/*
    path.h -- A simple class for manipulating paths on Linux/Windows/Mac OS

    Copyright (c) 2015 Wenzel Jakob <wenzel@inf.ethz.ch>

    All rights reserved. Use of this source code is governed by a
    BSD-style license that can be found in the LICENSE file.
*/

#pragma once

#include "fwd.h"
#include <string>
#include <vector>
#include <stdexcept>
#include <sstream>
#include <cctype>
#include <cstdlib>
#include <cerrno>
#include <cstring>

#if defined(_WIN32)
# include <windows.h>
#else
# include <unistd.h>
#endif
#include <sys/stat.h>

#if defined(__linux)
# include <linux/limits.h>
#endif

NAMESPACE_BEGIN(filesystem)

/**
 * \brief Simple class for manipulating paths on Linux/Windows/Mac OS
 *
 * This class is just a temporary workaround to avoid the heavy boost
 * dependency until boost::filesystem is integrated into the standard template
 * library at some point in the future.
 */
class path {
public:
    enum path_type {
        windows_path = 0,
        posix_path = 1,
#if defined(_WIN32)
        native_path = windows_path
#else
        native_path = posix_path
#endif
    };

    path() : m_type(native_path), m_absolute(false) { }

    path(const path &path)
        : m_type(path.m_type), m_path(path.m_path), m_absolute(path.m_absolute) {}

    path(path &&path)
        : m_type(path.m_type), m_path(std::move(path.m_path)),
          m_absolute(path.m_absolute) {}

    path(const char *string) { set(string); }

    path(const std::string &string) { set(string); }

#if defined(_WIN32)
    path(const std::wstring &wstring) { set(wstring); }
    path(const wchar_t *wstring) { set(wstring); }
#endif

    size_t length() const { return m_path.size(); }

    bool empty() const { return m_path.empty(); }

    bool is_absolute() const { return m_absolute; }

    path make_absolute() const {
#if !defined(_WIN32)
        char temp[PATH_MAX];
        if (realpath(str().c_str(), temp) == NULL)
            throw std::runtime_error("Internal error in realpath(): " + std::string(strerror(errno)));
        return path(temp);
#else
        std::wstring value = wstr(), out(MAX_PATH, '\0');
        DWORD length = GetFullPathNameW(value.c_str(), MAX_PATH, &out[0], NULL);
        if (length == 0)
            throw std::runtime_error("Internal error in realpath(): " + std::to_string(GetLastError()));
        return path(out.substr(0, length));
#endif
    }

    bool exists() const {
#if defined(_WIN32)
        return GetFileAttributesW(wstr().c_str()) != INVALID_FILE_ATTRIBUTES;
#else
        struct stat sb;
        return stat(str().c_str(), &sb) == 0;
#endif
    }

    size_t file_size() const {
#if defined(_WIN32)
        struct _stati64 sb;
        if (_wstati64(wstr().c_str(), &sb) != 0)
            throw std::runtime_error("path::file_size(): cannot stat file \"" + str() + "\"!");
#else
        struct stat sb;
        if (stat(str().c_str(), &sb) != 0)
            throw std::runtime_error("path::file_size(): cannot stat file \"" + str() + "\"!");
#endif
        return (size_t) sb.st_size;
    }

    bool is_directory() const {
#if defined(_WIN32)
        DWORD result = GetFileAttributesW(wstr().c_str());
        if (result == INVALID_FILE_ATTRIBUTES)
            return false;
        return (result & FILE_ATTRIBUTE_DIRECTORY) != 0;
#else
        struct stat sb;
        if (stat(str().c_str(), &sb))
            return false;
        return S_ISDIR(sb.st_mode);
#endif
    }

    bool is_file() const {
#if defined(_WIN32)
        DWORD attr = GetFileAttributesW(wstr().c_str());
        return (attr != INVALID_FILE_ATTRIBUTES && (attr & FILE_ATTRIBUTE_DIRECTORY) == 0);
#else
        struct stat sb;
        if (stat(str().c_str(), &sb))
            return false;
        return S_ISREG(sb.st_mode);
#endif
    }

    std::string extension() const {
        const std::string &name = filename();
        size_t pos = name.find_last_of(".");
        if (pos == std::string::npos)
            return "";
        return name.substr(pos+1);
    }

    std::string filename() const {
        if (empty())
            return "";
        const std::string &last = m_path[m_path.size()-1];
        return last;
    }

    path parent_path() const {
        path result;
        result.m_absolute = m_absolute;

        if (m_path.empty()) {
            if (!m_absolute)
                result.m_path.push_back("..");
        } else {
            size_t until = m_path.size() - 1;
            for (size_t i = 0; i < until; ++i)
                result.m_path.push_back(m_path[i]);
        }
        return result;
    }

    path operator/(const path &other) const {
        if (other.m_absolute)
            throw std::runtime_error("path::operator/(): expected a relative path!");
        if (m_type != other.m_type)
            throw std::runtime_error("path::operator/(): expected a path of the same type!");

        path result(*this);

        for (size_t i=0; i<other.m_path.size(); ++i)
            result.m_path.push_back(other.m_path[i]);

        return result;
    }

    std::string str(path_type type = native_path) const {
        std::ostringstream oss;

        if (m_type == posix_path && m_absolute)
            oss << "/";

        for (size_t i=0; i<m_path.size(); ++i) {
            oss << m_path[i];
            if (i+1 < m_path.size()) {
                if (type == posix_path)
                    oss << '/';
                else
                    oss << '\\';
            }
        }

        return oss.str();
    }

    void set(const std::string &str, path_type type = native_path) {
        m_type = type;
        if (type == windows_path) {
            m_path = tokenize(str, "/\\");
            m_absolute = str.size() >= 2 && std::isalpha(str[0]) && str[1] == ':';
        } else {
            m_path = tokenize(str, "/");
            m_absolute = !str.empty() && str[0] == '/';
        }
    }

    path &operator=(const path &path) {
        m_type = path.m_type;
        m_path = path.m_path;
        m_absolute = path.m_absolute;
        return *this;
    }

    path &operator=(path &&path) {
        if (this != &path) {
            m_type = path.m_type;
            m_path = std::move(path.m_path);
            m_absolute = path.m_absolute;
        }
        return *this;
    }

    friend std::ostream &operator<<(std::ostream &os, const path &path) {
        os << path.str();
        return os;
    }

    bool remove_file() {
#if !defined(_WIN32)
        return std::remove(str().c_str()) == 0;
#else
        return DeleteFileW(wstr().c_str()) != 0;
#endif
    }

    bool resize_file(size_t target_length) {
#if !defined(_WIN32)
        return ::truncate(str().c_str(), (off_t) target_length) == 0;
#else
        HANDLE handle = CreateFileW(wstr().c_str(), GENERIC_WRITE, 0, nullptr, 0, FILE_ATTRIBUTE_NORMAL, nullptr);
        if (handle == INVALID_HANDLE_VALUE)
            return false;
        LARGE_INTEGER size;
        size.QuadPart = (LONGLONG) target_length;
        if (SetFilePointerEx(handle, size, NULL, FILE_BEGIN) == 0) {
            CloseHandle(handle);
            return false;
        }
        if (SetEndOfFile(handle) == 0) {
            CloseHandle(handle);
            return false;
        }
        CloseHandle(handle);
        return true;
#endif
    }

    static path getcwd() {
#if !defined(_WIN32)
        char temp[PATH_MAX];
        if (::getcwd(temp, PATH_MAX) == NULL)
            throw std::runtime_error("Internal error in getcwd(): " + std::string(strerror(errno)));
        return path(temp);
#else
        std::wstring temp(MAX_PATH, '\0');
        if (!_wgetcwd(&temp[0], MAX_PATH))
            throw std::runtime_error("Internal error in getcwd(): " + std::to_string(GetLastError()));
        return path(temp.c_str());
#endif
    }

#if defined(_WIN32)
    std::wstring wstr(path_type type = native_path) const {
        std::string temp = str(type);
        int size = MultiByteToWideChar(CP_UTF8, 0, &temp[0], (int)temp.size(), NULL, 0);
        std::wstring result(size, 0);
        MultiByteToWideChar(CP_UTF8, 0, &temp[0], (int)temp.size(), &result[0], size);
        return result;
    }


    void set(const std::wstring &wstring, path_type type = native_path) {
        std::string string;
        if (!wstring.empty()) {
            int size = WideCharToMultiByte(CP_UTF8, 0, &wstring[0], (int)wstring.size(),
                            NULL, 0, NULL, NULL);
            string.resize(size, 0);
            WideCharToMultiByte(CP_UTF8, 0, &wstring[0], (int)wstring.size(),
                                &string[0], size, NULL, NULL);
        }
        set(string, type);
    }

    path &operator=(const std::wstring &str) { set(str); return *this; }
#endif

    bool operator==(const path &p) const { return p.m_path == m_path; }
    bool operator!=(const path &p) const { return p.m_path != m_path; }

protected:
    static std::vector<std::string> tokenize(const std::string &string, const std::string &delim) {
        std::string::size_type lastPos = 0, pos = string.find_first_of(delim, lastPos);
        std::vector<std::string> tokens;

        while (lastPos != std::string::npos) {
            if (pos != lastPos)
                tokens.push_back(string.substr(lastPos, pos - lastPos));
            lastPos = pos;
            if (lastPos == std::string::npos || lastPos + 1 == string.length())
                break;
            pos = string.find_first_of(delim, ++lastPos);
        }

        return tokens;
    }

protected:
    path_type m_type;
    std::vector<std::string> m_path;
    bool m_absolute;
};

inline bool create_directory(const path& p) {
#if defined(_WIN32)
    return CreateDirectoryW(p.wstr().c_str(), NULL) != 0;
#else
    return mkdir(p.str().c_str(), S_IRUSR | S_IWUSR | S_IXUSR) == 0;
#endif
}

NAMESPACE_END(filesystem)