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/**
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 * Copyright (c) 2009 Colony Project
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 *
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 * Permission is hereby granted, free of charge, to any person
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 * obtaining a copy of this software and associated documentation
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 * files (the "Software"), to deal in the Software without
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 * restriction, including without limitation the rights to use,
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 * copy, modify, merge, publish, distribute, sublicense, and/or sell
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 * copies of the Software, and to permit persons to whom the
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 * Software is furnished to do so, subject to the following
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 * conditions:
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 *
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 * The above copyright notice and this permission notice shall be
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 * included in all copies or substantial portions of the Software.
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 *
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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 * OTHER DEALINGS IN THE SOFTWARE.
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 **/
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/**
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 * @file wireless_receive.c
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 * @brief Wireless library receive functions
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 *
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 * Implementation of high level wireless communication.
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 * This is the receive functions portion of the library.
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 *
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 * @author Colony Project, CMU Robotics Club
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 **/
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#include <string.h>
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#include "wl_defs.h"
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#include "wireless.h"
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#include "xbee.h"
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/**
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 * Definition for wireless library receive packet structure
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 *
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 * Basic Buffer Packet:
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 *   byte 1: length of data
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 *   bytes 2-3: source
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 *   bytes 4-n: data
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 *
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 * Other Buffer Packet:
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 *   byte 1: length of data
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 *   byte 2: group number
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 *   bytes 3-4: source
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 *   bytes 5-n: data
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 *
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 **/
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extern uint8_t xbee_basic_buf[PACKET_BUFFER_SIZE];  // buffer for basic-group packets
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extern uint8_t xbee_other_buf[PACKET_BUFFER_SIZE];  // buffer for non-basic-group packets
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extern uint8_t basic_buf_first;        // beginning of first packet in basic buffer
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extern uint8_t basic_buf_last;        // end of last packet in basic buffer
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extern uint8_t other_buf_first; // beginning of first packet in other buffer
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extern uint8_t other_buf_last;  // end of last packet in other buffer
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/**
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 * @addtogroup wireless Wireless
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 * @{
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 **/
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/**
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 * the main receive function (similar to wl_do)
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 *
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 * when called, this function will receive the next packet on the default packet group
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 * it will also dispatch registered packet handler functions for any other packet groups it has received
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 *
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 * @param data an already-initialized array to store the default group packet data in
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 * @param length the length of the initialized data array
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 *
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 * @return the length of the used portion of data array or error (<0)
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 **/
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int8_t wl_get(char *data, uint8_t length) {
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  int8_t return_code = wl_dispatch(); // run dispatch of other packet groups
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  if (return_code != 0)
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    return return_code; // error, so end early
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  return wl_get_basic(data, length); // get a basic packet
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}
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/**
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 * function to receive only packets on the default group
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 * this function is only meant to receive packets sent using wl_send_basic()
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 *
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 * @param data an already-initialized array to store the default group packet data in
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 * @param length the length of the initialized data array
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 *
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 * @return the length of the used portion of data array or error (<0)
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 **/
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int8_t wl_get_basic(char *data, uint8_t length) {
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    uint8_t buf_pos = basic_buf_first;        // start at beginning of first (oldest) basic packet
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    uint8_t data_length = xbee_basic_buf[buf_pos % PACKET_BUFFER_SIZE];  // get packet length
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    if (data_length - 3 > length)   // not enough room for data in destination
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        return WL_ERROR_TOO_SMALL;
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    // packet has not fully arrived yet
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    if (buf_pos + data_length > basic_buf_last        // length goes farther than end of buffer
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            && !(buf_pos >= basic_buf_last && buf_pos + data_length > buf_pos))
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        /* basic test is Beginning + Length > Buffer End means packet isn't all there yet
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           if end counter overflows, a complete packet's end may still be greater than the buffer end index,
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           but such a packet can be read from the buffer
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         */
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        return WL_SUCCESS;  // no data written
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    buf_pos++;
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    buf_pos++;        // ignore the source ID
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    // copy data to destination, byte by byte to account for circular buffer
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    // don't copy the 3 header bytes. nobody wants those.
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    for (; buf_pos < basic_buf_first + data_length; buf_pos++)
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        memcpy(data + buf_pos - 3, xbee_basic_buf + (buf_pos % PACKET_BUFFER_SIZE), 1);
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    basic_buf_first += data_length; // "free up" this packet's buffer space
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    return data_length;
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}
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/*
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 * function to dispatch all registered packet handlers for received packets on non-default groups
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 *
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 * @return error codes (TBD)
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 */
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int8_t wl_dispatch(void) {
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    uint8_t buf_pos = other_buf_first;        // current position in buffer
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    uint8_t group;  // group of packet under consideration
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    void (*handler)(uint8_t *data, uint8_t length, uint8_t source);  // handler for group of packet under consideration
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    uint8_t length = xbee_other_buf[buf_pos % PACKET_BUFFER_SIZE];  // length of packet under consideration
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    uint8_t source; // robot ID of sender of packet under consideration
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    // consider packets one at a time until buffer contains no complete packets
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    while (buf_pos + length <= other_buf_last        // length goes farther than end of buffer
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            || (buf_pos >= other_buf_last && buf_pos + length > buf_pos)) {
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        /* basic test is Beginning + Length > Buffer End means packet isn't all there yet
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           if end counter overflows, a complete packet's end may still be greater than the buffer end index,
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           but such a packet can be read from the buffer
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         */
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        buf_pos++;
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        group = xbee_other_buf[buf_pos];    // get group from packet
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        if (group >= MAX_PACKET_GROUPS)  // invalid group number
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            buf_pos += length - 1 + 1;        // go to first byte of next packet
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        else {        // valid group number
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            handler = wl_packet_handlers[group].FUNC;        // get function from handler array
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            buf_pos++;
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            buf_pos++;  // ignore 1st byte of ID (will be all 0s)
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            source = xbee_other_buf[buf_pos];   // get sender ID from packet
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            buf_pos++;  // now index of beginning of packet data (mod PACKET_BUFFER_SIZE)
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            if (handler)        // check whether group is handled
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                (*handler)(xbee_other_buf + (buf_pos & PACKET_BUFFER_SIZE), length - 4, source);
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            // go to next packet
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            buf_pos += length - 4 + 1;  // go to first byte of next packet
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        }
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        length = xbee_other_buf[buf_pos & PACKET_BUFFER_SIZE];        // get length of next packet
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    }
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    return WL_SUCCESS;
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}
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/**@} **/ //end defgroup
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// Define all private functions down here
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