/*-
    * #%L
    * prolobjectlink-jpi
    * %%
    * Copyright (C) 2012 - 2019 Prolobjectlink Project
    * %%
    * Permission is hereby granted, free of charge, to any person obtaining a copy
    * of this software and associated documentation files (the "Software"), to deal
    * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   * 
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   * 
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   * #L%
   */
  package io.github.prolobjectlink.prolog;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.Reader;
  import java.io.StringReader;
  import java.util.Map;
  import java.util.Map.Entry;
  
  import javax.script.AbstractScriptEngine;
  import javax.script.Bindings;
  import javax.script.ScriptContext;
  import javax.script.ScriptEngine;
  import javax.script.ScriptEngineFactory;
  import javax.script.ScriptException;
  import javax.script.SimpleBindings;
  
  /**
   * Partial implementation of {@link ScriptEngine}
   * 
   * @author Jose Zalacain
   * @since 1.0
   */
  public final class PrologScriptEngine extends AbstractScriptEngine implements ScriptEngine {
  
  	private final PrologEngine prolog;
  	private final ScriptEngineFactory factory;
  
  	PrologScriptEngine(ScriptEngineFactory factory, PrologEngine prolog) {
  		this.factory = factory;
  		this.prolog = prolog;
  	}
  
  	public Bindings createBindings() {
  		return new SimpleBindings();
  	}
  
  	public ScriptEngineFactory getFactory() {
  		return factory;
  	}
  
  	public Object eval(String script, ScriptContext context) throws ScriptException {
  		return eval(script, context.getBindings(ScriptContext.ENGINE_SCOPE));
  	}
  
  	public Object eval(Reader reader, ScriptContext context) throws ScriptException {
  		return eval(reader, context.getBindings(ScriptContext.ENGINE_SCOPE));
  	}
  
  	@Override
  	public Object eval(Reader reader, Bindings bindings) throws ScriptException {
  		BufferedReader bfr = new BufferedReader(reader);
  		StringBuilder script = new StringBuilder();
  		try {
  			String line = bfr.readLine();
  			while (line != null) {
  				script.append(line);
  				script.append("\n");
  				line = bfr.readLine();
  			}
  		} catch (IOException ex) {
  			throw new ScriptException(ex);
  		}
  		return eval("" + script + "", bindings);
  	}
  
  	@Override
  	public Object eval(String script, Bindings bindings) throws ScriptException {
  
  		String code = script;
  
  		// check code goal to query
  		if (code.startsWith("?-")) {
  
 			// replace all bindings
 			for (Entry<String, Object> entry : bindings.entrySet()) {
 				code = code.replace(entry.getKey(), "" + entry.getValue() + "");
 			}
 
 			code = code.substring(2).trim();
 
 			// remove dot at the end if needed
 			if (code.endsWith(".")) {
 				code = code.substring(0, code.length() - 1);
 			}
 
 			PrologQuery query = prolog.query(code);
 			if (!query.hasSolution()) {
 				return false;
 			}
 
 			// set variables result in the binding map
 			Map<String, Object> map = query.oneVariablesResult();
 			for (Entry<String, Object> entry : map.entrySet()) {
 				put(entry.getKey(), entry.getValue());
 			}
 
 		}
 
 		// code is prolog program
 		// code need ensure_loaded
 		else {
 			prolog.include(new StringReader(code));
 		}
 
 		return true;
 
 	}
 
 	@Override
 	public Object eval(String string) throws ScriptException {
 		return eval(string, getContext());
 	}
 
 	@Override
 	public Object eval(Reader reader) throws ScriptException {
 		return eval(reader, getContext());
 	}
 
 	public PrologProvider getProvider() {
 		return prolog.getProvider();
 	}
 
 }