package org.asamk.signal;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.*;
import org.whispersystems.libsignal.IdentityKey;
import org.whispersystems.libsignal.IdentityKeyPair;
import org.whispersystems.libsignal.InvalidKeyException;
import org.whispersystems.libsignal.state.IdentityKeyStore;

import java.io.IOException;
import java.util.*;

class JsonIdentityKeyStore implements IdentityKeyStore {

    private final Map<String, List<Identity>> trustedKeys = new HashMap<>();

    private final IdentityKeyPair identityKeyPair;
    private final int localRegistrationId;


    public JsonIdentityKeyStore(IdentityKeyPair identityKeyPair, int localRegistrationId) {
        this.identityKeyPair = identityKeyPair;
        this.localRegistrationId = localRegistrationId;
    }

    @Override
    public IdentityKeyPair getIdentityKeyPair() {
        return identityKeyPair;
    }

    @Override
    public int getLocalRegistrationId() {
        return localRegistrationId;
    }

    @Override
    public void saveIdentity(String name, IdentityKey identityKey) {
        saveIdentity(name, identityKey, TrustLevel.TRUSTED_UNVERIFIED, null);
    }

    /**
     * Adds or updates the given identityKey for the user name and sets the trustLevel and added timestamp.
     *
     * @param name        User name, i.e. phone number
     * @param identityKey The user's public key
     * @param trustLevel
     * @param added       Added timestamp, if null and the key is newly added, the current time is used.
     */
    public void saveIdentity(String name, IdentityKey identityKey, TrustLevel trustLevel, Date added) {
        List<Identity> identities = trustedKeys.get(name);
        if (identities == null) {
            identities = new ArrayList<>();
            trustedKeys.put(name, identities);
        } else {
            for (Identity id : identities) {
                if (!id.identityKey.equals(identityKey))
                    continue;

                if (id.trustLevel.compareTo(trustLevel) < 0) {
                    id.trustLevel = trustLevel;
                }
                if (added != null) {
                    id.added = added;
                }
                return;
            }
        }
        identities.add(new Identity(identityKey, trustLevel, added != null ? added : new Date()));
    }

    @Override
    public boolean isTrustedIdentity(String name, IdentityKey identityKey) {
        List<Identity> identities = trustedKeys.get(name);
        if (identities == null) {
            // Trust on first use
            return true;
        }

        for (Identity id : identities) {
            if (id.identityKey.equals(identityKey)) {
                return id.isTrusted();
            }
        }

        return false;
    }

    public Map<String, List<Identity>> getIdentities() {
        // TODO deep copy
        return trustedKeys;
    }

    public List<Identity> getIdentities(String name) {
        // TODO deep copy
        return trustedKeys.get(name);
    }

    public static class JsonIdentityKeyStoreDeserializer extends JsonDeserializer<JsonIdentityKeyStore> {

        @Override
        public JsonIdentityKeyStore deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException {
            JsonNode node = jsonParser.getCodec().readTree(jsonParser);

            try {
                int localRegistrationId = node.get("registrationId").asInt();
                IdentityKeyPair identityKeyPair = new IdentityKeyPair(Base64.decode(node.get("identityKey").asText()));


                JsonIdentityKeyStore keyStore = new JsonIdentityKeyStore(identityKeyPair, localRegistrationId);

                JsonNode trustedKeysNode = node.get("trustedKeys");
                if (trustedKeysNode.isArray()) {
                    for (JsonNode trustedKey : trustedKeysNode) {
                        String trustedKeyName = trustedKey.get("name").asText();
                        try {
                            IdentityKey id = new IdentityKey(Base64.decode(trustedKey.get("identityKey").asText()), 0);
                            TrustLevel trustLevel = trustedKey.has("trustLevel") ? TrustLevel.fromInt(trustedKey.get("trustLevel").asInt()) : TrustLevel.TRUSTED_UNVERIFIED;
                            Date added = trustedKey.has("addedTimestamp") ? new Date(trustedKey.get("addedTimestamp").asLong()) : new Date();
                            keyStore.saveIdentity(trustedKeyName, id, trustLevel, added);
                        } catch (InvalidKeyException | IOException e) {
                            System.out.println(String.format("Error while decoding key for: %s", trustedKeyName));
                        }
                    }
                }

                return keyStore;
            } catch (InvalidKeyException e) {
                throw new IOException(e);
            }
        }
    }

    public static class JsonIdentityKeyStoreSerializer extends JsonSerializer<JsonIdentityKeyStore> {

        @Override
        public void serialize(JsonIdentityKeyStore jsonIdentityKeyStore, JsonGenerator json, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
            json.writeStartObject();
            json.writeNumberField("registrationId", jsonIdentityKeyStore.getLocalRegistrationId());
            json.writeStringField("identityKey", Base64.encodeBytes(jsonIdentityKeyStore.getIdentityKeyPair().serialize()));
            json.writeArrayFieldStart("trustedKeys");
            for (Map.Entry<String, List<Identity>> trustedKey : jsonIdentityKeyStore.trustedKeys.entrySet()) {
                for (Identity id : trustedKey.getValue()) {
                    json.writeStartObject();
                    json.writeStringField("name", trustedKey.getKey());
                    json.writeStringField("identityKey", Base64.encodeBytes(id.identityKey.serialize()));
                    json.writeNumberField("trustLevel", id.trustLevel.ordinal());
                    json.writeNumberField("addedTimestamp", id.added.getTime());
                    json.writeEndObject();
                }
            }
            json.writeEndArray();
            json.writeEndObject();
        }
    }

    public class Identity {
        IdentityKey identityKey;
        TrustLevel trustLevel;
        Date added;

        public Identity(IdentityKey identityKey, TrustLevel trustLevel) {
            this.identityKey = identityKey;
            this.trustLevel = trustLevel;
            this.added = new Date();
        }

        public Identity(IdentityKey identityKey, TrustLevel trustLevel, Date added) {
            this.identityKey = identityKey;
            this.trustLevel = trustLevel;
            this.added = added;
        }

        public boolean isTrusted() {
            return trustLevel == TrustLevel.TRUSTED_UNVERIFIED ||
                    trustLevel == TrustLevel.TRUSTED_VERIFIED;
        }

        public byte[] getFingerprint() {
            return identityKey.getPublicKey().serialize();
        }
    }
}