//===-- configfile.cpp ----------------------------------------------------===//
//
//                         LDC – the LLVM D compiler
//
// This file is distributed under the BSD-style LDC license. See the LICENSE
// file for details.
//
//===----------------------------------------------------------------------===//

#include "driver/configfile.h"
#include "driver/exe_path.h"
#include "mars.h"
#include "libconfig.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
#include <cassert>
#include <cstring>
#include <iostream>
#include <string>
#if _WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <shlobj.h>
// Prevent name clash with LLVM
#undef GetCurrentDirectory
#endif

namespace sys = llvm::sys;

// dummy only; needs to be parsed manually earlier as the switches contained in
// the config file are injected into the command line options fed to the parser
llvm::cl::opt<std::string> clConf("conf",
    llvm::cl::desc("Use configuration file <filename>"),
    llvm::cl::value_desc("filename"));

#if _WIN32
std::string getUserHomeDirectory() {
  char buff[MAX_PATH];
  HRESULT res = SHGetFolderPathA(NULL,
                                 CSIDL_FLAG_CREATE | CSIDL_APPDATA,
                                 NULL,
                                 SHGFP_TYPE_CURRENT,
                                 buff);
  if (res != S_OK)
    assert(0 && "Failed to get user home directory");
  return buff;
}
#else
std::string getUserHomeDirectory() {
  const char* home = getenv("HOME");
  return home ? home : "/";
}
#endif

#if _WIN32
static bool ReadPathFromRegistry(llvm::SmallString<128> &p)
{
    HKEY hkey;
    bool res = false;
    if (RegOpenKeyEx(HKEY_LOCAL_MACHINE,
                     "SOFTWARE\\ldc-developers\\LDC\\0.11.0", //FIXME Version number should be a define
                     NULL, KEY_QUERY_VALUE, &hkey) == ERROR_SUCCESS)
    {
        DWORD length;
        if (RegGetValue(hkey, NULL, "Path", RRF_RT_REG_SZ, NULL, NULL, &length) == ERROR_SUCCESS)
        {
            char *data = static_cast<char *>(_alloca(length));
            if (RegGetValue(hkey, NULL, "Path", RRF_RT_REG_SZ, NULL, data, &length) == ERROR_SUCCESS)
            {
                p = std::string(data);
                res = true;
            }
        }
        RegCloseKey(hkey);
    }
    return res;
}
#endif

ConfigFile::ConfigFile()
{
    cfg = new config_t;
    config_init(cfg);
}

ConfigFile::~ConfigFile()
{
   // delete cfg;
}


bool ConfigFile::locate()
{
    // temporary configuration

    llvm::SmallString<128> p;
    const char* filename = "ldc2.conf";

#define APPEND_FILENAME_AND_RETURN_IF_EXISTS \
    { \
        sys::path::append(p, filename); \
        if (sys::fs::exists(p.str())) \
        { \
            pathstr = p.str(); \
            return true; \
        } \
    }

    // try the current working dir
    if (!sys::fs::current_path(p))
        APPEND_FILENAME_AND_RETURN_IF_EXISTS

    // try next to the executable
    p = exe_path::getBinDir();
    APPEND_FILENAME_AND_RETURN_IF_EXISTS

    // user configuration

    // try ~/.ldc
    p = getUserHomeDirectory();
    sys::path::append(p, ".ldc");
    APPEND_FILENAME_AND_RETURN_IF_EXISTS

#if _WIN32
    // try home dir
    p = getUserHomeDirectory();
    APPEND_FILENAME_AND_RETURN_IF_EXISTS
#endif

    // system configuration

    // try in etc relative to the executable: exe\..\etc
    // do not use .. in path because of security risks
    p = exe_path::getBaseDir();
    if (!p.empty())
    {
        sys::path::append(p, "etc");
        APPEND_FILENAME_AND_RETURN_IF_EXISTS
    }

#if _WIN32
    // Try reading path from registry
    if (ReadPathFromRegistry(p))
    {
        sys::path::append(p, "etc");
        APPEND_FILENAME_AND_RETURN_IF_EXISTS
    }
#else
    // try the install-prefix/etc
    p = LDC_INSTALL_PREFIX;
    sys::path::append(p, "etc");
    APPEND_FILENAME_AND_RETURN_IF_EXISTS

    // try the install-prefix/etc/ldc
    p = LDC_INSTALL_PREFIX;
    sys::path::append(p, "etc");
    sys::path::append(p, "ldc");
    APPEND_FILENAME_AND_RETURN_IF_EXISTS

    // try /etc (absolute path)
    p = "/etc";
    APPEND_FILENAME_AND_RETURN_IF_EXISTS

    // try /etc/ldc (absolute path)
    p = "/etc/ldc";
    APPEND_FILENAME_AND_RETURN_IF_EXISTS
#endif

#undef APPEND_FILENAME_AND_RETURN_IF_EXISTS

    fprintf(stderr, "Warning: failed to locate the configuration file %s\n", filename);
    return false;
}

bool ConfigFile::read(const char* explicitConfFile)
{
    // explicitly provided by user in command line?
    if (explicitConfFile)
    {
        const std::string clPath = explicitConfFile;
        // treat an empty path (`-conf=`) as missing command-line option,
        // defaulting to an auto-located config file, analogous to DMD
        if (!clPath.empty())
        {
            if (sys::fs::exists(clPath))
                pathstr = clPath;
            else
                fprintf(stderr, "Warning: configuration file '%s' not found, falling back to default\n", clPath.c_str());
        }
    }

    // locate file automatically if path is not set yet
    if (pathstr.empty())
        if (!locate())
            return false;

    // read the cfg
    if (!config_read_file(cfg, pathstr.c_str()))
    {
        std::cerr << "error reading configuration file" << std::endl;
        return false;
    }

    // make sure there's a default group
    config_setting_t *root = config_lookup(cfg, "default");
    if (!root)
    {
        std::cerr << "no default settings in configuration file" << std::endl;
        return false;
    }
    if (!config_setting_is_group(root))
    {
        std::cerr << "default is not a group" << std::endl;
        return false;
    }

    // handle switches
    if (config_setting_t *sw = config_setting_get_member(root, "switches"))
    {
        // replace all %%ldcbinarypath%% occurrences by the path to the
        // LDC bin directory (using forward slashes)
        std::string binpathkey = "%%ldcbinarypath%%";

        std::string binpath = exe_path::getBinDir();
        std::replace(binpath.begin(), binpath.end(), '\\', '/');

        int len = config_setting_length(sw);
        for (int i = 0; i < len; i++)
        {
            std::string v(config_setting_get_string(config_setting_get_elem(sw, i)));

            size_t p;
            while (std::string::npos != (p = v.find(binpathkey)))
                v.replace(p, binpathkey.size(), binpath);

            switches.push_back(strdup(v.c_str()));
        }
    }

    return true;
}