package com.yono.messeripos.nfc.record;

import android.nfc.FormatException;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;

import com.google.common.base.Charsets;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.yono.messeripos.nfc.parser.NdefMessageParser;

import java.util.Arrays;
import java.util.NoSuchElementException;

public class SmartPoster implements ParsedNdefRecord {
    /**
     * NFC Forum Smart Poster Record Type Definition section 3.2.1.
     *
     * "The Title record for the service (there can be many of these in
     * different languages, but a language MUST NOT be repeated). This record is
     * optional."
     */
    private final TextRecord mTitleRecord;

    /**
     * NFC Forum Smart Poster Record Type Definition section 3.2.1.
     *
     * "The URI record. This is the core of the Smart Poster, and all other
     * records are just metadata about this record. There MUST be one URI record
     * and there MUST NOT be more than one."
     */
    private final UriRecord mUriRecord;

    /**
     * NFC Forum Smart Poster Record Type Definition section 3.2.1.
     *
     * "The Action record. This record describes how the service should be
     * treated. For example, the action may indicate that the device should save
     * the URI as a bookmark or open a browser. The Action record is optional.
     * If it does not exist, the device may decide what to do with the service.
     * If the action record exists, it should be treated as a strong suggestion;
     * the UI designer may ignore it, but doing so will induce a different user
     * experience from device to device."
     */
    private final RecommendedAction mAction;

    /**
     * NFC Forum Smart Poster Record Type Definition section 3.2.1.
     *
     * "The Type record. If the URI references an external entity (e.g., via a
     * URL), the Type record may be used to declare the MIME type of the entity.
     * This can be used to tell the mobile device what kind of an object it can
     * expect before it opens the connection. The Type record is optional."
     */
    private final String mType;

    public SmartPoster(UriRecord uri, TextRecord title, RecommendedAction action, String type) {
        mUriRecord = Preconditions.checkNotNull(uri);
        mTitleRecord = title;
        mAction = Preconditions.checkNotNull(action);
        mType = type;
    }

    public UriRecord getUriRecord() {
        return mUriRecord;
    }

    /**
     * Returns the title of the smart poster. This may be {@code null}.
     */
    public TextRecord getTitle() {
        return mTitleRecord;
    }

    public static SmartPoster parse(NdefRecord record) {
        Preconditions.checkArgument(record.getTnf() == NdefRecord.TNF_WELL_KNOWN);
        Preconditions.checkArgument(Arrays.equals(record.getType(), NdefRecord.RTD_SMART_POSTER));
        try {
            NdefMessage subRecords = new NdefMessage(record.getPayload());
            return parse(subRecords.getRecords());
        } catch (FormatException e) {
            throw new IllegalArgumentException(e);
        }
    }

    public static SmartPoster parse(NdefRecord[] recordsRaw) {
        try {
            Iterable<ParsedNdefRecord> records = NdefMessageParser.getRecords(recordsRaw);
            UriRecord uri = Iterables.getOnlyElement(Iterables.filter(records, UriRecord.class));
            TextRecord title = getFirstIfExists(records, TextRecord.class);
            RecommendedAction action = parseRecommendedAction(recordsRaw);
            String type = parseType(recordsRaw);
            return new SmartPoster(uri, title, action, type);
        } catch (NoSuchElementException e) {
            throw new IllegalArgumentException(e);
        }
    }

    public static boolean isPoster(NdefRecord record) {
        try {
            parse(record);
            return true;
        } catch (IllegalArgumentException e) {
            return false;
        }
    }
    @Override
    public String str() {
        if (mTitleRecord != null) {
            return mTitleRecord.str() + "\n" + mUriRecord.str();
        } else {
            return mUriRecord.str();
        }
    }

    /**
     * Returns the first element of {@code elements} which is an instance of
     * {@code type}, or {@code null} if no such element exists.
     */
    private static <T> T getFirstIfExists(Iterable<?> elements, Class<T> type) {
        Iterable<T> filtered = Iterables.filter(elements, type);
        T instance = null;
        if (!Iterables.isEmpty(filtered)) {
            instance = Iterables.get(filtered, 0);
        }
        return instance;
    }

    public enum RecommendedAction {
        UNKNOWN((byte) -1), DO_ACTION((byte) 0), SAVE_FOR_LATER((byte) 1), OPEN_FOR_EDITING(
                (byte) 2);

        private static final ImmutableMap<Byte, RecommendedAction> LOOKUP;
        static {
            ImmutableMap.Builder<Byte, RecommendedAction> builder = ImmutableMap.builder();
            for (RecommendedAction action : RecommendedAction.values()) {
                builder.put(action.getByte(), action);
            }
            LOOKUP = builder.build();
        }

        private final byte mAction;

        private RecommendedAction(byte val) {
            this.mAction = val;
        }

        private byte getByte() {
            return mAction;
        }
    }

    private static NdefRecord getByType(byte[] type, NdefRecord[] records) {
        for (NdefRecord record : records) {
            if (Arrays.equals(type, record.getType())) {
                return record;
            }
        }
        return null;
    }

    private static final byte[] ACTION_RECORD_TYPE = new byte[] {'a', 'c', 't'};

    private static RecommendedAction parseRecommendedAction(NdefRecord[] records) {
        NdefRecord record = getByType(ACTION_RECORD_TYPE, records);
        if (record == null) {
            return RecommendedAction.UNKNOWN;
        }
        byte action = record.getPayload()[0];
        if (RecommendedAction.LOOKUP.containsKey(action)) {
            return RecommendedAction.LOOKUP.get(action);
        }
        return RecommendedAction.UNKNOWN;
    }

    private static final byte[] TYPE_TYPE = new byte[] {'t'};

    private static String parseType(NdefRecord[] records) {
        NdefRecord type = getByType(TYPE_TYPE, records);
        if (type == null) {
            return null;
        }
        return new String(type.getPayload(), Charsets.UTF_8);
    }
}
