/* DAT-900 claw animation rendering. */

#include "tdkpin_render.h"

enum {
    DGROUP_BACKGROUND_BITMAP = 0x085b,
    DGROUP_CLAW_BITMAP = 0x0863,
    CLAW_DESTINATION_X = 238,
    CLAW_DESTINATION_Y = 47,
    CLAW_WIDTH = 100,
    CLAW_HEIGHT = 74,
    WIN16_SRCCOPY = 0x00cc0020,
};

/*
 * 1008:0e08 — frame zero restores the background. Frames 1..18 select one of
 * two nine-frame horizontal sequences; the byte flag selects the lower/upper
 * pair of 74-pixel atlas rows. Both background and destination receive the
 * exact same SRCCOPY from DAT 900.
 */
void tdkpin_draw_claw_frame(
    uint8_t alternate, uint16_t frame, HDC16 destination)
{
    if (frame == 0) {
        tdkpin_restore_background_region_b(
            CLAW_HEIGHT,
            CLAW_WIDTH,
            CLAW_DESTINATION_Y,
            CLAW_DESTINATION_X,
            destination);
        tdkpin_present_background_region(
            CLAW_HEIGHT,
            CLAW_WIDTH,
            CLAW_DESTINATION_Y,
            CLAW_DESTINATION_X,
            destination);
        return;
    }

    HDC16 background_dc = CreateCompatibleDC16(destination);
    HDC16 claw_dc = CreateCompatibleDC16(destination);
    HGDIOBJ16 old_background = SelectObject16(
        background_dc,
        win16_read_u16(win16_dgroup_pointer(DGROUP_BACKGROUND_BITMAP)));
    HGDIOBJ16 old_claw = SelectObject16(
        claw_dc,
        win16_read_u16(win16_dgroup_pointer(DGROUP_CLAW_BITMAP)));
    uint16_t source_y = alternate == 0 ? CLAW_HEIGHT * 2 : 0;
    if (frame > 9) {
        source_y = (uint16_t)(source_y + CLAW_HEIGHT);
        frame = (uint16_t)(frame - 9);
    }
    uint16_t source_x = (uint16_t)((frame - 1) * CLAW_WIDTH);
    (void)BitBlt16(
        background_dc,
        CLAW_DESTINATION_X,
        CLAW_DESTINATION_Y,
        CLAW_WIDTH,
        CLAW_HEIGHT,
        claw_dc,
        (INT16)source_x,
        (INT16)source_y,
        WIN16_SRCCOPY);
    (void)BitBlt16(
        destination,
        CLAW_DESTINATION_X,
        CLAW_DESTINATION_Y,
        CLAW_WIDTH,
        CLAW_HEIGHT,
        claw_dc,
        (INT16)source_x,
        (INT16)source_y,
        WIN16_SRCCOPY);
    (void)SelectObject16(background_dc, old_background);
    (void)SelectObject16(claw_dc, old_claw);
    (void)DeleteDC16(claw_dc);
    (void)DeleteDC16(background_dc);
}