package org.bouncycastle.jcajce.provider.config;

import java.security.BasicPermission;
import java.security.Permission;
import java.util.StringTokenizer;

import org.bouncycastle.util.Strings;

A permission class to define what can be done with the ConfigurableProvider interface.

Available permissions are "threadLocalEcImplicitlyCa" and "ecImplicitlyCa" which allow the setting
of the thread local and global ecImplicitlyCa parameters respectively.


Examples:

ProviderConfigurationPermission("BC"); // enable all permissions
ProviderConfigurationPermission("BC", "threadLocalEcImplicitlyCa"); // enable thread local only
ProviderConfigurationPermission("BC", "ecImplicitlyCa"); // enable global setting only
ProviderConfigurationPermission("BC", "threadLocalEcImplicitlyCa, ecImplicitlyCa"); // enable both explicitly


Note: permission checks are only enforced if a security manager is present.

/**
 * A permission class to define what can be done with the ConfigurableProvider interface.
 * <p>
 * Available permissions are "threadLocalEcImplicitlyCa" and "ecImplicitlyCa" which allow the setting
 * of the thread local and global ecImplicitlyCa parameters respectively.
 * </p>
 * <p>
 * Examples:
 * <ul>
 * <li>ProviderConfigurationPermission("BC"); // enable all permissions</li>
 * <li>ProviderConfigurationPermission("BC", "threadLocalEcImplicitlyCa"); // enable thread local only</li>
 * <li>ProviderConfigurationPermission("BC", "ecImplicitlyCa"); // enable global setting only</li>
 * <li>ProviderConfigurationPermission("BC", "threadLocalEcImplicitlyCa, ecImplicitlyCa"); // enable both explicitly</li>
 * </ul>
 * <p>
 * Note: permission checks are only enforced if a security manager is present.
 * </p>
 */
public class ProviderConfigurationPermission
    extends BasicPermission
{
    private static final int THREAD_LOCAL_EC_IMPLICITLY_CA = 0x01;
    private static final int EC_IMPLICITLY_CA = 0x02;
    private static final int THREAD_LOCAL_DH_DEFAULT_PARAMS = 0x04;
    private static final int DH_DEFAULT_PARAMS = 0x08;
    private static final int ACCEPTABLE_EC_CURVES = 0x10;
    private static final int ADDITIONAL_EC_PARAMETERS = 0x20;

    private static final int  ALL =
            THREAD_LOCAL_EC_IMPLICITLY_CA | EC_IMPLICITLY_CA | THREAD_LOCAL_DH_DEFAULT_PARAMS | DH_DEFAULT_PARAMS |
            ACCEPTABLE_EC_CURVES | ADDITIONAL_EC_PARAMETERS;

    private static final String THREAD_LOCAL_EC_IMPLICITLY_CA_STR = "threadlocalecimplicitlyca";
    private static final String EC_IMPLICITLY_CA_STR = "ecimplicitlyca";
    private static final String THREAD_LOCAL_DH_DEFAULT_PARAMS_STR = "threadlocaldhdefaultparams";
    private static final String DH_DEFAULT_PARAMS_STR = "dhdefaultparams";
    private static final String ACCEPTABLE_EC_CURVES_STR = "acceptableeccurves";
    private static final String ADDITIONAL_EC_PARAMETERS_STR = "additionalecparameters";
    private static final String ALL_STR = "all";

    private final String actions;
    private final int permissionMask;

    public ProviderConfigurationPermission(String name)
    {
        super(name);
        this.actions = "all";
        this.permissionMask = ALL;
    }

    public ProviderConfigurationPermission(String name, String actions)
    {
        super(name, actions);
        this.actions = actions;
        this.permissionMask = calculateMask(actions);
    }

    private int calculateMask(
        String actions)
    {
        StringTokenizer tok = new StringTokenizer(Strings.toLowerCase(actions), " ,");
        int             mask = 0;

        while (tok.hasMoreTokens())
        {
            String s = tok.nextToken();

            if (s.equals(THREAD_LOCAL_EC_IMPLICITLY_CA_STR))
            {
                mask |= THREAD_LOCAL_EC_IMPLICITLY_CA;
            }
            else if (s.equals(EC_IMPLICITLY_CA_STR))
            {
                mask |= EC_IMPLICITLY_CA;
            }
            else if (s.equals(THREAD_LOCAL_DH_DEFAULT_PARAMS_STR))
            {
                mask |= THREAD_LOCAL_DH_DEFAULT_PARAMS;
            }
            else if (s.equals(DH_DEFAULT_PARAMS_STR))
            {
                mask |= DH_DEFAULT_PARAMS;
            }
            else if (s.equals(ACCEPTABLE_EC_CURVES_STR))
            {
                mask |= ACCEPTABLE_EC_CURVES;
            }
            else if (s.equals(ADDITIONAL_EC_PARAMETERS_STR))
            {
                mask |= ADDITIONAL_EC_PARAMETERS;
            }
            else if (s.equals(ALL_STR))
            {
                mask |= ALL;
            }
        }

        if (mask == 0)
        {
            throw new IllegalArgumentException("unknown permissions passed to mask");
        }
        
        return mask;
    }

    public String getActions()
    {
        return actions;
    }

    public boolean implies(
        Permission permission)
    {
        if (!(permission instanceof ProviderConfigurationPermission))
        {
            return false;
        }

        if (!this.getName().equals(permission.getName()))
        {
            return false;
        }
        
        ProviderConfigurationPermission other = (ProviderConfigurationPermission)permission;
        
        return (this.permissionMask & other.permissionMask) == other.permissionMask;
    }

    public boolean equals(
        Object obj)
    {
        if (obj == this)
        {
            return true;
        }

        if (obj instanceof ProviderConfigurationPermission)
        {
            ProviderConfigurationPermission other = (ProviderConfigurationPermission)obj;

            return this.permissionMask == other.permissionMask && this.getName().equals(other.getName());
        }

        return false;
    }

    public int hashCode()
    {
        return this.getName().hashCode() + this.permissionMask;
    }
}