/**
 * @file app_ble_proto.h
 * @brief BLE frame protocol frontend (over the CLS write/notify
 *        characteristics): frame reassembly, CLI request/response transport
 *        and OTA frame dispatch.
 *
 * Frame format (little endian):
 *   [0]    SOF = 0xCA
 *   [1]    TYPE
 *   [2]    SEQ
 *   [3:4]  LEN (payload length, LE)
 *   [5..]  PAYLOAD
 *   [end-2..end] CRC16-CCITT (init 0xFFFF, poly 0x1021), LE, over TYPE..PAYLOAD
 *
 * All functions run in the BLE schedule task context only.
 */
#ifndef __APP_BLE_PROTO_H__
#define __APP_BLE_PROTO_H__

#ifdef __cplusplus
extern "C" {
#endif

#include <stdint.h>

/* Frame types */
#define BLE_FRAME_CLI_REQ       0x01    /* phone -> device: one command line */
#define BLE_FRAME_CLI_RSP       0x02    /* device -> phone: response text chunk */
#define BLE_FRAME_CLI_RSP_END   0x03    /* device -> phone: {status u8} */
#define BLE_FRAME_OTA_BEGIN     0x10    /* {total_size u32, image_crc32 u32, version u32} */
#define BLE_FRAME_OTA_DATA      0x11    /* {offset u32 + data}, strictly sequential */
#define BLE_FRAME_OTA_END       0x12    /* {crc32 u32} */
#define BLE_FRAME_OTA_RSP       0x1F    /* device -> phone: {cmd_echo u8, status u8, offset u32} */

/* OTA_RSP status codes */
#define BLE_OTA_ST_OK           0
#define BLE_OTA_ST_BAD_FRAME    1
#define BLE_OTA_ST_BAD_STATE    2   /* bad state / bad offset sequence */
#define BLE_OTA_ST_SIZE_TOO_BIG 3
#define BLE_OTA_ST_CRC_FAIL     4
#define BLE_OTA_ST_FLASH_FAIL   5

/**
 * @brief Reset the protocol state machine and pending buffer.
 */
void app_ble_proto_init(void);

/**
 * @brief Feed a received BLE write chunk into the frame reassembler.
 *        Registered as the app_ble downlink callback (BLE task context).
 */
void app_ble_proto_rx_bytes(const uint8_t* data, uint16_t len);

/**
 * @brief Retry flushing pending TX frames. Called every BleTask loop round.
 */
void app_ble_proto_poll(void);

/**
 * @brief BLE disconnect hook: abort OTA session, drop pending TX, reset RX.
 */
void app_ble_proto_on_disconnect(void);

/**
 * @brief Build and send (or queue) one frame. Used by app_ota.c for OTA_RSP.
 * @return 0 if sent or queued, -1 if dropped (not connected / pending full).
 */
int app_ble_proto_send_frame(uint8_t type, uint8_t seq, const uint8_t* payload, uint16_t len);

#ifdef __cplusplus
}
#endif

#endif /* __APP_BLE_PROTO_H__ */