/*
 * Copyright (C) 2018 CESNET, https://photonics.cesnet.cz/
 * Copyright (C) 2018 FIT CVUT, https://fit.cvut.cz/
 *
 * Written by Václav Kubernát <kubervac@fit.cvut.cz>
 *
*/

#include <libyang/Libyang.hpp>
#include <libyang/Tree_Schema.hpp>
#include <string_view>
#include "utils.hpp"
#include "yang_schema.hpp"

class YangLoadError : public std::runtime_error {
public:
    using std::runtime_error::runtime_error;
    ~YangLoadError() override = default;
};

class UnsupportedYangTypeException : public std::runtime_error {
public:
    using std::runtime_error::runtime_error;
    ~UnsupportedYangTypeException() override = default;
};

class InvalidSchemaQueryException : public std::runtime_error {
public:
    using std::runtime_error::runtime_error;
    ~InvalidSchemaQueryException() override = default;
};

std::string pathToYangAbsSchemPath(const path_& path)
{
    std::string res = "/";
    std::string currentModule;

    for (const auto& it : path.m_nodes) {
        const auto name = nodeToSchemaString(it);

        if (it.m_suffix.type() == typeid(module_)) {
            currentModule = name;
            continue;
        } else {
            res += currentModule + ":";
            res += name + "/";
        }
    }

    return res;
}

YangSchema::YangSchema()
    : m_context(std::make_shared<libyang::Context>())
{
}

YangSchema::~YangSchema() = default;

void YangSchema::addSchemaString(const char* schema)
{
    if (!m_context->parse_module_mem(schema, LYS_IN_YANG)) {
        throw YangLoadError("Couldn't load schema");
    }
}

void YangSchema::addSchemaDirectory(const char* directoryName)
{
    if (m_context->set_searchdir(directoryName)) {
        throw YangLoadError("Couldn't add schema search directory");
    }
}

void YangSchema::addSchemaFile(const char* filename)
{
    if (!m_context->parse_module_path(filename, LYS_IN_YANG)) {
        throw YangLoadError("Couldn't load schema");
    }
}

bool YangSchema::isModule(const path_&, const std::string& name) const
{
    const auto set = modules();
    return set.find(name) != set.end();
}

bool YangSchema::isContainer(const path_& location, const ModuleNodePair& node) const
{
    const auto schemaNode = getSchemaNode(location, node);
    return schemaNode && schemaNode->nodetype() == LYS_CONTAINER;
}

bool YangSchema::isLeaf(const path_& location, const ModuleNodePair& node) const
{
    const auto schemaNode = getSchemaNode(location, node);
    return schemaNode && schemaNode->nodetype() == LYS_LEAF;
}

bool YangSchema::isList(const path_& location, const ModuleNodePair& node) const
{
    const auto schemaNode = getSchemaNode(location, node);
    return schemaNode && schemaNode->nodetype() == LYS_LIST;
}

bool YangSchema::isPresenceContainer(const path_& location, const ModuleNodePair& node) const
{
    if (!isContainer(location, node))
        return false;
    return libyang::Schema_Node_Container(getSchemaNode(location, node)).presence();
}

bool YangSchema::leafEnumHasValue(const path_& location, const ModuleNodePair& node, const std::string& value) const
{
    if (!isLeaf(location, node) || leafType(location, node) != yang::LeafDataTypes::Enum)
        return false;

    libyang::Schema_Node_Leaf leaf(getSchemaNode(location, node));
    const auto& enm = leaf.type()->info()->enums()->enm();

    return std::any_of(enm.begin(), enm.end(), [=](const auto& x) { return x->name() == value; });
}

bool YangSchema::listHasKey(const path_& location, const ModuleNodePair& node, const std::string& key) const
{
    if (!isList(location, node))
        return false;
    const auto keys = listKeys(location, node);
    return keys.find(key) != keys.end();
}

bool YangSchema::nodeExists(const std::string& location, const std::string& node) const
{
    const auto absPath = location + "/" + node;
    const auto set = m_context->find_path(absPath.c_str());
    return set->number() == 1;
}

libyang::S_Set YangSchema::getNodeSet(const path_& location, const ModuleNodePair& node) const
{
    std::string absPath = location.m_nodes.empty() ? "" : "/";
    absPath += pathToAbsoluteSchemaString(location) + "/" + fullNodeName(location, node);
    return m_context->find_path(absPath.c_str());
}

libyang::S_Schema_Node YangSchema::getSchemaNode(const path_& location, const ModuleNodePair& node) const
{
    const auto set = getNodeSet(location, node);
    if (!set)
        return nullptr;
    const auto& schemaSet = set->schema();
    if (set->number() != 1)
        return nullptr;
    return *schemaSet.begin();
}

const std::set<std::string> YangSchema::listKeys(const path_& location, const ModuleNodePair& node) const
{
    std::set<std::string> keys;
    if (!isList(location, node))
        return keys;
    libyang::Schema_Node_List list(getSchemaNode(location, node));
    const auto& keysVec = list.keys();

    std::transform(keysVec.begin(), keysVec.end(), std::inserter(keys, keys.begin()),
            [] (const auto& it) {return it->name();});
    return keys;
}

yang::LeafDataTypes YangSchema::leafType(const path_& location, const ModuleNodePair& node) const
{
    using namespace std::string_literals;
    if (!isLeaf(location, node))
        throw InvalidSchemaQueryException(fullNodeName(location, node) + " is not a leaf");

    libyang::Schema_Node_Leaf leaf(getSchemaNode(location, node));
    switch (leaf.type()->base()) {
    case LY_TYPE_STRING:
        return yang::LeafDataTypes::String;
    case LY_TYPE_DEC64:
        return yang::LeafDataTypes::Decimal;
    case LY_TYPE_BOOL:
        return yang::LeafDataTypes::Bool;
    case LY_TYPE_INT32:
        return yang::LeafDataTypes::Int;
    case LY_TYPE_UINT32:
        return yang::LeafDataTypes::Uint;
    case LY_TYPE_ENUM:
        return yang::LeafDataTypes::Enum;
    default:
        throw UnsupportedYangTypeException("the type of "s + fullNodeName(location, node) + " is not supported");
    }
}

std::set<std::string> YangSchema::modules() const
{
    const auto& modules = m_context->get_module_iter();

    std::set<std::string> res;
    std::transform(modules.begin(), modules.end(),
                   std::inserter(res, res.end()),
                   [] (const auto module) { return module->name(); });
    return res;
}

std::set<std::string> YangSchema::childNodes(const path_& path) const
{
    using namespace std::string_view_literals;
    std::set<std::string> res;
    if (path.m_nodes.empty()) {
        const auto& nodeVec = m_context->data_instantiables(0);
        for (const auto it : nodeVec) {
            if (it->module()->name() == "ietf-yang-library"sv)
                continue;
            res.insert(std::string(it->module()->name()) + ":" + it->name());
        }
    } else {
        const auto absolutePath = "/" + pathToAbsoluteSchemaString(path);
        const auto set = m_context->find_path(absolutePath.c_str());
        const auto& schemaSet = set->schema();
        for (auto it = (*schemaSet.begin())->child(); it; it = it->next()) {
            res.insert(std::string(it->module()->name()) + ":" + it->name());
        }
    }
    return res;
}