// Copyright 2000-2005 the Contributors, as shown in the revision logs.
// Licensed under the Apache Public Source License 2.0 ("the License").
// You may not use this file except in compliance with the License.

package org.ibex.mail;
import java.lang.reflect.*;
import org.ibex.crypto.*;
import org.ibex.util.*;
import org.ibex.mail.protocol.*;
import org.ibex.io.*;
import java.util.*;
import java.util.zip.*;
import java.net.*;
import java.io.*;

/**
 *  A convenient way to verify that the agent requesting an action
 *  owns a particular email address.  Extend this class; the
 *  Transaction.executeOn() method will be invoked when the user
 *  clicks through.
 */
public abstract class Confirmation implements Externalizable {

    public static final long serialVersionUID = 0x981879f18a11ffeeL;

    public static int master_serial = 0;

    public    transient Address who         = null;
    public              long    expiration;
    public     abstract String  getDescription();
    public     abstract String  getURL(String tail);
    public              int     serial;

    private static HashMap<Integer,Confirmation> all = new HashMap<Integer,Confirmation>();

    public static Confirmation get(int serial) {
        return all.get(serial);
    }

    protected Confirmation(Address who, long expiration) {
        this.who = who;
        this.expiration = expiration;
        this.serial = master_serial++;
        all.put(serial, this);
    }

    public void readExternal(ObjectInput s) throws IOException {
        try {
            int numfields = s.readInt();
            Class c = this.getClass();
            for(int i=0; i<numfields; i++) {
                String name = s.readUTF();
                Field f = c.getField(name);
                Class c2 = f.getType();
                if (c2 == Boolean.TYPE) f.setBoolean(this, s.readBoolean());
                else if (c2 == Byte.TYPE) f.setByte(this, s.readByte());
                else if (c2 == Long.TYPE) f.setLong(this, s.readLong());
                else if (c2 == Integer.TYPE) f.setInt(this, s.readInt());
                else if (c2 == Character.TYPE) f.setChar(this, s.readChar());
                else if (c2 == Short.TYPE) f.setShort(this, s.readShort());
                else if (c2 == Float.TYPE) f.setFloat(this, s.readFloat());
                else if (c2 == Double.TYPE) f.setDouble(this, s.readDouble());
                else if (c2 == String.class) f.set(this, s.readObject());
                else f.set(this, s.readObject());
            }
        } catch (Exception e) {
            Log.error(this, e);
        }
    }

    public void writeExternal(ObjectOutput s) throws IOException {
        try {
            Class c = this.getClass();
            Field[] fields = c.getFields();
            int numfields = 0;
            for(int i=0; i<fields.length; i++) {
                Field f = fields[i];
                if ((f.getModifiers() & (Modifier.STATIC | Modifier.TRANSIENT)) != 0) continue;
                numfields++;
            }
            s.writeInt(numfields);
            for(int i=0; i<fields.length; i++) {
                Field f = fields[i];
                if ((f.getModifiers() & (Modifier.STATIC | Modifier.TRANSIENT)) != 0) continue;
                s.writeUTF(fields[i].getName());
                Class c2 = f.getType();
                if (c2 == Boolean.TYPE) s.writeBoolean(f.getBoolean(this));
                else if (c2 == Byte.TYPE) s.writeByte(f.getByte(this));
                else if (c2 == Long.TYPE) s.writeLong(f.getLong(this));
                else if (c2 == Integer.TYPE) s.writeInt(f.getInt(this));
                else if (c2 == Character.TYPE) s.writeChar(f.getChar(this));
                else if (c2 == Short.TYPE) s.writeShort(f.getShort(this));
                else if (c2 == Float.TYPE) s.writeFloat(f.getFloat(this));
                else if (c2 == Double.TYPE) s.writeDouble(f.getDouble(this));
                else if (c2 == String.class) s.writeUTF((String)f.get(this));
                else s.writeObject(f.get(this));
            }
        } catch (Exception e) {
            Log.error(this, e);
        }
    }

    public void signAndSend(Address sender, long secret, Date now) throws IOException, Message.Malformed {

        Headers h = new Headers(new String[] {
            "From",        sender.toString(true),
            "To",          who.toString(true),
            "Message-Id",  Message.generateFreshMessageId(),
            "Date",        new Date()+"" /*FIXME!!!*/,
            "Subject",     "confirm " + getDescription()
        });

        Fountain fountain = Fountain.Util.create("Please click the link below to " +
                                                 getDescription() + "\r\n" +
                                                 getURL(sign(secret)));
        Message m = Message.newMessageFromHeadersAndBody(h, fountain, sender, who);
        SMTP.Outgoing.enqueue(m);
    }

    public String sign(long secret) throws IOException {
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(new DeflaterOutputStream(os));
        oos.writeObject(this);
        oos.flush();
        oos.close();
        byte[] b = os.toByteArray();
        StringBuffer sb = new StringBuffer();
        sb.append(serial);
        //sb.append(new String(Encode.toBase64(b)));
        sb.append('.');
        SHA1 sha1 = new SHA1();
        sha1.update(b, 0, b.length);
        b = new byte[sha1.getDigestSize()];
        sha1.doFinal(b, 0);
        sb.append(new String(Encode.toBase64(b)));
        return sb.toString();
    }

    public static Confirmation decode(String encoded, long secret, Date now) {
        try {
            String serial = encoded.substring(0, encoded.indexOf('.'));
            Confirmation cve = get(Integer.parseInt(serial));
            if (!cve.sign(secret).equals(encoded)) throw new InvalidSignature();
            if (now.getTime() > cve.expiration) throw new Expired();
            return cve;
        } catch (IOException e) { 
           Log.error(Confirmation.class, e);
           throw new InvalidSignature();
        }
    }

    public static class Exn extends RuntimeException { }
    public static class Expired extends Exn { }
    public static class InvalidSignature extends Exn { }
}