/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "ValidatingCodec.hh"

#include <algorithm>
#include <map>
#include <memory>
#include <utility>

#include "Decoder.hh"
#include "Encoder.hh"
#include "NodeImpl.hh"
#include "ValidSchema.hh"

namespace avro {

using std::make_shared;

namespace parsing {

using std::shared_ptr;
using std::static_pointer_cast;

using std::map;
using std::ostringstream;
using std::pair;
using std::reverse;
using std::string;
using std::vector;

/** Follows the design of Avro Parser in Java. */
ProductionPtr ValidatingGrammarGenerator::generate(const NodePtr &n) {
    map<NodePtr, ProductionPtr> m;
    ProductionPtr result = doGenerate(n, m);
    fixup(result, m);
    return result;
}

Symbol ValidatingGrammarGenerator::generate(const ValidSchema &schema) {
    ProductionPtr r = generate(schema.root());
    return Symbol::rootSymbol(r);
}

ProductionPtr ValidatingGrammarGenerator::doGenerate(const NodePtr &n,
                                                     map<NodePtr, ProductionPtr> &m) {
    switch (n->type()) {
        case AVRO_NULL:
            return make_shared<Production>(1, Symbol::nullSymbol());
        case AVRO_BOOL:
            return make_shared<Production>(1, Symbol::boolSymbol());
        case AVRO_INT:
            return make_shared<Production>(1, Symbol::intSymbol());
        case AVRO_LONG:
            return make_shared<Production>(1, Symbol::longSymbol());
        case AVRO_FLOAT:
            return make_shared<Production>(1, Symbol::floatSymbol());
        case AVRO_DOUBLE:
            return make_shared<Production>(1, Symbol::doubleSymbol());
        case AVRO_STRING:
            return make_shared<Production>(1, Symbol::stringSymbol());
        case AVRO_BYTES:
            return make_shared<Production>(1, Symbol::bytesSymbol());
        case AVRO_FIXED: {
            ProductionPtr result = make_shared<Production>();
            result->push_back(Symbol::sizeCheckSymbol(n->fixedSize()));
            result->push_back(Symbol::fixedSymbol());
            m[n] = result;
            return result;
        }
        case AVRO_RECORD: {
            ProductionPtr result = make_shared<Production>();

            m.erase(n);
            size_t c = n->leaves();
            for (size_t i = 0; i < c; ++i) {
                const NodePtr &leaf = n->leafAt(i);
                ProductionPtr v = doGenerate(leaf, m);
                copy(v->rbegin(), v->rend(), back_inserter(*result));
            }
            reverse(result->begin(), result->end());

            m[n] = result;
            return make_shared<Production>(1, Symbol::indirect(result));
        }
        case AVRO_ENUM: {
            ProductionPtr result = make_shared<Production>();
            result->push_back(Symbol::sizeCheckSymbol(n->names()));
            result->push_back(Symbol::enumSymbol());
            m[n] = result;
            return result;
        }
        case AVRO_ARRAY: {
            ProductionPtr result = make_shared<Production>();
            result->push_back(Symbol::arrayEndSymbol());
            result->push_back(Symbol::repeater(doGenerate(n->leafAt(0), m), true));
            result->push_back(Symbol::arrayStartSymbol());
            return result;
        }
        case AVRO_MAP: {
            ProductionPtr pp = doGenerate(n->leafAt(1), m);
            ProductionPtr v(new Production(*pp));
            v->push_back(Symbol::stringSymbol());
            ProductionPtr result = make_shared<Production>();
            result->push_back(Symbol::mapEndSymbol());
            result->push_back(Symbol::repeater(v, false));
            result->push_back(Symbol::mapStartSymbol());
            return result;
        }
        case AVRO_UNION: {
            vector<ProductionPtr> vv;
            size_t c = n->leaves();
            vv.reserve(c);
            for (size_t i = 0; i < c; ++i) {
                vv.push_back(doGenerate(n->leafAt(i), m));
            }
            ProductionPtr result = make_shared<Production>();
            result->push_back(Symbol::alternative(vv));
            result->push_back(Symbol::unionSymbol());
            return result;
        }
        case AVRO_SYMBOLIC: {
            shared_ptr<NodeSymbolic> ns = static_pointer_cast<NodeSymbolic>(n);
            NodePtr nn = ns->getNode();
            auto it = m.find(nn);
            if (it != m.end() && it->second) {
                return it->second;
            } else {
                m[nn] = ProductionPtr();
                return make_shared<Production>(1, Symbol::placeholder(nn));
            }
        }
        default:
            throw Exception("Unknown node type");
    }
}

struct DummyHandler {
    static size_t handle(const Symbol &) {
        return 0;
    }
};

template<typename P>
class ValidatingDecoder : public Decoder {
    const shared_ptr<Decoder> base;
    DummyHandler handler_;
    P parser;

    void init(InputStream &is) final;
    void decodeNull() final;
    bool decodeBool() final;
    int32_t decodeInt() final;
    int64_t decodeLong() final;
    float decodeFloat() final;
    double decodeDouble() final;
    void decodeString(string &value) final;
    void skipString() final;
    void decodeBytes(vector<uint8_t> &value) final;
    void skipBytes() final;
    void decodeFixed(size_t n, vector<uint8_t> &value) final;
    void skipFixed(size_t n) final;
    size_t decodeEnum() final;
    size_t arrayStart() final;
    size_t arrayNext() final;
    size_t skipArray() final;
    size_t mapStart() final;
    size_t mapNext() final;
    size_t skipMap() final;
    size_t decodeUnionIndex() final;
    void drain() final {
        base->drain();
    }

public:
    ValidatingDecoder(const ValidSchema &s, const shared_ptr<Decoder> &b) : base(b),
                                                                            parser(ValidatingGrammarGenerator().generate(s), NULL, handler_) {}
};

template<typename P>
void ValidatingDecoder<P>::init(InputStream &is) {
    base->init(is);
}

template<typename P>
void ValidatingDecoder<P>::decodeNull() {
    parser.advance(Symbol::Kind::Null);
    base->decodeNull();
}

template<typename P>
bool ValidatingDecoder<P>::decodeBool() {
    parser.advance(Symbol::Kind::Bool);
    return base->decodeBool();
}

template<typename P>
int32_t ValidatingDecoder<P>::decodeInt() {
    parser.advance(Symbol::Kind::Int);
    return base->decodeInt();
}

template<typename P>
int64_t ValidatingDecoder<P>::decodeLong() {
    parser.advance(Symbol::Kind::Long);
    return base->decodeLong();
}

template<typename P>
float ValidatingDecoder<P>::decodeFloat() {
    parser.advance(Symbol::Kind::Float);
    return base->decodeFloat();
}

template<typename P>
double ValidatingDecoder<P>::decodeDouble() {
    parser.advance(Symbol::Kind::Double);
    return base->decodeDouble();
}

template<typename P>
void ValidatingDecoder<P>::decodeString(string &value) {
    parser.advance(Symbol::Kind::String);
    base->decodeString(value);
}

template<typename P>
void ValidatingDecoder<P>::skipString() {
    parser.advance(Symbol::Kind::String);
    base->skipString();
}

template<typename P>
void ValidatingDecoder<P>::decodeBytes(vector<uint8_t> &value) {
    parser.advance(Symbol::Kind::Bytes);
    base->decodeBytes(value);
}

template<typename P>
void ValidatingDecoder<P>::skipBytes() {
    parser.advance(Symbol::Kind::Bytes);
    base->skipBytes();
}

template<typename P>
void ValidatingDecoder<P>::decodeFixed(size_t n, vector<uint8_t> &value) {
    parser.advance(Symbol::Kind::Fixed);
    parser.assertSize(n);
    base->decodeFixed(n, value);
}

template<typename P>
void ValidatingDecoder<P>::skipFixed(size_t n) {
    parser.advance(Symbol::Kind::Fixed);
    parser.assertSize(n);
    base->skipFixed(n);
}

template<typename P>
size_t ValidatingDecoder<P>::decodeEnum() {
    parser.advance(Symbol::Kind::Enum);
    size_t result = base->decodeEnum();
    parser.assertLessThanSize(result);
    return result;
}

template<typename P>
size_t ValidatingDecoder<P>::arrayStart() {
    parser.advance(Symbol::Kind::ArrayStart);
    size_t result = base->arrayStart();
    parser.pushRepeatCount(result);
    if (result == 0) {
        parser.popRepeater();
        parser.advance(Symbol::Kind::ArrayEnd);
    }
    return result;
}

template<typename P>
size_t ValidatingDecoder<P>::arrayNext() {
    size_t result = base->arrayNext();
    parser.nextRepeatCount(result);
    if (result == 0) {
        parser.popRepeater();
        parser.advance(Symbol::Kind::ArrayEnd);
    }
    return result;
}

template<typename P>
size_t ValidatingDecoder<P>::skipArray() {
    parser.advance(Symbol::Kind::ArrayStart);
    size_t n = base->skipArray();
    if (n == 0) {
        parser.pop();
    } else {
        parser.pushRepeatCount(n);
        parser.skip(*base);
    }
    parser.advance(Symbol::Kind::ArrayEnd);
    return 0;
}

template<typename P>
size_t ValidatingDecoder<P>::mapStart() {
    parser.advance(Symbol::Kind::MapStart);
    size_t result = base->mapStart();
    parser.pushRepeatCount(result);
    if (result == 0) {
        parser.popRepeater();
        parser.advance(Symbol::Kind::MapEnd);
    }
    return result;
}

template<typename P>
size_t ValidatingDecoder<P>::mapNext() {
    size_t result = base->mapNext();
    parser.nextRepeatCount(result);
    if (result == 0) {
        parser.popRepeater();
        parser.advance(Symbol::Kind::MapEnd);
    }
    return result;
}

template<typename P>
size_t ValidatingDecoder<P>::skipMap() {
    parser.advance(Symbol::Kind::MapStart);
    size_t n = base->skipMap();
    if (n == 0) {
        parser.pop();
    } else {
        parser.pushRepeatCount(n);
        parser.skip(*base);
    }
    parser.advance(Symbol::Kind::MapEnd);
    return 0;
}

template<typename P>
size_t ValidatingDecoder<P>::decodeUnionIndex() {
    parser.advance(Symbol::Kind::Union);
    size_t result = base->decodeUnionIndex();
    parser.selectBranch(result);
    return result;
}

template<typename P>
class ValidatingEncoder : public Encoder {
    DummyHandler handler_;
    P parser_;
    EncoderPtr base_;

    void init(OutputStream &os) final;
    void flush() final;
    int64_t byteCount() const final;
    void encodeNull() final;
    void encodeBool(bool b) final;
    void encodeInt(int32_t i) final;
    void encodeLong(int64_t l) final;
    void encodeFloat(float f) final;
    void encodeDouble(double d) final;
    void encodeString(const std::string &s) final;
    void encodeBytes(const uint8_t *bytes, size_t len) final;
    void encodeFixed(const uint8_t *bytes, size_t len) final;
    void encodeEnum(size_t e) final;
    void arrayStart() final;
    void arrayEnd() final;
    void mapStart() final;
    void mapEnd() final;
    void setItemCount(size_t count) final;
    void startItem() final;
    void encodeUnionIndex(size_t e) final;

public:
    ValidatingEncoder(const ValidSchema &schema, EncoderPtr base) : parser_(ValidatingGrammarGenerator().generate(schema), NULL, handler_),
                                                                    base_(std::move(base)) {}
};

template<typename P>
void ValidatingEncoder<P>::init(OutputStream &os) {
    base_->init(os);
}

template<typename P>
void ValidatingEncoder<P>::flush() {
    base_->flush();
}

template<typename P>
void ValidatingEncoder<P>::encodeNull() {
    parser_.advance(Symbol::Kind::Null);
    base_->encodeNull();
}

template<typename P>
void ValidatingEncoder<P>::encodeBool(bool b) {
    parser_.advance(Symbol::Kind::Bool);
    base_->encodeBool(b);
}

template<typename P>
void ValidatingEncoder<P>::encodeInt(int32_t i) {
    parser_.advance(Symbol::Kind::Int);
    base_->encodeInt(i);
}

template<typename P>
void ValidatingEncoder<P>::encodeLong(int64_t l) {
    parser_.advance(Symbol::Kind::Long);
    base_->encodeLong(l);
}

template<typename P>
void ValidatingEncoder<P>::encodeFloat(float f) {
    parser_.advance(Symbol::Kind::Float);
    base_->encodeFloat(f);
}

template<typename P>
void ValidatingEncoder<P>::encodeDouble(double d) {
    parser_.advance(Symbol::Kind::Double);
    base_->encodeDouble(d);
}

template<typename P>
void ValidatingEncoder<P>::encodeString(const std::string &s) {
    parser_.advance(Symbol::Kind::String);
    base_->encodeString(s);
}

template<typename P>
void ValidatingEncoder<P>::encodeBytes(const uint8_t *bytes, size_t len) {
    parser_.advance(Symbol::Kind::Bytes);
    base_->encodeBytes(bytes, len);
}

template<typename P>
void ValidatingEncoder<P>::encodeFixed(const uint8_t *bytes, size_t len) {
    parser_.advance(Symbol::Kind::Fixed);
    parser_.assertSize(len);
    base_->encodeFixed(bytes, len);
}

template<typename P>
void ValidatingEncoder<P>::encodeEnum(size_t e) {
    parser_.advance(Symbol::Kind::Enum);
    parser_.assertLessThanSize(e);
    base_->encodeEnum(e);
}

template<typename P>
void ValidatingEncoder<P>::arrayStart() {
    parser_.advance(Symbol::Kind::ArrayStart);
    parser_.pushRepeatCount(0);
    base_->arrayStart();
}

template<typename P>
void ValidatingEncoder<P>::arrayEnd() {
    parser_.popRepeater();
    parser_.advance(Symbol::Kind::ArrayEnd);
    base_->arrayEnd();
}

template<typename P>
void ValidatingEncoder<P>::mapStart() {
    parser_.advance(Symbol::Kind::MapStart);
    parser_.pushRepeatCount(0);
    base_->mapStart();
}

template<typename P>
void ValidatingEncoder<P>::mapEnd() {
    parser_.popRepeater();
    parser_.advance(Symbol::Kind::MapEnd);
    base_->mapEnd();
}

template<typename P>
void ValidatingEncoder<P>::setItemCount(size_t count) {
    parser_.nextRepeatCount(count);
    base_->setItemCount(count);
}

template<typename P>
void ValidatingEncoder<P>::startItem() {
    parser_.processImplicitActions();
    if (parser_.top() != Symbol::Kind::Repeater) {
        throw Exception("startItem at not an item boundary");
    }
    base_->startItem();
}

template<typename P>
void ValidatingEncoder<P>::encodeUnionIndex(size_t e) {
    parser_.advance(Symbol::Kind::Union);
    parser_.selectBranch(e);
    base_->encodeUnionIndex(e);
}

template<typename P>
int64_t ValidatingEncoder<P>::byteCount() const {
    return base_->byteCount();
}

} // namespace parsing

DecoderPtr validatingDecoder(const ValidSchema &s,
                             const DecoderPtr &base) {
    return make_shared<parsing::ValidatingDecoder<parsing::SimpleParser<parsing::DummyHandler>>>(s, base);
}

EncoderPtr validatingEncoder(const ValidSchema &schema, const EncoderPtr &base) {
    return make_shared<parsing::ValidatingEncoder<parsing::SimpleParser<parsing::DummyHandler>>>(schema, base);
}

} // namespace avro
