#include "pom.hpp"

#include <pom.h>
#include <cstring>
#include <cstdlib>
#include <string>
#include <istream>

namespace pom {

Configuration::~Configuration() {
	pom_conf_free(static_cast<pom_conf *>(C));
}

Configuration::Configuration(): C(nullptr) {}

Error::~Error() { if (m_is_original) free(C); }

Error::Error(void *C_error): C(C_error), m_is_original(true) {
	const pom_error *next = pom_error_next(static_cast<const pom_error *>(C));
	if (next)
		m_next = std::unique_ptr<Error>(new Error(static_cast<const void *>(next)));
}

// const_cast here to avoid creating a separate ConstError type
Error::Error(const void *C_error): C(const_cast<void *>(C_error)), m_is_original(false) {
	const pom_error *next = pom_error_next(static_cast<const pom_error *>(C));
	if (next)
		m_next = std::unique_ptr<Error>(new Error(static_cast<const void *>(next)));
}

std::string_view Error::file() const noexcept {
	return pom_error_file(static_cast<const pom_error *>(C));
}

uint64_t Error::line() const noexcept {
	return pom_error_line(static_cast<const pom_error *>(C));
}

std::string_view Error::message() const noexcept {
	return pom_error_message(static_cast<const pom_error *>(C));
}

const Error *Error::next() const noexcept {
	return m_next.get();
}

const char *Error::what() const noexcept {
	return m_is_original ? pom_error_to_string(static_cast<pom_error *>(C))
		: pom_error_message(static_cast<const pom_error *>(C));
}

std::string_view Error::to_string() noexcept {
	return what();
}

Configuration Configuration::section(std::string_view name) const {
	std::string name_str(name);
	const pom_conf *C_section = pom_conf_section(
		static_cast<const pom_conf *>(C), name_str.c_str());
	pom_conf *C_section_copy = pom_conf_copy(C_section);
	return Configuration(static_cast<void *>(C_section_copy));
}

static void *allocator_calloc(void *udata, size_t n, size_t sz) {
	return static_cast<Allocator *>(udata)->calloc(n, sz);
}

static void *allocator_realloc(void *udata, void *ptr, size_t sz) {
	return static_cast<Allocator *>(udata)->realloc(ptr, sz);
}

static void allocator_free(void *udata, void *ptr) {
	return static_cast<Allocator *>(udata)->free(ptr);
}

void Settings::to_C(void *C) const {
	pom_settings &C_settings = *static_cast<pom_settings *>(C);
	strcpy(C_settings.error_lang, m_error_lang);
	if (m_allocator) {
		C_settings.allocator_udata = m_allocator.get();
		C_settings.calloc = allocator_calloc;
		C_settings.realloc = allocator_realloc;
		C_settings.free = allocator_free;
	}
}

static size_t readable_read(void *udata, char *buf, size_t count) {
	return static_cast<Reader *>(udata)->read(buf, count);
}

Configuration::Configuration(std::string_view filename, Reader &source, const Settings *settings) {
 	pom_settings C_settings = {};
	if (settings) {
		settings->to_C(static_cast<void *>(&C_settings));
	}
	pom_error *error;
	std::string filename_str(filename);
	C = pom_load(&C_settings, filename_str.c_str(), readable_read, &source, &error);
	if (error) {
		throw Error(static_cast<void *>(error));
	}
}

Configuration::Configuration(std::string_view path, const Settings *settings) {
 	pom_settings C_settings = {};
	if (settings) {
		settings->to_C(static_cast<void *>(&C_settings));
	}
	pom_error *error;
	std::string path_str(path);
	C = pom_load_path(&C_settings, path_str.c_str(), &error);
	if (error) {
		throw Error(static_cast<void *>(error));
	}
}

class StringViewReader: public Reader {
public:
	explicit StringViewReader(std::string_view v): string(v) {}
	virtual size_t read(char *buf, size_t count) {
		count = std::min(count, string.size());
		memcpy(buf, string.data(), count);
		return count;
	}
private:
	std::string_view string;
};

Configuration::Configuration(std::string_view filename, std::string_view string, const Settings *settings) {
	StringViewReader reader(string);
 	Configuration(filename, reader, settings);
}

class IStreamReader: public Reader {
public:
	explicit IStreamReader(std::istream &stream): ifstream(stream) {}
	virtual size_t read(char *buf, size_t count) {
		ifstream.read(buf, count);
		return ifstream.gcount();
	}
private:
	std::istream &ifstream;
};


Configuration::Configuration(std::string_view filename, std::istream &stream, const Settings *settings) {
	IStreamReader reader(stream);
 	Configuration(filename, reader, settings);
}

void Configuration::merge(const Configuration &other) {
	if (!other.C) return;
	if (!C) {
		C = pom_conf_copy(static_cast<const pom_conf *>(other.C));
		return;
	}
	pom_conf_merge(static_cast<pom_conf *>(C), static_cast<const pom_conf *>(other.C));
}

std::optional<std::string_view> Configuration::get(std::string_view key) const {
	if (!C) return {};
	std::string key_str(key);
	const char *value = pom_conf_get(static_cast<const pom_conf *>(C), key_str.c_str());
	if (!value)
		return {};
	else
		return value;
}

std::string_view Configuration::get_or_default(std::string_view key, std::string_view dflt) const {
	return get(key).value_or(dflt);
}

} // namespace pom