package tui

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"image"
	"image/color"
	_ "image/jpeg"
	_ "image/png"
	"io"
	"net/http"
	"os"
	"strings"
	"time"

	"github.com/disintegration/imaging"
	"github.com/mattn/go-sixel"
)

func FetchAndProcessThumbnail(url string) (string, error) {
	if url == "" {
		return "", fmt.Errorf("empty URL")
	}

	client := &http.Client{
		Timeout: 10 * time.Second,
	}

	resp, err := client.Get(url)
	if err != nil {
		return "", fmt.Errorf("failed to fetch image: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("failed to fetch image: status %d", resp.StatusCode)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", fmt.Errorf("failed to read image data: %w", err)
	}

	img, _, err := image.Decode(bytes.NewReader(body))
	if err != nil {
		return "", fmt.Errorf("failed to decode image: %w", err)
	}

	// Consistent thumbnail size
	width := 40
	height := 15

	img = imaging.Resize(img, width*2, height*2, imaging.Lanczos)

	// Try iTerm2 protocol first
	if isITerm() {
		return getITermImageSequence(img), nil
	}

	// Try Sixel next
	var buf bytes.Buffer
	enc := sixel.NewEncoder(&buf)
	err = enc.Encode(img)
	if err == nil {
		return buf.String(), nil
	}

	// Fall back to ASCII art
	return imageToASCII(img), nil
}

func imageToASCII(img image.Image) string {
	bounds := img.Bounds()
	width := 40
	height := 15
	chars := []string{"█", "▓", "▒", "░", " "}

	var ascii strings.Builder
	stepX := float64(bounds.Dx()) / float64(width)
	stepY := float64(bounds.Dy()) / float64(height)

	for y := 0; y < height; y++ {
		for x := 0; x < width; x++ {
			px := int(float64(x) * stepX)
			py := int(float64(y) * stepY)
			c := color.GrayModel.Convert(img.At(px+bounds.Min.X, py+bounds.Min.Y)).(color.Gray)
			index := int(c.Y) * (len(chars) - 1) / 255
			ascii.WriteString(chars[index])
		}
		ascii.WriteString("\n")
	}

	return ascii.String()
}

func getITermImageSequence(img image.Image) string {
	var buf bytes.Buffer
	imaging.Encode(&buf, img, imaging.PNG)
	encoded := base64.StdEncoding.EncodeToString(buf.Bytes())
	
	return fmt.Sprintf("\033]1337;File=inline=1;width=40ch;height=15;preserveAspectRatio=1:%s\a", encoded)
}

func isITerm() bool {
	return os.Getenv("TERM_PROGRAM") == "iTerm.app"
}