ConstraintsBuilder.java

package net.sourceforge.mayfly.evaluation.command;

import net.sourceforge.mayfly.datastore.Columns;
import net.sourceforge.mayfly.datastore.DataStore;
import net.sourceforge.mayfly.datastore.TableData;
import net.sourceforge.mayfly.datastore.TableReference;
import net.sourceforge.mayfly.datastore.constraint.Constraint;
import net.sourceforge.mayfly.datastore.constraint.Constraints;
import net.sourceforge.mayfly.datastore.constraint.ForeignKey;
import net.sourceforge.mayfly.util.ImmutableList;

import java.util.ArrayList;
import java.util.List;

public class ConstraintsBuilder {

    public static ConstraintsBuilder fromTable(
        DataStore store, TableReference table) {
        return new ConstraintsBuilder(store, table.schema(), table.tableName(), 
            findNextForeignKeyNumber(store, table));
    }

    static int findNextForeignKeyNumber(
        DataStore store, TableReference table) {
        String namePrefix = table.tableName() + "_ibfk_";
        int prefixLength = namePrefix.length();
        int nextForeignKeyNumber = 1;

        TableData tableData = store.table(table);
        for (Constraint constraint : tableData.constraints) {
            String name = constraint.constraintName;
            if (constraint instanceof ForeignKey
                && name.startsWith(namePrefix)) {
                String remaining = name.substring(prefixLength);
                int thisNumber;
                try {
                    thisNumber = Integer.parseInt(remaining);
                }
                catch (NumberFormatException e) {
                    continue;
                }
                if (nextForeignKeyNumber <= thisNumber) {
                    nextForeignKeyNumber = thisNumber + 1;
                }
            }
        }
        return nextForeignKeyNumber;
    }

    private List<Constraint> resolved = new ArrayList<Constraint>();
    
    private int nextForeignKeyNumber = 1;

    public final DataStore store;
    public final String schema;
    public final String table;
    public final Columns columns;

    public ConstraintsBuilder(
        DataStore store, String schema, String table, Columns columns) {
        this.store = store;
        this.schema = schema;
        this.table = table;
        this.columns = columns;
    }
    
    private ConstraintsBuilder(DataStore store, String schema, String table,
        int nextForeignKeyNumber) {
        this.store = store;
        this.schema = schema;
        this.table = table;
        this.nextForeignKeyNumber = nextForeignKeyNumber;
        this.columns = null;
    }

    public void add(Constraint constraint) {
        resolved.add(constraint);
    }

    public Constraints asConstraints() {
        return new Constraints(new ImmutableList(resolved));
    }

    public void add(UnresolvedConstraint constraint) {
        add(constraint.resolve(this));
    }

    public String assignForeignKeyName() {
        return table + "_ibfk_" + nextForeignKeyNumber++;
    }

}