package com.android.hotspot2;

import com.android.anqp.Constants;

import java.nio.ByteBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collection;
import java.util.LinkedList;
import java.util.List;
import java.util.TimeZone;

import static com.android.anqp.Constants.BYTE_MASK;
import static com.android.anqp.Constants.NIBBLE_MASK;

public abstract class Utils {

    public static final long UNSET_TIME = -1;

    private static final int EUI48Length = 6;
    private static final int EUI64Length = 8;
    private static final long EUI48Mask = 0xffffffffffffL;
    private static final String[] PLMNText = {"org", "3gppnetwork", "mcc*", "mnc*", "wlan"};

    public static List<String> splitDomain(String domain) {

        if (domain.endsWith("."))
            domain = domain.substring(0, domain.length() - 1);
        int at = domain.indexOf('@');
        if (at >= 0)
            domain = domain.substring(at + 1);

        String[] labels = domain.toLowerCase().split("\\.");
        LinkedList<String> labelList = new LinkedList<String>();
        for (String label : labels) {
            labelList.addFirst(label);
        }

        return labelList;
    }

    public static long parseMac(String s) {

        long mac = 0;
        int count = 0;
        for (int n = 0; n < s.length(); n++) {
            int nibble = Utils.fromHex(s.charAt(n), true);  // Set lenient to not blow up on ':'
            if (nibble >= 0) {                              // ... and use only legit hex.
                mac = (mac << 4) | nibble;
                count++;
            }
        }
        if (count < 12 || (count & 1) == 1) {
            throw new IllegalArgumentException("Bad MAC address: '" + s + "'");
        }
        return mac;
    }

    public static String macToString(long mac) {
        int len = (mac & ~EUI48Mask) != 0 ? EUI64Length : EUI48Length;
        StringBuilder sb = new StringBuilder();
        boolean first = true;
        for (int n = (len - 1) * Byte.SIZE; n >= 0; n -= Byte.SIZE) {
            if (first) {
                first = false;
            } else {
                sb.append(':');
            }
            sb.append(String.format("%02x", (mac >>> n) & Constants.BYTE_MASK));
        }
        return sb.toString();
    }

    public static String getMccMnc(List<String> domain) {
        if (domain.size() != PLMNText.length) {
            return null;
        }

        for (int n = 0; n < PLMNText.length; n++) {
            String expect = PLMNText[n];
            int len = expect.endsWith("*") ? expect.length() - 1 : expect.length();
            if (!domain.get(n).regionMatches(0, expect, 0, len)) {
                return null;
            }
        }

        String prefix = domain.get(2).substring(3) + domain.get(3).substring(3);
        for (int n = 0; n < prefix.length(); n++) {
            char ch = prefix.charAt(n);
            if (ch < '0' || ch > '9') {
                return null;
            }
        }
        return prefix;
    }

    public static String toIpString(int leIp) {
        return String.format("%d.%d.%d.%d",
                leIp & BYTE_MASK,
                (leIp >> 8) & BYTE_MASK,
                (leIp >> 16) & BYTE_MASK,
                (leIp >> 24) & BYTE_MASK);
    }

    public static String bssidsToString(Collection<Long> bssids) {
        StringBuilder sb = new StringBuilder();
        for (Long bssid : bssids) {
            sb.append(String.format(" %012x", bssid));
        }
        return sb.toString();
    }

    public static String roamingConsortiumsToString(long[] ois) {
        if (ois == null) {
            return "null";
        }
        List<Long> list = new ArrayList<Long>(ois.length);
        for (long oi : ois) {
            list.add(oi);
        }
        return roamingConsortiumsToString(list);
    }

    public static String roamingConsortiumsToString(Collection<Long> ois) {
        StringBuilder sb = new StringBuilder();
        boolean first = true;
        for (long oi : ois) {
            if (first) {
                first = false;
            } else {
                sb.append(", ");
            }
            if (Long.numberOfLeadingZeros(oi) > 40) {
                sb.append(String.format("%06x", oi));
            } else {
                sb.append(String.format("%010x", oi));
            }
        }
        return sb.toString();
    }

    public static String toUnicodeEscapedString(String s) {
        StringBuilder sb = new StringBuilder(s.length());
        for (int n = 0; n < s.length(); n++) {
            char ch = s.charAt(n);
            if (ch >= ' ' && ch < 127) {
                sb.append(ch);
            } else {
                sb.append("\\u").append(String.format("%04x", (int) ch));
            }
        }
        return sb.toString();
    }

    public static String toHexString(byte[] data) {
        if (data == null) {
            return "null";
        }
        StringBuilder sb = new StringBuilder(data.length * 3);

        boolean first = true;
        for (byte b : data) {
            if (first) {
                first = false;
            } else {
                sb.append(' ');
            }
            sb.append(String.format("%02x", b & BYTE_MASK));
        }
        return sb.toString();
    }

    public static String toHex(byte[] octets) {
        StringBuilder sb = new StringBuilder(octets.length * 2);
        for (byte o : octets) {
            sb.append(String.format("%02x", o & BYTE_MASK));
        }
        return sb.toString();
    }

    public static byte[] hexToBytes(String text) {
        if ((text.length() & 1) == 1) {
            throw new NumberFormatException("Odd length hex string: " + text.length());
        }
        byte[] data = new byte[text.length() >> 1];
        int position = 0;
        for (int n = 0; n < text.length(); n += 2) {
            data[position] =
                    (byte) (((fromHex(text.charAt(n), false) & NIBBLE_MASK) << 4) |
                            (fromHex(text.charAt(n + 1), false) & NIBBLE_MASK));
            position++;
        }
        return data;
    }

    public static int fromHex(char ch, boolean lenient) throws NumberFormatException {
        if (ch <= '9' && ch >= '0') {
            return ch - '0';
        } else if (ch >= 'a' && ch <= 'f') {
            return ch + 10 - 'a';
        } else if (ch <= 'F' && ch >= 'A') {
            return ch + 10 - 'A';
        } else if (lenient) {
            return -1;
        } else {
            throw new NumberFormatException("Bad hex-character: " + ch);
        }
    }

    private static char toAscii(int b) {
        return b >= ' ' && b < 0x7f ? (char) b : '.';
    }

    static boolean isDecimal(String s) {
        for (int n = 0; n < s.length(); n++) {
            char ch = s.charAt(n);
            if (ch < '0' || ch > '9') {
                return false;
            }
        }
        return true;
    }

    public static <T extends Comparable> int compare(Comparable<T> c1, T c2) {
        if (c1 == null) {
            return c2 == null ? 0 : -1;
        } else if (c2 == null) {
            return 1;
        } else {
            return c1.compareTo(c2);
        }
    }

    public static String bytesToBingoCard(ByteBuffer data, int len) {
        ByteBuffer dup = data.duplicate();
        dup.limit(dup.position() + len);
        return bytesToBingoCard(dup);
    }

    public static String bytesToBingoCard(ByteBuffer data) {
        ByteBuffer dup = data.duplicate();
        StringBuilder sbx = new StringBuilder();
        while (dup.hasRemaining()) {
            sbx.append(String.format("%02x ", dup.get() & BYTE_MASK));
        }
        dup = data.duplicate();
        sbx.append(' ');
        while (dup.hasRemaining()) {
            sbx.append(String.format("%c", toAscii(dup.get() & BYTE_MASK)));
        }
        return sbx.toString();
    }

    public static String toHMS(long millis) {
        long time = millis >= 0 ? millis : -millis;
        long tmp = time / 1000L;
        long ms = time - tmp * 1000L;

        time = tmp;
        tmp /= 60L;
        long s = time - tmp * 60L;

        time = tmp;
        tmp /= 60L;
        long m = time - tmp * 60L;

        return String.format("%s%d:%02d:%02d.%03d", millis < 0 ? "-" : "", tmp, m, s, ms);
    }

    public static String toUTCString(long ms) {
        if (ms < 0) {
            return "unset";
        }
        Calendar c = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
        c.setTimeInMillis(ms);
        return String.format("%4d/%02d/%02d %2d:%02d:%02dZ",
                c.get(Calendar.YEAR),
                c.get(Calendar.MONTH) + 1,
                c.get(Calendar.DAY_OF_MONTH),
                c.get(Calendar.HOUR_OF_DAY),
                c.get(Calendar.MINUTE),
                c.get(Calendar.SECOND));
    }

    /**
     * Decode a wpa_supplicant SSID. wpa_supplicant uses double quotes around plain strings, or
     * expects a hex-string if no quotes appear.
     * For Ascii encoded string, any octet < 32 or > 127 is encoded as
     * a "\x" followed by the hex representation of the octet.
     * Exception chars are ", \, \e, \n, \r, \t which are escaped by a \
     * See src/utils/common.c for the implementation in the supplicant.
     *
     * @param ssid The SSID from the config.
     * @return The actual string content of the SSID
     */
    public static String decodeSsid(String ssid) {
        if (ssid.length() <= 1) {
            return ssid;
        } else if (ssid.startsWith("\"") && ssid.endsWith("\"")) {
            return unescapeSsid(ssid.substring(1, ssid.length() - 1));
        } else if ((ssid.length() & 1) == 1) {
            return ssid;
        }

        byte[] codepoints;
        try {
            codepoints = new byte[ssid.length() / 2];
            for (int n = 0; n < ssid.length(); n += 2) {
                codepoints[n / 2] = (byte) decodeHexPair(ssid, n);
            }
        } catch (NumberFormatException nfe) {
            return ssid;
        }

        try {
            CharsetDecoder decoder = StandardCharsets.UTF_8.newDecoder();
            return decoder.decode(ByteBuffer.wrap(codepoints)).toString();
        } catch (CharacterCodingException cce) {
            /* Do nothing, try LATIN-1 */
        }
        try {
            CharsetDecoder decoder = StandardCharsets.ISO_8859_1.newDecoder();
            return decoder.decode(ByteBuffer.wrap(codepoints)).toString();
        } catch (CharacterCodingException cce) {    // Should not be possible.
            return ssid;
        }
    }

    private static String unescapeSsid(String s) {
        StringBuilder sb = new StringBuilder();
        for (int n = 0; n < s.length(); n++) {
            char ch = s.charAt(n);
            if (ch != '\\' || n >= s.length() - 1) {
                sb.append(ch);
            } else {
                n++;
                ch = s.charAt(n);
                switch (ch) {
                    case '"':
                    case '\\':
                    default:
                        sb.append(ch);
                        break;
                    case 'e':
                        sb.append((char) 27);    // Escape char
                        break;
                    case 'n':
                        sb.append('\n');
                        break;
                    case 'r':
                        sb.append('\r');
                        break;
                    case 't':
                        sb.append('\t');
                        break;
                    case 'x':
                        if (s.length() - n < 3) {
                            sb.append('\\').append(ch);
                        } else {
                            n++;
                            sb.append((char) decodeHexPair(s, n));
                            n++;
                        }
                        break;
                }
            }
        }
        return sb.toString();
    }

    private static int decodeHexPair(String s, int position) {
        return fromHex(s.charAt(position)) << 4 | fromHex(s.charAt(position + 1));
    }

    private static int fromHex(char ch) {
        if (ch >= '0' && ch <= '9') {
            return ch - '0';
        } else if (ch >= 'A' && ch <= 'F') {
            return ch - 'A' + 10;
        } else if (ch >= 'a' && ch <= 'f') {
            return ch - 'a' + 10;
        } else {
            throw new NumberFormatException(String.format("Not hex: '%c'", ch));
        }
    }

    public static void delay(long ms) {
        long until = System.currentTimeMillis() + ms;
        for (; ; ) {
            long remainder = until - System.currentTimeMillis();
            if (remainder <= 0) {
                break;
            }
            try {
                Thread.sleep(remainder);
            } catch (InterruptedException ie) { /**/ }
        }
    }

    public static <T extends Enum<T>> T mapEnum(int ordinal, Class<T> enumClass) {
        T[] constants = enumClass.getEnumConstants();
        return ordinal >= 0 && ordinal < constants.length ? constants[ordinal]: null;
    }
}