/**
 * @file stk.h
 * @brief EdgeTX RC library interface for HID joystick mode.
 *
 * Reads raw HID input reports from the EdgeTX radio and exposes
 * 4 analog axes (sticks + throttle) and 24 digital buttons
 * (switches, rockers, paddles).
 *
 * @par Report layout (20 bytes):
 * @code
 *   byte  0      : report ID (0x00)
 *   byte  1      : buttons bits 0..7
 *   bytes 2..17  : 8 axes x 16-bit LE (HID usage 0x30..0x37)
 *   bytes 18..19 : buttons bits 8..23
 * @endcode
 *
 * @par Active axes:
 * | Index | Usage | Physical control | Rest value |
 * |-------|-------|-----------------|------------|
 * | 0     | —     | unused          | always 0   |
 * | 1     | RX    | right stick X   | ~1024      |
 * | 2     | RY    | right stick Y   | ~1024      |
 * | 3     | —     | unused          | always 0   |
 * | 4     | Z     | left stick Y    | 0..2047    |
 * | 5     | VR    | left stick X    | ~1024      |
 * | 6..7  | —     | unused          | always 0   |
 */
#pragma once

#include <stdint.h>

// ---------------------------------------------------------------------------
// Axis range (10-bit ADC on the radio)
// ---------------------------------------------------------------------------

#define STK_AXIS_MIN   0
#define STK_AXIS_MAX   2047
#define STK_AXIS_MID   1024

// ---------------------------------------------------------------------------
// Default device IDs (EdgeTX radio in HID joystick mode)
// ---------------------------------------------------------------------------

#define STK_DEFAULT_VID  0x1209
#define STK_DEFAULT_PID  0x4F54

// ---------------------------------------------------------------------------
// Configuration
// ---------------------------------------------------------------------------

typedef struct {
    uint16_t vendor_id;
    uint16_t product_id;
} stk_config_t;

// ---------------------------------------------------------------------------
// Radio state
//
// axes[] holds all 8 HID axes (indices 0-7). Only indices 1, 2, 4, 5
// are wired to physical controls. The rest stay at 0.
//
// buttons is a 24-bit bitmask: bit N set = switch/button N+1 pressed.
// ---------------------------------------------------------------------------

#define STK_NUM_AXES    8
#define STK_NUM_BUTTONS 24

typedef struct {
    int16_t axes[STK_NUM_AXES];
    uint32_t buttons;
} stk_state_t;

// ---------------------------------------------------------------------------
// Convenience accessors for the 4 active axes
// ---------------------------------------------------------------------------

static inline int16_t stk_right_x(stk_state_t const* s) {
    return s->axes[1];
}

static inline int16_t stk_right_y(stk_state_t const* s) {
    return s->axes[2];
}

static inline int16_t stk_throttle(stk_state_t const* s) {
    return s->axes[4];
}

static inline int16_t stk_left_x(stk_state_t const* s) {
    return s->axes[5];
}

// ---------------------------------------------------------------------------
// Button bitmask helpers (bit 0 = first switch, bit 23 = last)
// ---------------------------------------------------------------------------

static inline bool stk_button_pressed(stk_state_t const* s,
                                      uint8_t index) {
    if (index >= STK_NUM_BUTTONS)
        return false;
    return (s->buttons >> index) & 1;
}

// ---------------------------------------------------------------------------
// API
// ---------------------------------------------------------------------------

/**
 * Open the HID radio device.
 * config must remain valid for the lifetime of the open session.
 * Returns 0 on success, -1 on failure.
 */
int stk_open(stk_config_t const* config);

/**
 * Read the current radio state (non-blocking).
 * Returns 0 on success, -1 on failure or no new data.
 */
int stk_read(stk_state_t* state);

/**
 * Close the radio device. Safe to call multiple times.
 */
void stk_close(void);