package com.jsoniter;

import com.jsoniter.any.Any;
import com.jsoniter.spi.JsonException;
import com.jsoniter.spi.Slice;

import java.io.IOException;
import java.math.BigInteger;

class IterImpl {

    private static BigInteger maxLong = BigInteger.valueOf(Long.MAX_VALUE);
    private static BigInteger minLong = BigInteger.valueOf(Long.MIN_VALUE);
    private static BigInteger maxInt = BigInteger.valueOf(Integer.MAX_VALUE);
    private static BigInteger minInt = BigInteger.valueOf(Integer.MIN_VALUE);

    public static final int readObjectFieldAsHash(JsonIterator iter) throws IOException {
        if (readByte(iter) != '"') {
            if (nextToken(iter) != '"') {
                throw iter.reportError("readObjectFieldAsHash", "expect \"");
            }
        }
        long hash = 0x811c9dc5;
        int i = iter.head;
        for (; i < iter.tail; i++) {
            byte c = iter.buf[i];
            if (c == '"') {
                break;
            }
            hash ^= c;
            hash *= 0x1000193;
        }
        iter.head = i + 1;
        if (readByte(iter) != ':') {
            if (nextToken(iter) != ':') {
                throw iter.reportError("readObjectFieldAsHash", "expect :");
            }
        }
        return (int) hash;
    }

    public static final Slice readObjectFieldAsSlice(JsonIterator iter) throws IOException {
        Slice field = readSlice(iter);
        if (nextToken(iter) != ':') {
            throw iter.reportError("readObjectFieldAsSlice", "expect : after object field");
        }
        return field;
    }

    final static void skipArray(JsonIterator iter) throws IOException {
        int level = 1;
        for (int i = iter.head; i < iter.tail; i++) {
            switch (iter.buf[i]) {
                case '"': // If inside string, skip it
                    iter.head = i + 1;
                    skipString(iter);
                    i = iter.head - 1; // it will be i++ soon
                    break;
                case '[': // If open symbol, increase level
                    level++;
                    break;
                case ']': // If close symbol, increase level
                    level--;

                    // If we have returned to the original level, we're done
                    if (level == 0) {
                        iter.head = i + 1;
                        return;
                    }
                    break;
            }
        }
        throw iter.reportError("skipArray", "incomplete array");
    }

    final static void skipObject(JsonIterator iter) throws IOException {
        int level = 1;
        for (int i = iter.head; i < iter.tail; i++) {
            switch (iter.buf[i]) {
                case '"': // If inside string, skip it
                    iter.head = i + 1;
                    skipString(iter);
                    i = iter.head - 1; // it will be i++ soon
                    break;
                case '{': // If open symbol, increase level
                    level++;
                    break;
                case '}': // If close symbol, increase level
                    level--;

                    // If we have returned to the original level, we're done
                    if (level == 0) {
                        iter.head = i + 1;
                        return;
                    }
                    break;
            }
        }
        throw iter.reportError("skipObject", "incomplete object");
    }

    final static void skipString(JsonIterator iter) throws IOException {
        int end = IterImplSkip.findStringEnd(iter);
        if (end == -1) {
            throw iter.reportError("skipString", "incomplete string");
        } else {
            iter.head = end;
        }
    }

    final static void skipUntilBreak(JsonIterator iter) throws IOException {
        // true, false, null, number
        for (int i = iter.head; i < iter.tail; i++) {
            byte c = iter.buf[i];
            if (IterImplSkip.breaks[c]) {
                iter.head = i;
                return;
            }
        }
        iter.head = iter.tail;
    }

    final static boolean skipNumber(JsonIterator iter) throws IOException {
        // true, false, null, number
        boolean dotFound = false;
        for (int i = iter.head; i < iter.tail; i++) {
            byte c = iter.buf[i];
            if (c == '.' || c == 'e' || c == 'E') {
                dotFound = true;
                continue;
            }
            if (IterImplSkip.breaks[c]) {
                iter.head = i;
                return dotFound;
            }
        }
        iter.head = iter.tail;
        return dotFound;
    }

    // read the bytes between " "
    public final static Slice readSlice(JsonIterator iter) throws IOException {
        if (IterImpl.nextToken(iter) != '"') {
            throw iter.reportError("readSlice", "expect \" for string");
        }
        int end = IterImplString.findSliceEnd(iter);
        if (end == -1) {
            throw iter.reportError("readSlice", "incomplete string");
        } else {
            // reuse current buffer
            iter.reusableSlice.reset(iter.buf, iter.head, end - 1);
            iter.head = end;
            return iter.reusableSlice;
        }
    }

    final static byte nextToken(final JsonIterator iter) throws IOException {
        int i = iter.head;
        for (; ; ) {
            byte c = iter.buf[i++];
            switch (c) {
                case ' ':
                case '\n':
                case '\r':
                case '\t':
                    continue;
                default:
                    iter.head = i;
                    return c;
            }
        }
    }

    final static byte readByte(JsonIterator iter) throws IOException {
        return iter.buf[iter.head++];
    }

    public static Any readAny(JsonIterator iter) throws IOException {
        int start = iter.head;
        byte c = nextToken(iter);
        switch (c) {
            case '"':
                skipString(iter);
                return Any.lazyString(iter.buf, start, iter.head);
            case 't':
                skipFixedBytes(iter, 3);
                return Any.wrap(true);
            case 'f':
                skipFixedBytes(iter, 4);
                return Any.wrap(false);
            case 'n':
                skipFixedBytes(iter, 3);
                return Any.wrap((Object) null);
            case '[':
                skipArray(iter);
                return Any.lazyArray(iter.buf, start, iter.head);
            case '{':
                skipObject(iter);
                return Any.lazyObject(iter.buf, start, iter.head);
            default:
                if (skipNumber(iter)) {
                    return Any.lazyDouble(iter.buf, start, iter.head);
                } else {
                    return Any.lazyLong(iter.buf, start, iter.head);
                }
        }
    }

    public static void skipFixedBytes(JsonIterator iter, int n) throws IOException {
        iter.head += n;
    }

    public final static boolean loadMore(JsonIterator iter) throws IOException {
        return false;
    }

    public final static int readStringSlowPath(JsonIterator iter, int j) throws IOException {
        try {
            boolean isExpectingLowSurrogate = false;
            for (int i = iter.head; i < iter.tail; ) {
                int bc = iter.buf[i++];
                if (bc == '"') {
                    iter.head = i;
                    return j;
                }
                if (bc == '\\') {
                    bc = iter.buf[i++];
                    switch (bc) {
                        case 'b':
                            bc = '\b';
                            break;
                        case 't':
                            bc = '\t';
                            break;
                        case 'n':
                            bc = '\n';
                            break;
                        case 'f':
                            bc = '\f';
                            break;
                        case 'r':
                            bc = '\r';
                            break;
                        case '"':
                        case '/':
                        case '\\':
                            break;
                        case 'u':
                            bc = (IterImplString.translateHex(iter.buf[i++])