/*
 * Copyright 2004-2008 H2 Group. Licensed under the H2 License, Version 1.0
 * (http://h2database.com/html/license.html).
 * Initial Developer: H2 Group
 */
package org.h2.constraint;

import java.sql.SQLException;

import org.h2.command.Parser;
import org.h2.command.Prepared;
import org.h2.constant.ErrorCode;
import org.h2.engine.Session;
import org.h2.expression.Expression;
import org.h2.expression.Parameter;
import org.h2.index.Cursor;
import org.h2.index.Index;
import org.h2.message.Message;
import org.h2.result.LocalResult;
import org.h2.result.Row;
import org.h2.result.SearchRow;
import org.h2.schema.Schema;
import org.h2.table.Column;
import org.h2.table.IndexColumn;
import org.h2.table.Table;
import org.h2.util.ObjectArray;
import org.h2.util.StringUtils;
import org.h2.value.Value;
import org.h2.value.ValueNull;

/**
 * A referential constraint.
 */
public class ConstraintReferential extends Constraint {
    public static final int RESTRICT = 0, CASCADE = 1, SET_DEFAULT = 2, SET_NULL = 3;

    private int deleteAction;
    private int updateAction;
    private Table refTable;
    private Index index;
    private Index refIndex;
    private boolean indexOwner;
    private boolean refIndexOwner;
    protected IndexColumn[] columns;
    protected IndexColumn[] refColumns;
    private String deleteSQL, updateSQL;
    private boolean skipOwnTable;

    public ConstraintReferential(Schema schema, int id, String name, Table table) {
        super(schema, id, name, table);
    }

    public String getConstraintType() {
        return Constraint.REFERENTIAL;
    }

    private void appendAction(StringBuffer buff, int action) {
        switch (action) {
        case CASCADE:
            buff.append("CASCADE");
            break;
        case SET_DEFAULT:
            buff.append("SET DEFAULT");
            break;
        case SET_NULL:
            buff.append("SET NULL");
            break;
        default:
            throw Message.getInternalError("action=" + action);
        }
    }

    /**
     * Create the SQL statement of this object so a copy of the table can be made.
     * 
     * @param table the table to create the object for
     * @param quotedName the name of this object (quoted if necessary)
     * @return the SQL statement
     */
    public String getCreateSQLForCopy(Table table, String quotedName) {
        return getCreateSQLForCopy(table, refTable, quotedName, true);
    }

    /**
     * Create the SQL statement of this object so a copy of the table can be made.
     * 
     * @param table the table to create the object for
     * @param refTable the referenced table
     * @param quotedName the name of this object (quoted if necessary)
     * @param internalIndex add the index name to the statement
     * @return the SQL statement
     */
    public String getCreateSQLForCopy(Table table, Table refTable, String quotedName, boolean internalIndex) {
        StringBuffer buff = new StringBuffer();
        buff.append("ALTER TABLE ");
        String mainTable = table.getSQL();
        buff.append(mainTable);
        buff.append(" ADD CONSTRAINT ");
        buff.append(quotedName);
        if (comment != null) {
            buff.append(" COMMENT ");
            buff.append(StringUtils.quoteStringSQL(comment));
        }
        IndexColumn[] cols = columns;
        IndexColumn[] refCols = refColumns;
        buff.append(" FOREIGN KEY(");
        for (int i = 0; i < cols.length; i++) {
            if (i > 0) {
                buff.append(", ");
            }
            buff.append(cols[i].getSQL());
        }
        buff.append(")");
        if (internalIndex && indexOwner && table == this.table) {
            buff.append(" INDEX ");
            buff.append(index.getSQL());
        }
        buff.append(" REFERENCES ");
        String quotedRefTable;
        if (this.table == this.refTable) {
            // self-referencing constraints: need to use new table
            quotedRefTable = table.getSQL();
        } else {
            quotedRefTable = refTable.getSQL();
        }
        buff.append(quotedRefTable);
        buff.append("(");
        for (int i = 0; i < refCols.length; i++) {
            if (i > 0) {
                buff.append(", ");
            }
            buff.append(refCols[i].getSQL());
        }
        buff.append(")");
        if (internalIndex && refIndexOwner && table == this.table) {
            buff.append(" INDEX ");
            buff.append(refIndex.getSQL());
        }
        if (deleteAction != RESTRICT) {
            buff.append(" ON DELETE ");
            appendAction(buff, deleteAction);
        }
        if (updateAction != RESTRICT) {
            buff.append(" ON UPDATE ");
            appendAction(buff, updateAction);
        }
        buff.append(" NOCHECK");
        return buff.toString();
    }

    public String getShortDescription() {
        StringBuffer buff = new StringBuffer();
        buff.append(getName());
        buff.append(": ");
        buff.append(table.getSQL());
        buff.append(" FOREIGN KEY(");
        for (int i = 0; i < columns.length; i++) {
            if (i > 0) {
                buff.append(", ");
            }
            buff.append(columns[i].getSQL());
        }
        buff.append(")");
        buff.append(" REFERENCES ");
        buff.append(refTable.getSQL());
        buff.append("(");
        for (int i = 0; i < refColumns.length; i++) {
            if (i > 0) {
                buff.append(", ");
            }
            buff.append(refColumns[i].getSQL());
        }
        buff.append(")");
        return buff.toString();
    }

    public String getCreateSQLWithoutIndexes() {
        return getCreateSQLForCopy(table, refTable, getSQL(), false);
    }

    public String getCreateSQL() {
        return getCreateSQLForCopy(table, getSQL());
    }

    public void setColumns(IndexColumn[] cols) {
        columns = cols;
    }

    public IndexColumn[] getColumns() {
        return columns;
    }

    public void setRefColumns(IndexColumn[] refCols) {
        refColumns = refCols;
    }

    public IndexColumn[] getRefColumns() {
        return refColumns;
    }

    public void setRefTable(Table refTable) {
        this.refTable = refTable;
        if (refTable.getTemporary()) {
            setTemporary(true);
        }
    }

    public void setIndex(Index index, boolean isOwner) {
        this.index = index;
        this.indexOwner = isOwner;
    }

    public void setRefIndex(Index refIndex, boolean isRefOwner) {
        this.refIndex = refIndex;
        this.refIndexOwner = isRefOwner;
    }

    public void removeChildrenAndResources(Session session) throws SQLException {
        table.removeConstraint(this);
        refTable.removeConstraint(this);
        if (indexOwner) {
            table.removeIndexOrTransferOwnership(session, index);
        }
        if (refIndexOwner) {
            refTable.removeIndexOrTransferOwnership(session, refIndex);
        }
        database.removeMeta(session, getId());
        refTable = null;
        index = null;
        refIndex = null;
        columns = null;
        refColumns = null;
        deleteSQL = null;
        updateSQL = null;
        table = null;
        invalidate();
    }

    public void checkRow(Session session, Table t, Row oldRow, Row newRow) throws SQLException {
        if (!database.getReferentialIntegrity()) {
            return;
        }
        if (!table.getCheckForeignKeyConstraints() || !refTable.getCheckForeignKeyConstraints()) {
            return;
        }
        if (t == table) {
            if (!skipOwnTable) {
                checkRowOwnTable(session, newRow);
            }
        }
        if (t == refTable) {
            checkRowRefTable(session, oldRow, newRow);
        }
    }

    private void checkRowOwnTable(Session session, Row newRow) throws SQLException {
        if (newRow == null) {
            return;
        }
        boolean containsNull = false;
        for (int i = 0; i < columns.length; i++) {
            int idx = columns[i].column.getColumnId();
            Value v = newRow.getValue(idx);
            if (v == ValueNull.INSTANCE) {
                containsNull = true;
                break;
            }
        }
        if (containsNull) {
            return;
        }
        if (refTable == table) {
            // special case self referencing constraints: check the inserted row
            // first
            boolean self = true;
            for (int i = 0; i < columns.length; i++) {
                int idx = columns[i].column.getColumnId();
                Value v = newRow.getValue(idx);
                Column refCol = refColumns[i].column;
                int refIdx = refCol.getColumnId();
                Value r = newRow.getValue(refIdx);
                if (!database.areEqual(r, v)) {
                    self = false;
                    break;
                }
            }
            if (self) {
                return;
            }
        }
        Row check = refTable.getTemplateRow();
        for (int i = 0; i < columns.length; i++) {
            int idx = columns[i].column.getColumnId();
            Value v = newRow.getValue(idx);
            Column refCol = refColumns[i].column;
            int refIdx = refCol.getColumnId();
            check.setValue(refIdx, v.convertTo(refCol.getType()));
        }
        if (!found(session, refIndex, check)) {
            throw Message.getSQLException(ErrorCode.REFERENTIAL_INTEGRITY_VIOLATED_PARENT_MISSING_1,
                    getShortDescription());
        }
    }

    private boolean found(Session session, Index index, SearchRow check) throws SQLException {
        index.getTable().lock(session, false, false);
        Cursor cursor = index.find(session, check, check);
        while (cursor.next()) {
            SearchRow found;