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/*
 * Jython Database Specification API 2.0
 *
 *
 * Copyright (c) 2001 brian zimmer 
 *
 */
package com.ziclix.python.sql;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Collections;
import java.util.WeakHashMap;
import java.util.Set;

import org.python.core.ClassDictInit;
import org.python.core.ContextManager;
import org.python.core.Py;
import org.python.core.PyBuiltinMethodSet;
import org.python.core.PyException;
import org.python.core.PyInteger;
import org.python.core.PyList;
import org.python.core.PyObject;
import org.python.core.PyString;
import org.python.core.PyUnicode;
import org.python.core.ThreadState;
import org.python.core.Traverseproc;
import org.python.core.Visitproc;

import com.ziclix.python.sql.util.PyArgParser;

/**
 * A connection to the database.
 *
 * @author brian zimmer
 */
public class PyConnection extends PyObject implements ClassDictInit, ContextManager, Traverseproc {

    /** True if closed. */
    protected boolean closed;

    /** Whether transactions are supported. */
    protected boolean supportsTransactions;

    /** Whether multiple ResultSets are supported. */
    protected boolean supportsMultipleResultSets;

    /** The underlying java.sql.Connection. */
    protected Connection connection;

    /** Underlying cursors. */
    private Set cursors;

    /** Underlying statements. */
    private Set statements;

    /** Field __members__ */
    protected static PyList __members__;

    /** Field __methods__ */
    protected static PyList __methods__;

    static {
        PyObject[] m = new PyObject[5];

        m[0] = new PyString("close");
        m[1] = new PyString("commit");
        m[2] = new PyString("cursor");
        m[3] = new PyString("rollback");
        m[4] = new PyString("nativesql");
        __methods__ = new PyList(m);
        m = new PyObject[10];
        m[0] = new PyString("autocommit");
        m[1] = new PyString("dbname");
        m[2] = new PyString("dbversion");
        m[3] = new PyString("drivername");
        m[4] = new PyString("driverversion");
        m[5] = new PyString("url");
        m[6] = new PyString("__connection__");
        m[7] = new PyString("__cursors__");
        m[8] = new PyString("__statements__");
        m[9] = new PyString("closed");
        __members__ = new PyList(m);
    }

    /**
     * Create a PyConnection with the open connection.
     *
     * @param connection
     * @throws SQLException
     */
    public PyConnection(Connection connection) throws SQLException {
        this.closed = false;
        cursors = Collections.newSetFromMap(new WeakHashMap());
        cursors = Collections.synchronizedSet(cursors);
        this.connection = connection;
        statements = Collections.newSetFromMap(new WeakHashMap());
        statements = Collections.synchronizedSet(statements);
        this.supportsTransactions = this.connection.getMetaData().supportsTransactions();
        this.supportsMultipleResultSets =
                this.connection.getMetaData().supportsMultipleResultSets();

        if (this.supportsTransactions) {
            this.connection.setAutoCommit(false);
        }
    }

    /**
     * Produces a string representation of the object.
     *
     * @return string representation of the object.
     */
    @Override
    public String toString() {
        try {
            return String.format("", Py.idstr(this),
                                 connection.getMetaData().getUserName(),
                                 connection.getMetaData().getURL());
        } catch (SQLException e) {
            return String.format("
     * Database modules that do not support transactions should implement this method with
     * void functionality.
     */
    public void commit() {
        if (closed) {
            throw zxJDBC.makeException(zxJDBC.ProgrammingError, "connection is closed");
        }

        if (!this.supportsTransactions) {
            return;
        }

        try {
            this.connection.commit();
        } catch (SQLException e) {
            throw zxJDBC.makeException(e);
        }
    }

    /**
     * This method is optional since not all databases provide transaction support.
     * 
     * In case a database does provide transactions this method causes the database to
     * roll back to the start of any pending transaction. Closing a connection without
     * committing the changes first will cause an implicit rollback to be performed.
     */
    public void rollback() {
        if (closed) {
            throw zxJDBC.makeException(zxJDBC.ProgrammingError, "connection is closed");
        }

        if (!this.supportsTransactions) {
            return;
        }

        try {
            this.connection.rollback();
        } catch (SQLException e) {
            throw zxJDBC.makeException(e);
        }
    }

    /**
     * Converts the given SQL statement into the system's native SQL grammar. A driver may
     * convert the JDBC sql grammar into its system's native SQL grammar prior to sending
     * it; this method returns the native form of the statement that the driver would have
     * sent.
     *
     * @param nativeSQL
     * @return the native form of this statement
     */
    public PyObject nativesql(PyObject nativeSQL) {
        if (closed) {
            throw zxJDBC.makeException(zxJDBC.ProgrammingError, "connection is closed");
        }

        if (nativeSQL == Py.None) {
            return Py.None;
        }

        try {
            if (nativeSQL instanceof PyUnicode) {
                return Py.newUnicode(this.connection.nativeSQL(nativeSQL.toString()));
            }
            return Py.newString(this.connection.nativeSQL(nativeSQL.__str__().toString()));
        } catch (SQLException e) {
            throw zxJDBC.makeException(e);
        }
    }

    /**
     * Return a new Cursor Object using the connection. If the database does not provide a
     * direct cursor concept, the module will have to emulate cursors using other means to
     * the extent needed by this specification.
     *
     * @return a new cursor using this connection
     */
    public PyCursor cursor() {
        return cursor(false);
    }

    /**
     * Return a new Cursor Object using the connection. If the database does not provide a
     * direct cursor concept, the module will have to emulate cursors using other means to
     * the extent needed by this specification.
     *
     * @param dynamicFetch if true, dynamically iterate the result
     * @return a new cursor using this connection
     */
    public PyCursor cursor(boolean dynamicFetch) {
        return this.cursor(dynamicFetch, Py.None, Py.None);
    }

    /**
     * Return a new Cursor Object using the connection. If the database does not provide a
     * direct cursor concept, the module will have to emulate cursors using other means to
     * the extent needed by this specification.
     *
     * @param dynamicFetch if true, dynamically iterate the result
     * @param rsType       the type of the underlying ResultSet
     * @param rsConcur     the concurrency of the underlying ResultSet
     * @return a new cursor using this connection
     */
    public PyCursor cursor(boolean dynamicFetch, PyObject rsType, PyObject rsConcur) {
        if (closed) {
            throw zxJDBC.makeException(zxJDBC.ProgrammingError, "connection is closed");
        }

        PyCursor cursor = new PyExtendedCursor(this, dynamicFetch, rsType, rsConcur);
        this.cursors.add(cursor);
        return cursor;
    }

    /**
     * Remove an open PyCursor.
     *
     * @param cursor
     */
    void remove(PyCursor cursor) {
        if (closed) {
            return;
        }
        this.cursors.remove(cursor);
    }

    /**
     * Method register
     *
     * @param statement statement
     */
    void add(PyStatement statement) {
        if (closed) {
            return;
        }
        this.statements.add(statement);
    }

    /**
     * Method contains
     *
     * @param statement statement
     * @return boolean
     */
    boolean contains(PyStatement statement) {
        if (closed) {
            return false;
        }
        return this.statements.contains(statement);
    }

    public PyObject __enter__(ThreadState ts) {
        return this;
    }

    public PyObject __enter__() {
        return this;
    }

    public boolean __exit__(ThreadState ts, PyException exception) {
        if (exception == null) {
            commit();
        } else {
            rollback();
        }
        return false;
    }

    public boolean __exit__(PyObject type, PyObject value, PyObject traceback) {
        if (type == null || type == Py.None) {
            commit();
        } else {
            rollback();
        }
        return false;
    }


    /* Traverseproc implementation */
    @Override
    public int traverse(Visitproc visit, Object arg) {
        int retVal;
        for (PyObject ob: cursors) {
            if (ob != null) {
                retVal = visit.visit(ob, arg);
                if (retVal != 0) {
                    return retVal;
                }
            }
        }
        for (PyObject ob: statements) {
            if (ob != null) {
                retVal = visit.visit(ob, arg);
                if (retVal != 0) {
                    return retVal;
                }
            }
        }
        return 0;
    }

    @Override
    public boolean refersDirectlyTo(PyObject ob) {
        if (ob == null) {
            return false;
        }
        if (cursors != null && cursors.contains(ob)) {
            return true;
        } else if (statements != null && statements.contains(ob)) {
            return true;
        } else {
            return false;
        }
    }
}

class ConnectionFunc extends PyBuiltinMethodSet {

    ConnectionFunc(String name, int index, int minargs, int maxargs, String doc) {
        super(name, index, minargs, maxargs, doc, PyConnection.class);
    }

    @Override
    public PyObject __call__() {
        PyConnection c = (PyConnection) __self__;
        switch (index) {
            case 0:
                c.close();
                return Py.None;
            case 1:
                c.commit();
                return Py.None;
            case 2:
                return c.cursor();
            case 3:
                c.rollback();
                return Py.None;
            case 5:
                return c.__enter__();
            default:
                throw info.unexpectedCall(0, false);
        }
    }

    @Override
    public PyObject __call__(PyObject arg) {
        PyConnection c = (PyConnection) __self__;
        switch (index) {
            case 2:
                return c.cursor(arg.__nonzero__());
            case 4:
                return c.nativesql(arg);
            default:
                throw info.unexpectedCall(1, false);
        }
    }

    @Override
    public PyObject __call__(PyObject arg1, PyObject arg2, PyObject arg3) {
        PyConnection c = (PyConnection) __self__;
        switch (index) {
            case 2:
                return c.cursor(arg1.__nonzero__(), arg2, arg3);
            case 6:
                return Py.newBoolean(c.__exit__(arg1, arg2, arg3));
            default:
                throw info.unexpectedCall(3, false);
        }
    }

    @Override
    public PyObject __call__(PyObject[] args, String[] keywords) {
        PyConnection c = (PyConnection) __self__;
        PyArgParser parser = new PyArgParser(args, keywords);
        switch (index) {
            case 2:
                PyObject dynamic = parser.kw("dynamic", Py.None);
                PyObject rstype = parser.kw("rstype", Py.None);
                PyObject rsconcur = parser.kw("rsconcur", Py.None);

                dynamic = (parser.numArg() >= 1) ? parser.arg(0) : dynamic;
                rstype = (parser.numArg() >= 2) ? parser.arg(1) : rstype;
                rsconcur = (parser.numArg() >= 3) ? parser.arg(2) : rsconcur;

                return c.cursor(dynamic.__nonzero__(), rstype, rsconcur);

            default:
                throw info.unexpectedCall(args.length, true);
        }
    }
}