/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2020 Jacob Berg Potter
 * Copyright (c) 2020 Peter Lawrence
 * Copyright (c) 2019 Ha Thach (tinyusb.org)
 *
 * 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.
 *
 * This file is part of the TinyUSB stack.
 */

#include "tusb_option.h"

#if ( CFG_TUD_ENABLED && CFG_TUD_NCM )

#include "device/usbd.h"
#include "device/usbd_pvt.h"
#include "net_device.h"

//--------------------------------------------------------------------+
// MACRO CONSTANT TYPEDEF
//--------------------------------------------------------------------+

#define NTH16_SIGNATURE      0x484D434E
#define NDP16_SIGNATURE_NCM0 0x304D434E
#define NDP16_SIGNATURE_NCM1 0x314D434E

typedef struct TU_ATTR_PACKED
{
  uint16_t wLength;
  uint16_t bmNtbFormatsSupported;
  uint32_t dwNtbInMaxSize;
  uint16_t wNdbInDivisor;
  uint16_t wNdbInPayloadRemainder;
  uint16_t wNdbInAlignment;
  uint16_t wReserved;
  uint32_t dwNtbOutMaxSize;
  uint16_t wNdbOutDivisor;
  uint16_t wNdbOutPayloadRemainder;
  uint16_t wNdbOutAlignment;
  uint16_t wNtbOutMaxDatagrams;
} ntb_parameters_t;

typedef struct TU_ATTR_PACKED
{
  uint32_t dwSignature;
  uint16_t wHeaderLength;
  uint16_t wSequence;
  uint16_t wBlockLength;
  uint16_t wNdpIndex;
} nth16_t;

typedef struct TU_ATTR_PACKED
{
  uint16_t wDatagramIndex;
  uint16_t wDatagramLength;
} ndp16_datagram_t;

typedef struct TU_ATTR_PACKED
{
  uint32_t dwSignature;
  uint16_t wLength;
  uint16_t wNextNdpIndex;
  ndp16_datagram_t datagram[];
} ndp16_t;

typedef union TU_ATTR_PACKED {
  struct {
    nth16_t nth;
    ndp16_t ndp;
  };
  uint8_t data[CFG_TUD_NCM_IN_NTB_MAX_SIZE];
} transmit_ntb_t;

struct ecm_notify_struct
{
  tusb_control_request_t header;
  uint32_t downlink, uplink;
};

typedef struct
{
  uint8_t itf_num;      // Index number of Management Interface, +1 for Data Interface
  uint8_t itf_data_alt; // Alternate setting of Data Interface. 0 : inactive, 1 : active

  uint8_t ep_notif;
  uint8_t ep_in;
  uint8_t ep_out;

  const ndp16_t *ndp;
  uint8_t num_datagrams, current_datagram_index;

  enum {
    REPORT_SPEED,
    REPORT_CONNECTED,
    REPORT_DONE
  } report_state;
  bool report_pending;

  uint8_t  current_ntb;           // Index in transmit_ntb[] that is currently being filled with datagrams
  uint8_t  datagram_count;        // Number of datagrams in transmit_ntb[current_ntb]
  uint16_t next_datagram_offset;  // Offset in transmit_ntb[current_ntb].data to place the next datagram
  uint16_t ntb_in_size;           // Maximum size of transmitted (IN to host) NTBs; initially CFG_TUD_NCM_IN_NTB_MAX_SIZE
  uint8_t  max_datagrams_per_ntb; // Maximum number of datagrams per NTB; initially CFG_TUD_NCM_MAX_DATAGRAMS_PER_NTB

  uint16_t nth_sequence;          // Sequence number counter for transmitted NTBs

  bool transferring;

} ncm_interface_t;

//--------------------------------------------------------------------+
// INTERNAL OBJECT & FUNCTION DECLARATION
//--------------------------------------------------------------------+

CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static const ntb_parameters_t ntb_parameters = {
    .wLength                 = sizeof(ntb_parameters_t),
    .bmNtbFormatsSupported   = 0x01,
    .dwNtbInMaxSize          = CFG_TUD_NCM_IN_NTB_MAX_SIZE,
    .wNdbInDivisor           = 4,
    .wNdbInPayloadRemainder  = 0,
    .wNdbInAlignment         = CFG_TUD_NCM_ALIGNMENT,
    .wReserved               = 0,
    .dwNtbOutMaxSize         = CFG_TUD_NCM_OUT_NTB_MAX_SIZE,
    .wNdbOutDivisor          = 4,
    .wNdbOutPayloadRemainder = 0,
    .wNdbOutAlignment        = CFG_TUD_NCM_ALIGNMENT,
    .wNtbOutMaxDatagrams     = 0
};

CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static transmit_ntb_t transmit_ntb[2];

CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static uint8_t receive_ntb[CFG_TUD_NCM_OUT_NTB_MAX_SIZE];

static ncm_interface_t ncm_interface;

/*
 * Set up the NTB state in ncm_interface to be ready to add datagrams.
 */
static void ncm_prepare_for_tx(void) {
  ncm_interface.datagram_count = 0;
  // datagrams start after all the headers
  ncm_interface.next_datagram_offset = sizeof(nth16_t) + sizeof(ndp16_t)
      + ((CFG_TUD_NCM_MAX_DATAGRAMS_PER_NTB + 1) * sizeof(ndp16_datagram_t));
}

/*
 * If not already transmitting, start sending the current NTB to the host and swap buffers
 * to start filling the other one with datagrams.
 */
static void ncm_start_tx(void) {
  if (ncm_interface.transferring) {
    return;
  }

  transmit_ntb_t *ntb = &transmit_ntb[ncm_interface.current_ntb];
  size_t ntb_length = ncm_interface.next_datagram_offset;

  // Fill in NTB header
  ntb->nth.dwSignature = NTH16_SIGNATURE;
  ntb->nth.wHeaderLength = sizeof(nth16_t);
  ntb->nth.wSequence = ncm_interface.nth_sequence++;
  ntb->nth.wBlockLength = ntb_length;
  ntb->nth.wNdpIndex = sizeof(nth16_t);

  // Fill in NDP16 header and terminator
  ntb->ndp.dwSignature = NDP16_SIGNATURE_NCM0;
  ntb->ndp.wLength = sizeof(ndp16_t) + (ncm_interface.datagram_count + 1) * sizeof(ndp16_datagram_t);
  ntb->ndp.wNextNdpIndex = 0;
  ntb->ndp.datagram[ncm_interface.datagram_count].wDatagramIndex = 0;
  ntb->ndp.datagram[ncm_interface.datagram_count].wDatagramLength = 0;

  // Kick off an endpoint transfer
  usbd_edpt_xfer(0, ncm_interface.ep_in, ntb->data, ntb_length);
  ncm_interface.transferring = true;

  // Swap to the other NTB and clear it out
  ncm_interface.current_ntb = 1 - ncm_interface.current_ntb;
  ncm_prepare_for_tx();
}

static struct ecm_notify_struct ncm_notify_connected =
{
    .header = {
        .bmRequestType_bit = {
          .recipient = TUSB_REQ_RCPT_INTERFACE,
          .type      = TUSB_REQ_TYPE_CLASS,
          .direction = TUSB_DIR_IN
        },
        .bRequest      = CDC_NOTIF_NETWORK_CONNECTION,
        .wValue        = 1 /* Connected */,
        .wLength       = 0,
    },
};

static struct ecm_notify_struct ncm_notify_speed_change =
{
    .header = {
        .bmRequestType_bit = {
          .recipient = TUSB_REQ_RCPT_INTERFACE,
          .type      = TUSB_REQ_TYPE_CLASS,
          .direction = TUSB_DIR_IN
        },
        .bRequest = CDC_NOTIF_CONNECTION_SPEED_CHANGE,
        .wLength = 8,
    },
    .downlink = 10000000,
    .uplink = 10000000,
};

void tud_network_recv_renew(void)
{
  if (!ncm_interface.num_datagrams)
  {
    usbd_edpt_xfer(0, ncm_interface.ep_out, receive_ntb, sizeof(receive_ntb));
    return;
  }

  const ndp16_t *ndp = ncm_interface.ndp;
  const int i = ncm_interface.current_datagram_index;
  ncm_interface.current_datagram_index++;
  ncm_interface.num_datagrams--;

  tud_network_recv_cb(receive_ntb + ndp->datagram[i].wDatagramIndex, ndp->datagram[i].wDatagramLength);
}

//--------------------------------------------------------------------+
// USBD Driver API
//--------------------------------------------------------------------+

void netd_init(void)
{
  tu_memclr(&ncm_interface, sizeof(ncm_interface));
  ncm_interface.ntb_in_size = CFG_TUD_NCM_IN_NTB_MAX_SIZE;
  ncm_interface.max_datagrams_per_ntb = CFG_TUD_NCM_MAX_DATAGRAMS_PER_NTB;
  ncm_prepare_for_tx();
}

void netd_reset(uint8_t rhport)
{
  (void) rhport;

  netd_init();
}

uint16_t netd_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint16_t max_len)
{
  // confirm interface hasn't already been allocated
  TU_ASSERT(0 == ncm_interface.ep_notif, 0);

  //------------- Management Interface -------------//
  ncm_interface.itf_num = itf_desc->bInterfaceNumber;

  uint16_t drv_len = sizeof(tusb_desc_interface_t);
  uint8_t const * p_desc = tu_desc_next( itf_desc );

  // Communication Functional Descriptors
  while ( TUSB_DESC_CS_INTERFACE == tu_desc_type(p_desc) && drv_len <= max_len )
  {
    drv_len += tu_desc_len(p_desc);
    p_desc   = tu_desc_next(p_desc);
  }

  // notification endpoint (if any)
  if ( TUSB_DESC_ENDPOINT == tu_desc_type(p_desc) )
  {
    TU_ASSERT( usbd_edpt_open(rhport, (tusb_desc_endpoint_t const *) p_desc), 0 );

    ncm_interface.ep_notif = ((tusb_desc_endpoint_t const *) p_desc)->bEndpointAddress;

    drv_len += tu_desc_len(p_desc);
    p_desc   = tu_desc_next(p_desc);
  }

  //------------- Data Interface -------------//
  // - CDC-NCM data interface has 2 alternate settings
  //   - 0 : zero endpoints for inactive (default)
  //   - 1 : IN & OUT endpoints for transfer of NTBs
  TU_ASSERT(TUSB_DESC_INTERFACE == tu_desc_type(p_desc), 0);

  do
  {
    tusb_desc_interface_t const * data_itf_desc = (tusb_desc_interface_t const *) p_desc;
    TU_ASSERT(TUSB_CLASS_CDC_DATA == data_itf_desc->bInterfaceClass, 0);

    drv_len += tu_desc_len(p_desc);
    p_desc   = tu_desc_next(p_desc);
  } while((TUSB_DESC_INTERFACE == tu_desc_type(p_desc)) && (drv_len <= max_len));

  // Pair of endpoints
  TU_ASSERT(TUSB_DESC_ENDPOINT == tu_desc_type(p_desc), 0);

  TU_ASSERT(usbd_open_edpt_pair(rhport, p_desc, 2, TUSB_XFER_BULK, &ncm_interface.ep_out, &ncm_interface.ep_in) );

  drv_len += 2*sizeof(tusb_desc_endpoint_t);

  return drv_len;
}

static void ncm_report(void)
{
  uint8_t const rhport = 0;
  if (ncm_interface.report_state == REPORT_SPEED) {
    ncm_notify_speed_change.header.wIndex = ncm_interface.itf_num;
    usbd_edpt_xfer(rhport, ncm_interface.ep_notif, (uint8_t *) &ncm_notify_speed_change, sizeof(ncm_notify_speed_change));
    ncm_interface.report_state = REPORT_CONNECTED;
    ncm_interface.report_pending = true;
  } else if (ncm_interface.report_state == REPORT_CONNECTED) {
    ncm_notify_connected.header.wIndex = ncm_interface.itf_num;
    usbd_edpt_xfer(rhport, ncm_interface.ep_notif, (uint8_t *) &ncm_notify_connected, sizeof(ncm_notify_connected));
    ncm_interface.report_state = REPORT_DONE;
    ncm_interface.report_pending = true;
  }
}

TU_ATTR_WEAK void tud_network_link_state_cb(bool state)
{
  (void)state;
}

// Handle class control request
// return false to stall control endpoint (e.g unsupported request)
bool netd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const * request)
{
  if ( stage != CONTROL_STAGE_SETUP ) return true;

  switch ( request->bmRequestType_bit.type )
  {
    case TUSB_REQ_TYPE_STANDARD:
      switch ( request->bRequest )
      {
        case TUSB_REQ_GET_INTERFACE:
        {
          uint8_t const req_itfnum = (uint8_t) request->wIndex;
          TU_VERIFY(ncm_interface.itf_num + 1 == req_itfnum);

          tud_control_xfer(rhport, request, &ncm_interface.itf_data_alt, 1);
        }
          break;

        case TUSB_REQ_SET_INTERFACE:
        {
          uint8_t const req_itfnum = (uint8_t) request->wIndex;
          uint8_t const req_alt    = (uint8_t) request->wValue;

          // Only valid for Data Interface with Alternate is either 0 or 1
          TU_VERIFY(ncm_interface.itf_num + 1 == req_itfnum && req_alt < 2);

          if (req_alt != ncm_interface.itf_data_alt) {
            ncm_interface.itf_data_alt = req_alt;

            if (ncm_interface.itf_data_alt) {
              if (!usbd_edpt_busy(rhport, ncm_interface.ep_out)) {
                tud_network_recv_renew(); // prepare for incoming datagrams
              }
              if (!ncm_interface.report_pending) {
                ncm_report();
              }
            }

            tud_network_link_state_cb(ncm_interface.itf_data_alt);
          }

          tud_control_status(rhport, request);
        }
          break;

          // unsupported request
        default: return false;
      }
      break;

    case TUSB_REQ_TYPE_CLASS:
      TU_VERIFY (ncm_interface.itf_num == request->wIndex);

      if (NCM_GET_NTB_PARAMETERS == request->bRequest)
      {
        tud_control_xfer(rhport, request, (void*)(uintptr_t) &ntb_parameters, sizeof(ntb_parameters));
      }

      break;

      // unsupported request
    default: return false;
  }

  return true;
}

static void handle_incoming_datagram(uint32_t len)
{
  uint32_t size = len;

  if (len == 0) {
    return;
  }

  TU_ASSERT(size >= sizeof(nth16_t), );

  const nth16_t *hdr = (const nth16_t *)receive_ntb;
  TU_ASSERT(hdr->dwSignature == NTH16_SIGNATURE, );
  TU_ASSERT(hdr->wNdpIndex >= sizeof(nth16_t) && (hdr->wNdpIndex + sizeof(ndp16_t)) <= len, );

  const ndp16_t *ndp = (const ndp16_t *)(receive_ntb + hdr->wNdpIndex);
  TU_ASSERT(ndp->dwSignature == NDP16_SIGNATURE_NCM0 || ndp->dwSignature == NDP16_SIGNATURE_NCM1, );
  TU_ASSERT(hdr->wNdpIndex + ndp->wLength <= len, );

  int num_datagrams = (ndp->wLength - 12) / 4;
  ncm_interface.current_datagram_index = 0;
  ncm_interface.num_datagrams = 0;
  ncm_interface.ndp = ndp;
  for (int i = 0; i < num_datagrams && ndp->datagram[i].wDatagramIndex && ndp->datagram[i].wDatagramLength; i++)
  {
    ncm_interface.num_datagrams++;
  }
  
  tud_network_recv_renew();
}

bool netd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
{
  (void) rhport;
  (void) result;

  /* new datagram receive_ntb */
  if (ep_addr == ncm_interface.ep_out )
  {
    handle_incoming_datagram(xferred_bytes);
  }

  /* data transmission finished */
  if (ep_addr == ncm_interface.ep_in )
  {
    if (ncm_interface.transferring) {
      ncm_interface.transferring = false;
    }

    // If there are datagrams queued up that we tried to send while this NTB was being emitted, send them now
    if (ncm_interface.datagram_count && ncm_interface.itf_data_alt == 1) {
      ncm_start_tx();
    }
  }

  if (ep_addr == ncm_interface.ep_notif )
  {
    ncm_interface.report_pending = false;
    ncm_report();
  }

  return true;
}

// poll network driver for its ability to accept another packet to transmit
bool tud_network_can_xmit(uint16_t size)
{
  TU_VERIFY(ncm_interface.itf_data_alt == 1);

  if (ncm_interface.datagram_count >= ncm_interface.max_datagrams_per_ntb) {
    TU_LOG2("NTB full [by count]\r\n");
    return false;
  }

  size_t next_datagram_offset = ncm_interface.next_datagram_offset;
  if (next_datagram_offset + size > ncm_interface.ntb_in_size) {
    TU_LOG2("ntb full [by size]\r\n");
    return false;
  }

  return true;
}

void tud_network_xmit(void *ref, uint16_t arg)
{
  transmit_ntb_t *ntb = &transmit_ntb[ncm_interface.current_ntb];
  size_t next_datagram_offset = ncm_interface.next_datagram_offset;

  uint16_t size = tud_network_xmit_cb(ntb->data + next_datagram_offset, ref, arg);

  ntb->ndp.datagram[ncm_interface.datagram_count].wDatagramIndex = ncm_interface.next_datagram_offset;
  ntb->ndp.datagram[ncm_interface.datagram_count].wDatagramLength = size;

  ncm_interface.datagram_count++;
  next_datagram_offset += size;

  // round up so the next datagram is aligned correctly
  next_datagram_offset += (CFG_TUD_NCM_ALIGNMENT - 1);
  next_datagram_offset -= (next_datagram_offset % CFG_TUD_NCM_ALIGNMENT);

  ncm_interface.next_datagram_offset = next_datagram_offset;

  ncm_start_tx();
}

#endif
