#include "name_service.h"

#include "name_index.h"

#include <yql/essentials/sql/v1/ide/completion/name/service/ranking/ranking.h>
#include <yql/essentials/sql/v1/ide/completion/name/service/union/name_service.h>
#include <yql/essentials/sql/v1/ide/completion/text/case.h>

namespace NSQLComplete {

TVector<TStringBuf> FilteredByPrefix(
    const TString& prefix,
    const TVector<TString>& sorted Y_LIFETIME_BOUND) {
    auto [first, last] = EqualRange(
        std::begin(sorted), std::end(sorted),
        prefix, NoCaseCompareLimit(prefix.size()));
    return TVector<TStringBuf>(first, last);
}

template <class T, class S = TStringBuf>
void AppendAs(TVector<TGenericName>& target, const TVector<S>& source) {
    for (const auto& element : source) {
        T name;

        TString* content = nullptr;
        if constexpr (std::is_same_v<TKeyword, T>) {
            content = &name.Content;
        } else {
            content = &name.Identifier;
        }

        *content = element;

        target.emplace_back(std::move(name));
    }
}

template <class T>
void NameIndexScan(
    const TNameIndex& index,
    const TString& prefix,
    const TNameConstraints& constraints,
    TVector<TGenericName>& out) {
    T name;
    name.Identifier = prefix;
    name = std::get<T>(constraints.Qualified(std::move(name)));

    AppendAs<T>(out, FilteredByPrefix(name.Identifier, index, NormalizeName));
    out = constraints.Unqualified(std::move(out));
}

class IRankingNameService: public INameService {
private:
    auto Ranking(const TNameRequest& request) const {
        // TODO(YQL-20095): Explore real problem to fix this.
        // NOLINTNEXTLINE(bugprone-exception-escape)
        return [request, this](auto f) {
            TNameResponse response = f.ExtractValue();
            Ranking_->CropToSortedPrefix(
                response.RankedNames,
                request.Constraints,
                request.Limit);
            return response;
        };
    }

public:
    explicit IRankingNameService(IRanking::TPtr ranking)
        : Ranking_(std::move(ranking))
    {
    }

    NThreading::TFuture<TNameResponse> Lookup(const TNameRequest& request) const override {
        return LookupAllUnranked(request).Apply(Ranking(request));
    }

    virtual NThreading::TFuture<TNameResponse> LookupAllUnranked(const TNameRequest& request) const = 0;

private:
    IRanking::TPtr Ranking_;
};

class TKeywordNameService: public IRankingNameService {
public:
    explicit TKeywordNameService(IRanking::TPtr ranking)
        : IRankingNameService(std::move(ranking))
    {
    }

    NThreading::TFuture<TNameResponse> LookupAllUnranked(const TNameRequest& request) const override {
        TVector<TString> keywords = request.Keywords;

        TNameResponse response;
        Sort(keywords, NoCaseCompare);
        AppendAs<TKeyword>(response.RankedNames, FilteredByPrefix(request.Prefix, keywords));
        return NThreading::MakeFuture<TNameResponse>(std::move(response));
    }
};

class TPragmaNameService: public IRankingNameService {
public:
    TPragmaNameService(IRanking::TPtr ranking, TVector<TString> pragmas)
        : IRankingNameService(std::move(ranking))
        , Pragmas_(BuildNameIndex(std::move(pragmas), NormalizeName))
    {
    }

    NThreading::TFuture<TNameResponse> LookupAllUnranked(const TNameRequest& request) const override {
        TNameResponse response;
        if (request.Constraints.Pragma) {
            NameIndexScan<TPragmaName>(
                Pragmas_,
                request.Prefix,
                request.Constraints,
                response.RankedNames);
        }
        return NThreading::MakeFuture<TNameResponse>(std::move(response));
    }

private:
    TNameIndex Pragmas_;
};

class TTypeNameService: public IRankingNameService {
public:
    TTypeNameService(IRanking::TPtr ranking, TVector<TString> types)
        : IRankingNameService(std::move(ranking))
        , SimpleTypes_(BuildNameIndex(WithNull(std::move(types)), NormalizeName))
        , ContainerTypes_(BuildNameIndex(
              {
                  "Optional",
                  "Tuple",
                  "Struct",
                  "Variant",
                  "List",
                  "Stream",
                  "Flow",
                  "Dict",
                  "Set",
                  "Enum",
                  "Resource",
                  "Tagged",
                  "Callable",
                  "Linear",
                  "DynamicLinear",
              }, NormalizeName))
        , ParameterizedTypes_(BuildNameIndex(
              {
                  "Decimal",
              }, NormalizeName))
    {
    }

    NThreading::TFuture<TNameResponse> LookupAllUnranked(const TNameRequest& request) const override {
        TNameResponse response;
        if (request.Constraints.Type) {
            SimpleTypesScan(request, response.RankedNames);

            size_t previousSize = response.RankedNames.size();
            NameIndexScan<TTypeName>(ContainerTypes_, request.Prefix, request.Constraints, response.RankedNames);
            for (size_t i = previousSize; i < response.RankedNames.size(); ++i) {
                std::get<TTypeName>(response.RankedNames[i]).Kind = TTypeName::EKind::Container;
            }

            previousSize = response.RankedNames.size();
            NameIndexScan<TTypeName>(ParameterizedTypes_, request.Prefix, request.Constraints, response.RankedNames);
            for (size_t i = previousSize; i < response.RankedNames.size(); ++i) {
                std::get<TTypeName>(response.RankedNames[i]).Kind = TTypeName::EKind::Parameterized;
            }
        }
        return NThreading::MakeFuture<TNameResponse>(std::move(response));
    }

private:
    void SimpleTypesScan(const TNameRequest& request, TVector<TGenericName>& names) const {
        NameIndexScan<TTypeName>(SimpleTypes_, request.Prefix, request.Constraints, names);

        if (!IsIn(request.Keywords, "NULL")) {
            return;
        }

        EraseIf(names, [](const TGenericName& name) {
            const auto* type = std::get_if<TTypeName>(&name);
            return type && type->Identifier == "Null";
        });
    }

    static TVector<TString> WithNull(TVector<TString> types) {
        if (!IsIn(types, "Null")) {
            types.emplace_back("Null");
        }

        return types;
    }

    TNameIndex SimpleTypes_;
    TNameIndex ContainerTypes_;
    TNameIndex ParameterizedTypes_;
};

class TFunctionNameService: public IRankingNameService {
public:
    TFunctionNameService(IRanking::TPtr ranking, TVector<TString> functions)
        : IRankingNameService(std::move(ranking))
        , Functions_(BuildNameIndex(std::move(functions), NormalizeName))
        , TableFunctions_(BuildNameIndex(
              {
                  "CONCAT",
                  "RANGE",
                  "LIKE",
                  "REGEXP",
                  "FILTER",
                  "FOLDER",
                  "WalkFolders",
                  "EACH",
                  "PARTITION_LIST",
                  "PARTITIONS",
              }, NormalizeName))
    {
    }

    NThreading::TFuture<TNameResponse> LookupAllUnranked(const TNameRequest& request) const override {
        TNameResponse response;
        if (auto function = request.Constraints.Function) {
            const TNameIndex* index = nullptr;
            switch (function->ReturnType) {
                case ENodeKind::Any: {
                    index = &Functions_;
                } break;
                case ENodeKind::Table: {
                    index = &TableFunctions_;
                } break;
            }

            NameIndexScan<TFunctionName>(
                *index,
                request.Prefix,
                request.Constraints,
                response.RankedNames);
        }
        return NThreading::MakeFuture<TNameResponse>(std::move(response));
    }

private:
    TNameIndex Functions_;
    TNameIndex TableFunctions_;
};

class THintNameService: public IRankingNameService {
public:
    THintNameService(
        IRanking::TPtr ranking,
        THashMap<EStatementKind, TVector<TString>> hints)
        : IRankingNameService(std::move(ranking))
        , Hints_([hints = std::move(hints)] {
            THashMap<EStatementKind, TNameIndex> index;
            for (auto& [k, hints] : hints) {
                index.emplace(k, BuildNameIndex(std::move(hints), NormalizeName));
            }
            return index;
        }())
    {
    }

    NThreading::TFuture<TNameResponse> LookupAllUnranked(const TNameRequest& request) const override {
        TNameResponse response;
        if (request.Constraints.Hint) {
            const auto stmt = request.Constraints.Hint->Statement;
            if (const auto* hints = Hints_.FindPtr(stmt)) {
                NameIndexScan<THintName>(
                    *hints,
                    request.Prefix,
                    request.Constraints,
                    response.RankedNames);
            }
        }
        return NThreading::MakeFuture<TNameResponse>(std::move(response));
    }

private:
    THashMap<EStatementKind, TNameIndex> Hints_;
};

INameService::TPtr MakeStaticNameService(TNameSet names, TFrequencyData frequency) {
    names = Pruned(std::move(names), frequency);
    names = Filtered(std::move(names), DefaultNameFilter());
    IRanking::TPtr ranking = MakeDefaultRanking(std::move(frequency));
    return MakeStaticNameService(std::move(names), std::move(ranking));
}

INameService::TPtr MakeStaticNameService(TNameSet names, IRanking::TPtr ranking) {
    TVector<INameService::TPtr> children = {
        new TKeywordNameService(ranking),
        new TPragmaNameService(ranking, std::move(names.Pragmas)),
        new TTypeNameService(ranking, std::move(names.Types)),
        new TFunctionNameService(ranking, std::move(names.Functions)),
        new THintNameService(ranking, std::move(names.Hints)),
    };
    return MakeUnionNameService(std::move(children), ranking);
}

} // namespace NSQLComplete