package org.apidesign.livedb.impl;

 import java.io.IOException;

 import java.io.Writer;

 import java.sql.CallableStatement;

 import java.sql.Connection;

 import java.sql.DatabaseMetaData;

 import java.sql.Driver;

 import java.sql.ResultSet;

 import java.sql.ResultSetMetaData;

 import java.sql.SQLException;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.List;

 import java.util.Map.Entry;

 import java.util.Properties;

 import java.util.ServiceLoader;

 import java.util.Set;

 import javax.annotation.processing.AbstractProcessor;

 import javax.annotation.processing.Completion;

 import javax.annotation.processing.Completions;

 import javax.annotation.processing.Filer;

 import javax.annotation.processing.Processor;

 import javax.annotation.processing.RoundEnvironment;

 import javax.annotation.processing.SupportedAnnotationTypes;

 import javax.annotation.processing.SupportedSourceVersion;

 import javax.lang.model.SourceVersion;

 import javax.lang.model.element.AnnotationMirror;

 import javax.lang.model.element.AnnotationValue;

 import javax.lang.model.element.Element;

 import javax.lang.model.element.ExecutableElement;

 import javax.lang.model.element.PackageElement;

 import javax.lang.model.element.TypeElement;

 import javax.tools.Diagnostic;

 import javax.tools.JavaFileObject;

 import org.apidesign.livedb.LiveDB;

 import org.openide.util.lookup.ServiceProvider;

 /**

  *

  * @author Jaroslav Tulach <jtulach@netbeans.org>

  */

 // BEGIN: livedb.processor

 @SupportedAnnotationTypes("org.apidesign.livedb.LiveDB")

 @SupportedSourceVersion(SourceVersion.RELEASE_6)

 @ServiceProvider(service=Processor.class)

 public final class LiveDBProcessor extends AbstractProcessor {

     @Override

     public boolean process(

         Set<? extends TypeElement> annotations, RoundEnvironment roundEnv

     ) {

         final Filer filer = processingEnv.getFiler();

         for (Element e : roundEnv.getElementsAnnotatedWith(LiveDB.class)) {

             LiveDB db = e.getAnnotation(LiveDB.class);

             PackageElement pe = (PackageElement)e;

             String clsName = pe.getQualifiedName() + "." + db.classname();

             try {

                 JavaFileObject src = filer.createSourceFile(clsName, pe);

                 Writer w = src.openWriter();

                 Connection c = getConnection(

                     db.url(), db.user(), db.password()

                 );

                 CallableStatement s = c.prepareCall(db.query());

                 ResultSet rs = s.executeQuery();

                 ResultSetMetaData md = rs.getMetaData();

                 generateClassHeader(w, pe, db);

                 w.append("class " + db.classname() + " {\n");

                 for (int i = 1; i <= md.getColumnCount(); i++) {

                     generateField(w, md, i);

                 }

                 generateConstructor(w, db, md);

                 generateQueryMethod(w, db, md);

                 w.append("}");

                 w.close();

             } catch (IOException | SQLException ex) {

                 processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, ex.getMessage(), e);

             }

         }

         return true;

     }

 // FINISH: livedb.processor

     private void generateQueryMethod(Writer w, LiveDB db, ResultSetMetaData md) throws SQLException, IOException {

         w.append("  public static List<" + db.classname() + "> ")

          .append("query() throws SQLException {\n");

         w.append("    Connection c = DriverManager.getConnection(\"")

          .append(db.url()).append("\", \"")

          .append(db.user()).append("\", \"")

          .append(db.password()).append("\");\n");

         w.append("    List<").append(db.classname())

          .append("> res = new ArrayList<")

          .append(db.classname()).append(">();\n");

         w.append("    CallableStatement s = c.prepareCall(\"")

          .append(db.query()).append("\");\n");

         w.append("    ResultSet rs = s.executeQuery();\n");

         w.append("    ResultSetMetaData md = rs.getMetaData();\n");

         w.append("    while (rs.next()) {\n");

         w.append("      res.add(new " + db.classname() + "(\n");

         for (int i = 1; i <= md.getColumnCount(); i++) {

             w.append("        (")

              .append(md.getColumnClassName(i))

              .append(")rs.getObject(" + i).append(")");

             if (i < md.getColumnCount()) {

                 w.append(",\n");

             } else {

                 w.append("\n");

             }

         }

         w.append("      ));\n");

         w.append("    };\n");

         w.append("    return res;\n");

         w.append("  }");

     }

     private void generateConstructor(Writer w, LiveDB db, ResultSetMetaData md) throws SQLException, IOException {

         w.append("  private " + db.classname() + "(\n");

         for (int i = 1; i <= md.getColumnCount(); i++) {

             w.append("    ").append(md.getColumnClassName(i))

              .append(" ").append(md.getColumnName(i));

             if (i < md.getColumnCount()) {

                 w.append(",\n");

             } else {

                 w.append("\n");

             }

         }

         w.append("  ) {\n");

         for (int i = 1; i <= md.getColumnCount(); i++) {

             w.append("    this.")

              .append(md.getColumnName(i))

              .append(" = ")

              .append(md.getColumnName(i))

              .append(";\n");

         }

         w.append("  }\n");

     }

     private void generateField(Writer w, ResultSetMetaData md, int i) throws IOException, SQLException {

         w.append("  public final ")

          .append(md.getColumnClassName(i))

          .append(" ")

          .append(md.getColumnName(i))

          .append(";\n");

     }

     private void generateClassHeader(Writer w, PackageElement pe, LiveDB db) throws IOException {

         w.append("package " + pe.getQualifiedName() + ";\n");

         w.append("import java.util.List;\n");

         w.append("import java.util.ArrayList;\n");

         w.append("import java.sql.*;\n");

     }

     private static Connection getConnection(String url, String user, String password) 

     throws SQLException {

         final ClassLoader cl = LiveDBProcessor.class.getClassLoader();

         for (Driver d : ServiceLoader.load(Driver.class, cl)) {

 //            System.out.println("looked up: " + d);

             if (d.acceptsURL(url)) {

                 //System.out.println("accepts: " + d);

                 Properties p = new Properties();

                 p.put("user", user);

                 p.put("password", password);

                 return d.connect(url, p);

             }

         }

         throw new SQLException("No driver found for " + url);

     }

     // BEGIN: livedb.completions

     @Override

     public Iterable<? extends Completion> getCompletions(

         Element element, AnnotationMirror annotation, 

         ExecutableElement member, String userText

     ) {

         if (!"query".equals(member.getSimpleName().toString())) {

             return Collections.emptyList();

         }

         if (userText == null || userText.length() <= 1) {

             return Collections.singleton(Completions.of("\"SELECT "));

         }

         if (userText.toUpperCase().matches(".*FROM *")) {

             String user = extractValue(annotation, "user");

             String password = extractValue(annotation, "password");

             String url = extractValue(annotation, "url");

             if (user == null || password == null || url == null) {

                 return Collections.emptyList();

             }

             try {

                 List<Completion> arr = new ArrayList<Completion>();

                 Connection c = getConnection(url, user, password);

                 DatabaseMetaData meta = c.getMetaData();

                 ResultSet res = meta.getTables(null, null, "%", null);

                 boolean ok = res.first();

                 while (ok) {

                     String txt = userText + res.getString("TABLE_NAME");

                     arr.add(Completions.of(txt));

                     ok = res.next();

                 }

                 return arr;

             } catch (SQLException ex) {

                 throw new IllegalStateException(ex);

             }

         }

         return Collections.emptyList();

     }

     // END: livedb.completions

     private static String extractValue(AnnotationMirror am, String param) {

         AnnotationValue av = null;

         for (Entry<? extends ExecutableElement, ? extends AnnotationValue> entry : am.getElementValues().entrySet()) {

             if (entry.getKey().toString().equals(param + "()")) {

                 av = entry.getValue();

                 break;

             }

         }

         if (av == null) {

             return null;

         }

         String s = av.toString();

         if (s.startsWith("\"")) {

             s = s.substring(1);

         }

         if (s.endsWith("\"")) {

             s = s.substring(0, s.length() - 1);

         }

         return s;

     }

 }