/**
 * \file
 * \copyright
 * Copyright (c) 2012-2021, OpenGeoSys Community (http://www.opengeosys.org)
 *            Distributed under a Modified BSD License.
 *              See accompanying file LICENSE.txt or
 *              http://www.opengeosys.org/project/license
 *
 */

#include "ConfigTree.h"

#include <sstream>
#include <utility>

namespace BaseLib
{

//! Wraps a pair of iterators for use as a range in range-based for-loops.
template<typename Iterator>
class Range
{
public:
    explicit Range(Iterator begin, Iterator end)
        : _begin(std::move(begin)), _end(std::move(end))
    {}

    Iterator begin() const { return _begin; }
    Iterator end()   const { return _end; }
    std::size_t size() const { return std::distance(_begin, _end); }
    bool empty() const { return size() == 0; }

private:
    Iterator _begin;
    Iterator _end;
};

template<typename T>
T
ConfigTree::
getConfigParameter(std::string const& param) const
{
    if (auto p = getConfigParameterOptional<T>(param))
    {
        return *p;
    }

    error("Key <" + param + "> has not been found");
}

template<typename T>
T
ConfigTree::
getConfigParameter(std::string const& param, T const& default_value) const
{
    if (auto p = getConfigParameterOptional<T>(param))
    {
        return *p;
    }

    return default_value;
}

template <typename T>
std::optional<T> ConfigTree::getConfigParameterOptional(
    std::string const& param) const
{
    checkUnique(param);

    return getConfigParameterOptionalImpl(param, static_cast<T*>(nullptr));
}

template <typename T>
std::optional<T> ConfigTree::getConfigParameterOptionalImpl(
    std::string const& param, T* /*unused*/) const
{
    if (auto p = getConfigSubtreeOptional(param))
    {
        return p->getValue<T>();
    }

    return std::nullopt;
}

template <typename T>
std::optional<std::vector<T>> ConfigTree::getConfigParameterOptionalImpl(
    std::string const& param, std::vector<T>* /*unused*/) const
{
    if (auto p = getConfigSubtreeOptional(param))
    {
        std::istringstream sstr{p->getValue<std::string>()};
        std::vector<T> result;
        T value;
        while (sstr >> value)
        {
            result.push_back(value);
        }
        if (!sstr.eof())  // The stream is not read until the end, must be an
                        // error. result contains number of read values.
        {
            error("Value for key <" + param + "> `" +
                  shortString(sstr.str()) +
                  "' not convertible to a vector of the desired type."
                  " Could not convert token no. " +
                  std::to_string(result.size() + 1) + ".");
            return std::nullopt;
        }

        return std::make_optional(result);
    }

    return std::nullopt;
}

template<typename T>
Range<ConfigTree::ValueIterator<T> >
ConfigTree::
getConfigParameterList(std::string const& param) const
{
    checkUnique(param);
    markVisited<T>(param, Attr::TAG, true);

    auto p = _tree->equal_range(param);
    return Range<ValueIterator<T> >(
                ValueIterator<T>(p.first,  param, *this),
                ValueIterator<T>(p.second, param, *this));
}

template<typename T>
T
ConfigTree::
peekConfigParameter(std::string const& param) const
{
    checkKeyname(param);

    if (auto p = _tree->get_child_optional(param))
    {
        try
        {
            return p->get_value<T>();
        }
        catch (boost::property_tree::ptree_bad_data const&)
        {
            error("Value for key <" + param + "> `" + shortString(p->data()) +
                  "' not convertible to the desired type.");
        }
    }
    else
    {
        error("Key <" + param + "> has not been found");
    }
}

template<typename T>
void
ConfigTree::
checkConfigParameter(std::string const& param, T const& value) const
{
    if (getConfigParameter<T>(param) != value) {
        error("The value of key <" + param + "> is not the expected one.");
    }
}

template<typename Ch>
void
ConfigTree::
checkConfigParameter(std::string const& param, Ch const* value) const
{
    if (getConfigParameter<std::string>(param) != value) {
        error("The value of key <" + param + "> is not the expected one.");
    }
}

template<typename T>
T
ConfigTree::
getValue() const
{
    if (_have_read_data) {
        error("The data of this subtree has already been read.");
    }

    _have_read_data = true;

    if (auto v = _tree->get_value_optional<T>()) {
        return *v;
    }
    error("Value `" + shortString(_tree->data()) +
          "' is not convertible to the desired type.");
}

template<typename T>
T
ConfigTree::
getConfigAttribute(std::string const& attr) const
{
    if (auto a = getConfigAttributeOptional<T>(attr))
    {
        return *a;
    }

    error("Did not find XML attribute with name '" + attr + "'.");
}

template <typename T>
T ConfigTree::getConfigAttribute(std::string const& attr,
                                 T const& default_value) const
{
    if (auto a = getConfigAttributeOptional<T>(attr))
    {
        return *a;
    }

    return default_value;
}

template <typename T>
std::optional<T> ConfigTree::getConfigAttributeOptional(
    std::string const& attr) const
{
    checkUniqueAttr(attr);
    auto& ct = markVisited<T>(attr, Attr::ATTR, true);

    if (auto attrs = _tree->get_child_optional("<xmlattr>")) {
        if (auto a = attrs->get_child_optional(attr)) {
            ++ct.count; // count only if attribute has been found
            if (auto v = a->get_value_optional<T>()) {
                return std::make_optional(*v);
            }
            error("Value for XML attribute '" + attr + "' `" +
                  shortString(a->data()) +
                  "' not convertible to the desired type.");
        }
    }

    return std::nullopt;
}

template<typename T>
ConfigTree::CountType&
ConfigTree::
markVisited(std::string const& key, Attr const is_attr,
            bool const peek_only) const
{
    auto const type = std::type_index(typeid(T));

    auto p = _visited_params.emplace(std::make_pair(is_attr, key),
                                     CountType{peek_only ? 0 : 1, type});

    if (!p.second) { // no insertion happened
        auto& v = p.first->second;
        if (v.type == type) {
            if (!peek_only)
            {
                ++v.count;
            }
        } else {
            error("There already was an attempt to obtain key <" + key +
                  "> with type '" + v.type.name() + "' (now: '" + type.name() +
                  "').");
        }
    }

    return p.first->second;
}

}  // namespace BaseLib