/**
 * Copyright (c) 2025 Dominic Masters
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "screen.h"
#include "assert/assert.h"
#include "display/spritebatch.h"

screen_t SCREEN;

void screenInit(void) {
  // Virtual backbuffer for dynamic resolution scaling
  #if DISPLAY_SIZE_DYNAMIC == 1
    frameBufferInit(&SCREEN.frameBuffer, DISPLAY_WIDTH, DISPLAY_HEIGHT);
    cameraInit(&SCREEN.frameBufferCamera);
    SCREEN.frameBufferCamera.projType = CAMERA_PROJECTION_TYPE_ORTHOGRAPHIC;
    SCREEN.frameBufferCamera.viewType = CAMERA_VIEW_TYPE_MATRIX;
    glm_lookat(
      (vec3){0.0f, 0.0f, 1.0f},
      (vec3){0.0f, 0.0f, 0.0f},
      (vec3){0.0f, 1.0f, 0.0f},
      SCREEN.frameBufferCamera.view
    );
    SCREEN.frameBufferCamera.nearClip = -1.0f;
    SCREEN.frameBufferCamera.farClip = 1.0f;
  #endif
}

void screenBind(void) {
  #if DISPLAY_SIZE_DYNAMIC == 1
    frameBufferBind(&SCREEN.frameBuffer);
  #else
    frameBufferBind(NULL);
  #endif

  frameBufferClear(
    FRAMEBUFFER_CLEAR_COLOR | FRAMEBUFFER_CLEAR_DEPTH,
    COLOR_CORNFLOWER_BLUE
  );
}

void screenUnbindAndRender(void) {
  assertTrue(SPRITEBATCH.spriteCount == 0, "Sprite batch not flushed");

  // Render to real backbuffer
  #if DISPLAY_SIZE_DYNAMIC == 1
    frameBufferBind(NULL);
    frameBufferClear(
      FRAMEBUFFER_CLEAR_COLOR | FRAMEBUFFER_CLEAR_DEPTH,
      COLOR_BLACK
    );
    

    SCREEN.frameBufferCamera.orthographic.left = 0;
    SCREEN.frameBufferCamera.orthographic.right = frameBufferGetWidth(
      FRAMEBUFFER_BOUND
    );
    SCREEN.frameBufferCamera.orthographic.bottom = frameBufferGetHeight(
      FRAMEBUFFER_BOUND
    );
    SCREEN.frameBufferCamera.orthographic.top = 0;
    cameraPushMatrix(&SCREEN.frameBufferCamera);

    vec2 backbuffer = {
      (float_t)frameBufferGetWidth(FRAMEBUFFER_BOUND),
      (float_t)frameBufferGetHeight(FRAMEBUFFER_BOUND)
    };
    vec2 virtual = {
      (float_t)frameBufferGetWidth(&SCREEN.frameBuffer),
      (float_t)frameBufferGetHeight(&SCREEN.frameBuffer)
    };

    // Compare aspect ratios.
    vec4 viewport;
    float_t backbufferAspect = backbuffer[0] / backbuffer[1];
    float_t virtualAspect = virtual[0] / virtual[1];
    if (backbufferAspect > virtualAspect) {
      // Backbuffer is wider: pillarbox
      float_t scale = backbuffer[1] / virtual[1];
      float_t width = virtual[0] * scale;
      viewport[0] = (backbuffer[0] - width) * 0.5f;
      viewport[1] = 0;
      viewport[2] = width;
      viewport[3] = backbuffer[1];
    } else {
      // Backbuffer is taller: letterbox
      float_t scale = backbuffer[0] / virtual[0];
      float_t height = virtual[1] * scale;
      viewport[0] = 0;
      viewport[1] = (backbuffer[1] - height) * 0.5f;
      viewport[2] = backbuffer[0];
      viewport[3] = height;
    }

    spriteBatchPush(
      &SCREEN.frameBuffer.texture,
      viewport[0], viewport[1],
      viewport[0] + viewport[2], viewport[1] + viewport[3],
      COLOR_WHITE,
      0.0f, 1.0f, 1.0f, 0.0f
    );
    spriteBatchFlush();
    cameraPopMatrix();
  #endif
}

void screenDispose(void) {
  frameBufferDispose(&SCREEN.frameBuffer);
}