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#include "tile.h"

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#include "render_struct.h"

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#define MIN(a, b) ((a) < (b) ? (a) : (b))

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#define MAX(a, b) ((a) > (b) ? (a) : (b))

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int render_set_tile (struct render *render_info, u_int32_t view_w, u_int32_t view_h, u_int32_t x, u_int32_t y, u_int16_t zoom) {

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    // figure out how many tiles will fit onto the view area

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    u_int16_t tiles = MIN(

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        MAX(view_w / TILE_WIDTH, 1),

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        MAX(view_h / TILE_HEIGHT, 1)

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    ) + 1;

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    // have it be square

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    view_w = tiles * TILE_WIDTH;

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    view_h = tiles * TILE_HEIGHT;

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    // the image width is fixed

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    render_info->img_w = TILE_WIDTH;

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    render_info->img_h = TILE_HEIGHT;

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    // calcuate how wide each pixel is

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    double width_scale = REGION_W/(view_w << zoom);

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    double height_scale = REGION_H/(view_h << zoom);

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    // calcuate the region

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    render_info->x1 = REGION_X1 + x * width_scale;

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    render_info->y1 = REGION_Y1 + y * height_scale;

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    render_info->x2 = render_info->x1 + TILE_WIDTH * width_scale;

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    render_info->y2 = render_info->y1 + TILE_HEIGHT * height_scale;

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    // ok

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    return 0;

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}