/*
 * Amirine Cosplay Lights
 *
 * Plays lightshows defined in shows.h on a WS2812B LED strip.
 * A single button navigates between shows:
 *   1 tap  — next show
 *   2 taps — previous show
 *   hold   — reset to show 0 (blue breath)
 *
 * To add or update shows:
 *   1. Add or edit a .txt file in converter/shows/
 *   2. Run:   make shows
 *   3. Run:   make upload
 *
 * Required library: FastLED  (Sketch > Include Library > Manage Libraries)
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include "config.h"
#include "led_controller.h"
#include "button.h"
#include "shows.h"

// Milliseconds between LED updates. 16ms ≈ 60 refreshes/second.
#define UPDATE_INTERVAL_MS  16

// ---- Color math --------------------------------------------------------

// Interpolate a single 8-bit channel from a to b by ratio t (0.0 – 1.0).
static uint8_t lerp_channel(uint8_t a, uint8_t b, float t) {
    return (uint8_t)(a + (b - a) * t);
}

// Blend two colors: t=0.0 returns 'from', t=1.0 returns 'to'.
static CRGB blend_colors(CRGB from, CRGB to, float t) {
    return CRGB(
        lerp_channel(from.r, to.r, t),
        lerp_channel(from.g, to.g, t),
        lerp_channel(from.b, to.b, t)
    );
}

// ---- Playback state ----------------------------------------------------

static uint8_t  s_show_index  = 0;           // which show is active (index into SHOWS[])
static ShowDef  s_show;                       // active show, read from PROGMEM once on load
static uint16_t s_step_index  = 0;           // current step within the active show
static uint32_t s_step_start  = 0;           // millis() when this step began
static CRGB     s_from_color  = CRGB::Black; // color at the start of this transition

// Load show at 'index', resetting playback to the first step.
static void load_show(uint8_t index) {
    s_show_index = index;
    s_show       = read_show_def(&SHOWS[index]);
    s_step_index = 0;
    s_step_start = millis();
    s_from_color = CRGB::Black;
}

// How far through the current step we are (0.0 – 1.0).
// Returns 1.0 immediately for instant steps (duration_ms == 0).
static float step_progress(const Step& step) {
    if (step.duration_ms == 0) return 1.0f;
    uint32_t elapsed = millis() - s_step_start;
    float t = (float)elapsed / step.duration_ms;
    return (t < 1.0f) ? t : 1.0f;
}

// Complete the current step and advance to the next.
// SHOW_LOOP wraps back to step 0; SHOW_SINGLE loads the next show when the last step ends.
static void advance_step(CRGB reached_color) {
    s_from_color = reached_color;
    uint16_t next = s_step_index + 1;
    if (next >= s_show.length) {
        if (s_show.mode == SHOW_SINGLE) {
            load_show((s_show_index + 1) % SHOW_COUNT);
            return;
        }
        next = 0;
    }
    s_step_index = next;
    s_step_start = millis();
}

// ---- Arduino entry points ----------------------------------------------

void setup() {
    leds_begin();
    button_begin(BUTTON_PIN);
    load_show(0);   // start on show 0 — blue breath
}

void loop() {
    // ---- Button navigation ----
    ButtonEvent evt = button_update();
    if (evt == BTN_TAP) {
        // Next show, wrapping around to 0 after the last one.
        load_show((s_show_index + 1) % SHOW_COUNT);
    }
    if (evt == BTN_DOUBLE_TAP) {
        // Previous show, wrapping around to the last one from show 0.
        load_show((s_show_index + SHOW_COUNT - 1) % SHOW_COUNT);
    }
    if (evt == BTN_HOLD) {
        // Reset to show 0 (blue breath) from any position.
        load_show(0);
    }

    // ---- Playback ----
    Step  step    = read_step(&s_show.steps[s_step_index]);
    CRGB  to      = CRGB(step.r, step.g, step.b);
    float t       = step_progress(step);

    leds_apply_color(blend_colors(s_from_color, to, t));
    leds_show();

    if (t >= 1.0f) {
        advance_step(to);
    }

    delay(UPDATE_INTERVAL_MS);
}