// Copyright (C) 2018-2022 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef ISC_TRANSLATOR_TEST_H
#define ISC_TRANSLATOR_TEST_H 1

#include <yang/translator.h>

#include <vector>
#include <unordered_map>

namespace isc {
namespace yang {
namespace test {

/// @brief Yang/sysrepo datastore textual representation class.
///
/// This class allows to store a configuration tree in YANG format.
/// It is used in tests to conduct operations on whole configurations.
class YangRepr {
public:
    /// @brief Constructor.
    ///
    /// @param model The model name.
    YangRepr(const std::string& model) : model_(model) {
    }

    /// @brief A struct representing a single entry.
    struct YangReprItem {
        /// @brief Constructor with content.
        ///
        /// @param xpath The xpath.
        /// @param value The textual value.
        /// @param type The type of the value.
        /// @param settable The settable flag.
        YangReprItem(std::string xpath, std::optional<std::string> value,
                     libyang::LeafBaseType type, bool settable)
            : xpath_(xpath), value_(value), type_(type), settable_(settable) {
        }

        /// @brief Retrieves configuration parameter from sysrepo.
        ///
        /// @param xpath The xpath of an element to be retrieved.
        /// @param session Sysrepo session.
        /// @return YangReprItem instance representing configuration parameter.
        static YangReprItem get(const std::string& xpath,
                                sysrepo::Session session);

        /// @brief The xpath.
        std::string xpath_;

        /// @brief The textual value.
        std::optional<std::string> value_;

        /// @brief The type of the value.
        libyang::LeafBaseType type_;

        /// @brief The settable flag.
        bool settable_;

        /// @brief The equal operator ignoring settable.
        ///
        /// @param other the other object to compare with.
        /// @return true if equal.
        bool operator==(const YangReprItem& other) const {
            return ((xpath_ == other.xpath_) &&
                    (value_ == other.value_) &&
                    (type_ == other.type_));
        }

        /// @brief The unequal operator ignoring settable.
        ///
        /// @param other the other object to compare with.
        /// @return false if equal.
        bool operator!=(const YangReprItem& other) const {
            return (!(*this == other));
        }

    private:
        /// @brief Gets the underlying type behind a union node.
        ///
        /// @param value the value obtained from the union node with ->asTerm().value()
        ///
        /// @return the underlying type
        static libyang::LeafBaseType getUnionType(libyang::Value const& value);
    };  // YangReprItem

    /// @brief Tree type.
    ///
    /// Indexed by xpath so that we can check against an entry received from
    /// sysrepo which has empirically proven to not come in a certain order
    /// starting with sysrepo 1.x. Relying on the order would have made a linear
    /// data structure more fitting.
    using Tree = std::unordered_map<std::string, YangReprItem>;

    /// @brief Get tree from session.
    ///
    /// @param session Sysrepo session.
    Tree get(sysrepo::Session session) const;

    /// @brief Verifies a tree.
    ///
    /// @param expected The expected value.
    /// @param session Sysrepo session.
    /// @param errs Error stream.
    /// @return true if verification succeeds, false with errors displayed.
    /// on errs if it fails.
    bool verify(const Tree& expected, sysrepo::Session session,
                std::ostream& errs) const;

    /// @brief Sets specified tree in a sysrepo.
    ///
    /// The actual access parameters are specified within session.
    ///
    /// @param tree The tree to install.
    /// @param session Sysrepo session.
    void set(const Tree& tree, sysrepo::Session session) const;

    /// @brief Convenience function that indexes a collection of items by xpath.
    ///
    /// @param v the input vector
    ///
    /// @return the output map
    static Tree buildTreeFromVector(std::vector<YangReprItem> const& v) {
        Tree tree;
        for (YangReprItem const& item : v) {
            if (tree.contains(item.xpath_)) {
                isc_throw(BadValue, "YangRepr::buildTreeFromVector(): duplicate " << item.xpath_);
            }
            tree.emplace(item.xpath_, item);
        }
        return tree;
    }

private:
    /// @brief The model name.
    std::string model_;
};  // YangRepr

/// @brief Alias for Items.
using YRItem = YangRepr::YangReprItem;

/// @brief Alias for Trees.
using YRTree = YangRepr::Tree;

/// @brief Overrides standard output operator for LeafBaseType.
std::ostream& operator<<(std::ostream& os, libyang::LeafBaseType type);

/// @brief Overrides standard output operator for @c YangReprItem object.
std::ostream& operator<<(std::ostream& os, const YRItem& item);

/// @brief Overrides standard output operator for @c Tree object.
std::ostream& operator<<(std::ostream& os, const YRTree& tree);

}  // namespace test
}  // namespace yang
}  // namespace isc

#endif  // ISC_TRANSLATOR_TEST_H