/**
 * =========================================================================
 * File        : wsdl.cpp
 * Project     : 0 A.D.
 * Description : sound card detection on Windows.
 * =========================================================================
 */

// license: GPL; see lib/license.txt

#include "precompiled.h"
#include "lib/sysdep/snd.h"

#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <set>

#include "lib/path_util.h"
#include "lib/res/file/file.h"
#include "dll_ver.h"	// dll_list_*
#include "win.h"
#include "wutil.h"


// indicate if this directory entry is an OpenAL DLL.
// (matches "*oal.dll" and "*OpenAL*", as with OpenAL router's search)
static LibError IsOpenAlDll(const DirEnt* ent)
{
	// not a file
	if(!DIRENT_IS_DIR(ent))
		return false;

	// name doesn't match
	const size_t len = strlen(ent->name);
	const bool oal = len >= 7 && !strcasecmp(ent->name+len-7, "oal.dll");
	const bool openal = strstr(ent->name, "OpenAL") != 0;
	if(!oal && !openal)
		return false;

	return true;
}

// ensures each OpenAL DLL is only listed once (even if present in several
// directories on our search path).
typedef std::set<std::string> StringSet;

// find all OpenAL DLLs in a dir (via file_enum and IsOpenAlDll).
// call in library search order (exe dir, then win sys dir); otherwise,
// DLLs in the executable's starting directory hide those of the
// same name in the system directory.
//
// <dir>: no trailing.
static LibError add_oal_dlls_in_dir(const char* dir, StringSet* dlls)
{
	// note: dll_list_add requires the full DLL path but DirEnt only gives us
	// the name. for efficiency, we append this via PathPackage.
	PathPackage pp;
	RETURN_ERR(path_package_set_dir(&pp, dir));

	DirIterator d;
	RETURN_ERR(dir_open(dir, &d));

	for(;;)	// instead of while to avoid warning
	{
		DirEnt ent;
		LibError err = dir_next_ent(&d, &ent);
		if(err != INFO::OK)
			break;

		if(!IsOpenAlDll(&ent))
			continue;

		// already in StringSet (i.e. has already been dll_list_add-ed)
		std::pair<StringSet::iterator, bool> ret = dlls->insert(ent.name);
		if(!ret.second)	// insert failed - element already there
			continue;

		(void)path_package_append_file(&pp, ent.name);
		(void)dll_list_add(pp.path);
	}

	(void)dir_close(&d);
	return INFO::OK;
}


//-----------------------------------------------------------------------------
// DirectSound driver version

// we've seen audio problems caused by buggy DirectSound drivers (because
// OpenAL can use them in its implementation), so their version should be
// retrieved as well. the only way I know of is to enumerate all DS devices.
//
// unfortunately this fails with Vista's DS emulation - it returns some
// GUID crap as the module name. to avoid crashing when attempting to get
// the version info for that bogus driver path, we'll skip this code there.
// (delay-loading dsound.dll eliminates any overhead)

static char directSoundDriverPath[MAX_PATH+1];

// store sound card name and path to DirectSound driver.
// called for each DirectSound driver, but aborts after first valid driver.
static BOOL CALLBACK DirectSoundCallback(void* guid, const char* UNUSED(description),
	const char* module, void* UNUSED(ctx))
{
	// skip first dummy entry (description == "Primary Sound Driver")
	if(guid == NULL)
		return TRUE;	// continue calling

	// note: $system\\drivers is not in LoadLibrary's search list,
	// so we have to give the full pathname.
	snprintf(directSoundDriverPath, ARRAY_SIZE(directSoundDriverPath), "%s\\drivers\\%s", win_sys_dir, module);

	// we assume the first "driver name" (sound card) is the one we want;
	// stick with that and stop calling.
	return FALSE;
}

static const char* GetDirectSoundDriverPath()
{
#define DS_OK 0
	typedef BOOL (CALLBACK* LPDSENUMCALLBACKA)(void*, const char*, const char*, void*);
	HRESULT (WINAPI *pDirectSoundEnumerateA)(LPDSENUMCALLBACKA, void*);
	HMODULE hDsoundDll = LoadLibrary("dsound.dll");
	*(void**)&pDirectSoundEnumerateA = GetProcAddress(hDsoundDll, "DirectSoundEnumerateA");
	if(pDirectSoundEnumerateA)
	{
		if(pDirectSoundEnumerateA(DirectSoundCallback, (void*)0) != DS_OK)
			debug_warn("DirectSoundEnumerate failed");
	}
	FreeLibrary(hDsoundDll);

	return directSoundDriverPath;
}

//-----------------------------------------------------------------------------

LibError win_get_snd_info()
{
	// find all DLLs related to OpenAL, retrieve their versions,
	// and store in snd_drv_ver string.
	dll_list_init(snd_drv_ver, SND_DRV_VER_LEN);
	if(!wutil_IsVista())
		(void)dll_list_add(GetDirectSoundDriverPath());
	StringSet dlls;	// ensures uniqueness
	(void)add_oal_dlls_in_dir(win_exe_dir, &dlls);
	(void)add_oal_dlls_in_dir(win_sys_dir, &dlls);
	return INFO::OK;
}