#include "MSP.h"

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


void msp_init(msp_port_t *msp)
{

}

uint8_t crc8_dvb_s2_apm(uint8_t crc, unsigned char a)
{
    crc ^= a;
    for (int ii = 0; ii < 8; ++ii)
    {
        if (crc & 0x80)
        {
            crc = (crc << 1) ^ 0xD5;
        }
        else
        {
            crc = crc << 1;
        }
    }
    return crc;
}
void msp_send(msp_port_t *msp, uint8_t messageID, void *payload, uint8_t size)
{
    uint8_t msp_data_packet[6 + size];
    msp_data_packet[0] = '$';
    msp_data_packet[1] = 'M';
    msp_data_packet[2] = '<';
    msp_data_packet[3] = size;
    msp_data_packet[4] = messageID;

    uint8_t checksum = size ^ messageID;
    uint8_t *payloadPtr = (uint8_t *)payload;
    for (int i = 0; i < size; i++)
    {
        uint8_t b = *(payloadPtr++);
        checksum ^= b;
        msp_data_packet[5 + i] = b;
    }
    msp_data_packet[6 + size - 1] = checksum;
    msp->write(&msp_data_packet[0], 6 + size, 10);
}
void msp_send2(msp_port_t *msp, uint16_t messageID, void *payload, uint16_t size)
{
    uint8_t _crc = 0;
    uint8_t msp_data_packet[size + 9];
    msp_data_packet[0] = '$';
    msp_data_packet[1] = 'X';
    msp_data_packet[2] = '<';
    msp_data_packet[3] = 0;         // flag
    msp_data_packet[4] = messageID; // function
    msp_data_packet[5] = messageID >> 8;
    msp_data_packet[6] = size; // payload size
    msp_data_packet[7] = size >> 8;
    for (uint8_t i = 3; i < 8; i++)
    {
        _crc = crc8_dvb_s2_apm(_crc, msp_data_packet[i]);
    }
    // Start of Payload
    uint8_t *payloadPtr = (uint8_t *)payload;
    for (uint16_t i = 0; i < size; ++i)
    {
        msp_data_packet[i + 8] = *(payloadPtr++);
        _crc = crc8_dvb_s2_apm(_crc, msp_data_packet[i + 8]);
    }
    msp_data_packet[size + 8] = _crc;

    msp->write(&msp_data_packet[0], 9 + size, 10);
}
// 解析接收数据是否正确
bool msp_parse_received_data(msp_port_t *msp, uint8_t c)
{
    switch (msp->c_state)
    {
    default:
    case MSP_IDLE: // Waiting for '$' character
        if (c == '$')
        {
            msp->msp_version = MSP_V1;
            msp->c_state = MSP_HEADER_START;
        }
        else
        {
            return false;
        }
        break;

    case MSP_HEADER_START: // Waiting for 'M' (MSPv1 / MSPv2_over_v1) or 'X' (MSPv2 native)
        switch (c)
        {
        case 'M':
            msp->c_state = MSP_HEADER_M;
            break;
        case 'X':
            msp->c_state = MSP_HEADER_X;
            break;
        default:
            msp->c_state = MSP_IDLE;
            break;
        }
        break;

    case MSP_HEADER_M: // Waiting for '<'
        if (c == '<' || c == '>')
        {
            msp->offset = 0;
            msp->checksum1 = 0;
            msp->checksum2 = 0;
            msp->c_state = MSP_HEADER_V1;
        }
        else
        {
            msp->c_state = MSP_IDLE;
        }
        break;

    case MSP_HEADER_X:
        if (c == '<' || c == '>')
        {
            msp->offset = 0;
            msp->checksum2 = 0;
            msp->msp_version = MSP_V2_NATIVE;
            msp->c_state = MSP_HEADER_V2_NATIVE;
        }
        else
        {
            msp->c_state = MSP_IDLE;
        }
        break;

    case MSP_HEADER_V1: // Now receive v1 header (size/cmd), this is already checksummable
        msp->in_buf[msp->offset++] = c;
        msp->checksum1 ^= c;
        if (msp->offset == sizeof(msp_header_v1_t))
        {
            msp_header_v1_t *hdr = (msp_header_v1_t *)&msp->in_buf[0];
            // Check incoming buffer size limit
            if (hdr->size > MSP_PORT_INBUF_SIZE)
            {
                msp->c_state = MSP_IDLE;
            }
            else if (hdr->cmd == MSP_V2_FRAME_ID)
            {
                // MSPv1 payload must be big enough to hold V2 header + extra checksum
                if (hdr->size >= sizeof(msp_header_v2_t) + 1)
                {
                    msp->msp_version = MSP_V2_OVER_V1;
                    msp->c_state = MSP_HEADER_V2_OVER_V1;
                }
                else
                {
                    msp->c_state = MSP_IDLE;
                }
            }
            else
            {
                msp->data_size = hdr->size;
                msp->cmd_msp = hdr->cmd;
                msp->cmd_flags = 0;
                msp->offset = 0;                                                      // re-use buffer
                msp->c_state = msp->data_size > 0 ? MSP_PAYLOAD_V1 : MSP_CHECKSUM_V1; // If no payload - jump to checksum byte
                msp->msp_packet_type = msp->data_size > 0 ? 1 : 2;
            }
        }
        break;

    case MSP_PAYLOAD_V1:
        msp->in_buf[msp->offset++] = c;
        msp->checksum1 ^= c;
        if (msp->offset == msp->data_size)
        {
            msp->c_state = MSP_CHECKSUM_V1;
        }
        break;

    case MSP_CHECKSUM_V1:
        if (msp->checksum1 == c)
        {
            msp->c_state = MSP_COMMAND_RECEIVED;
        }
        else
        {
            msp->c_state = MSP_IDLE;
        }
        break;

    case MSP_HEADER_V2_OVER_V1: // V2 header is part of V1 payload - we need to calculate both checksums now
        msp->in_buf[msp->offset++] = c;
        msp->checksum1 ^= c;
        msp->checksum2 = crc8_dvb_s2_apm(msp->checksum2, c);
        if (msp->offset == (sizeof(msp_header_v2_t) + sizeof(msp_header_v1_t)))
        {
            msp_header_v2_t *hdrv2 = (msp_header_v2_t *)&msp->in_buf[sizeof(msp_header_v1_t)];
            msp->data_size = hdrv2->size;

            // Check for potential buffer overflow
            if (hdrv2->size > MSP_PORT_INBUF_SIZE)
            {
                msp->c_state = MSP_IDLE;
            }
            else
            {
                msp->cmd_msp = hdrv2->cmd;
                msp->cmd_flags = hdrv2->flags;
                msp->offset = 0; // re-use buffer
                msp->c_state = msp->data_size > 0 ? MSP_PAYLOAD_V2_OVER_V1 : MSP_CHECKSUM_V2_OVER_V1;
                msp->msp_packet_type = msp->data_size > 0 ? 1 : 2;
            }
        }
        break;

    case MSP_PAYLOAD_V2_OVER_V1:
        msp->checksum2 = crc8_dvb_s2_apm(msp->checksum2, c);
        msp->checksum1 ^= c;
        msp->in_buf[msp->offset++] = c;

        if (msp->offset == msp->data_size)
        {
            msp->c_state = MSP_CHECKSUM_V2_OVER_V1;
        }
        break;

    case MSP_CHECKSUM_V2_OVER_V1:
        msp->checksum1 ^= c;
        if (msp->checksum2 == c)
        {
            msp->c_state = MSP_CHECKSUM_V1; // Checksum 2 correct - verify v1 checksum
        }
        else
        {
            msp->c_state = MSP_IDLE;
        }
        break;

    case MSP_HEADER_V2_NATIVE:
        msp->in_buf[msp->offset++] = c;
        msp->checksum2 = crc8_dvb_s2_apm(msp->checksum2, c);
        if (msp->offset == sizeof(msp_header_v2_t))
        {
            msp_header_v2_t *hdrv2 = (msp_header_v2_t *)&msp->in_buf[0];

            // Check for potential buffer overflow
            if (hdrv2->size > MSP_PORT_INBUF_SIZE)
            {
                msp->c_state = MSP_IDLE;
            }
            else
            {
                msp->data_size = hdrv2->size;
                msp->cmd_msp = hdrv2->cmd;
                msp->cmd_flags = hdrv2->flags;
                msp->offset = 0; // re-use buffer
                msp->c_state = msp->data_size > 0 ? MSP_PAYLOAD_V2_NATIVE : MSP_CHECKSUM_V2_NATIVE;
                msp->msp_packet_type = msp->data_size > 0 ? 1 : 2;
            }
        }
        break;

    case MSP_PAYLOAD_V2_NATIVE:
        msp->checksum2 = crc8_dvb_s2_apm(msp->checksum2, c);
        msp->in_buf[msp->offset++] = c;

        if (msp->offset == msp->data_size)
        {
            msp->c_state = MSP_CHECKSUM_V2_NATIVE;
        }
        break;

    case MSP_CHECKSUM_V2_NATIVE:
        if (msp->checksum2 == c)
        {
            msp->c_state = MSP_COMMAND_RECEIVED;
        }
        else
        {
            msp->c_state = MSP_IDLE;
        }
        break;
    }
    return true;
}
// MSP解析成功还会进行数据处理
void msp_process_received_command(msp_port_t *msp)
{
    uint8_t out_buf[MSP_PORT_OUTBUF_SIZE];

    msp_packet_t reply = {
        .buf = {
            .ptr = out_buf,
            .end = MSP_ARRAYEND(out_buf),
        },
        .cmd = -1,
        .flags = 0,
        .result = 0,
        .msp_packet_type = msp->msp_packet_type,
    };

    // uint8_t *out_buf_head = reply.buf.ptr;

    msp_packet_t command = {
        .buf = {
            .ptr = msp->in_buf,
            .end = msp->in_buf + msp->data_size,
        },
        .cmd = (int16_t)msp->cmd_msp,
        .flags = msp->cmd_flags,
        .result = 0,
        .msp_packet_type = msp->msp_packet_type,
    };

    const MSPCommandResult status = msp_process_command(&command, &reply);

    if (status != MSP_RESULT_NO_REPLY)
    {
        // sbuf_switch_to_reader(&reply.buf, out_buf_head); // change streambuf direction
        // msp_serial_encode(msp, &reply, msp->msp_version);
    }

    msp->c_state = MSP_IDLE;
}
MSPCommandResult msp_process_command(msp_packet_t *cmd, msp_packet_t *reply)
{
    MSPCommandResult ret = MSP_RESULT_ACK;
    sbuf_t *dst = &reply->buf;
    sbuf_t *src = &cmd->buf;
    const uint16_t cmd_msp = cmd->cmd;
    // initialize reply by default
    reply->cmd = cmd->cmd;
    // 收到有数据包
    if (cmd->msp_packet_type == 1)
    {
        ret = msp_process_sensor_command(cmd_msp, src);
    }
    else if (cmd->msp_packet_type == 2)
    { // 收到无数据包
        ret = msp_process_out_command(cmd_msp, dst);
    }

    // Process DONT_REPLY flag
    if (cmd->flags & 0x1)
    {
        ret = MSP_RESULT_NO_REPLY;
    }

    reply->result = ret;
    return ret;
}

// MSP解析数据处理
MSPCommandResult msp_process_sensor_command(uint16_t cmd_msp, sbuf_t *src)
{
    MSP_UNUSED(src);
    switch (cmd_msp)
    {
    case 1:
    {
    }
    break;
    case MSP_FC_VARIANT:
    {
        const msp_apm_data_t *pkt = (const msp_apm_data_t *)src->ptr;
        msp_handle_fc(*pkt);
    }
    break;
    case MSP_GCS_DATA:
    {
        const msp_gcs_t *pkt = (const msp_gcs_t *)src->ptr;
        msp_handle_get_gcs(*pkt);
    }
    break;
    case MSP_FC_DATA:
    {
        const msp_fc_t *pkt = (const msp_fc_t *)src->ptr;
        msp_handle_get_fc(*pkt);
    }
    break;
    case MSP_RAW_GPS:
    {
        const msp_raw_gps_t *pkt = (const msp_raw_gps_t *)src->ptr;
        msp_handle_get_gps(*pkt);
    }
    break;
    case MSP_ANALOG:
    {
        const msp_analog_t *pkt = (const msp_analog_t *)src->ptr;
        msp_handle_get_analog(*pkt);
    }
    break;
    case MSP_ATTITUDE:
    {
        // const msp_attitude_t *pkt = (const msp_attitude_t *)src->ptr;
        // msp_handle_get_attitude(*pkt);
        printf("ATTITUDE\n");
    }
    break;
    }
    

    return MSP_RESULT_NO_REPLY;
}
// 接收数据包处理
void msp_handle_fc(msp_apm_data_t pkt)
{

}
void msp_handle_get_gps(msp_raw_gps_t pkt)
{

}
void msp_handle_get_fc(msp_fc_t pkt)
{
}
void msp_handle_get_analog(msp_analog_t pkt)
{

}
void msp_handle_get_gcs(msp_gcs_t pkt)
{

}
// MSP回复请求包处理
MSPCommandResult msp_process_out_command(uint16_t cmd_msp, sbuf_t *dst)
{
    switch (cmd_msp)
    {
    case MSP_FC_VARIANT:
    {
        fc_put_ack();
        return MSP_RESULT_ACK;
    }
    break;
    default:
        // MSP always requires an ACK even for unsupported messages
        return MSP_RESULT_ACK;
    }
}

// 请求回复包
void fc_put_ack(void)
{
    // uint8_t data[5] = {'T', 'X', 'S', 'T', 0};
    // msp_send(2, &data[0], 5);
    // printf("ACK\n");
}


// MSP数据读取,并根据读取的数据进行处理
void msp_recv_loop(msp_port_t *msp)
{
    uint8_t c;

    while (msp->read(&c, 1, 0) > 0)
    {
        if (msp_parse_received_data(msp, c))
        {
            if (msp->c_state == MSP_COMMAND_RECEIVED)
            {
                msp_process_received_command(msp);
                break;
            }
        }
    }
}
int msp_recv_buf(msp_port_t *msp, void *data, uint32_t size)
{
    uint8_t res = 0;
    uint32_t size_lat = size;
    uint8_t* data_char = (uint8_t*)data;

    while (size_lat --)
    {
        uint8_t c = data_char[size - size_lat - 1];
        if (msp_parse_received_data(msp, c))
        {
            if (msp->c_state == MSP_COMMAND_RECEIVED)
            {
                msp_process_received_command(msp);
                res ++;
            }
        }
    }
    return res;
}