#include "map.h"

#include <string.h>

#include "game.h"
#include "player.h"
#include "sdk/hardware.h"
#include "vram.h"

#define INIT_SCX ((SCRN_VX - SCRN_X) / 2)
#define INIT_SCY ((SCRN_VY - SCRN_Y) / 2)

map_t MAP;

#define ROW_BUFFER_SIZE (SCRN_X_B + 4)
#define COL_BUFFER_SIZE (SCRN_Y_B + 4)

uint8_t pending_row[ROW_BUFFER_SIZE];
uint16_t pending_row_dest;

uint8_t pending_col[COL_BUFFER_SIZE];
uint16_t pending_col_dest;

static void map_write_row(uint16_t map_ptr, int8_t x0, int8_t y0);

static void map_write_col(uint16_t map_ptr, int8_t x0, int8_t y0);

void map_load(map_t *map) {
    MAP = *map;

    rSCX = INIT_SCX;
    rSCY = INIT_SCY;

    PLAYER.x = (MAP.spawn_x - MAP.camera_x) * 8;
    PLAYER.y = (MAP.spawn_y - MAP.camera_y) * 8;

    memcpy(VRAM_TILE_PTR(TILE_INDEX_BACKGROUND), (uint8_t *)MAP.tile_ptr,
           MAP.tile_size);

    int8_t x0 = MAP.camera_x - INIT_SCX / 8;
    int8_t y0 = MAP.camera_y - INIT_SCY / 8;
    uint16_t map_ptr = _SCRN0;

    for (uint8_t i = 0; i < SCRN_VY_B; ++i) {
        map_write_row(map_ptr, x0, y0);
        map_ptr += SCRN_VX_B;
        y0++;
    }

    pending_row_dest = 0;
    pending_col_dest = 0;
}

void map_update(void) {
    if (pending_row_dest != 0) {
        vram_enqueue_mem_xfer(XFER_TYPE_ROW, pending_row_dest, &pending_row[0],
                              sizeof pending_row);
        pending_row_dest = 0;
    }

    if (pending_col_dest != 0) {
        vram_enqueue_mem_xfer(XFER_TYPE_COL, pending_col_dest, &pending_col[0],
                              sizeof pending_col);
        pending_col_dest = 0;
    }
}

static void map_enqueue_row(uint16_t vram_ptr, int8_t x0, int8_t y0) {
    pending_row_dest = vram_ptr;

    if (y0 < 0 || y0 >= MAP.map_height) {
        memset(&pending_row[0], TILE_INDEX_BACKGROUND, sizeof pending_row);
        return;
    }

    uint8_t *map_ptr = (uint8_t *)(MAP.map_ptr + y0 * MAP.map_width);
    uint8_t left = sizeof pending_row;
    uint8_t *row = &pending_row[0];

    while (left > 0 && x0 < 0) {
        *row++ = TILE_INDEX_BACKGROUND;
        x0++;
        left--;
    }

    while (left > 0 && x0 < MAP.map_height) {
        *row++ = TILE_INDEX_BACKGROUND + *map_ptr++;
        x0++;
        left--;
    }

    while (left > 0) {
        *row++ = TILE_INDEX_BACKGROUND;
        left--;
    }
}

static void map_write_row(uint16_t vram_ptr, int8_t x0, int8_t y0) {
    uint8_t *row = (uint8_t *)vram_ptr;

    if (y0 < 0 || y0 >= MAP.map_height) {
        memset(row, TILE_INDEX_BACKGROUND, SCRN_VX_B);
        return;
    }

    uint8_t *map_ptr = (uint8_t *)(MAP.map_ptr + y0 * MAP.map_width);
    uint8_t left = SCRN_VX_B;

    while (left > 0 && x0 < 0) {
        *row++ = TILE_INDEX_BACKGROUND;
        x0++;
        left--;
    }

    while (left > 0 && x0 < MAP.map_height) {
        *row++ = TILE_INDEX_BACKGROUND + *map_ptr++;
        x0++;
        left--;
    }

    while (left > 0) {
        *row++ = TILE_INDEX_BACKGROUND;
        left--;
    }
}

static void map_write_col(uint16_t map_ptr, int8_t x0, int8_t y0) {}