package tools

import (
	"fmt"
	"log"
	"time"

	"github.com/veandco/go-sdl2/sdl"
	"github.com/veandco/go-sdl2/ttf"
)

var (
	oldTime = time.Now()
	font    *ttf.Font
)

// Initialize font once (call this in setup)
func InitFont(fontPath string, fontSize int) {
	var err error
	if err := ttf.Init(); err != nil {
		log.Fatal(err)
	}
	font, err = ttf.OpenFont(fontPath, fontSize)
	if err != nil {
		log.Fatalf("Failed to load font: %v", err)
	}
}

// Converts text to raw []uint32 pixels
func textToPixels(text string, color sdl.Color) ([]uint32, int, int) {
	surface, err := font.RenderUTF8Blended(text, color)
	if err != nil {
		log.Fatalf("Render failed: %v", err)
	}
	defer surface.Free()

	w := int(surface.W)
	h := int(surface.H)

	if err := surface.Lock(); err != nil {
		log.Fatalf("Failed to lock surface: %v", err)
	}
	defer surface.Unlock()

	converted, err := surface.ConvertFormat(sdl.PIXELFORMAT_ARGB8888, 0)
	if err != nil {
		log.Fatal(err)
	}
	defer converted.Free()

	pixelBytes := converted.Pixels()
	pixels := make([]uint32, w*h)

	for i := 0; i < w*h; i++ {
		b := pixelBytes[i*4 : i*4+4]
		pixels[i] = uint32(b[3])<<24 | uint32(b[2])<<16 | uint32(b[1])<<8 | uint32(b[0])
	}
	dst := make([]uint32, w*h)
	copy(dst, pixels)
	return dst, w, h
}

// Draws text pixels onto your screen framebuffer
func blitTextToBuffer(dst []uint32, dstW, dstH, dstPitch int, src []uint32, srcW, srcH, posX, posY int) {
	for y := 0; y < srcH; y++ {
		for x := 0; x < srcW; x++ {
			dx := posX + x
			dy := posY + y
			if dx < 0 || dx >= dstW || dy < 0 || dy >= dstH {
				continue
			}
			srcPixel := src[y*srcW+x]

			// Only draw non-transparent pixels
			if (srcPixel>>24)&0xFF > 0 {
				dst[dy*dstPitch+dx] = srcPixel
			}
		}
	}
}

func FpsCounter(pixels []uint32, screenWidth, screenHeight int) {
	now := time.Now()
	frameTime := now.Sub(oldTime).Seconds()
	oldTime = now

	if frameTime == 0 {
		return
	}

	fps := 1.0 / frameTime
	fpsText := fmt.Sprintf("FPS: %.0f", fps)

	color := sdl.Color{R: 255, G: 255, B: 255, A: 255}
	textPixels, textW, textH := textToPixels(fpsText, color)

	// Draw text at top-left (10,10)
	blitTextToBuffer(pixels, screenWidth, screenHeight, screenWidth, textPixels, textW, textH, 10, 10)
}