#include "render.h"
#include <gint/display.h>

//---
// Camera management
//---

void camera_init(struct camera *c, struct map *m)
{
    c->zoom = 1;

    c->limits.x_min = fix(-CAMERA_BORDER);
    c->limits.x_max = fix(m->width + CAMERA_BORDER);
    c->limits.y_min = fix(-CAMERA_BORDER);
    c->limits.y_max = fix(m->height + CAMERA_BORDER);

    /* Fullscreen */
    c->viewport.x_min = 0;
    c->viewport.x_max = DWIDTH;
    c->viewport.y_min = 0;
    c->viewport.y_max = DHEIGHT;

    c->width  = fix(c->viewport.x_max - c->viewport.x_min) / TILE_WIDTH;
    c->height = fix(c->viewport.y_max - c->viewport.y_min) / TILE_HEIGHT;

    c->x = (c->limits.x_min + c->limits.x_max) / 2;
    c->y = (c->limits.y_min + c->limits.y_max) / 2;
}

ipoint_t camera_map2screen(struct camera *c, fpoint_t p)
{
    return (ipoint_t){
        .x = DWIDTH  / 2 + fround((p.x - c->x) * TILE_WIDTH  * c->zoom),
        .y = DHEIGHT / 2 + fround((p.y - c->y) * TILE_HEIGHT * c->zoom),
    };
}
/* Translate screen coordinates to map coordinates */
fpoint_t camera_screen2map(struct camera *c, ipoint_t p)
{
    return (fpoint_t){
        .x = c->x + fix(p.x - DWIDTH  / 2) / TILE_WIDTH  / c->zoom,
        .y = c->y + fix(p.y - DHEIGHT / 2) / TILE_HEIGHT / c->zoom,
    };
}

/* Lock the camera at the center if set by settings. */
static bool camera_lock(struct camera *c)
{
    if(c->zoom == 1 && CAMERA_LOCK_AT_x1)
    {
        c->x = (c->limits.x_min + c->limits.x_max) / 2;
        c->y = (c->limits.y_min + c->limits.y_max) / 2;
        return true;
    }
    return false;
}

/* Bound the camera to the map limits */
static void camera_bound(struct camera *c)
{
    /* Project top left and bottom-right corners of viewport onto the map */
    ipoint_t v_tl = { c->viewport.x_min, c->viewport.y_min };
    ipoint_t v_br = { c->viewport.x_max, c->viewport.y_max };

    fpoint_t m_tl = camera_screen2map(c, v_tl);
    fpoint_t m_br = camera_screen2map(c, v_br);

    /* Bound viewport to map limits */
    if(m_tl.x < c->limits.x_min)
        c->x += (c->limits.x_min - m_tl.x);
    else if(m_br.x > c->limits.x_max)
        c->x += (c->limits.x_max - m_br.x);
    if(m_tl.y < c->limits.y_min)
        c->y += (c->limits.y_min - m_tl.y);
    else if(m_br.y > c->limits.y_max)
        c->y += (c->limits.y_max - m_br.y);
}

void camera_move(struct camera *c, map_coord_t dx, map_coord_t dy)
{
    if(camera_lock(c)) return;
    c->x += dx;
    c->y += dy;
    camera_bound(c);
}

void camera_zoom(struct camera *c, int zoom)
{
    if(zoom < ZOOM_MIN) zoom = ZOOM_MIN;
    if(zoom > ZOOM_MAX) zoom = ZOOM_MAX;

    c->zoom = zoom;
    if(camera_lock(c)) return;
    camera_bound(c);
}

fixed_t camera_ppu(struct camera *c)
{
    /* Since this assumes isotropic space we can use TILE_WIDTH or TILE_HEIGHT
       indifferently (they're assumed equal) */
    return fix(1) * c->zoom * TILE_WIDTH;
}

//---
// Rendering
//---

void render_map(struct map *m, struct camera *c)
{
    extern bopti_image_t img_tileset_base;
    extern bopti_image_t img_tileset_decor;

    /* Render floor and walls */
    for(int row = 0; row < m->height; row++)
    for(int col = 0; col < m->width; col++) {
        struct tile *t = map_tile(m, col, row);
        if(!t) continue;

        fpoint_t tile_pos = { fix(col), fix(row) };
        ipoint_t p = camera_map2screen(c, tile_pos);

        /* Floor/wall layer */
        dsubimage(p.x, p.y, &img_tileset_base, TILE_WIDTH * (t->base % 16),
            TILE_HEIGHT * (t->base / 16), TILE_WIDTH, TILE_HEIGHT,
            DIMAGE_NONE);
        /* Decoration layer */
        dsubimage(p.x, p.y, &img_tileset_decor, TILE_WIDTH * (t->decor % 16),
            TILE_HEIGHT * (t->decor / 16), TILE_WIDTH, TILE_HEIGHT,
            DIMAGE_NONE);
    }

    /* Render entities */
    for(int i = 0; i < m->entity_count; i++) {
        struct entity *e = m->entities[i];

        ipoint_t p = camera_map2screen(c, (fpoint_t){ e->x, e->y });

        /* Translate entity hitbox to the map coordinate system */
        shape_t s = e->hitbox;
        shape_scale(&s, camera_ppu(c));
        shape_translate(&s, point_i2f(p));
        shape_draw(&s);

        /* Show entity center */
        dline(p.x-1, p.y, p.x+1, p.y, s.color);
        dline(p.x, p.y-1, p.x, p.y+1, s.color);
    }
}