/*
 * lightshow_format.h — Core data structures for show playback.
 *
 * All show data lives in PROGMEM (flash memory) to preserve the
 * Arduino Uno's 2KB of RAM. The read_* helpers copy values out of
 * PROGMEM so the rest of the code can work with them normally.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once
#include <avr/pgmspace.h>
#include <stdint.h>

// Show playback modes.
#define SHOW_LOOP   0  // repeat the show indefinitely
#define SHOW_SINGLE 1  // play once, then auto-advance to the next show

// One step in a lightshow: a target color and the time to reach it.
struct Step {
    uint8_t  r, g, b;        // Target RGB color (0–255 each)
    uint16_t duration_ms;    // Milliseconds to fade from the previous color (0 = instant)
};

// Descriptor for one complete show.
struct ShowDef {
    const Step* steps;    // Pointer to a PROGMEM Step array
    uint16_t    length;   // Number of steps in the array
    uint8_t     mode;     // SHOW_LOOP or SHOW_SINGLE
};

// Read one Step from PROGMEM into a regular struct.
// Direct pointer access does not work for PROGMEM on AVR — use this helper.
inline Step read_step(const Step* ptr) {
    Step s;
    s.r           = pgm_read_byte(&ptr->r);
    s.g           = pgm_read_byte(&ptr->g);
    s.b           = pgm_read_byte(&ptr->b);
    s.duration_ms = pgm_read_word(&ptr->duration_ms);
    return s;
}

// Read one ShowDef from a PROGMEM ShowDef array.
// On AVR, pointers are 2 bytes wide, so pgm_read_word works for both fields.
inline ShowDef read_show_def(const ShowDef* ptr) {
    ShowDef sd;
    sd.steps  = (const Step*)pgm_read_word(&ptr->steps);
    sd.length = pgm_read_word(&ptr->length);
    sd.mode   = pgm_read_byte(&ptr->mode);
    return sd;
}
`