package com.fasterxml.jackson.databind.deser.std;

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

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
import com.fasterxml.jackson.databind.cfg.CoercionAction;
import com.fasterxml.jackson.databind.cfg.CoercionInputShape;
import com.fasterxml.jackson.databind.deser.*;
import com.fasterxml.jackson.databind.deser.impl.ReadableObjectId.Referring;
import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
import com.fasterxml.jackson.databind.type.LogicalType;
import com.fasterxml.jackson.databind.util.ClassUtil;

Basic serializer that can take JSON "Array" structure and construct a Collection instance, with typed contents. 
 Note: for untyped content (one indicated by passing Object.class as the type), UntypedObjectDeserializer is used instead. It can also construct Lists, but not with specific POJO types, only other containers and primitives/wrappers. /**
 * Basic serializer that can take JSON "Array" structure and
 * construct a {@link java.util.Collection} instance, with typed contents.
 *<p>
 * Note: for untyped content (one indicated by passing Object.class
 * as the type), {@link UntypedObjectDeserializer} is used instead.
 * It can also construct {@link java.util.List}s, but not with specific
 * POJO types, only other containers and primitives/wrappers.
 */
@JacksonStdImpl
public class CollectionDeserializer
    extends ContainerDeserializerBase<Collection<Object>>
    implements ContextualDeserializer
{
    private static final long serialVersionUID = -1L; // since 2.5

    // // Configuration

    
Value deserializer.
/**
     * Value deserializer.
     */
    protected final JsonDeserializer<Object> _valueDeserializer;

    
If element instances have polymorphic type information, this
is the type deserializer that can handle it
/**
     * If element instances have polymorphic type information, this
     * is the type deserializer that can handle it
     */
    protected final TypeDeserializer _valueTypeDeserializer;

    // // Instance construction settings:

    protected final ValueInstantiator _valueInstantiator;

    
Deserializer that is used iff delegate-based creator is
to be used for deserializing from JSON Object.
/**
     * Deserializer that is used iff delegate-based creator is
     * to be used for deserializing from JSON Object.
     */
    protected final JsonDeserializer<Object> _delegateDeserializer;

    // NOTE: no PropertyBasedCreator, as JSON Arrays have no properties

    /*
    /**********************************************************
    /* Life-cycle
    /**********************************************************
     */

    
Constructor for context-free instances, where we do not yet know
which property is using this deserializer.
/**
     * Constructor for context-free instances, where we do not yet know
     * which property is using this deserializer.
     */
    public CollectionDeserializer(JavaType collectionType,
            JsonDeserializer<Object> valueDeser,
            TypeDeserializer valueTypeDeser, ValueInstantiator valueInstantiator)
    {
        this(collectionType, valueDeser, valueTypeDeser, valueInstantiator, null, null, null);
    }

    
Constructor used when creating contextualized instances.
Since:
2.9/**
     * Constructor used when creating contextualized instances.
     *
     * @since 2.9
     */
    protected CollectionDeserializer(JavaType collectionType,
            JsonDeserializer<Object> valueDeser, TypeDeserializer valueTypeDeser,
            ValueInstantiator valueInstantiator, JsonDeserializer<Object> delegateDeser,
            NullValueProvider nuller, Boolean unwrapSingle)
    {
        super(collectionType, nuller, unwrapSingle);
        _valueDeserializer = valueDeser;
        _valueTypeDeserializer = valueTypeDeser;
        _valueInstantiator = valueInstantiator;
        _delegateDeserializer = delegateDeser;
    }

    
Copy-constructor that can be used by sub-classes to allow
copy-on-write styling copying of settings of an existing instance.
/**
     * Copy-constructor that can be used by sub-classes to allow
     * copy-on-write styling copying of settings of an existing instance.
     */
    protected CollectionDeserializer(CollectionDeserializer src)
    {
        super(src);
        _valueDeserializer = src._valueDeserializer;
        _valueTypeDeserializer = src._valueTypeDeserializer;
        _valueInstantiator = src._valueInstantiator;
        _delegateDeserializer = src._delegateDeserializer;
    }

    
Fluent-factory method call to construct contextual instance.
Since:
2.9/**
     * Fluent-factory method call to construct contextual instance.
     *
     * @since 2.9
     */
    @SuppressWarnings("unchecked")
    protected CollectionDeserializer withResolved(JsonDeserializer<?> dd,
            JsonDeserializer<?> vd, TypeDeserializer vtd,
            NullValueProvider nuller, Boolean unwrapSingle)
    {
        return new CollectionDeserializer(_containerType,
                (JsonDeserializer<Object>) vd, vtd,
                _valueInstantiator, (JsonDeserializer<Object>) dd,
                nuller, unwrapSingle);
    }

    // Important: do NOT cache if polymorphic values
    @Override // since 2.5
    public boolean isCachable() {
        // 26-Mar-2015, tatu: As per [databind#735], need to be careful
        return (_valueDeserializer == null)
                && (_valueTypeDeserializer == null)
                && (_delegateDeserializer == null)
                ;
    }

    @Override // since 2.12
    public LogicalType logicalType() {
        return LogicalType.Collection;
    }

    /*
    /**********************************************************
    /* Validation, post-processing (ResolvableDeserializer)
    /**********************************************************
     */

    
Method called to finalize setup of this deserializer,
when it is known for which property deserializer is needed
for.
/**
     * Method called to finalize setup of this deserializer,
     * when it is known for which property deserializer is needed
     * for.
     */
    @Override
    public CollectionDeserializer createContextual(DeserializationContext ctxt,
            BeanProperty property) throws JsonMappingException
    {
        // May need to resolve types for delegate-based creators:
        JsonDeserializer<Object> delegateDeser = null;
        if (_valueInstantiator != null) {
            if (_valueInstantiator.canCreateUsingDelegate()) {
                JavaType delegateType = _valueInstantiator.getDelegateType(ctxt.getConfig());
                if (delegateType == null) {
                    ctxt.reportBadDefinition(_containerType, String.format(
"Invalid delegate-creator definition for %s: value instantiator (%s) returned true for 'canCreateUsingDelegate()', but null for 'getDelegateType()'",
_containerType,
                            _valueInstantiator.getClass().getName()));
                }
                delegateDeser = findDeserializer(ctxt, delegateType, property);
            } else if (_valueInstantiator.canCreateUsingArrayDelegate()) {
                JavaType delegateType = _valueInstantiator.getArrayDelegateType(ctxt.getConfig());
                if (delegateType == null) {
                    ctxt.reportBadDefinition(_containerType, String.format(
"Invalid delegate-creator definition for %s: value instantiator (%s) returned true for 'canCreateUsingArrayDelegate()', but null for 'getArrayDelegateType()'",
                            _containerType,
                            _valueInstantiator.getClass().getName()));
                }
                delegateDeser = findDeserializer(ctxt, delegateType, property);
            }
        }
        // [databind#1043]: allow per-property allow-wrapping of single overrides:
        // 11-Dec-2015, tatu: Should we pass basic `Collection.class`, or more refined? Mostly
        //   comes down to "List vs Collection" I suppose... for now, pass Collection
        Boolean unwrapSingle = findFormatFeature(ctxt, property, Collection.class,
                JsonFormat.Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY);
        // also, often value deserializer is resolved here:
        JsonDeserializer<?> valueDeser = _valueDeserializer;
        
        // May have a content converter
        valueDeser = findConvertingContentDeserializer(ctxt, property, valueDeser);
        final JavaType vt = _containerType.getContentType();
        if (valueDeser == null) {
            valueDeser = ctxt.findContextualValueDeserializer(vt, property);
        } else { // if directly assigned, probably not yet contextual, so:
            valueDeser = ctxt.handleSecondaryContextualization(valueDeser, property, vt);
        }
        // and finally, type deserializer needs context as well
        TypeDeserializer valueTypeDeser = _valueTypeDeserializer;
        if (valueTypeDeser != null) {
            valueTypeDeser = valueTypeDeser.forProperty(property);
        }
        NullValueProvider nuller = findContentNullProvider(ctxt, property, valueDeser);
        if ((!Objects.equals(unwrapSingle, _unwrapSingle))
                || (nuller != _nullProvider)
                || (delegateDeser != _delegateDeserializer)
                || (valueDeser != _valueDeserializer)
                || (valueTypeDeser != _valueTypeDeserializer)
        ) {
            return withResolved(delegateDeser, valueDeser, valueTypeDeser,
                    nuller, unwrapSingle);
        }
        return this;
    }

    /*
    /**********************************************************
    /* ContainerDeserializerBase API
    /**********************************************************
     */

    @Override
    public JsonDeserializer<Object> getContentDeserializer() {
        return _valueDeserializer;
    }

    @Override
    public ValueInstantiator getValueInstantiator() {
        return _valueInstantiator;
    }

    /*
    /**********************************************************
    /* JsonDeserializer API
    /**********************************************************
     */

    @SuppressWarnings("unchecked")
    @Override
    public Collection<Object> deserialize(JsonParser p, DeserializationContext ctxt)
        throws IOException
    {
        if (_delegateDeserializer != null) {
            return (Collection<Object>) _valueInstantiator.createUsingDelegate(ctxt,
                    _delegateDeserializer.deserialize(p, ctxt));
        }
        // 16-May-2020, tatu: As per [dataformats-text#199] need to first check for
        //   possible Array-coercion and only after that String coercion
        if (p.isExpectedStartArrayToken()) {
            return _deserializeFromArray(p, ctxt, createDefaultInstance(ctxt));
        }
        // Empty String may be ok; bit tricky to check, however, since
        // there is also possibility of "auto-wrapping" of single-element arrays.
        // Hence we only accept empty String here.
        if (p.hasToken(JsonToken.VALUE_STRING)) {
            return _deserializeFromString(p, ctxt, p.getText());
        }
        return handleNonArray(p, ctxt, createDefaultInstance(ctxt));
    }

    
Since:
2.9/**
     * @since 2.9
     */
    @SuppressWarnings("unchecked")
    protected Collection<Object> createDefaultInstance(DeserializationContext ctxt)
        throws IOException
    {
        return (Collection<Object>) _valueInstantiator.createUsingDefault(ctxt);
    }

    @Override
    public Collection<Object> deserialize(JsonParser p, DeserializationContext ctxt,
            Collection<Object> result)
        throws IOException
    {
        // Ok: must point to START_ARRAY (or equivalent)
        if (p.isExpectedStartArrayToken()) {
            return _deserializeFromArray(p, ctxt, result);
        }
        return handleNonArray(p, ctxt, result);
    }

    @Override
    public Object deserializeWithType(JsonParser p, DeserializationContext ctxt,
            TypeDeserializer typeDeserializer)
        throws IOException
    {
        // In future could check current token... for now this should be enough:
        return typeDeserializer.deserializeTypedFromArray(p, ctxt);
    }

    
Logic extracted to deal with incoming String value.
Since:
2.12/**
     * Logic extracted to deal with incoming String value.
     *
     * @since 2.12
     */
    @SuppressWarnings("unchecked")
    protected Collection<Object> _deserializeFromString(JsonParser p, DeserializationContext ctxt,
            String value)
        throws IOException
    {
        final Class<?> rawTargetType = handledType();

        // 05-Nov-2020, ckozak: As per [jackson-databind#2922] string values may be handled
        // using handleNonArray, however empty strings may result in a null or empty collection
        // depending on configuration.

        // Start by verifying if we got empty/blank string since accessing
        // CoercionAction may be costlier than String value we'll almost certainly
        // need anyway
        if (value.isEmpty()) { // ... in future may want to allow blank, too?
            CoercionAction act = ctxt.findCoercionAction(logicalType(), rawTargetType,
                    CoercionInputShape.EmptyString);
            act = _checkCoercionFail(ctxt, act, rawTargetType, value,
                    "empty String (\"\")");
            if (act != null) {
                    // handleNonArray may successfully deserialize the result (if
                    // ACCEPT_SINGLE_VALUE_AS_ARRAY is enabled, for example) otherwise it
                    // is capable of failing just as well as _deserializeFromEmptyString.
                return (Collection<Object>) _deserializeFromEmptyString(
                        p, ctxt, act, rawTargetType, "empty String (\"\")");
            }
        }
        return handleNonArray(p, ctxt, createDefaultInstance(ctxt));
    }

    
Since:
2.12/**
     * @since 2.12
     */
    protected Collection<Object> _deserializeFromArray(JsonParser p, DeserializationContext ctxt,
            Collection<Object> result)
        throws IOException
    {
        // [databind#631]: Assign current value, to be accessible by custom serializers
        p.setCurrentValue(result);

        JsonDeserializer<Object> valueDes = _valueDeserializer;
        // Let's offline handling of values with Object Ids (simplifies code here)
        if (valueDes.getObjectIdReader() != null) {
            return _deserializeWithObjectId(p, ctxt, result);
        }
        final TypeDeserializer typeDeser = _valueTypeDeserializer;
        JsonToken t;
        while ((t = p.nextToken()) != JsonToken.END_ARRAY) {
            try {
                Object value;
                if (t == JsonToken.VALUE_NULL) {
                    if (_skipNullValues) {
                        continue;
                    }
                    value = _nullProvider.getNullValue(ctxt);
                } else if (typeDeser == null) {
                    value = valueDes.deserialize(p, ctxt);
                } else {
                    value = valueDes.deserializeWithType(p, ctxt, typeDeser);
                }
                result.add(value);

                /* 17-Dec-2017, tatu: should not occur at this level...
            } catch (UnresolvedForwardReference reference) {
                throw JsonMappingException
                    .from(p, "Unresolved forward reference but no identity info", reference);
                */
            } catch (Exception e) {
                boolean wrap = (ctxt == null) || ctxt.isEnabled(DeserializationFeature.WRAP_EXCEPTIONS);
                if (!wrap) {
                    ClassUtil.throwIfRTE(e);
                }
                throw JsonMappingException.wrapWithPath(e, result, result.size());
            }
        }
        return result;
    }

    
Helper method called when current token is no START_ARRAY. Will either
throw an exception, or try to handle value as if member of implicit
array, depending on configuration.
/**
     * Helper method called when current token is no START_ARRAY. Will either
     * throw an exception, or try to handle value as if member of implicit
     * array, depending on configuration.
     */
    @SuppressWarnings("unchecked")
    protected final Collection<Object> handleNonArray(JsonParser p, DeserializationContext ctxt,
            Collection<Object> result)
        throws IOException
    {
        // Implicit arrays from single values?
        boolean canWrap = (_unwrapSingle == Boolean.TRUE) ||
                ((_unwrapSingle == null) &&
                        ctxt.isEnabled(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY));
        if (!canWrap) {
            return (Collection<Object>) ctxt.handleUnexpectedToken(_containerType, p);
        }
        JsonDeserializer<Object> valueDes = _valueDeserializer;
        final TypeDeserializer typeDeser = _valueTypeDeserializer;

        Object value;

        try {
            if (p.hasToken(JsonToken.VALUE_NULL)) {
                // 03-Feb-2017, tatu: Hmmh. I wonder... let's try skipping here, too
                if (_skipNullValues) {
                    return result;
                }
                value = _nullProvider.getNullValue(ctxt);
            } else if (typeDeser == null) {
                value = valueDes.deserialize(p, ctxt);
            } else {
                value = valueDes.deserializeWithType(p, ctxt, typeDeser);
            }
        } catch (Exception e) {
            boolean wrap = (ctxt == null) || ctxt.isEnabled(DeserializationFeature.WRAP_EXCEPTIONS);
            if (!wrap) {
                ClassUtil.throwIfRTE(e);
            }
            // note: pass Object.class, not Object[].class, as we need element type for error info
            throw JsonMappingException.wrapWithPath(e, Object.class, result.size());
        }
        result.add(value);
        return result;
    }

    protected Collection<Object> _deserializeWithObjectId(JsonParser p, DeserializationContext ctxt,
            Collection<Object> result)
        throws IOException
    {
        // Ok: must point to START_ARRAY (or equivalent)
        if (!p.isExpectedStartArrayToken()) {
            return handleNonArray(p, ctxt, result);
        }
        // [databind#631]: Assign current value, to be accessible by custom serializers
        p.setCurrentValue(result);

        final JsonDeserializer<Object> valueDes = _valueDeserializer;
        final TypeDeserializer typeDeser = _valueTypeDeserializer;
        CollectionReferringAccumulator referringAccumulator =
                new CollectionReferringAccumulator(_containerType.getContentType().getRawClass(), result);

        JsonToken t;
        while ((t = p.nextToken()) != JsonToken.END_ARRAY) {
            try {
                Object value;
                if (t == JsonToken.VALUE_NULL) {
                    if (_skipNullValues) {
                        continue;
                    }
                    value = _nullProvider.getNullValue(ctxt);
                } else if (typeDeser == null) {
                    value = valueDes.deserialize(p, ctxt);
                } else {
                    value = valueDes.deserializeWithType(p, ctxt, typeDeser);
                }
                referringAccumulator.add(value);
            } catch (UnresolvedForwardReference reference) {
                Referring ref = referringAccumulator.handleUnresolvedReference(reference);
                reference.getRoid().appendReferring(ref);
            } catch (Exception e) {
                boolean wrap = (ctxt == null) || ctxt.isEnabled(DeserializationFeature.WRAP_EXCEPTIONS);
                if (!wrap) {
                    ClassUtil.throwIfRTE(e);
                }
                throw JsonMappingException.wrapWithPath(e, result, result.size());
            }
        }
        return result;
    }

    
Helper class for dealing with Object Id references for values contained in
collections being deserialized.
/**
     * Helper class for dealing with Object Id references for values contained in
     * collections being deserialized.
     */
    public static class CollectionReferringAccumulator {
        private final Class<?> _elementType;
        private final Collection<Object> _result;

        
A list of CollectionReferring to maintain ordering. /**
         * A list of {@link CollectionReferring} to maintain ordering.
         */
        private List<CollectionReferring> _accumulator = new ArrayList<CollectionReferring>();

        public CollectionReferringAccumulator(Class<?> elementType, Collection<Object> result) {
            _elementType = elementType;
            _result = result;
        }

        public void add(Object value)
        {
            if (_accumulator.isEmpty()) {
                _result.add(value);
            } else {
                CollectionReferring ref = _accumulator.get(_accumulator.size() - 1);
                ref.next.add(value);
            }
        }

        public Referring handleUnresolvedReference(UnresolvedForwardReference reference)
        {
            CollectionReferring id = new CollectionReferring(this, reference, _elementType);
            _accumulator.add(id);
            return id;
        }

        public void resolveForwardReference(Object id, Object value) throws IOException
        {
            Iterator<CollectionReferring> iterator = _accumulator.iterator();
            // Resolve ordering after resolution of an id. This mean either:
            // 1- adding to the result collection in case of the first unresolved id.
            // 2- merge the content of the resolved id with its previous unresolved id.
            Collection<Object> previous = _result;
            while (iterator.hasNext()) {
                CollectionReferring ref = iterator.next();
                if (ref.hasId(id)) {
                    iterator.remove();
                    previous.add(value);
                    previous.addAll(ref.next);
                    return;
                }
                previous = ref.next;
            }

            throw new IllegalArgumentException("Trying to resolve a forward reference with id [" + id
                    + "] that wasn't previously seen as unresolved.");
        }
    }

    
Helper class to maintain processing order of value. The resolved object associated with _id comes before the values in next. /**
     * Helper class to maintain processing order of value. The resolved
     * object associated with {@link #_id} comes before the values in
     * {@link #next}.
     */
    private final static class CollectionReferring extends Referring {
        private final CollectionReferringAccumulator _parent;
        public final List<Object> next = new ArrayList<Object>();
        
        CollectionReferring(CollectionReferringAccumulator parent,
                UnresolvedForwardReference reference, Class<?> contentType)
        {
            super(reference, contentType);
            _parent = parent;
        }
        
        @Override
        public void handleResolvedForwardReference(Object id, Object value) throws IOException {
            _parent.resolveForwardReference(id, value);
        }
    }
}