/******************************************************************************
 * $Id$
 *
 * Copyright (c) 2005-2008 Transmission authors and contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *****************************************************************************/

#ifdef __BEOS__
  #include <signal.h> 
  #include <fs_info.h>
  #include <FindDirectory.h>
  #include <kernel/OS.h>
  #define BEOS_MAX_THREADS 256
#elif defined(WIN32)
  #include <windows.h>
  #include <shlobj.h> /* for CSIDL_APPDATA, CSIDL_PROFILE */
#else
  #define _XOPEN_SOURCE 500 /* needed for recursive locks. */
  #ifndef __USE_UNIX98
  #define __USE_UNIX98 /* some older Linuxes need it spelt out for them */
  #endif
  #include <pthread.h>
#endif

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

#include <sys/types.h>
#include <dirent.h>
#include <fcntl.h>
#include <unistd.h> /* getuid getpid close */

#include "transmission.h"
#include "platform.h"
#include "trcompat.h"
#include "utils.h"

/***
****  THREADS
***/

#ifdef __BEOS__
typedef thread_id tr_thread_id;
#elif defined(WIN32)
typedef DWORD tr_thread_id;
#else
typedef pthread_t tr_thread_id;
#endif

static tr_thread_id
tr_getCurrentThread( void )
{
#ifdef __BEOS__
    return find_thread( NULL );
#elif defined(WIN32)
    return GetCurrentThreadId();
#else
    return pthread_self( );
#endif
}

static int
tr_areThreadsEqual( tr_thread_id a, tr_thread_id b )
{
#ifdef __BEOS__
    return a == b;
#elif defined(WIN32)
    return a == b;
#else
    return pthread_equal( a, b );
#endif
}

struct tr_thread
{
    void          (* func ) ( void * );
    void           * arg;
    const char     * name;

#ifdef __BEOS__
    thread_id        thread;
#elif defined(WIN32)
    HANDLE           thread;
    unsigned int     thread_id;
#else
    pthread_t        thread;
#endif

};

int
tr_amInThread ( const tr_thread * t )
{
    return tr_areThreadsEqual( tr_getCurrentThread(), t->thread );
}

#ifdef WIN32
#define ThreadFuncReturnType unsigned WINAPI
#else
#define ThreadFuncReturnType void
#endif

static ThreadFuncReturnType
ThreadFunc( void * _t )
{
    tr_thread * t = _t;
    const char * name = t->name;

#ifdef __BEOS__
    /* This is required because on BeOS, SIGINT is sent to each thread,
       which kills them not nicely */
    signal( SIGINT, SIG_IGN );
#endif

    tr_dbg( "Thread '%s' started", name );
    t->func( t->arg );
    tr_dbg( "Thread '%s' exited", name );

#ifdef WIN32
    _endthreadex( 0 );
    return 0;
#endif
}

tr_thread *
tr_threadNew( void (*func)(void *),
              void * arg,
              const char * name )
{
    tr_thread * t = tr_new0( tr_thread, 1 );
    t->func = func;
    t->arg  = arg;
    t->name = name;

#ifdef __BEOS__
    t->thread = spawn_thread( (void*)ThreadFunc, name, B_NORMAL_PRIORITY, t );
    resume_thread( t->thread );
#elif defined(WIN32)
    t->thread = (HANDLE) _beginthreadex( NULL, 0, &ThreadFunc, t, 0, &t->thread_id );
#else
    pthread_create( &t->thread, NULL, (void * (*) (void *)) ThreadFunc, t );
#endif

    return t;
}
    
void
tr_threadJoin( tr_thread * t )
{
    if( t != NULL )
    {
#ifdef __BEOS__
        long exit;
        wait_for_thread( t->thread, &exit );
#elif defined(WIN32)
        WaitForSingleObject( t->thread, INFINITE );
        CloseHandle( t->thread );
#else
        pthread_join( t->thread, NULL );
#endif

        tr_dbg( "Thread '%s' joined", t->name );
        t->name = NULL;
        t->func = NULL;
        tr_free( t );
    }
}

/***
****  LOCKS
***/

struct tr_lock
{
    int depth;
#ifdef __BEOS__
    sem_id lock;
    thread_id lockThread;
#elif defined(WIN32)
    CRITICAL_SECTION lock;
    DWORD lockThread;
#else
    pthread_mutex_t lock;
    pthread_t lockThread;
#endif
};

tr_lock*
tr_lockNew( void )
{
    tr_lock * l = tr_new0( tr_lock, 1 );

#ifdef __BEOS__
    l->lock = create_sem( 1, "" );
#elif defined(WIN32)
    InitializeCriticalSection( &l->lock ); /* critical sections support recursion */
#else
    pthread_mutexattr_t attr;
    pthread_mutexattr_init( &attr );
    pthread_mutexattr_settype( &attr, PTHREAD_MUTEX_RECURSIVE );
    pthread_mutex_init( &l->lock, &attr );
#endif

    return l;
}

void
tr_lockFree( tr_lock * l )
{
#ifdef __BEOS__
    delete_sem( l->lock );
#elif defined(WIN32)
    DeleteCriticalSection( &l->lock );
#else
    pthread_mutex_destroy( &l->lock );
#endif
    tr_free( l );
}

void
tr_lockLock( tr_lock * l )
{
#ifdef __BEOS__
    acquire_sem( l->lock );
#elif defined(WIN32)
    EnterCriticalSection( &l->lock );
#else
    pthread_mutex_lock( &l->lock );
#endif
    assert( l->depth >= 0 );
    if( l->depth )
        assert( tr_areThreadsEqual( l->lockThread, tr_getCurrentThread() ) );
    l->lockThread = tr_getCurrentThread( );
    ++l->depth;
}

int
tr_lockHave( const tr_lock * l )
{
    return ( l->depth > 0 )
        && ( tr_areThreadsEqual( l->lockThread, tr_getCurrentThread() ) );
}

void
tr_lockUnlock( tr_lock * l )
{
    assert( l->depth > 0 );
    assert( tr_areThreadsEqual( l->lockThread, tr_getCurrentThread() ));

    --l->depth;
    assert( l->depth >= 0 );
#ifdef __BEOS__
    release_sem( l->lock );
#elif defined(WIN32)
    LeaveCriticalSection( &l->lock );
#else
    pthread_mutex_unlock( &l->lock );
#endif
}

/***
****  PATHS
***/

#if !defined(WIN32) && !defined(__BEOS__) && !defined(__AMIGAOS4__)
#include <pwd.h>
#endif

static const char *
tr_getHomeDirectory( void )
{
    static char buf[MAX_PATH_LENGTH];
    static int init = 0;
    const char * envHome;

    if( init )
        return buf;

    envHome = getenv( "HOME" );
    if( envHome )
        snprintf( buf, sizeof(buf), "%s", envHome );
    else {
#ifdef WIN32
        SHGetFolderPath( NULL, CSIDL_PROFILE, NULL, 0, buf );
#elif defined(__BEOS__) || defined(__AMIGAOS4__)
        *buf = '\0';
#else
        struct passwd * pw = getpwuid( getuid() );
        endpwent();
        if( pw != NULL )
            snprintf( buf, sizeof(buf), "%s", pw->pw_dir );
#endif
    }

    init = 1;
    return buf;
}


static void
tr_migrateResume( const char *oldDirectory, const char *newDirectory )
{
    DIR * dirh = opendir( oldDirectory );

    if( dirh != NULL )
    {
        struct dirent * dirp;

        while( ( dirp = readdir( dirh ) ) )
        {
            if( !strncmp( "resume.", dirp->d_name, 7 ) )
            {
                char o[MAX_PATH_LENGTH];
                char n[MAX_PATH_LENGTH];
                tr_buildPath( o, sizeof(o), oldDirectory, dirp->d_name, NULL );
                tr_buildPath( n, sizeof(n), newDirectory, dirp->d_name, NULL );
                rename( o, n );
            }
        }

        closedir( dirh );
    }
}

const char *
tr_getPrefsDirectory( void )
{
    static char   buf[MAX_PATH_LENGTH];
    static int    init = 0;
    const char * trhome;

    if( init )
        return buf;

    trhome = getenv( "TRANSMISSION_HOME" );
    if( trhome != NULL )
    {
        strlcpy( buf, trhome, sizeof( buf ) );
    }
    else
    {
#ifdef __BEOS__
        find_directory( B_USER_SETTINGS_DIRECTORY,
                        dev_for_path("/boot"), true,
                        buf, sizeof( buf ) );
        strcat( buf, "/Transmission" );
#elif defined( SYS_DARWIN )
        tr_buildPath ( buf, sizeof( buf ),
                       tr_getHomeDirectory( ),
                       "Library",
                       "Application Support",
                       "Transmission",
                       NULL );
#elif defined(__AMIGAOS4__)
        strlcpy( buf, "PROGDIR:.transmission", sizeof( buf ) );
#elif defined(WIN32)
        char appdata[MAX_PATH_LENGTH];
        SHGetFolderPath( NULL, CSIDL_APPDATA, NULL, 0, appdata );
        tr_buildPath( buf, sizeof(buf),
                      appdata,
                      "Transmission",
                      NULL );
#else
        tr_buildPath ( buf, sizeof(buf), tr_getHomeDirectory( ), ".transmission", NULL );
#endif
    }

    tr_mkdirp( buf, 0777 );
    init = 1;

#ifdef SYS_DARWIN
    char old[MAX_PATH_LENGTH];
    tr_buildPath ( old, sizeof(old),
                   tr_getHomeDirectory(), ".transmission", NULL );
    tr_migrateResume( old, buf );
    rmdir( old );
#endif

    return buf;
}

const char *
tr_getCacheDirectory( void )
{
    static char buf[MAX_PATH_LENGTH];
    static int  init = 0;
    static const size_t buflen = sizeof(buf);
    const char * p;

    if( init )
        return buf;

    p = tr_getPrefsDirectory();
#if defined(__BEOS__) || defined(WIN32)
    tr_buildPath( buf, buflen, p, "Cache", NULL );
#elif defined( SYS_DARWIN )
    tr_buildPath( buf, buflen, tr_getHomeDirectory(),
                  "Library", "Caches", "Transmission", NULL );
#else
    tr_buildPath( buf, buflen, p, "cache", NULL );
#endif

    tr_mkdirp( buf, 0777 );
    init = 1;

    if( strcmp( p, buf ) )
        tr_migrateResume( p, buf );

    return buf;
}

const char *
tr_getTorrentsDirectory( void )
{
    static char buf[MAX_PATH_LENGTH];
    static int  init = 0;
    static const size_t buflen = sizeof(buf);
    const char * p;

    if( init )
        return buf;

    p = tr_getPrefsDirectory ();

#if defined(__BEOS__) || defined(WIN32)
    tr_buildPath( buf, buflen, p, "Torrents", NULL );
#elif defined( SYS_DARWIN )
    tr_buildPath( buf, buflen, p, "Torrents", NULL );
#else
    tr_buildPath( buf, buflen, p, "torrents", NULL );
#endif

    tr_mkdirp( buf, 0777 );
    init = 1;
    return buf;
}