const DATA_LEN_POS: u16 = 0;
const VERSION_POS: u16 = 4;
const API_ID_POS: u16 = VERSION_POS + 2;
const REQ_ID_POS: u16 = API_ID_POS + 2; // 请求的id
const CHANNEL_ID_POS: u16 = REQ_ID_POS + 8; // 请求的id
const FIX_LEN_POS: u16 = CHANNEL_ID_POS + 8;




pub mod xport {
    //
    pub const SEND_MESSAGE_API_ID: u16 = 1001;
    pub const GET_ALL_CONN_ID_API_ID: u16 = 1002;
    pub const GET_CHANNEL_ID_BY_CONN_API_ID: u16 = 1003;
    pub const GEN_ID: u16 = 1004;
    pub const RESP_MESSAGE_API_ID: u16 = 1005;
    pub const GET_CONFIG_API_ID: u16 = 1006;
    pub const NOTICE_READY_API_ID: u16 = 1007;
    pub const NOTICE_FINIALIZE_API_ID: u16 = 1008;
}




// http
pub mod log {
    pub const OUTPUT_API_ID: u16 = 5001;
}

pub struct ProtocolIPCReader<'a> {
    msg_buffer: &'a [u8],
}
impl<'a> ProtocolIPCReader<'a> {
    pub fn new(msg_buffer: &'a [u8]) -> ProtocolIPCReader<'a> {
        ProtocolIPCReader { msg_buffer }
    }

    // 获取 api_id
    pub fn api_id(&self) -> u16 {
        unsafe {
            let ptr = self.msg_buffer.as_ptr().offset(API_ID_POS as isize);

            let bytes = *(ptr as *const [u8; 2]);

            u16::from_le_bytes(bytes)
        }
    }

    // 获取 request_id
    pub fn request_id(&self) -> i64 {
        unsafe {
            let ptr = self.msg_buffer.as_ptr().offset(REQ_ID_POS as isize);

            let bytes = *(ptr as *const [u8; 8]);

            i64::from_le_bytes(bytes)
        }
    }

    // 获取 channel_id
    pub fn channel_id(&self) -> i64 {
        unsafe {
            let ptr = self.msg_buffer.as_ptr().offset(CHANNEL_ID_POS as isize);

            let bytes = *(ptr as *const [u8; 8]);

            i64::from_le_bytes(bytes)
        }
    }

    pub fn version(&self) -> u16 {
        unsafe {
            let ptr = self.msg_buffer.as_ptr().offset(VERSION_POS as isize);

            let bytes = *(ptr as *const [u8; 2]);

            u16::from_le_bytes(bytes)
        }
    }

    /**
     * 获取消息长度
     */
    pub fn msg_size(&self) -> u32 {
        self.msg_buffer.len() as u32
    }

    pub fn msg_body(&self) -> &[u8] {
        &self.msg_buffer[FIX_LEN_POS as usize..]
    }
}

pub struct ProtocolIPCWriter {
    pub msg_buffer: Vec<u8>,
    pub msg_body_size: u32,
}

impl ProtocolIPCWriter {
    pub fn new(msg_size: u32, api_id: u16, request_id: i64) -> ProtocolIPCWriter {
        let msg_len = (FIX_LEN_POS as u32 + msg_size) as usize;

        let mut msg_buffer: Vec<u8> = Vec::with_capacity(msg_len);
        unsafe {
            msg_buffer.set_len(msg_len);
        }

        let mut writer = ProtocolIPCWriter {
            msg_buffer,
            msg_body_size: msg_size,
        };
        //
        writer.write_api_id(api_id);
        writer.write_request_id(request_id);

        writer.write_version();
        writer.write_data_len(msg_len as u32);

        writer
    }

    pub fn write_api_id(&mut self, api_id: u16) {
        unsafe {
            let bytes = api_id.to_le_bytes();

            let ptr = self.msg_buffer.as_mut_ptr().offset(API_ID_POS as isize);

            std::ptr::copy_nonoverlapping(bytes.as_ptr(), ptr, 2);
        }
    }

    pub fn write_request_id(&mut self, request_id: i64) {
        unsafe {
            let bytes = request_id.to_le_bytes();

            let ptr = self.msg_buffer.as_mut_ptr().offset(REQ_ID_POS as isize);

            std::ptr::copy_nonoverlapping(bytes.as_ptr(), ptr, 8);
        }
    }

    pub fn write_channel_id(&mut self, channel_id: i64) {
        unsafe {
            let bytes = channel_id.to_le_bytes();

            let ptr = self.msg_buffer.as_mut_ptr().offset(CHANNEL_ID_POS as isize);

            std::ptr::copy_nonoverlapping(bytes.as_ptr(), ptr, 8);
        }
    }

    pub fn msg_body_buffer(&mut self) -> &mut [u8] {
        // msg_body_size

        let msg_body_pos = self.msg_buffer.len() - self.msg_body_size as usize;

        &mut self.msg_buffer[msg_body_pos as usize..]
    }

    fn write_version(&mut self) {
        unsafe {
            let bytes = (1 as u16).to_le_bytes();
            let ptr = self.msg_buffer.as_mut_ptr().offset(VERSION_POS as isize);
            std::ptr::copy_nonoverlapping(bytes.as_ptr(), ptr, 2);
        }
    }

    pub fn write_msg_body(&mut self, message: &Vec<u8>) {
        unsafe {
            let msg_body_pos = self.msg_buffer.len() - self.msg_body_size as usize;

            println!(
                "msg_body_pos = {} FIX_LEN_POS = {}",
                msg_body_pos, FIX_LEN_POS
            );
            let dst_ptr = self.msg_buffer.as_mut_ptr().offset(msg_body_pos as isize);
            std::ptr::copy_nonoverlapping(message.as_ptr(), dst_ptr, message.len());
        }
    }

    pub fn write_u8_msg_body(&mut self, message: &[u8]) {
        unsafe {
            let msg_body_pos = self.msg_buffer.len() - self.msg_body_size as usize;
            let dst_ptr = self.msg_buffer.as_mut_ptr().offset(msg_body_pos as isize);
            std::ptr::copy_nonoverlapping(message.as_ptr(), dst_ptr, message.len());
        }
    }

    /**
     * 写入长度
     */
    fn write_data_len(&mut self, data_len: u32) {
        unsafe {
            let bytes = data_len.to_le_bytes();

            let ptr = self.msg_buffer.as_mut_ptr().offset(DATA_LEN_POS as isize);

            std::ptr::copy_nonoverlapping(bytes.as_ptr(), ptr, 4);
        }
    }
}