// Part of JoeyLib, Copyright (c) 2026 Scott Duensing, under the MIT License.
// See LICENSE.md for license information.
// SPDX-License-Identifier: MIT
//
// Palette-change probe (PALPROBE, a gate's program, not an example): how
// fast palette and SCB changes reach the screen, and whether they reach it
// right.
//
// It times, over PROBE_FRAMES frames each, a palette change followed by a
// present, and an SCB change followed by a present, on a screen of four SCB
// bands, and logs the rates. Then it paints the bands (colour 1 of palettes
// 0..3 red, green, blue, white), makes one palette change (palette 2's
// colour 1 to yellow) and one SCB change that keeps every band where it was
// (band 3 to palette 0), logs "PALPROBE: ready" and holds the screen for
// HOLD_FRAMES frames, so a gate can look at it: top to bottom red, green,
// yellow, red. scripts/verify-amiga-palette.sh is that gate.

#include <string.h>

#include <joey/joey.h>

#define PROBE_FRAMES     200u
#define HOLD_FRAMES      400u
#define BANDS            4u
#define BAND_LINES       50u
#define PAINT_COLOR      1u
#define MS_PER_SECOND    1000ul
#define COLOR_MASK       0x0FFFu
#define PALETTE_MASK     3u
#define SCB_SWAP_FIRST   0u
#define SCB_SWAP_LAST    (BAND_LINES - 1u)
#define YELLOW           0xFF0u
#define CHANGED_PALETTE  2u
#define MOVED_BAND       3u
#define MOVED_TO         0u

static void check(void);
static void timeChanges(const char *name, bool scb);


// Paint the bands, make the two changes, and hold the screen.
static void check(void) {
    static const uint16_t firsts[BANDS] = { 0xF00, 0x0F0, 0x00F, 0xFFF };
    uint16_t              colors[JL_SURFACE_COLORS_PER_PALETTE];
    jlSurfaceT           *stage;
    uint16_t              band;
    uint16_t              frame;

    stage = jlStageGet();
    for (band = 0; band < BANDS; band++) {
        memset(colors, 0, sizeof(colors));
        colors[PAINT_COLOR] = firsts[band];
        jlPaletteSet(stage, (uint8_t)band, colors);
        jlScbSetRange(stage, (uint16_t)(band * BAND_LINES), (uint16_t)(band * BAND_LINES + BAND_LINES - 1u), (uint8_t)band);
        jlFillRect(stage, 0, (int16_t)(band * BAND_LINES), JL_SURFACE_WIDTH, BAND_LINES, PAINT_COLOR);
    }
    jlStagePresent();
    jlWaitVBL();
    memset(colors, 0, sizeof(colors));
    colors[PAINT_COLOR] = YELLOW;
    jlPaletteSet(stage, CHANGED_PALETTE, colors);
    jlStagePresent();
    jlScbSetRange(stage, (uint16_t)(MOVED_BAND * BAND_LINES), (uint16_t)(MOVED_BAND * BAND_LINES + BAND_LINES - 1u), MOVED_TO);
    jlStagePresent();
    jlLogF("PALPROBE: ready");
    for (frame = 0; frame < HOLD_FRAMES; frame++) {
        jlWaitVBL();
    }
}


// PROBE_FRAMES frames of palette changes (or SCB changes), each presented.
static void timeChanges(const char *name, bool scb) {
    uint16_t      colors[JL_SURFACE_COLORS_PER_PALETTE];
    jlSurfaceT   *stage;
    uint16_t      start;
    uint32_t      ms0;
    uint32_t      elapsed;
    unsigned long count;

    stage = jlStageGet();
    memset(colors, 0, sizeof(colors));
    count = 0;
    jlWaitVBL();
    start = jlFrameCount();
    ms0   = jlMillisElapsed();
    while ((uint16_t)(jlFrameCount() - start) < PROBE_FRAMES) {
        if (scb) {
            jlScbSetRange(stage, SCB_SWAP_FIRST, SCB_SWAP_LAST, (uint8_t)(count & PALETTE_MASK));
        } else {
            colors[PAINT_COLOR] = (uint16_t)(count & COLOR_MASK);
            jlPaletteSet(stage, (uint8_t)(count & PALETTE_MASK), colors);
        }
        jlStagePresent();
        count++;
    }
    elapsed = jlMillisElapsed() - ms0;
    jlLogF("PALPROBE: %s: %lu in %lu ms = %lu/s", name, count, (unsigned long)elapsed, (unsigned long)(count * MS_PER_SECOND / elapsed));
}


int main(void) {
    jlConfigT   cfg;
    jlSurfaceT *stage;
    uint16_t    band;

    cfg.codegenBytes = 0;
    cfg.noAudio      = true;
    if (!jlInit(&cfg)) {
        return 1;
    }
    stage = jlStageGet();
    for (band = 0; band < BANDS; band++) {
        jlScbSetRange(stage, (uint16_t)(band * BAND_LINES), (uint16_t)(band * BAND_LINES + BAND_LINES - 1u), (uint8_t)band);
        jlFillRect(stage, 0, (int16_t)(band * BAND_LINES), JL_SURFACE_WIDTH, BAND_LINES, (uint8_t)(band + 1u));
    }
    jlStagePresent();
    timeChanges("palette+present", false);
    timeChanges("scb+present", true);
    check();
    jlLogF("PALPROBE: done");
    jlShutdown();
    return 0;
}