//===-- 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 "mars.h"
#include "libconfig.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;

#if LDC_LLVM_VER >= 304
#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
#else
std::string getUserHomeDirectory() {
  return llvm::sys::Path::GetUserHomeDirectory().str();
}
#endif

#if LDC_LLVM_VER >= 304
static std::string getMainExecutable(const char *argv0, void *MainExecAddr) {
  return sys::fs::getMainExecutable(argv0, MainExecAddr);
}
#else
static std::string getMainExecutable(const char *argv0, void *MainExecAddr) {
  return llvm::sys::Path::GetMainExecutable(argv0, MainExecAddr).str();
}
#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 libconfig::Config;
}

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


bool ConfigFile::locate(llvm::SmallString<128> &p, const char* argv0, void* mainAddr, const char* filename)
{
    // temporary configuration

    // try the current working dir
    if (!sys::fs::current_path(p))
    {
        sys::path::append(p, filename);
        if (sys::fs::exists(p.str()))
            return true;
    }

    // try next to the executable
    p = getMainExecutable(argv0, mainAddr);
    sys::path::remove_filename(p);
    sys::path::append(p, filename);
    if (sys::fs::exists(p.str()))
        return true;

    // user configuration

    // try ~/.ldc
    p = getUserHomeDirectory();
    sys::path::append(p, ".ldc");
    sys::path::append(p, filename);
    if (sys::fs::exists(p.str()))
        return true;

#if _WIN32
    // try home dir
    p = getUserHomeDirectory();
    sys::path::append(p, filename);
    if (sys::fs::exists(p.str()))
        return true;
#endif

    // system configuration

    // try in etc relative to the executable: exe\..\etc
    // do not use .. in path because of security risks
    p = getMainExecutable(argv0, mainAddr);
    sys::path::remove_filename(p);
    sys::path::remove_filename(p);
    if (!p.empty())
    {
        sys::path::append(p, "etc");
        sys::path::append(p, filename);
        if (sys::fs::exists(p.str()))
            return true;
    }

#if _WIN32
    // Try reading path from registry
    if (ReadPathFromRegistry(p))
    {
        sys::path::append(p, "etc");
        sys::path::append(p, filename);
        if (sys::fs::exists(p.str()))
            return true;
    }
#else
    // try the install-prefix/etc
    p = LDC_INSTALL_PREFIX;
    sys::path::append(p, "etc");
    sys::path::append(p, filename);
    if (sys::fs::exists(p.str()))
        return true;

    // try the install-prefix/etc/ldc
    p = LDC_INSTALL_PREFIX;
    sys::path::append(p, "etc");
    sys::path::append(p, "ldc");
    sys::path::append(p, filename);
    if (sys::fs::exists(p.str()))
        return true;

    // try /etc (absolute path)
    p = "/etc";
    sys::path::append(p, filename);
    if (sys::fs::exists(p.str()))
        return true;

    // try /etc/ldc (absolute path)
    p = "/etc/ldc";
    sys::path::append(p, filename);
    if (sys::fs::exists(p.str()))
        return true;
#endif

    return false;
}

bool ConfigFile::read(const char* argv0, void* mainAddr, const char* filename)
{
    llvm::SmallString<128> p;
    if (!locate(p, argv0, mainAddr, filename))
    {
        // failed to find cfg, users still have the DFLAGS environment var
        std::cerr << "Error failed to locate the configuration file: " << filename << std::endl;
        return false;
    }

    // save config file path for -v output
    pathstr = p.str();

    try
    {
        // read the cfg
        cfg->readFile(p.c_str());

        // make sure there's a default group
        if (!cfg->exists("default"))
        {
            std::cerr << "no default settings in configuration file" << std::endl;
            return false;
        }
        libconfig::Setting& root = cfg->lookup("default");
        if (!root.isGroup())
        {
            std::cerr << "default is not a group" << std::endl;
            return false;
        }

        // handle switches
        if (root.exists("switches"))
        {
            std::string binpathkey = "%%ldcbinarypath%%";

            std::string binpath = sys::path::parent_path(getMainExecutable(argv0, mainAddr));

            libconfig::Setting& arr = cfg->lookup("default.switches");
            int len = arr.getLength();
            for (int i=0; i<len; i++)
            {
                std::string v = arr[i].operator std::string();

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

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

    }
    catch(libconfig::FileIOException& fioe)
    {
        std::cerr << "Error reading configuration file: " << filename << std::endl;
        return false;
    }
    catch(libconfig::ParseException& pe)
    {
        std::cerr << "Error parsing configuration file: " << filename
            << "(" << pe.getLine() << "): " << pe.getError() << std::endl;
        return false;
    }
    catch(...)
    {
        std::cerr << "Unknown exception caught!" << std::endl;
        return false;
    }

    return true;
}