#include "smartbotic/webserver/collection_service.hpp"

#include <chrono>
#include <functional>
#include <iomanip>
#include <regex>
#include <sstream>

#include <nlohmann/json.hpp>
#include <spdlog/spdlog.h>

namespace smartbotic::webserver {

namespace {

/// System collection for storing collection settings/metadata
constexpr const char* kSettingsCollection = "_collection_settings";

/// Convert timestamp to ISO 8601 string
auto TimestampToString(const ::smartbotic::database::Timestamp& ts) -> std::string {
    if (ts.seconds() == 0 && ts.nanos() == 0) {
        return "";
    }

    std::time_t time = ts.seconds();
    std::tm tm{};
    gmtime_r(&time, &tm);

    std::ostringstream oss;
    oss << std::put_time(&tm, "%Y-%m-%dT%H:%M:%S");

    if (ts.nanos() > 0) {
        oss << "." << std::setfill('0') << std::setw(3) << (ts.nanos() / 1000000);
    }
    oss << "Z";

    return oss.str();
}

}  // namespace

CollectionService::CollectionService(DatabaseClient& db_client) : db_client_(db_client) {
    // Ensure settings collection exists
    grpc::ClientContext ctx;
    ::smartbotic::database::CreateCollectionRequest req;
    ::smartbotic::database::CollectionMetadata resp;

    req.set_name(kSettingsCollection);

    auto status = db_client_.GetCollectionService()->CreateCollection(&ctx, req, &resp);
    if (status.ok()) {
        spdlog::info("Created system collection {}", kSettingsCollection);
    } else if (status.error_code() == grpc::StatusCode::ALREADY_EXISTS) {
        spdlog::debug("System collection {} already exists", kSettingsCollection);
    } else {
        spdlog::warn("Failed to ensure {} collection: {}", kSettingsCollection, status.error_message());
    }
}

CollectionService::~CollectionService() = default;

CollectionService::CollectionService(CollectionService&&) noexcept = default;
auto CollectionService::operator=(CollectionService&& /*other*/) noexcept -> CollectionService& {
    // Cannot reassign reference member, so this is essentially a no-op
    return *this;
}

auto CollectionService::CreateCollection(const CreateCollectionRequest& request) -> CollectionResult {
    // Validate collection name
    if (!IsValidCollectionName(request.name)) {
        return {.success = false, .error = "Invalid collection name. Must be alphanumeric with underscores, 1-64 chars.", .collection = std::nullopt};
    }

    // System collection names are reserved
    if (IsSystemCollection(request.name)) {
        return {.success = false, .error = "Collection name is reserved for system use", .collection = std::nullopt};
    }

    std::string internal_name = GetInternalName(request.workspace_id, request.name);

    // Create the collection via gRPC
    grpc::ClientContext ctx;
    ::smartbotic::database::CreateCollectionRequest req;
    ::smartbotic::database::CollectionMetadata resp;

    req.set_name(internal_name);

    auto status = db_client_.GetCollectionService()->CreateCollection(&ctx, req, &resp);
    if (!status.ok()) {
        if (status.error_code() == grpc::StatusCode::ALREADY_EXISTS) {
            return {.success = false, .error = "Collection already exists", .collection = std::nullopt};
        }
        spdlog::error("Failed to create collection {}: {}", internal_name, status.error_message());
        return {.success = false, .error = "Failed to create collection: " + status.error_message(), .collection = std::nullopt};
    }

    // Store settings in metadata collection
    if (!StoreSettings(request.workspace_id, request.name, request.settings)) {
        spdlog::warn("Collection {} created but failed to store settings", internal_name);
    }

    auto info = MetadataToInfo(request.workspace_id, resp);
    info.settings = request.settings;

    spdlog::info("Created collection {} in workspace {}", request.name, request.workspace_id);
    return {.success = true, .error = "", .collection = info};
}

auto CollectionService::GetCollection(const std::string& workspace_id, const std::string& name) -> CollectionResult {
    std::string internal_name = GetInternalName(workspace_id, name);

    grpc::ClientContext ctx;
    ::smartbotic::database::GetCollectionMetadataRequest req;
    ::smartbotic::database::CollectionMetadata resp;

    req.set_name(internal_name);

    auto status = db_client_.GetCollectionService()->GetCollectionMetadata(&ctx, req, &resp);
    if (!status.ok()) {
        if (status.error_code() == grpc::StatusCode::NOT_FOUND) {
            return {.success = false, .error = "Collection not found", .collection = std::nullopt};
        }
        spdlog::error("Failed to get collection {}: {}", internal_name, status.error_message());
        return {.success = false, .error = "Failed to get collection: " + status.error_message(), .collection = std::nullopt};
    }

    auto info = MetadataToInfo(workspace_id, resp);
    info.settings = LoadSettings(workspace_id, name);

    return {.success = true, .error = "", .collection = info};
}

auto CollectionService::ListCollections(const std::string& workspace_id) -> CollectionListResult {
    grpc::ClientContext ctx;
    ::smartbotic::database::ListCollectionsRequest req;
    ::smartbotic::database::ListCollectionsResponse resp;

    req.set_page_size(1000);  // Get all collections

    auto status = db_client_.GetCollectionService()->ListCollections(&ctx, req, &resp);
    if (!status.ok()) {
        spdlog::error("Failed to list collections: {}", status.error_message());
        return {.success = false, .error = "Failed to list collections: " + status.error_message(), .collections = {}, .total_count = 0};
    }

    std::string prefix = GetInternalName(workspace_id, "");
    std::vector<CollectionInfo> collections;

    for (const auto& meta : resp.collections()) {
        // Only include collections that belong to this workspace
        if (meta.name().rfind(prefix, 0) == 0) {
            auto info = MetadataToInfo(workspace_id, meta);
            info.settings = LoadSettings(workspace_id, info.name);
            collections.push_back(std::move(info));
        }
    }

    int64_t count = static_cast<int64_t>(collections.size());
    return {
        .success = true,
        .error = "",
        .collections = std::move(collections),
        .total_count = count
    };
}

auto CollectionService::ListSystemCollections() -> CollectionListResult {
    grpc::ClientContext ctx;
    ::smartbotic::database::ListCollectionsRequest req;
    ::smartbotic::database::ListCollectionsResponse resp;

    req.set_page_size(1000);

    auto status = db_client_.GetCollectionService()->ListCollections(&ctx, req, &resp);
    if (!status.ok()) {
        spdlog::error("Failed to list system collections: {}", status.error_message());
        return {.success = false, .error = "Failed to list collections: " + status.error_message(), .collections = {}, .total_count = 0};
    }

    std::vector<CollectionInfo> collections;

    for (const auto& meta : resp.collections()) {
        // System collections start with underscore and are not workspace-prefixed
        if (!meta.name().empty() && meta.name()[0] == '_') {
            CollectionInfo info;
            info.name = meta.name();
            info.workspace_id = "";  // Global collection
            info.document_count = meta.document_count();
            info.size_bytes = meta.size_bytes();
            info.created_at = TimestampToString(meta.created_at());
            info.updated_at = TimestampToString(meta.updated_at());
            collections.push_back(std::move(info));
        }
    }

    int64_t count = static_cast<int64_t>(collections.size());
    return {
        .success = true,
        .error = "",
        .collections = std::move(collections),
        .total_count = count
    };
}

auto CollectionService::UpdateCollection(const std::string& workspace_id, const std::string& name,
                                          const CollectionSettings& settings) -> CollectionResult {
    // First verify the collection exists
    auto get_result = GetCollection(workspace_id, name);
    if (!get_result.success) {
        return get_result;
    }

    // Update settings in metadata collection
    if (!StoreSettings(workspace_id, name, settings)) {
        return {.success = false, .error = "Failed to update collection settings", .collection = std::nullopt};
    }

    // Return updated info
    auto info = *get_result.collection;
    info.settings = settings;

    spdlog::info("Updated collection {} in workspace {}", name, workspace_id);
    return {.success = true, .error = "", .collection = info};
}

auto CollectionService::DropCollection(const std::string& workspace_id, const std::string& name,
                                        bool force) -> CollectionResult {
    std::string internal_name = GetInternalName(workspace_id, name);

    grpc::ClientContext ctx;
    ::smartbotic::database::DropCollectionRequest req;
    ::smartbotic::database::DropCollectionResponse resp;

    req.set_name(internal_name);
    req.set_force(force);

    auto status = db_client_.GetCollectionService()->DropCollection(&ctx, req, &resp);
    if (!status.ok()) {
        if (status.error_code() == grpc::StatusCode::NOT_FOUND) {
            return {.success = false, .error = "Collection not found", .collection = std::nullopt};
        }
        if (status.error_code() == grpc::StatusCode::FAILED_PRECONDITION) {
            return {.success = false, .error = "Collection is not empty. Use force=true to drop anyway.", .collection = std::nullopt};
        }
        spdlog::error("Failed to drop collection {}: {}", internal_name, status.error_message());
        return {.success = false, .error = "Failed to drop collection: " + status.error_message(), .collection = std::nullopt};
    }

    // Delete settings
    DeleteSettings(workspace_id, name);

    spdlog::info("Dropped collection {} from workspace {}", name, workspace_id);
    return {.success = true, .error = "", .collection = std::nullopt};
}

auto CollectionService::IsValidCollectionName(const std::string& name) -> bool {
    if (name.empty() || name.length() > 64) {
        return false;
    }

    // Must start with letter or underscore, contain only alphanumeric and underscores
    static const std::regex pattern("^[a-zA-Z_][a-zA-Z0-9_]*$");
    return std::regex_match(name, pattern);
}

auto CollectionService::IsSystemCollection(const std::string& name) -> bool {
    return !name.empty() && name[0] == '_';
}

auto CollectionService::GetInternalName(const std::string& workspace_id, const std::string& name) -> std::string {
    return std::string(kCollectionPrefix) + workspace_id + "_" + name;
}

auto CollectionService::GetDisplayName(const std::string& workspace_id, const std::string& internal_name) -> std::string {
    std::string prefix = GetInternalName(workspace_id, "");
    if (internal_name.rfind(prefix, 0) == 0) {
        return internal_name.substr(prefix.length());
    }
    return internal_name;
}

auto CollectionService::MetadataToInfo(const std::string& workspace_id,
                                        const ::smartbotic::database::CollectionMetadata& meta) -> CollectionInfo {
    CollectionInfo info;
    info.name = GetDisplayName(workspace_id, meta.name());
    info.workspace_id = workspace_id;
    info.document_count = meta.document_count();
    info.size_bytes = meta.size_bytes();
    info.created_at = TimestampToString(meta.created_at());
    info.updated_at = TimestampToString(meta.updated_at());
    return info;
}

auto CollectionService::GetCurrentTimestamp() -> std::string {
    auto now = std::chrono::system_clock::now();
    auto time_t = std::chrono::system_clock::to_time_t(now);
    auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(now.time_since_epoch()) % 1000;

    std::tm tm{};
    gmtime_r(&time_t, &tm);

    std::ostringstream oss;
    oss << std::put_time(&tm, "%Y-%m-%dT%H:%M:%S");
    oss << "." << std::setfill('0') << std::setw(3) << ms.count() << "Z";

    return oss.str();
}

auto CollectionService::StoreSettings(const std::string& workspace_id, const std::string& name,
                                       const CollectionSettings& settings) -> bool {
    std::string doc_id = workspace_id + "_" + name;

    nlohmann::json json_settings;
    json_settings["workspace_id"] = workspace_id;
    json_settings["collection_name"] = name;
    json_settings["schema"] = settings.schema;
    json_settings["is_system"] = settings.is_system;
    json_settings["encrypted_fields"] = settings.encrypted_fields;
    json_settings["ttl_seconds"] = settings.ttl_seconds;
    json_settings["updated_at"] = GetCurrentTimestamp();

    // Serialize field_permissions
    nlohmann::json field_perms_json = nlohmann::json::array();
    for (const auto& fp : settings.field_permissions) {
        nlohmann::json fp_json;
        fp_json["field_name"] = fp.field_name;
        fp_json["read_groups"] = fp.read_groups;
        fp_json["write_groups"] = fp.write_groups;
        field_perms_json.push_back(fp_json);
    }
    json_settings["field_permissions"] = field_perms_json;

    // Build the proto document using a recursive lambda to handle nested structures
    std::function<void(const nlohmann::json&, ::smartbotic::database::Value*)> json_to_proto;
    json_to_proto = [&json_to_proto](const nlohmann::json& j, ::smartbotic::database::Value* val) {
        if (j.is_string()) {
            val->set_string_value(j.get<std::string>());
        } else if (j.is_boolean()) {
            val->set_bool_value(j.get<bool>());
        } else if (j.is_number_integer()) {
            val->set_int_value(j.get<int64_t>());
        } else if (j.is_number_float()) {
            val->set_double_value(j.get<double>());
        } else if (j.is_array()) {
            auto* arr = val->mutable_array_value();
            for (const auto& item : j) {
                json_to_proto(item, arr->add_values());
            }
        } else if (j.is_object()) {
            auto* map = val->mutable_map_value();
            for (const auto& [k, v] : j.items()) {
                json_to_proto(v, &(*map->mutable_fields())[k]);
            }
        } else if (j.is_null()) {
            val->set_null_value(true);
        }
    };

    ::smartbotic::database::MapValue data;
    for (const auto& [key, value] : json_settings.items()) {
        json_to_proto(value, &(*data.mutable_fields())[key]);
    }

    // Try update first, then create
    {
        grpc::ClientContext ctx;
        ::smartbotic::database::UpdateDocumentRequest req;
        ::smartbotic::database::Document resp;

        req.set_collection(kSettingsCollection);
        req.set_id(doc_id);
        req.set_merge(true);
        *req.mutable_data() = data;

        auto status = db_client_.GetDocumentService()->UpdateDocument(&ctx, req, &resp);
        if (status.ok()) {
            return true;
        }
    }

    // Create if update failed
    {
        grpc::ClientContext ctx;
        ::smartbotic::database::CreateDocumentRequest req;
        ::smartbotic::database::Document resp;

        req.set_collection(kSettingsCollection);
        req.set_id(doc_id);
        *req.mutable_data() = data;

        auto status = db_client_.GetDocumentService()->CreateDocument(&ctx, req, &resp);
        if (!status.ok()) {
            spdlog::error("Failed to store collection settings: {}", status.error_message());
            return false;
        }
    }

    return true;
}

auto CollectionService::LoadSettings(const std::string& workspace_id, const std::string& name) -> CollectionSettings {
    std::string doc_id = workspace_id + "_" + name;

    grpc::ClientContext ctx;
    ::smartbotic::database::GetDocumentRequest req;
    ::smartbotic::database::Document resp;

    req.set_collection(kSettingsCollection);
    req.set_id(doc_id);

    auto status = db_client_.GetDocumentService()->GetDocument(&ctx, req, &resp);
    if (!status.ok()) {
        return {};  // Return defaults if not found
    }

    CollectionSettings settings;
    const auto& fields = resp.data().fields();

    if (auto it = fields.find("schema"); it != fields.end() && it->second.has_string_value()) {
        settings.schema = it->second.string_value();
    }
    if (auto it = fields.find("is_system"); it != fields.end() && it->second.has_bool_value()) {
        settings.is_system = it->second.bool_value();
    }
    if (auto it = fields.find("ttl_seconds"); it != fields.end() && it->second.has_int_value()) {
        settings.ttl_seconds = it->second.int_value();
    }
    if (auto it = fields.find("encrypted_fields"); it != fields.end() && it->second.has_array_value()) {
        for (const auto& val : it->second.array_value().values()) {
            if (val.has_string_value()) {
                settings.encrypted_fields.push_back(val.string_value());
            }
        }
    }

    // Load field_permissions
    if (auto it = fields.find("field_permissions"); it != fields.end() && it->second.has_array_value()) {
        for (const auto& fp_val : it->second.array_value().values()) {
            if (fp_val.has_map_value()) {
                FieldPermission fp;
                const auto& fp_fields = fp_val.map_value().fields();

                if (auto fn_it = fp_fields.find("field_name"); fn_it != fp_fields.end() && fn_it->second.has_string_value()) {
                    fp.field_name = fn_it->second.string_value();
                }

                if (auto rg_it = fp_fields.find("read_groups"); rg_it != fp_fields.end() && rg_it->second.has_array_value()) {
                    for (const auto& rg : rg_it->second.array_value().values()) {
                        if (rg.has_string_value()) {
                            fp.read_groups.push_back(rg.string_value());
                        }
                    }
                }

                if (auto wg_it = fp_fields.find("write_groups"); wg_it != fp_fields.end() && wg_it->second.has_array_value()) {
                    for (const auto& wg : wg_it->second.array_value().values()) {
                        if (wg.has_string_value()) {
                            fp.write_groups.push_back(wg.string_value());
                        }
                    }
                }

                settings.field_permissions.push_back(std::move(fp));
            }
        }
    }

    return settings;
}

auto CollectionService::DeleteSettings(const std::string& workspace_id, const std::string& name) -> bool {
    std::string doc_id = workspace_id + "_" + name;

    grpc::ClientContext ctx;
    ::smartbotic::database::DeleteDocumentRequest req;
    ::smartbotic::database::DeleteDocumentResponse resp;

    req.set_collection(kSettingsCollection);
    req.set_id(doc_id);

    auto status = db_client_.GetDocumentService()->DeleteDocument(&ctx, req, &resp);
    return status.ok();
}

}  // namespace smartbotic::webserver