }