//
// Copyright 2010-2012,2015 Ettus Research LLC
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
//

#include <uhd/config.hpp>
#include <uhd/exception.hpp>
#include <uhd/utils/paths.hpp>

#include <boost/algorithm/string.hpp>
#include <boost/bind.hpp>
#include <boost/filesystem.hpp>
#include <boost/format.hpp>
#include <boost/regex.hpp>
#include <boost/tokenizer.hpp>

#include <cstdio>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <streambuf>
#include <string>
#include <vector>

#ifdef BOOST_MSVC
#define USE_GET_TEMP_PATH
#include <windows.h> //GetTempPath
#endif

namespace fs = boost::filesystem;

/*! Get the value of an environment variable.
 *
 * The returned std::string is the full environment variable string, and thus
 * may actually contain multiple fields in the string with delimiters.
 *
 * \param var_name The name of the variable to search for.
 * \param default_val A default string value to use if the path isn't found.
 * \returns The string value of the environment variable.
 */
static std::string get_env_var(const std::string &var_name,
        const std::string &default_val = "") {

    std::string env_result = default_val;
    char *env_var_str = NULL;

    /* Some versions of MinGW don't expose `_dupenv_s` */
#if defined(UHD_PLATFORM_WIN32) && !defined(__MINGW32__)
    size_t len;
    errno_t err = _dupenv_s(&env_var_str, &len, var_name.c_str());
    if((not err) and (env_var_str != NULL))
        env_result = std::string(env_var_str);
    free(env_var_str);
#else
    env_var_str = std::getenv(var_name.c_str());
    if(env_var_str != NULL)
        env_result = std::string(env_var_str);
#endif

    return env_result;
}

/*! Get a vector of paths from an environment variable.
 *
 * Reads an environment variable, which should contain a list of paths, and
 * returns a vector of those paths in the form of strings.
 *
 * \param var_name The environment variable name to read.
 * \returns The vector of paths from the environment variable.
 */
static std::vector<std::string> get_env_paths(const std::string &var_name){
#ifdef UHD_PLATFORM_WIN32
    static const std::string env_path_sep = ";";
#else
    static const std::string env_path_sep = ":";
#endif /*UHD_PLATFORM_WIN32*/

#define path_tokenizer(inp) \
    boost::tokenizer<boost::char_separator<char> > \
    (inp, boost::char_separator<char>(env_path_sep.c_str()))

    std::string var_value = get_env_var(var_name);

    std::vector<std::string> paths;

    //convert to full filesystem path, filter blank paths
    if (var_value.empty()) return paths;
    for(const std::string &path_string:  path_tokenizer(var_value)){
        if (path_string.empty()) continue;
        paths.push_back(fs::system_complete(path_string).string());
    }

    return paths;
}

#ifndef UHD_PLATFORM_WIN32
/*! Expand a tilde character to the $HOME path.
 *
 * The path passed to this function must start with the tilde character in order
 * for this function to work properly. If it does not, it will simply return the
 * original path. The $HOME environment variable must exist.
 *
 * \param path The path starting with the tilde character
 * \returns The same path with the tilde expanded to contents of $HOME.
 */
static std::string expand_home_directory(std::string path) {
    boost::trim(path);

    if(path.empty() || (path[0] != '~')) {
        return path;
    }

    std::string user_home_path = get_env_var("HOME");
    path.replace(0, 1, user_home_path);

    return path;
}
#endif

/***********************************************************************
 * Implement the functions in paths.hpp
 **********************************************************************/


std::string uhd::get_tmp_path(void){
    const char *tmp_path = NULL;

    //try the official uhd temp path environment variable
    tmp_path = std::getenv("UHD_TEMP_PATH");
    if (tmp_path != NULL) return tmp_path;

    //try the windows function if available
    #ifdef USE_GET_TEMP_PATH
    char lpBuffer[2048];
    if (GetTempPath(sizeof(lpBuffer), lpBuffer)) return lpBuffer;
    #endif

    //try windows environment variables
    tmp_path = std::getenv("TMP");
    if (tmp_path != NULL) return tmp_path;

    tmp_path = std::getenv("TEMP");
    if (tmp_path != NULL) return tmp_path;

    //try the stdio define if available
    #ifdef P_tmpdir
    return P_tmpdir;
    #else

    //try unix environment variables
    tmp_path = std::getenv("TMPDIR");
    if (tmp_path != NULL) return tmp_path;

    //give up and use the unix default
    return "/tmp";
    #endif
}

std::string uhd::get_app_path(void){
    const std::string uhdcalib_path = get_env_var("UHD_CONFIG_DIR");
    if (not uhdcalib_path.empty()) return uhdcalib_path;

    const std::string appdata_path = get_env_var("APPDATA");
    if (not appdata_path.empty()) return appdata_path;

    const std::string home_path = get_env_var("HOME");
    if (not home_path.empty()) return home_path;

    return uhd::get_tmp_path();
}

std::string uhd::get_pkg_path(void) {
    return get_env_var("UHD_PKG_PATH", UHD_PKG_PATH);
}

std::vector<fs::path> uhd::get_module_paths(void){
    std::vector<fs::path> paths;

    std::vector<std::string> env_paths = get_env_paths("UHD_MODULE_PATH");
    for(std::string &str_path:  env_paths) {
        paths.push_back(str_path);
    }

    paths.push_back(fs::path(uhd::get_pkg_path()) / UHD_LIB_DIR / "uhd" / "modules");
    paths.push_back(fs::path(uhd::get_pkg_path()) / "share" / "uhd" / "modules");

    return paths;
}

#ifdef UHD_PLATFORM_WIN32
#include <windows.h>
/*!
 * On Windows, query the system registry for the UHD images install path.
 * If the key isn't found in the registry, an empty string is returned.
 * \param registry_key_path The registry key to look for.
 * \return The images path, formatted for windows.
 */
std::string _get_images_path_from_registry(const std::string& registry_key_path) {
    boost::smatch reg_key_match;
    //If a substring in the search path is enclosed in [] (square brackets) then it is interpreted as a registry path
    if (not boost::regex_search(registry_key_path, reg_key_match, boost::regex("\\[(.+)\\](.*)", boost::regex::icase)))
        return std::string();
    std::string reg_key_path = std::string(reg_key_match[1].first, reg_key_match[1].second);
    std::string path_suffix = std::string(reg_key_match[2].first, reg_key_match[2].second);

    //Split the registry path into parent, key-path and value.
    boost::smatch reg_parent_match;
    if (not boost::regex_search(reg_key_path, reg_parent_match, boost::regex("^(.+?)\\\\(.+)\\\\(.+)$", boost::regex::icase)))
        return std::string();
    std::string reg_parent = std::string(reg_parent_match[1].first, reg_parent_match[1].second);
    std::string reg_path = std::string(reg_parent_match[2].first, reg_parent_match[2].second);
    std::string reg_val_name = std::string(reg_parent_match[3].first, reg_parent_match[3].second);

    HKEY hkey_parent = HKEY_LOCAL_MACHINE;
    if      (reg_parent == "HKEY_LOCAL_MACHINE")    hkey_parent = HKEY_LOCAL_MACHINE;
    else if (reg_parent == "HKEY_CURRENT_USER")     hkey_parent = HKEY_CURRENT_USER;
    else if (reg_parent == "HKEY_CLASSES_ROOT")     hkey_parent = HKEY_CLASSES_ROOT;
    else if (reg_parent == "HKEY_CURRENT_CONFIG")   hkey_parent = HKEY_CURRENT_CONFIG;
    else if (reg_parent == "HKEY_USERS")            hkey_parent = HKEY_CURRENT_USER;

    TCHAR value_buff[1024];
    DWORD value_buff_size = 1024*sizeof(TCHAR);

    //Get a handle to the key location
    HKEY hkey_location;
    if (RegOpenKeyExA(hkey_parent, reg_path.c_str(), 0, KEY_QUERY_VALUE, &hkey_location) != ERROR_SUCCESS)
        return std::string();

    //Query key value
    DWORD dw_type = REG_SZ;
    if(RegQueryValueExA(hkey_location, reg_val_name.c_str(), NULL, &dw_type, (LPBYTE)value_buff, &value_buff_size) == ERROR_SUCCESS) {
        RegCloseKey(hkey_location);
        if (value_buff_size >= 1024*sizeof(TCHAR)) {
            return std::string();
        } else {
            std::string return_value(value_buff, value_buff_size-1); //value_buff_size includes the null terminator
            return_value += path_suffix;
            return return_value;
        }
    } else {
        return std::string();
    }
}
#endif  /*UHD_PLATFORM_WIN32*/

std::string uhd::get_images_dir(const std::string &search_paths) {

    /*   This function will check for the existence of directories in this
     *   order:
     *
     *   1) `UHD_IMAGES_DIR` environment variable
     *   2) Any paths passed to this function via `search_paths' (may contain
     *      Windows registry keys)
     *   3) `UHD package path` / share / uhd / images
     */

    std::string possible_dir;

    /* We will start by looking for a path indicated by the `UHD_IMAGES_DIR`
     * environment variable. */
    std::vector<std::string> env_paths = get_env_paths("UHD_IMAGES_DIR");
    for(auto possible_dir:  env_paths) {
        if (fs::is_directory(fs::path(possible_dir))) {
                return possible_dir;
        }
    }

    /* On Windows systems, we may need to modify the `search_paths` parameter
     * (see below). Making a local copy for const correctness. */
    std::string _search_paths = search_paths;

#ifdef UHD_IMAGES_DIR_WINREG_KEY
    _search_paths = std::string(STR(UHD_IMAGES_DIR_WINREG_KEY)) + "," + search_paths;
#endif

    /* Now we will parse and attempt to qualify the paths in the `search_paths`
     * parameter. If this is Windows, we will check the system registry for
     * these strings. */
    if (!_search_paths.empty()) {
        std::vector<std::string> search_paths_vector;

        boost::split(search_paths_vector, _search_paths, boost::is_any_of(",;"));
        for(std::string& search_path:  search_paths_vector) {

            boost::algorithm::trim(search_path);
            if (search_path.empty()) continue;

#ifdef UHD_PLATFORM_WIN32
            possible_dir = _get_images_path_from_registry(search_path);
            if (possible_dir.empty()) {
                //Could not read from the registry due to missing key, invalid
                //values, etc Just use the search path. The is_directory check
                //will fail if this is a registry path and we will move on to
                //the next item in the list.
                possible_dir = search_path;
            }
#else
            possible_dir = expand_home_directory(search_path);
#endif

            if (fs::is_directory(fs::path(possible_dir))) {
                return possible_dir;
            }
        }
    }

    /* Finally, check for the default UHD images installation path. */
    fs::path pkg_path = fs::path(uhd::get_pkg_path()) / "share" / "uhd" / "images";
    if (fs::is_directory(pkg_path)) {
        return pkg_path.string();
    } else {
        /* No luck. Return an empty string. */
        return std::string("");
    }
}

std::string uhd::find_image_path(const std::string &image_name, const std::string &search_paths){
    /* If a path was provided on the command-line or as a hint from the caller,
     * we default to that. */
    if (fs::exists(image_name)){
        return fs::system_complete(image_name).string();
    }

    /* Otherwise, look for the image in the images directory. */
    std::string images_dir = get_images_dir(search_paths);
    if (!images_dir.empty()) {
        fs::path image_path = fs::path(images_dir) / image_name;
        if (fs::exists(image_path)) {
            return image_path.string();
        } else {
            throw uhd::io_error(
                "Could not find the image '" + image_name + "' in the image directory " + images_dir
                + "\nFor more information regarding image paths, please refer to the UHD manual.");
        }
    }

    /* If we made it this far, then we didn't find anything. */
    images_dir = "<no images directory located>";
    throw uhd::io_error("Could not find path for image: " + image_name
            + "\n\n"
            + "Using images directory: " + images_dir
            + "\n\n"
            + "Set the environment variable 'UHD_IMAGES_DIR' appropriately or"
            + " follow the below instructions to download the images package."
            + "\n\n"
            + uhd::print_utility_error("uhd_images_downloader.py"));
}

std::string uhd::find_utility(const std::string &name) {
    return fs::path(fs::path(uhd::get_pkg_path()) / UHD_LIB_DIR / "uhd" / "utils" / name)
        .string();
}

std::string uhd::print_utility_error(const std::string &name, const std::string &args){
    #ifdef UHD_PLATFORM_WIN32
    return "As an Administrator, please run:\n\n\"" + find_utility(name) + args +  "\"";
    #else
    return "Please run:\n\n \"" + find_utility(name) + (args.empty() ? "" : (" " + args)) + "\"";
    #endif
}