//
// Created by MightyPork on 2018/03/31.
//

#include <string.h>
#include "debug.h"
#include "msg_queue.h"
#include "gex_gateway.h"
#include "main.h"
#include "minmax.h"
#include "payload_parser.h"
#include "nrf.h"
#include "crc32.h"
#include "payload_builder.h"

static uint8_t gex_network[4];

// USB RX
enum USB_RX_STATE {
    CMD_STATE_IDLE = 0,
    CMD_STATE_TXMSG = 1,
};

#define MAX_FRAME_LEN 512

static enum USB_RX_STATE cmd_state = CMD_STATE_IDLE;

static uint32_t txmsg_len = 0; // total len to be collected
static uint32_t txmsg_collected = 0; // already collected len
static uint8_t  txmsg_payload[MAX_FRAME_LEN]; // equal buffer size in GEX
static uint8_t txmsg_addr = 0;
static uint8_t txmsg_cksum = 0;

#define MAGIC_GW_COMMAND 0x47U // 'G'

enum GW_CMD {
    CMD_GET_ID = 'i', // 105 - get network ID
    CMD_RESET = 'r', // reset the radio and network
    CMD_ADD_NODE = 'n', // add a node by address byte
    CMD_TXMSG = 'm', // 109 - send a message
};

void respond_gw_id(void);

void handle_cmd_addnode(PayloadParser *pp);

void handle_cmd_reset(void);

void start_slave_cmd(uint8_t slave_addr, uint16_t frame_len, uint8_t cksum)
{
    txmsg_len = frame_len;
    txmsg_collected = 0;
    txmsg_addr = slave_addr;
    txmsg_cksum = cksum;
}

void gw_handle_usb_out(uint8_t *buffer)
{
    if (cmd_state == CMD_STATE_IDLE) {
        PayloadParser pp = pp_start(buffer, MQ_SLOT_LEN, NULL);

        // handle binary commands for the gateway

        // magic twice, one inverted - denotes a gateway command
        const uint16_t magic1 = pp_u8(&pp);
        const uint16_t magic2 = pp_u8(&pp);
        if (magic1 == MAGIC_GW_COMMAND && magic2 == (0xFFU & (~MAGIC_GW_COMMAND))) {
            // third byte is the command code
            switch (pp_u8(&pp)) {
                case CMD_GET_ID:
                    respond_gw_id();
                    break;

                case CMD_RESET:
                    handle_cmd_reset();
                    break;

                case CMD_ADD_NODE:
                    handle_cmd_addnode(&pp);
                    break;

                case CMD_TXMSG:;
                    uint8_t slave_addr = pp_u8(&pp);
                    uint16_t frame_len = pp_u16(&pp);
                    uint8_t cksum = pp_u8(&pp);

                    if (frame_len == 0 || frame_len > MAX_FRAME_LEN) {
                        dbg("Frame too big!");
                        break;
                    }

                    start_slave_cmd(slave_addr, frame_len, cksum);
                    dbg("Collecting frame for slave %02x: %d bytes", (int)slave_addr, (int)frame_len);
                    cmd_state = CMD_STATE_TXMSG;
                    break;

                default:
                    dbg("Bad cmd");
            }
        } else {
            // Bad frame??
            dbg("Bad USB frame, starts %x,%x", buffer[0],buffer[1]);
        }
    }
    else if (cmd_state == CMD_STATE_TXMSG) {
        uint32_t wanted = MIN(txmsg_len - txmsg_collected, MQ_SLOT_LEN);
        memcpy(&txmsg_payload[txmsg_collected], buffer, wanted);
        txmsg_collected += wanted;

        if (wanted < MQ_SLOT_LEN) {
            // this was the end
            uint8_t ck = 0;
            for (int i = 0; i < txmsg_len; i++) {
                ck ^= txmsg_payload[i];
            }
            ck = ~ck;

            if (ck != txmsg_cksum) {
                dbg("Checksum mismatch!");
            }
            else {
                dbg("Verified, sending a %d B frame to slave.", (int) txmsg_len);
                // TODO send to slave
            }

            cmd_state = CMD_STATE_IDLE;
        }
    }
}

void handle_cmd_reset(void)
{
    NRF_Reset();
    // TODO also clear queues?
}

void handle_cmd_addnode(PayloadParser *pp)
{
    uint8_t node = pp_u8(pp);
    uint8_t pipenum;
    bool suc = NRF_AddPipe(node, &pipenum);
    if (!suc) dbg("Failed to add node.");
    // TODO response
}

void respond_gw_id(void)
{
    // TODO implement (after response system is added)
}

/**
 * Compute the GEX network ID based on the gateway MCU unique ID.
 * The ID is a 4-byte code that must be entered in each node to join the network.
 */
static void compute_network_id(void)
{
    uint8_t uid[12];
    PayloadBuilder pb = pb_start(uid, 12, NULL);
    pb_u32(&pb, LL_GetUID_Word0());
    pb_u32(&pb, LL_GetUID_Word1());
    pb_u32(&pb, LL_GetUID_Word2());

    uint32_t ck = CRC32_Start();
    for (int i = 0; i < 12; i++) {
        ck = CRC32_Add(ck, uid[i]);
    }
    ck = CRC32_End(ck);

    pb = pb_start(gex_network, 4, NULL);
    pb_u32(&pb, ck);

    dbg("Dongle network ID: %02X-%02X-%02X-%02X",
        gex_network[0], gex_network[1], gex_network[2], gex_network[3]);
}

void gw_setup_radio(void)
{
    bool suc;
    dbg("Init NRF");

    NRF_Init(NRF_SPEED_2M);

    compute_network_id();
    NRF_SetBaseAddress(gex_network);

    // TODO by config
    uint8_t pipenum;
    suc = NRF_AddPipe(0x01, &pipenum);
    dbg("Pipe added? %d, num %d", (int)suc, (int)pipenum);

    NRF_ModeRX(); // base state is RX

    dbg("Send a packet");

    suc = NRF_SendPacket(pipenum, (uint8_t *) "AHOJ", 5);
    dbg("Suc? %d", (int)suc);
}