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;

    }

}