/*
 * Copyright (c) 2015 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.yangtools.yang.parser.stmt.rfc6020;

import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.base.Splitter;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.opendaylight.yangtools.yang.common.QName;
import org.opendaylight.yangtools.yang.model.api.SchemaPath;
import org.opendaylight.yangtools.yang.model.api.type.LengthConstraint;
import org.opendaylight.yangtools.yang.model.api.type.RangeConstraint;
import org.opendaylight.yangtools.yang.model.util.UnresolvedNumber;
import org.opendaylight.yangtools.yang.parser.spi.meta.InferenceException;
import org.opendaylight.yangtools.yang.parser.spi.meta.QNameCacheNamespace;
import org.opendaylight.yangtools.yang.parser.spi.meta.StmtContext;
import org.opendaylight.yangtools.yang.parser.spi.source.SourceException;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.effective.type.LengthConstraintEffectiveImpl;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.effective.type.RangeConstraintEffectiveImpl;

/**
* util class for manipulating YANG base and extended types implementation
*/
public final class TypeUtils {

    public static final String BINARY = "binary";
    public static final String BITS = "bits";
    public static final String BOOLEAN = "boolean";
    public static final String DECIMAL64 = "decimal64";
    public static final String EMPTY = "empty";
    public static final String ENUMERATION = "enumeration";
    public static final String IDENTITY_REF = "identityref";
    public static final String INSTANCE_IDENTIFIER = "instance-identifier";
    public static final String INT8 = "int8";
    public static final String INT16 = "int16";
    public static final String INT32 = "int32";
    public static final String INT64 = "int64";
    public static final String LEAF_REF = "leafref";
    public static final String STRING = "string";
    public static final String UINT8 = "uint8";
    public static final String UINT16 = "uint16";
    public static final String UINT32 = "uint32";
    public static final String UINT64 = "uint64";
    public static final String UNION = "union";

    private static final Set<String> BUILT_IN_TYPES =
            ImmutableSet.of(BINARY, BITS, BOOLEAN, DECIMAL64, EMPTY, ENUMERATION, IDENTITY_REF, INSTANCE_IDENTIFIER,
                    INT8, INT16, INT32, INT64, LEAF_REF, STRING, UINT8, UINT16, UINT32, UINT64, UNION);

    private static final Set<String> TYPE_BODY_STMTS = ImmutableSet.of(
        DECIMAL64, ENUMERATION, LEAF_REF, IDENTITY_REF, BITS, UNION);
    private static final Splitter PIPE_SPLITTER = Splitter.on('|').trimResults();
    private static final Splitter TWO_DOTS_SPLITTER = Splitter.on("..").trimResults();

    private TypeUtils() {
    }

    private static BigDecimal yangConstraintToBigDecimal(final Number number) {
        if (UnresolvedNumber.max().equals(number)) {
            return RangeStatementImpl.YANG_MAX_NUM;
        }
        if (UnresolvedNumber.min().equals(number)) {
            return RangeStatementImpl.YANG_MIN_NUM;
        }

        return new BigDecimal(number.toString());
    }

    private static int compareNumbers(final Number n1, final Number n2) {

        final BigDecimal num1 = yangConstraintToBigDecimal(n1);
        final BigDecimal num2 = yangConstraintToBigDecimal(n2);

        return new BigDecimal(num1.toString()).compareTo(new BigDecimal(num2.toString()));
    }

    private static Number parseIntegerConstraintValue(final StmtContext<?, ?, ?> ctx, final String value) {
        if ("max".equals(value)) {
            return UnresolvedNumber.max();
        }
        if ("min".equals(value)) {
            return UnresolvedNumber.min();
        }

        try {
            return new BigInteger(value);
        } catch (NumberFormatException e) {
            throw new SourceException(String.format("Value %s is not a valid integer", value),
                    ctx.getStatementSourceReference(), e);
        }
    }

    private static Number parseDecimalConstraintValue(final StmtContext<?, ?, ?> ctx, final String value) {
        if ("max".equals(value)) {
            return UnresolvedNumber.max();
        }
        if ("min".equals(value)) {
            return UnresolvedNumber.min();
        }

        try {
            return value.indexOf('.') != -1 ? new BigDecimal(value) : new BigInteger(value);
        } catch (NumberFormatException e) {
            throw new SourceException(String.format("Value %s is not a valid decimal number", value),
                    ctx.getStatementSourceReference(), e);
        }
    }

    public static List<RangeConstraint> parseRangeListFromString(final StmtContext<?, ?, ?> ctx,
                                                                 final String rangeArgument) {

        Optional<String> description = Optional.absent();
        Optional<String> reference = Optional.absent();

        List<RangeConstraint> rangeConstraints = new ArrayList<>();

        for (final String singleRange : PIPE_SPLITTER.split(rangeArgument)) {
            final Iterator<String> boundaries = TWO_DOTS_SPLITTER.splitToList(singleRange).iterator();
            final Number min = parseDecimalConstraintValue(ctx, boundaries.next());

            final Number max;
            if (boundaries.hasNext()) {
                max = parseDecimalConstraintValue(ctx, boundaries.next());

                // if min larger than max then error
                InferenceException.throwIf(compareNumbers(min, max) == 1, ctx.getStatementSourceReference(),
                        "Range constraint %s has descending order of boundaries; should be ascending", singleRange);

                SourceException.throwIf(boundaries.hasNext(), ctx.getStatementSourceReference(),
                    "Wrong number of boundaries in range constraint %s", singleRange);
            } else {
                max = min;
            }

            // some of intervals overlapping
            if (rangeConstraints.size() > 1 && compareNumbers(min, Iterables.getLast(rangeConstraints).getMax()) != 1) {
                throw new InferenceException(ctx.getStatementSourceReference(),
                    "Some of the ranges in %s are not disjoint", rangeArgument);
            }

            rangeConstraints.add(new RangeConstraintEffectiveImpl(min, max, description, reference));
        }

        return rangeConstraints;
    }

    public static List<LengthConstraint> parseLengthListFromString(final StmtContext<?, ?, ?> ctx,
            final String lengthArgument) {
        Optional<String> description = Optional.absent();
        Optional<String> reference = Optional.absent();

        List<LengthConstraint> lengthConstraints = new ArrayList<>();

        for (final String singleRange : PIPE_SPLITTER.split(lengthArgument)) {
            final Iterator<String> boundaries = TWO_DOTS_SPLITTER.splitToList(singleRange).iterator();
            final Number min = parseIntegerConstraintValue(ctx, boundaries.next());

            final Number max;
            if (boundaries.hasNext()) {
                max = parseIntegerConstraintValue(ctx, boundaries.next());

                // if min larger than max then error
                Preconditions.checkArgument(compareNumbers(min, max) != 1,
                        "Length constraint %s has descending order of boundaries; should be ascending. Statement source at %s",
                        singleRange, ctx.getStatementSourceReference());
                Preconditions.checkArgument(!boundaries.hasNext(),
                        "Wrong number of boundaries in length constraint %s. Statement source at %s", singleRange,
                        ctx.getStatementSourceReference());
            } else {
                max = min;
            }

            // some of intervals overlapping
            if (lengthConstraints.size() > 1 && compareNumbers(min, Iterables.getLast(lengthConstraints).getMax()) != 1) {
                throw new InferenceException(ctx.getStatementSourceReference(),
                    "Some of the length ranges in %s are not disjoint", lengthArgument);
            }

            lengthConstraints.add(new LengthConstraintEffectiveImpl(min, max, description, reference));
        }

        return lengthConstraints;
    }

    public static boolean isYangTypeBodyStmtString(final String typeName) {
        return TYPE_BODY_STMTS.contains(typeName);
    }

    public static boolean isYangBuiltInTypeString(final String typeName) {
        return BUILT_IN_TYPES.contains(typeName);
    }


    public static SchemaPath typeEffectiveSchemaPath(final StmtContext<?, ?, ?> stmtCtx) {
        final SchemaPath path = stmtCtx.getSchemaPath().get();
        final QName qname = stmtCtx.getFromNamespace(QNameCacheNamespace.class,
            QName.create(path.getParent().getLastComponent(), path.getLastComponent().getLocalName()));
        return path.getParent().createChild(qname);
    }
}