/**
 * Looking Glass
 * Copyright © 2017-2026 The Looking Glass Authors
 * https://looking-glass.io
 *
 * 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 2 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, write to the Free Software Foundation, Inc., 59
 * Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include "network.h"
#include "connection.h"
#include "input.h"
#include "known_hosts.h"

#include "app.h"
#include "interface/renderer.h"

#include "common/debug.h"
#include "common/event.h"
#include "common/locking.h"
#include <LGProtocol/NetworkProtocol.h>
#include "common/option.h"

#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define NETWORK_ADDRESS_MAX        255U
#define NETWORK_ENDPOINT_TEXT_SIZE (NETWORK_ADDRESS_MAX + 9U)
#define NETWORK_MAX_PAYLOAD        (1024U * 1024U)
#define NETWORK_MAX_DATAGRAM       1136U

static const LGNetCapability NETWORK_CAPABILITIES[] =
{
  {
    .service                  = LG_NET_SERVICE_INPUT,
    .versionMin               = LG_NET_INPUT_VERSION_MIN,
    .versionMax               = LG_NET_INPUT_VERSION_CURRENT,
    .flags                    = LG_NET_CAPABILITY_RELIABLE |
      LG_NET_CAPABILITY_DATAGRAM,
    .features                 = 0,
    .maxPayloadLength         = NETWORK_MAX_PAYLOAD,
    .maxDatagramPayload       = NETWORK_MAX_DATAGRAM,
    .maxBidirectionalStreams  = 0,
    .maxUnidirectionalStreams = 0,
  },
};

struct NetworkTrustPrompt
{
  MsgBoxHandle            message;
  NetworkTrustDecisionFn  decision;
  void                  * decisionOpaque;
};

struct LG_Transport
{
  NetworkConnection * connection;
  NetworkInput      * input;
  NetworkKnownHosts   knownHosts;
  LGEvent           * frameEvent;
  LGEvent           * promptIdle;

  LG_Lock callbackLock;
  LG_Lock stateLock;
  LG_Lock promptLock;

  LG_VideoStatus   videoStatus;
  LG_VideoStatusFn videoStatusFn;
  void            * videoStatusOpaque;

  bool                      rendererAttached;
  bool                      promptCallbackActive;
  struct NetworkTrustPrompt prompt;
};

static bool networkAddressValidate(struct Option * option,
    const char ** error)
{
  const char * address = option->value.x_string;
  if (address && *address && strlen(address) <= NETWORK_ADDRESS_MAX)
  {
    for (const unsigned char * c = (const unsigned char *)address; *c; ++c)
      if (*c < 0x20U || *c == 0x7fU)
        goto invalid;
    return true;
  }

invalid:
  *error = "The network address must be 1-255 characters without controls";
  return false;
}

static bool networkPortValidate(struct Option * option, const char ** error)
{
  if (option->value.x_int > 0 && option->value.x_int <= UINT16_MAX)
    return true;

  *error = "The network port must be between 1 and 65535";
  return false;
}

static void networkSetup(void)
{
  static struct Option options[] =
  {
    {
      .module         = "network",
      .name           = "address",
      .description    = "Network server address",
      .type           = OPTION_TYPE_STRING,
      .value.x_string = "127.0.0.1",
      .validator      = networkAddressValidate,
    },
    {
      .module      = "network",
      .name        = "port",
      .description = "Network server UDP port",
      .type        = OPTION_TYPE_INT,
      .value.x_int = LG_NET_DEFAULT_PORT,
      .validator   = networkPortValidate,
    },
    {
      .module         = "network",
      .name           = "password",
      .description    =
        "Reserved network password (empty uses no authentication)",
      .type           = OPTION_TYPE_STRING,
      .value.x_string = NULL,
    },
    {
      .module       = "network",
      .name         = "forgetCertificate",
      .description  = "Forget the saved certificate for this server",
      .type         = OPTION_TYPE_BOOL,
      .value.x_bool = false,
    },
    {0}
  };

  option_register(options);
}

static void networkTrustDecision(bool trusted, void * opaque)
{
  LG_Transport * this = opaque;
  NetworkTrustDecisionFn decision;
  void                 * decisionOpaque;

  LG_LOCK(this->promptLock);
  decision                    = this->prompt.decision;
  decisionOpaque              = this->prompt.decisionOpaque;
  this->prompt.message        = NULL;
  this->prompt.decision       = NULL;
  this->prompt.decisionOpaque = NULL;
  if (decision)
  {
    this->promptCallbackActive = true;
    lgResetEvent(this->promptIdle);
  }
  LG_UNLOCK(this->promptLock);

  if (decision)
    decision(decisionOpaque, trusted);

  LG_LOCK(this->promptLock);
  this->promptCallbackActive = false;
  lgSignalEvent(this->promptIdle);
  LG_UNLOCK(this->promptLock);
}

static bool networkTrustPrompt(void * opaque, const char * endpoint,
    const char * fingerprint, NetworkTrustDecisionFn decision,
    void * decisionOpaque)
{
  LG_Transport * this = opaque;

  LG_LOCK(this->promptLock);
  if (this->prompt.message || this->prompt.decision ||
      this->promptCallbackActive)
  {
    LG_UNLOCK(this->promptLock);
    return false;
  }

  this->prompt.decision       = decision;
  this->prompt.decisionOpaque = decisionOpaque;
  this->prompt.message        = app_confirmMsgBox(
      "Trust network server?", networkTrustDecision, this,
      "The identity of %s has not been seen before.\n\n"
      "SHA-256 fingerprint:\n%s\n\n"
      "Trust and remember this server?", endpoint, fingerprint);
  const bool queued = this->prompt.message != NULL;
  if (!queued)
  {
    this->prompt.decision       = NULL;
    this->prompt.decisionOpaque = NULL;
  }
  LG_UNLOCK(this->promptLock);
  return queued;
}

static void networkCancelTrustPrompt(void * opaque)
{
  LG_Transport * this = opaque;
  MsgBoxHandle  message;

  LG_LOCK(this->promptLock);
  message                     = this->prompt.message;
  this->prompt.message        = NULL;
  this->prompt.decision       = NULL;
  this->prompt.decisionOpaque = NULL;
  LG_UNLOCK(this->promptLock);

  if (message)
    app_msgBoxClose(message);
  lgWaitEvent(this->promptIdle, TIMEOUT_INFINITE);
  LG_LOCK(this->promptLock);
  LG_UNLOCK(this->promptLock);
}

static void networkNotifyVideoStatus(LG_Transport * this)
{
  LG_VideoStatusFn    callback;
  void              * opaque;
  LG_VideoStatus      status;

  LG_LOCK(this->callbackLock);
  LG_LOCK(this->stateLock);
  callback = this->videoStatusFn;
  opaque   = this->videoStatusOpaque;
  status   = this->videoStatus;
  LG_UNLOCK(this->stateLock);

  if (callback)
    callback(opaque, &status);
  LG_UNLOCK(this->callbackLock);
}

static uint64_t networkNextEpoch(uint64_t epoch)
{
  ++epoch;
  return epoch ? epoch : 1U;
}

static void networkSetUnavailable(LG_VideoComponentStatus * status,
    LG_TransportStatus reason)
{
  if (status->available)
    status->epoch = networkNextEpoch(status->epoch);
  status->available = false;
  status->reason    = reason;
}

static void networkConnectionState(void * opaque, bool connected,
    LG_TransportStatus reason)
{
  LG_Transport             * this   = opaque;
  const LG_TransportStatus   status = connected ?
    LG_TRANSPORT_UNAVAILABLE : reason;

  networkInputConnectionState(this->input, connected);

  LG_LOCK(this->stateLock);
  networkSetUnavailable(&this->videoStatus.frame, status);
  networkSetUnavailable(&this->videoStatus.pointer, status);
  LG_UNLOCK(this->stateLock);

  lgSignalEvent(this->frameEvent);
  networkNotifyVideoStatus(this);
}

static void networkPacket(void * opaque, const LGNetPacketView * packet,
    bool datagram)
{
  LG_Transport * this = opaque;
  if (packet->envelope.service == LG_NET_SERVICE_INPUT &&
      !networkInputPacket(this->input, packet, datagram))
  {
    DEBUG_ERROR("Invalid network input message");
    networkConnectionCancel(this->connection);
  }
}

static bool networkCreate(LG_Transport ** result)
{
  if (!result)
    return false;

  LG_Transport * this = calloc(1, sizeof(*this));
  if (!this)
    return false;

  LG_LOCK_INIT(this->callbackLock);
  LG_LOCK_INIT(this->stateLock);
  LG_LOCK_INIT(this->promptLock);

  this->videoStatus.frame.epoch    = 1;
  this->videoStatus.frame.reason   = LG_TRANSPORT_DISCONNECTED;
  this->videoStatus.pointer.epoch  = 1;
  this->videoStatus.pointer.reason = LG_TRANSPORT_DISCONNECTED;
  if (!networkKnownHostsInit(&this->knownHosts))
    goto fail;

  this->frameEvent = lgCreateEvent(true, 0);
  this->promptIdle = lgCreateEvent(false, 0);
  if (!this->frameEvent || !this->promptIdle ||
      !lgSignalEvent(this->promptIdle))
    goto fail;

  const char    * address = option_get_string("network", "address");
  const uint16_t  port    = (uint16_t)option_get_int("network", "port");
  char            endpoint[NETWORK_ENDPOINT_TEXT_SIZE];
  if (!address)
    goto fail;
  snprintf(endpoint, sizeof(endpoint), "[%s]:%u", address, port);
  if (option_get_bool("network", "forgetCertificate") &&
      !networkKnownHostsForget(&this->knownHosts, endpoint))
  {
    DEBUG_ERROR("Failed to forget the network server certificate");
    goto fail;
  }

  const NetworkConnectionParams params =
  {
    .address         = address,
    .port            = port,
    .password        = option_get_string("network", "password"),
    .knownHosts      = &this->knownHosts,
    .trustPrompt     = networkTrustPrompt,
    .trustCancel     = networkCancelTrustPrompt,
    .packet          = networkPacket,
    .state           = networkConnectionState,
    .capabilities    = NETWORK_CAPABILITIES,
    .capabilityCount = sizeof(NETWORK_CAPABILITIES) /
      sizeof(NETWORK_CAPABILITIES[0]),
    .opaque          = this,
  };
  if (!networkConnectionCreate(&this->connection, &params))
    goto fail;
  if (!networkInputCreate(&this->input, this->connection))
    goto fail;

  *result = this;
  return true;

fail:
  networkInputDestroy(&this->input);
  networkConnectionDestroy(&this->connection);
  if (this->frameEvent)
    lgFreeEvent(this->frameEvent);
  if (this->promptIdle)
    lgFreeEvent(this->promptIdle);
  networkKnownHostsFree(&this->knownHosts);
  LG_LOCK_FREE(this->promptLock);
  LG_LOCK_FREE(this->stateLock);
  LG_LOCK_FREE(this->callbackLock);
  free(this);
  return false;
}

static void networkDisconnect(LG_Transport * this);

static void networkDestroy(LG_Transport ** transport)
{
  if (!transport || !*transport)
    return;

  LG_Transport * this = *transport;
  networkDisconnect(this);

  LG_LOCK(this->callbackLock);
  LG_LOCK(this->stateLock);
  this->videoStatusFn     = NULL;
  this->videoStatusOpaque = NULL;
  LG_UNLOCK(this->stateLock);
  LG_UNLOCK(this->callbackLock);

  networkInputDestroy(&this->input);
  networkConnectionDestroy(&this->connection);
  lgFreeEvent(this->frameEvent);
  lgFreeEvent(this->promptIdle);
  networkKnownHostsFree(&this->knownHosts);
  LG_LOCK_FREE(this->promptLock);
  LG_LOCK_FREE(this->stateLock);
  LG_LOCK_FREE(this->callbackLock);
  free(this);
  *transport = NULL;
}

static LG_TransportStatus networkConnectCancellable(LG_Transport * this,
    LG_TransportSession * session, LG_TransportCancelledFn cancelled,
    void * opaque)
{
  return networkConnectionConnect(
      this->connection, session, cancelled, opaque);
}

static LG_TransportStatus networkConnect(LG_Transport * this,
    LG_TransportSession * session)
{
  return networkConnectCancellable(this, session, NULL, NULL);
}

static void networkDisconnect(LG_Transport * this)
{
  networkInputConnectionState(this->input, false);
  networkConnectionDisconnect(this->connection);
  lgSignalEvent(this->frameEvent);
}

static bool networkSessionValid(LG_Transport * this)
{
  return networkConnectionValid(this->connection);
}

static void networkSetStatusListener(LG_Transport * this,
    LG_VideoStatusFn callback, void * opaque)
{
  LG_VideoStatus status;

  LG_LOCK(this->callbackLock);
  LG_LOCK(this->stateLock);
  this->videoStatusFn     = callback;
  this->videoStatusOpaque = opaque;
  status                  = this->videoStatus;
  LG_UNLOCK(this->stateLock);

  if (callback)
    callback(opaque, &status);
  LG_UNLOCK(this->callbackLock);
}

static bool networkSupportsDMA(LG_Transport * this)
{
  (void)this;
  return false;
}

static bool networkAttachRenderer(LG_Transport * this,
    const LG_RendererInterop * interop)
{
  const size_t requiredSize = offsetof(LG_RendererInterop,
      egl.sharedTextureImport) + sizeof(interop->egl.sharedTextureImport);
  if (!interop ||
      interop->version < LG_RENDERER_INTEROP_EGL_TEXTURE_VERSION ||
      interop->size < requiredSize ||
      interop->type != LG_RENDERER_INTEROP_EGL ||
      !interop->egl.display || !interop->egl.config ||
      !interop->egl.shareContext || !interop->egl.sharedTextureImport)
  {
    DEBUG_ERROR("The network transport requires EGL shared textures");
    return false;
  }

  this->rendererAttached = true;
  return true;
}

static void networkDetachRenderer(LG_Transport * this)
{
  this->rendererAttached = false;
}

static LG_TransportStatus networkNextFrame(LG_Transport * this, bool useDMA,
    LG_TransportFrame * frame)
{
  (void)useDMA;
  (void)frame;

  if (!this->rendererAttached)
    return LG_TRANSPORT_ERROR;
  if (!networkSessionValid(this))
    return LG_TRANSPORT_DISCONNECTED;

  lgWaitEvent(this->frameEvent, 100);
  return networkSessionValid(this) ?
    LG_TRANSPORT_UNAVAILABLE : LG_TRANSPORT_DISCONNECTED;
}

static void networkGetFrameTiming(LG_Transport * this,
    const LG_TransportFrame * frame, LG_TransportFrameTiming * timing)
{
  (void)this;
  (void)frame;
  memset(timing, 0, sizeof(*timing));
}

static void networkReleaseFrame(LG_Transport * this,
    LG_TransportFrame * frame)
{
  (void)this;
  (void)frame;
}

static void networkCancelFrameWait(LG_Transport * this)
{
  lgSignalEvent(this->frameEvent);
}

static void networkStopFrame(LG_Transport * this)
{
  lgSignalEvent(this->frameEvent);
}

static const LG_FrameOps networkFrameOps =
{
  .setStatusListener = networkSetStatusListener,
  .supportsDMA       = networkSupportsDMA,
  .attachRenderer    = networkAttachRenderer,
  .detachRenderer    = networkDetachRenderer,
  .nextFrame         = networkNextFrame,
  .getFrameTiming    = networkGetFrameTiming,
  .releaseFrame      = networkReleaseFrame,
  .cancelFrameWait   = networkCancelFrameWait,
  .stopFrame         = networkStopFrame,
};

static const LG_VideoOps networkVideoOps =
{
  .name  = "network",
  .type  = LG_VIDEO_TYPE_FRAME,
  .frame = &networkFrameOps,
};

static const LG_VideoOps * networkGetVideoOps(LG_Transport * this)
{
  (void)this;
  return &networkVideoOps;
}

static const LG_InputOps * networkGetInputOps(LG_Transport * this,
    void ** opaque)
{
  *opaque = this->input;
  return networkInputGetOps();
}

static const LG_AudioOps * networkGetAudioOps(LG_Transport * this,
    void ** opaque)
{
  (void)this;
  *opaque = NULL;
  return NULL;
}

static const LG_ClipboardOps * networkGetClipboardOps(LG_Transport * this,
    void ** opaque)
{
  (void)this;
  *opaque = NULL;
  return NULL;
}

static LG_TransportStatus networkSendControl(LG_Transport * this,
    const LG_TransportControl * control, LG_TransportControlToken * token)
{
  (void)control;
  (void)token;
  return networkSessionValid(this) ?
    LG_TRANSPORT_UNAVAILABLE : LG_TRANSPORT_DISCONNECTED;
}

static LG_TransportStatus networkControlStatus(LG_Transport * this,
    LG_TransportControlToken token)
{
  (void)token;
  return networkSessionValid(this) ?
    LG_TRANSPORT_UNAVAILABLE : LG_TRANSPORT_DISCONNECTED;
}

const LG_TransportOps LGT_Network =
{
  .name               = "network",
  .setup              = networkSetup,
  .create             = networkCreate,
  .destroy            = networkDestroy,
  .connect            = networkConnect,
  .connectCancellable = networkConnectCancellable,
  .disconnect         = networkDisconnect,
  .sessionValid       = networkSessionValid,
  .getVideoOps        = networkGetVideoOps,
  .getInputOps        = networkGetInputOps,
  .getAudioOps        = networkGetAudioOps,
  .getClipboardOps    = networkGetClipboardOps,
  .sendControl        = networkSendControl,
  .controlStatus      = networkControlStatus,
};