#include "database_service.hpp"
#include "logging/logger.hpp"
#include "common/time_utils.hpp"
#include <grpcpp/health_check_service_interface.h>

namespace smartbotic::database {

using namespace common;

// DatabaseServiceImpl implementation
DatabaseServiceImpl::DatabaseServiceImpl(MemoryStore& store)
    : store_(store) {}

grpc::Status DatabaseServiceImpl::Get(grpc::ServerContext* context,
                                      const proto::GetRequest* request,
                                      proto::Document* response) {
    auto result = store_.get(request->collection(), request->id());
    if (result.failed()) {
        return grpc::Status(grpc::StatusCode::NOT_FOUND, result.error().message());
    }

    documentToProto(result.value(), response);
    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::Query(grpc::ServerContext* context,
                                        const proto::QueryRequest* request,
                                        proto::QueryResponse* response) {
    struct Query q(request->collection());

    // Build filters
    for (const auto& f : request->filters()) {
        Filter filter;
        filter.field = f.field();
        filter.op = protoToFilterOp(f.op());
        filter.value = nlohmann::json::parse(f.value());
        q.filters.push_back(std::move(filter));
    }

    // Build sorts
    for (const auto& s : request->sorts()) {
        Sort sort;
        sort.field = s.field();
        sort.direction = s.direction() == proto::SORT_DIRECTION_DESC ?
                        SortDirection::Desc : SortDirection::Asc;
        q.sorts.push_back(std::move(sort));
    }

    // Pagination
    if (request->has_pagination()) {
        q.offset = (request->pagination().page() - 1) * request->pagination().page_size();
        q.limit = request->pagination().page_size();
    }

    // Projection
    for (const auto& field : request->fields()) {
        q.fields.push_back(field);
    }

    auto result = store_.query(q);

    for (const auto& doc : result.documents) {
        documentToProto(doc, response->add_documents());
    }

    auto* pagination = response->mutable_pagination();
    pagination->set_total_count(result.total_count);
    pagination->set_has_more(result.has_more);

    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::Insert(grpc::ServerContext* context,
                                         const proto::InsertRequest* request,
                                         proto::MutationResponse* response) {
    Document doc;
    doc.id = request->id();
    doc.collection = request->collection();
    doc.data = nlohmann::json::parse(request->data());

    if (request->ttl_ms() > 0) {
        doc.expires_at = TimeUtils::nowMs() + request->ttl_ms();
    }

    auto result = store_.insert(request->collection(), std::move(doc));
    if (result.failed()) {
        response->set_success(false);
        auto* error = response->mutable_error();
        error->set_code(static_cast<int32_t>(result.error().code()));
        error->set_message(result.error().message());
        return grpc::Status::OK;
    }

    response->set_id(result.value().id);
    response->set_version(result.value().version);
    response->set_success(true);
    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::Update(grpc::ServerContext* context,
                                         const proto::UpdateRequest* request,
                                         proto::MutationResponse* response) {
    auto data = nlohmann::json::parse(request->data());
    auto result = store_.update(request->collection(), request->id(), data,
                               request->expected_version(), request->partial());

    if (result.failed()) {
        response->set_success(false);
        auto* error = response->mutable_error();
        error->set_code(static_cast<int32_t>(result.error().code()));
        error->set_message(result.error().message());
        return grpc::Status::OK;
    }

    response->set_id(result.value().id);
    response->set_version(result.value().version);
    response->set_success(true);
    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::Delete(grpc::ServerContext* context,
                                         const proto::DeleteRequest* request,
                                         proto::MutationResponse* response) {
    auto result = store_.remove(request->collection(), request->id(),
                               request->expected_version());

    if (result.failed()) {
        response->set_success(false);
        auto* error = response->mutable_error();
        error->set_code(static_cast<int32_t>(result.error().code()));
        error->set_message(result.error().message());
        return grpc::Status::OK;
    }

    response->set_id(request->id());
    response->set_success(true);
    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::BatchInsert(grpc::ServerContext* context,
                                              const proto::BatchInsertRequest* request,
                                              proto::BatchMutationResponse* response) {
    int32_t success_count = 0;
    int32_t failure_count = 0;

    for (const auto& req : request->documents()) {
        Document doc;
        doc.id = req.id();
        doc.collection = request->collection();
        doc.data = nlohmann::json::parse(req.data());

        if (req.ttl_ms() > 0) {
            doc.expires_at = TimeUtils::nowMs() + req.ttl_ms();
        }

        auto result = store_.insert(request->collection(), std::move(doc));
        auto* mutation_result = response->add_results();

        if (result.ok()) {
            mutation_result->set_id(result.value().id);
            mutation_result->set_version(result.value().version);
            mutation_result->set_success(true);
            ++success_count;
        } else {
            mutation_result->set_success(false);
            auto* error = mutation_result->mutable_error();
            error->set_code(static_cast<int32_t>(result.error().code()));
            error->set_message(result.error().message());
            ++failure_count;
        }
    }

    response->set_success_count(success_count);
    response->set_failure_count(failure_count);
    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::BatchDelete(grpc::ServerContext* context,
                                              const proto::BatchDeleteRequest* request,
                                              proto::BatchMutationResponse* response) {
    int32_t success_count = 0;
    int32_t failure_count = 0;

    for (const auto& id : request->ids()) {
        auto result = store_.remove(request->collection(), id, 0);
        auto* mutation_result = response->add_results();
        mutation_result->set_id(id);

        if (result.ok()) {
            mutation_result->set_success(true);
            ++success_count;
        } else {
            mutation_result->set_success(false);
            auto* error = mutation_result->mutable_error();
            error->set_code(static_cast<int32_t>(result.error().code()));
            error->set_message(result.error().message());
            ++failure_count;
        }
    }

    response->set_success_count(success_count);
    response->set_failure_count(failure_count);
    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::CreateCollection(grpc::ServerContext* context,
                                                    const proto::CreateCollectionRequest* request,
                                                    proto::Empty* response) {
    CollectionConfig config(request->name());
    config.default_ttl_ms = request->default_ttl_ms();

    if (!request->schema().empty()) {
        config.schema = nlohmann::json::parse(request->schema());
    }

    // Handle versioning configuration
    if (request->has_versioning()) {
        VersioningConfig versioning;
        versioning.enabled = request->versioning().enabled();
        versioning.max_versions = request->versioning().max_versions();
        versioning.version_ttl_ms = request->versioning().version_ttl_ms();
        versioning.keep_on_delete = request->versioning().keep_on_delete();
        config.versioning = versioning;
    }

    auto result = store_.createCollection(config);
    if (result.failed()) {
        return grpc::Status(grpc::StatusCode::ALREADY_EXISTS, result.error().message());
    }

    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::DropCollection(grpc::ServerContext* context,
                                                  const proto::DropCollectionRequest* request,
                                                  proto::Empty* response) {
    auto result = store_.dropCollection(request->name());
    if (result.failed()) {
        return grpc::Status(grpc::StatusCode::NOT_FOUND, result.error().message());
    }

    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::ListCollections(grpc::ServerContext* context,
                                                   const proto::ListCollectionsRequest* request,
                                                   proto::ListCollectionsResponse* response) {
    auto collections = store_.listCollections();
    for (const auto& name : collections) {
        response->add_collections(name);
    }
    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::GetVersion(grpc::ServerContext* context,
                                             const proto::GetVersionRequest* request,
                                             proto::Document* response) {
    auto result = store_.getVersion(request->collection(), request->id(), request->version());
    if (result.failed()) {
        return grpc::Status(grpc::StatusCode::NOT_FOUND, result.error().message());
    }

    const auto& ver = result.value();
    response->set_id(ver.document_id);
    response->set_collection(request->collection());
    response->set_data(ver.data.dump());
    response->set_version(ver.version);
    response->set_created_at(ver.created_at);
    response->set_updated_at(ver.created_at);
    response->set_expires_at(ver.expires_at);

    return grpc::Status::OK;
}

grpc::Status DatabaseServiceImpl::ListVersions(grpc::ServerContext* context,
                                               const proto::ListVersionsRequest* request,
                                               proto::ListVersionsResponse* response) {
    int32_t limit = request->limit() > 0 ? request->limit() : 100;
    int32_t offset = request->offset();

    auto result = store_.listVersions(request->collection(), request->id(), limit, offset);

    for (const auto& doc : result.documents) {
        auto ver = DocumentVersion::fromJson(doc.data);
        auto* proto_ver = response->add_versions();
        documentVersionToProto(ver, proto_ver);
    }

    response->set_total_count(result.total_count);
    response->set_has_more(result.has_more);

    return grpc::Status::OK;
}

void DatabaseServiceImpl::documentToProto(const Document& doc, proto::Document* proto) {
    proto->set_id(doc.id);
    proto->set_collection(doc.collection);
    proto->set_data(doc.data.dump());
    proto->set_version(doc.version);
    proto->set_created_at(doc.created_at);
    proto->set_updated_at(doc.updated_at);
    proto->set_expires_at(doc.expires_at);
}

void DatabaseServiceImpl::documentVersionToProto(const DocumentVersion& ver, proto::DocumentVersion* proto) {
    proto->set_id(ver.id);
    proto->set_document_id(ver.document_id);
    proto->set_version(ver.version);
    proto->set_data(ver.data.dump());
    proto->set_created_at(ver.created_at);
    proto->set_expires_at(ver.expires_at);
}

FilterOp DatabaseServiceImpl::protoToFilterOp(proto::FilterOp op) {
    switch (op) {
        case proto::FILTER_OP_EQ: return FilterOp::Eq;
        case proto::FILTER_OP_NE: return FilterOp::Ne;
        case proto::FILTER_OP_GT: return FilterOp::Gt;
        case proto::FILTER_OP_GTE: return FilterOp::Gte;
        case proto::FILTER_OP_LT: return FilterOp::Lt;
        case proto::FILTER_OP_LTE: return FilterOp::Lte;
        case proto::FILTER_OP_IN: return FilterOp::In;
        case proto::FILTER_OP_NIN: return FilterOp::Nin;
        case proto::FILTER_OP_CONTAINS: return FilterOp::Contains;
        case proto::FILTER_OP_REGEX: return FilterOp::Regex;
        case proto::FILTER_OP_EXISTS: return FilterOp::Exists;
        default: return FilterOp::Eq;
    }
}

// DatabaseService implementation
DatabaseService::DatabaseService(const Config& config)
    : config_(config) {

    // Setup WAL
    WAL::Config wal_config;
    wal_config.directory = std::filesystem::path(config_.data_directory) / "wal";
    wal_config.sync_interval_ms = config_.wal.sync_interval_ms;
    wal_config.enabled = true;
    wal_ = std::make_unique<WAL>(wal_config);

    // Setup snapshot manager
    SnapshotManager::Config snapshot_config;
    snapshot_config.directory = std::filesystem::path(config_.data_directory) / "snapshots";
    snapshot_config.interval_sec = config_.snapshot.interval_sec;
    snapshot_config.enabled = true;
    snapshot_manager_ = std::make_unique<SnapshotManager>(snapshot_config);

    // Setup mutation callback for WAL
    store_.setMutationCallback([this](const WalEntry& entry) {
        wal_->append(entry);
    });
}

DatabaseService::~DatabaseService() {
    stop();
}

DatabaseService::Config DatabaseService::loadConfig(const std::filesystem::path& path) {
    Config config;

    auto result = config::Config::fromFile(path);
    if (result.ok()) {
        auto& cfg = result.value();
        config.grpc_port = cfg.getOr<int>("grpc_port", 9001);
        config.data_directory = cfg.getOr<std::string>("data_directory", "./data/database");
        config.max_message_size_mb = cfg.getOr<int>("max_message_size_mb", 64);
        config.wal.sync_interval_ms = cfg.getOr<int>("persistence.wal_sync_interval_ms", 100);
        config.snapshot.interval_sec = cfg.getOr<int>("persistence.snapshot_interval_sec", 3600);
    }

    return config;
}

void DatabaseService::start() {
    if (running_) {
        return;
    }

    LOG_INFO("Starting database service...");

    // Create data directory
    std::filesystem::create_directories(config_.data_directory);

    // Recovery from persistence
    recoveryFromPersistence();

    // Create predefined collections
    createPredefinedCollections();

    // Start WAL
    wal_->start();

    // Start gRPC server
    service_impl_ = std::make_unique<DatabaseServiceImpl>(store_);

    // Disable health check to avoid async completion queue issues
    // grpc::EnableDefaultHealthCheckService(true);
    grpc::ServerBuilder builder;
    builder.AddListeningPort("0.0.0.0:" + std::to_string(config_.grpc_port),
                            grpc::InsecureServerCredentials());
    builder.RegisterService(service_impl_.get());

    // Set max message size to handle large execution results
    int max_msg_size = config_.max_message_size_mb * 1024 * 1024;
    builder.SetMaxReceiveMessageSize(max_msg_size);
    builder.SetMaxSendMessageSize(max_msg_size);
    LOG_INFO("Max gRPC message size: {} MB", config_.max_message_size_mb);

    server_ = builder.BuildAndStart();
    LOG_INFO("Database gRPC server listening on port {}", config_.grpc_port);

    running_ = true;

    // Start background threads
    snapshot_thread_ = std::thread(&DatabaseService::snapshotLoop, this);
    ttl_thread_ = std::thread(&DatabaseService::ttlLoop, this);
}

void DatabaseService::stop() {
    if (!running_) {
        return;
    }

    LOG_INFO("Stopping database service...");

    // Signal shutdown to background threads
    {
        std::lock_guard<std::mutex> lock(shutdown_mutex_);
        running_ = false;
    }
    shutdown_cv_.notify_all();

    // Stop background threads (they will wake up immediately now)
    if (snapshot_thread_.joinable()) {
        snapshot_thread_.join();
    }
    if (ttl_thread_.joinable()) {
        ttl_thread_.join();
    }

    // Final snapshot before shutdown
    LOG_INFO("Creating final snapshot before shutdown...");
    createSnapshot();

    // Stop WAL
    wal_->stop();

    // Stop gRPC server
    if (server_) {
        server_->Shutdown();
    }

    LOG_INFO("Database service stopped");
}

void DatabaseService::createPredefinedCollections() {
    // Users collection
    store_.createCollection(CollectionConfig("users"));

    // Workflows collection
    store_.createCollection(CollectionConfig("workflows"));

    // Workflow groups collection
    store_.createCollection(CollectionConfig("workflow_groups"));

    // Executions collection with 7-day TTL
    store_.createCollection(
        CollectionConfig("executions").withTTL(7 * 24 * 60 * 60 * 1000));

    // Sessions collection with 1-day TTL
    store_.createCollection(
        CollectionConfig("sessions").withTTL(24 * 60 * 60 * 1000));

    // API keys collection
    store_.createCollection(CollectionConfig("api_keys"));

    // Credentials collection
    store_.createCollection(CollectionConfig("credentials"));

    // Runners collection
    store_.createCollection(CollectionConfig("runners"));

    // Nodes collection - stores node definitions
    store_.createCollection(CollectionConfig("nodes"));

    LOG_INFO("Created predefined collections");
}

void DatabaseService::createSnapshot() {
    auto snapshot = store_.createSnapshot();
    auto result = snapshot_manager_->save(snapshot);
    if (result.ok()) {
        // Truncate WAL after successful snapshot
        wal_->truncate(snapshot.value("sequence", 0));
    }
}

void DatabaseService::recoveryFromPersistence() {
    LOG_INFO("Starting recovery from persistence...");

    // Try to load latest snapshot
    auto snapshot_result = snapshot_manager_->loadLatest();
    if (snapshot_result.ok()) {
        store_.loadSnapshot(snapshot_result.value());
        LOG_INFO("Loaded snapshot");
    }

    // Replay WAL entries after snapshot
    int64_t last_sequence = snapshot_manager_->getLatestSequence();
    wal_->replay([this, last_sequence](const WalEntry& entry) {
        if (entry.sequence <= last_sequence) {
            return;  // Skip entries already in snapshot
        }

        // Apply WAL entry
        switch (entry.type) {
            case WalEntryType::Insert: {
                auto doc = Document::fromJson(entry.data);
                store_.getCollection(entry.collection)->loadFromSnapshot({doc});
                break;
            }
            case WalEntryType::Update: {
                auto doc = Document::fromJson(entry.data);
                store_.getCollection(entry.collection)->loadFromSnapshot({doc});
                break;
            }
            case WalEntryType::Delete: {
                auto* col = store_.getCollection(entry.collection);
                if (col) {
                    col->remove(entry.document_id, 0);
                }
                break;
            }
            case WalEntryType::CreateCollection: {
                CollectionConfig config(entry.collection);
                if (entry.data.contains("default_ttl_ms")) {
                    config.default_ttl_ms = entry.data["default_ttl_ms"];
                }
                if (entry.data.contains("versioning")) {
                    config.versioning = VersioningConfig::fromJson(entry.data["versioning"]);
                }
                store_.createCollection(config);
                break;
            }
            case WalEntryType::DropCollection: {
                store_.dropCollection(entry.collection);
                break;
            }
            case WalEntryType::StoreVersion: {
                // Version entries are stored in-memory, no special recovery needed
                // They are reconstructed from document updates during normal operation
                break;
            }
            case WalEntryType::DeleteVersion: {
                // Handled similarly to StoreVersion
                break;
            }
        }
    });

    LOG_INFO("Recovery complete");
}

void DatabaseService::snapshotLoop() {
    while (running_) {
        // Wait for shutdown signal or timeout
        {
            std::unique_lock<std::mutex> lock(shutdown_mutex_);
            if (shutdown_cv_.wait_for(lock,
                    std::chrono::seconds(config_.snapshot.interval_sec),
                    [this] { return !running_.load(); })) {
                // Shutdown signaled, exit loop
                break;
            }
        }

        if (!running_) break;

        // Check if WAL is large enough to trigger snapshot
        if (wal_->getSize() >= config_.snapshot.wal_size_trigger) {
            createSnapshot();
        }
    }
}

void DatabaseService::ttlLoop() {
    constexpr int ttl_check_interval_sec = 60;  // Check every minute

    while (running_) {
        // Wait for shutdown signal or timeout
        {
            std::unique_lock<std::mutex> lock(shutdown_mutex_);
            if (shutdown_cv_.wait_for(lock,
                    std::chrono::seconds(ttl_check_interval_sec),
                    [this] { return !running_.load(); })) {
                // Shutdown signaled, exit loop
                break;
            }
        }

        if (!running_) break;

        store_.expireAllDocuments();
        store_.expireAllVersions();
    }
}

} // namespace smartbotic::database