package de.thedevstack.conversationsplus.xmpp.jid;

import android.util.LruCache;

import net.java.otr4j.session.SessionID;

import java.net.IDN;

import gnu.inet.encoding.Stringprep;
import gnu.inet.encoding.StringprepException;

/**
 */
public class JidUtil {
    private static LruCache<String,Jid> cache = new LruCache<>(1024);

    public static Jid fromSessionID(final SessionID id) throws InvalidJidException {
        if (id.getUserID().isEmpty()) {
            return fromString(id.getAccountID());
        } else {
            return fromString(id.getAccountID()+"/"+id.getUserID());
        }
    }

    public static Jid fromString(final String jid) throws InvalidJidException {
        return fromString(jid, false);
    }

    public static Jid fromString(final String jid, final boolean safe) throws InvalidJidException {
        if (jid == null) throw new InvalidJidException(InvalidJidException.IS_NULL);

        Jid fromCache = JidUtil.cache.get(jid);
        if (fromCache != null) {
            return fromCache;
        }

        // Hackish Android way to count the number of chars in a string... should work everywhere.
        final int atCount = jid.length() - jid.replace("@", "").length();
        final int slashCount = jid.length() - jid.replace("/", "").length();

        // Throw an error if there's anything obvious wrong with the JID...
        if (jid.isEmpty() || jid.length() > 3071) {
            throw new InvalidJidException(InvalidJidException.INVALID_LENGTH);
        }

        // Go ahead and check if the localpart or resourcepart is empty.
        if (jid.startsWith("@") || (jid.endsWith("@") && slashCount == 0) || jid.startsWith("/") || (jid.endsWith("/") && slashCount < 2)) {
            throw new InvalidJidException(InvalidJidException.INVALID_CHARACTER);
        }

        String finaljid;
        String localpart;
        String domainpart;
        String resourcepart;

        final int domainpartStart;
        final int atLoc = jid.indexOf("@");
        final int slashLoc = jid.indexOf("/");
        // If there is no "@" in the JID (eg. "example.net" or "example.net/resource")
        // or there are one or more "@" signs but they're all in the resourcepart (eg. "example.net/@/rp@"):
        if (atCount == 0 || (atCount > 0 && slashLoc != -1 && atLoc > slashLoc)) {
            localpart = "";
            finaljid = "";
            domainpartStart = 0;
        } else {
            final String lp = jid.substring(0, atLoc);
            try {
                localpart = safe ? lp : Stringprep.nodeprep(lp);
            } catch (final StringprepException e) {
                throw new InvalidJidException(InvalidJidException.STRINGPREP_FAIL, e);
            }
            if (localpart.isEmpty() || localpart.length() > 1023) {
                throw new InvalidJidException(InvalidJidException.INVALID_PART_LENGTH);
            }
            domainpartStart = atLoc + 1;
            finaljid = lp + "@";
        }

        final String dp;
        if (slashCount > 0) {
            final String rp = jid.substring(slashLoc + 1, jid.length());
            try {
                resourcepart = safe ? rp : Stringprep.resourceprep(rp);
            } catch (final StringprepException e) {
                throw new InvalidJidException(InvalidJidException.STRINGPREP_FAIL, e);
            }
            if (resourcepart.isEmpty() || resourcepart.length() > 1023) {
                throw new InvalidJidException(InvalidJidException.INVALID_PART_LENGTH);
            }
            try {
                dp = IDN.toUnicode(Stringprep.nameprep(jid.substring(domainpartStart, slashLoc)), IDN.USE_STD3_ASCII_RULES);
            } catch (final StringprepException e) {
                throw new InvalidJidException(InvalidJidException.STRINGPREP_FAIL, e);
            }
            finaljid = finaljid + dp + "/" + rp;
        } else {
            resourcepart = "";
            try{
                dp = IDN.toUnicode(Stringprep.nameprep(jid.substring(domainpartStart, jid.length())), IDN.USE_STD3_ASCII_RULES);
            } catch (final StringprepException e) {
                throw new InvalidJidException(InvalidJidException.STRINGPREP_FAIL, e);
            }
            finaljid = finaljid + dp;
        }

        // Remove trailing "." before storing the domain part.
        if (dp.endsWith(".")) {
            try {
                domainpart = IDN.toASCII(dp.substring(0, dp.length() - 1), IDN.USE_STD3_ASCII_RULES);
            } catch (final IllegalArgumentException e) {
                throw new InvalidJidException(e);
            }
        } else {
            try {
                domainpart = IDN.toASCII(dp, IDN.USE_STD3_ASCII_RULES);
            } catch (final IllegalArgumentException e) {
                throw new InvalidJidException(e);
            }
        }

        // TODO: Find a proper domain validation library; validate individual parts, separators, etc.
        if (domainpart.isEmpty() || domainpart.length() > 1023) {
            throw new InvalidJidException(InvalidJidException.INVALID_PART_LENGTH);
        }

        Jid createdJid = new Jid(finaljid, localpart, domainpart, resourcepart);

        JidUtil.cache.put(jid, createdJid);

        return createdJid;
    }

    public static Jid fromParts(final String localpart, final String domainpart, final String resourcepart) throws InvalidJidException {
        String out;
        if (localpart == null || localpart.isEmpty()) {
            out = domainpart;
        } else {
            out = localpart + "@" + domainpart;
        }
        if (resourcepart != null && !resourcepart.isEmpty()) {
            out = out + "/" + resourcepart;
        }
        return JidUtil.fromString(out, false);
    }
}