/**
 * 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 "util/memory.h"
#include "display/mesh/quad.h"

screen_t SCREEN;

void screenInit() {
  memoryZero(&SCREEN, sizeof(screen_t));

  #if DISPLAY_SIZE_DYNAMIC == 1
    cameraInitOrthographic(&SCREEN.framebufferCamera);
    SCREEN.framebufferCamera.viewType = CAMERA_VIEW_TYPE_2D;
    SCREEN.framebufferCamera._2d.position[0] = 0;
    SCREEN.framebufferCamera._2d.position[1] = 0;
    SCREEN.framebufferCamera._2d.zoom = 1.0f;

    quadBuffer(
      SCREEN.frameBufferMeshVertices,
      0.0f, 0.0f,
      1.0f, 1.0f,
      COLOR_WHITE,
      0.0f, 0.0f,
      1.0f, 1.0f
    );
    meshInit(
      &SCREEN.frameBufferMesh,
      QUAD_PRIMITIVE_TYPE,
      QUAD_VERTEX_COUNT,
      SCREEN.frameBufferMeshVertices
    );
  #endif
}

void screenBind() {
  // Assume backbuffer is currently bound.
  switch(SCREEN.mode) {
    case SCREEN_MODE_BACKBUFFER: {
      // Screen mode backbuffer uses the full display size
      SCREEN.width = frameBufferGetWidth(FRAMEBUFFER_BOUND);
      SCREEN.height = frameBufferGetHeight(FRAMEBUFFER_BOUND);

      // No needd for a framebuffer.
      #if DISPLAY_SIZE_DYNAMIC == 1
        if(SCREEN.framebufferReady) {
          frameBufferDispose(&SCREEN.framebuffer);
          SCREEN.framebufferReady = false;
        }
      #endif
      break;
    }

    #if DISPLAY_SIZE_DYNAMIC == 1
      case SCREEN_MODE_FIXED_SIZE: {
        SCREEN.width = SCREEN.fixedSize.width;
        SCREEN.height = SCREEN.fixedSize.height;
        SCREEN.aspect = (float_t)SCREEN.width / (float_t)SCREEN.height;

        if(SCREEN.framebufferReady) {
          // Is current framebuffer the correct size?
          int32_t curFbWidth, curFbHeight;
          curFbWidth = frameBufferGetWidth(&SCREEN.framebuffer);
          curFbHeight = frameBufferGetHeight(&SCREEN.framebuffer);
          if(curFbWidth == SCREEN.width && curFbHeight == SCREEN.height) {
            // Correct size, nothing to do.
            frameBufferBind(&SCREEN.framebuffer);
            return;
          }

          // Need a new framebuffer.
          frameBufferDispose(&SCREEN.framebuffer);
          SCREEN.framebufferReady = false;
        }

        // Create new framebuffer
        frameBufferInit(&SCREEN.framebuffer, SCREEN.width, SCREEN.height);
        SCREEN.framebufferReady = true;
        frameBufferBind(&SCREEN.framebuffer);
        break;
      }

      case SCREEN_MODE_ASPECT_RATIO: {
        // Aspect ratio mode, requires a framebuffer.
        int32_t fbWidth, fbHeight;
        fbWidth = frameBufferGetWidth(FRAMEBUFFER_BOUND);
        fbHeight = frameBufferGetHeight(FRAMEBUFFER_BOUND);

        float_t currentAspect = (float_t)fbWidth / (float_t)fbHeight;
        if(currentAspect == SCREEN.aspectRatio.ratio) {
          // No need to use framebuffer.
          SCREEN.width = fbWidth;
          SCREEN.height = fbHeight;
          SCREEN.aspect = (float_t)SCREEN.width / (float_t)SCREEN.height;

          if(SCREEN.framebufferReady) {
            frameBufferDispose(&SCREEN.framebuffer);
            SCREEN.framebufferReady = false;
          }
          return;
        }

        int32_t newFbWidth, newFbHeight;
        if(currentAspect > SCREEN.aspectRatio.ratio) {
          // Wider than target aspect, limit by height
          newFbWidth = (int32_t)floorf(fbHeight * SCREEN.aspectRatio.ratio);
          newFbHeight = (int32_t)fbHeight;
        } else {
          // Taller than target aspect, limit by width
          newFbHeight = (int32_t)floorf(fbWidth / SCREEN.aspectRatio.ratio);
          newFbWidth = (int32_t)fbWidth;
        }

        if(SCREEN.framebufferReady) {
          // Is current framebuffer the correct size?
          int32_t curFbWidth, curFbHeight;
          curFbWidth = frameBufferGetWidth(&SCREEN.framebuffer);
          curFbHeight = frameBufferGetHeight(&SCREEN.framebuffer);
          if(curFbWidth == newFbWidth && curFbHeight == newFbHeight) {
            // Correct size, nothing to do.
            SCREEN.width = newFbWidth;
            SCREEN.height = newFbHeight;
            SCREEN.aspect = (float_t)SCREEN.width / (float_t)SCREEN.height;
            frameBufferBind(&SCREEN.framebuffer);
            return;
          }

          // Need a new framebuffer.
          frameBufferDispose(&SCREEN.framebuffer);
          SCREEN.framebufferReady = false;
        }

        // Create new framebuffer
        frameBufferInit(&SCREEN.framebuffer, newFbWidth, newFbHeight);
        SCREEN.width = newFbWidth;
        SCREEN.height = newFbHeight;
        SCREEN.aspect = (float_t)SCREEN.width / (float_t)SCREEN.height;
        SCREEN.framebufferReady = true;

        // Bind FB
        frameBufferBind(&SCREEN.framebuffer);
        break;
      }

      case SCREEN_MODE_FIXED_HEIGHT: {
        float_t fbWidth = (float_t)frameBufferGetWidth(FRAMEBUFFER_BOUND);
        float_t fbHeight = (float_t)frameBufferGetHeight(FRAMEBUFFER_BOUND);
        float_t fbAspect = fbWidth / fbHeight;

        int32_t newFbWidth, newFbHeight;
        newFbHeight = SCREEN.fixedHeight.height;
        newFbWidth = (int32_t)floorf(newFbHeight * fbAspect);

        SCREEN.width = newFbWidth;
        SCREEN.height = newFbHeight;
        SCREEN.aspect = (float_t)SCREEN.width / (float_t)SCREEN.height;

        if(fbWidth == newFbWidth && fbHeight == newFbHeight) {
          // No need to use framebuffer.
          if(SCREEN.framebufferReady) {
            frameBufferDispose(&SCREEN.framebuffer);
            SCREEN.framebufferReady = false;
          }
          return;
        }

        if(SCREEN.framebufferReady) {
          // Is current framebuffer the correct size?
          int32_t curFbWidth, curFbHeight;
          curFbWidth = frameBufferGetWidth(&SCREEN.framebuffer);
          curFbHeight = frameBufferGetHeight(&SCREEN.framebuffer);
          if(curFbWidth == newFbWidth && curFbHeight == newFbHeight) {
            frameBufferBind(&SCREEN.framebuffer);
            return;
          }

          // Need a new framebuffer.
          frameBufferDispose(&SCREEN.framebuffer);
          SCREEN.framebufferReady = false;
        }

        // Create a new framebuffer.
        frameBufferInit(&SCREEN.framebuffer, newFbWidth, newFbHeight);
        SCREEN.framebufferReady = true;
        frameBufferBind(&SCREEN.framebuffer);
        break;
      }

      case SCREEN_MODE_FIXED_WIDTH: {
        float_t fbWidth = (float_t)frameBufferGetWidth(FRAMEBUFFER_BOUND);
        float_t fbHeight = (float_t)frameBufferGetHeight(FRAMEBUFFER_BOUND);
        float_t fbAspect = fbWidth / fbHeight;

        int32_t newFbWidth, newFbHeight;
        newFbWidth = SCREEN.fixedWidth.width;
        newFbHeight = (int32_t)floorf(newFbWidth / fbAspect);

        SCREEN.width = newFbWidth;
        SCREEN.height = newFbHeight;
        SCREEN.aspect = (float_t)SCREEN.width / (float_t)SCREEN.height;

        if(fbWidth == newFbWidth && fbHeight == newFbHeight) {
          // No need to use framebuffer.
          if(SCREEN.framebufferReady) {
            frameBufferDispose(&SCREEN.framebuffer);
            SCREEN.framebufferReady = false;
          }
          return;
        }

        if(SCREEN.framebufferReady) {
          // Is current framebuffer the correct size?
          int32_t curFbWidth, curFbHeight;
          curFbWidth = frameBufferGetWidth(&SCREEN.framebuffer);
          curFbHeight = frameBufferGetHeight(&SCREEN.framebuffer);
          if(curFbWidth == newFbWidth && curFbHeight == newFbHeight) {
            frameBufferBind(&SCREEN.framebuffer);
            return;
          }

          // Need a new framebuffer.
          frameBufferDispose(&SCREEN.framebuffer);
          SCREEN.framebufferReady = false;
        }

        // Create a new framebuffer.
        frameBufferInit(&SCREEN.framebuffer, newFbWidth, newFbHeight);
        SCREEN.framebufferReady = true;
        frameBufferBind(&SCREEN.framebuffer);
        break;
      }
    #endif

    default: {
      assertUnreachable("Invalid screen mode.");
      break;
    }
  }
}

void screenUnbind() {
  switch(SCREEN.mode) {
    case SCREEN_MODE_BACKBUFFER: {
      // Nothing to do here.
      break;
    }
    
    #if DISPLAY_SIZE_DYNAMIC == 1
      case SCREEN_MODE_ASPECT_RATIO:
      case SCREEN_MODE_FIXED_HEIGHT:
      case SCREEN_MODE_FIXED_SIZE:
      case SCREEN_MODE_FIXED_WIDTH:
        if(SCREEN.framebufferReady) frameBufferBind(NULL);
        break;
    #endif

    default: {
      assertUnreachable("Invalid screen mode.");
      break;
    }
  }
}

void screenRender() {
  if(SCREEN.mode == SCREEN_MODE_BACKBUFFER) {
    return;
  }

  #if DISPLAY_SIZE_DYNAMIC == 1
    if(
      SCREEN.mode == SCREEN_MODE_ASPECT_RATIO ||
      SCREEN.mode == SCREEN_MODE_FIXED_HEIGHT ||
      SCREEN.mode == SCREEN_MODE_FIXED_SIZE ||
      SCREEN.mode == SCREEN_MODE_FIXED_WIDTH
    ) {
      if(!SCREEN.framebufferReady) {
        // Nothing to do here.
        return;
      }

      float_t bbWidth, bbHeight;
      bbWidth = (float_t)frameBufferGetWidth(FRAMEBUFFER_BOUND);
      bbHeight = (float_t)frameBufferGetHeight(FRAMEBUFFER_BOUND);

      float_t backBufferAspect = bbWidth / bbHeight;

      // Determine framebuffer centering
      float_t fbWidth, fbHeight, fbAspect;
      float_t fbX, fbY;

      fbWidth = frameBufferGetWidth(&SCREEN.framebuffer);
      fbHeight = frameBufferGetHeight(&SCREEN.framebuffer);
      fbAspect = fbWidth / fbHeight;
      
      if(backBufferAspect > fbAspect) {
        fbHeight = bbHeight;
        fbWidth = fbHeight * fbAspect;
        fbX = (bbWidth - fbWidth) * 0.5f;
        fbY = 0.0f;
      } else {
        fbWidth = bbWidth;
        fbHeight = fbWidth / fbAspect;
        fbX = 0.0f;
        fbY = (bbHeight - fbHeight) * 0.5f;
      }

      float_t centerX = bbWidth * 0.5f;
      float_t centerY = bbHeight * 0.5f;

      SCREEN.framebufferCamera.orthographic.left = 0.0f;
      SCREEN.framebufferCamera.orthographic.right = bbWidth;
      SCREEN.framebufferCamera.orthographic.top = 0.0f;
      SCREEN.framebufferCamera.orthographic.bottom = bbHeight;
      quadBuffer(
        SCREEN.frameBufferMeshVertices,
        centerX - fbWidth * 0.5f, centerY + fbHeight * 0.5f, // top-left
        centerX + fbWidth * 0.5f, centerY - fbHeight * 0.5f, // bottom-right
        COLOR_WHITE,
        0.0f, 0.0f,
        1.0f, 1.0f
      );

      frameBufferClear(
        FRAMEBUFFER_CLEAR_COLOR | FRAMEBUFFER_CLEAR_DEPTH,
        COLOR_BLACK
      );
      cameraPushMatrix(&SCREEN.framebufferCamera);
      textureBind(&SCREEN.framebuffer.texture);
      meshDraw(&SCREEN.frameBufferMesh, 0, -1);
      cameraPopMatrix();

      return;
    };
  #endif

  assertUnreachable("Invalid screen mode.");
}

void screenDispose() {
  #if DISPLAY_SIZE_DYNAMIC == 1
    if(SCREEN.framebufferReady) {
      frameBufferDispose(&SCREEN.framebuffer);
      SCREEN.framebufferReady = false;
    }
  #endif
}