package theme_files

import (
	"archive/zip"
	"bytes"
	"encoding/json"
	"fmt"
	"image"
	"image/jpeg"
	_ "image/png"
	"io"
	"log"
	"os"

	"autolibrary.top/webserver/backend/models/themes_model"
)

func CompressPreviewImage(data []byte) ([]byte, error) {
	config, _, err := image.DecodeConfig(bytes.NewReader(data))
	if err != nil || config.Width <= 0 || config.Height <= 0 || int64(config.Width)*int64(config.Height) > 40_000_000 {
		return nil, fmt.Errorf("invalid image or image dimensions exceed the limit")
	}
	img, format, err := image.Decode(bytes.NewReader(data))
	if err != nil {
		return nil, fmt.Errorf("cannot decode image: %v", err)
	}

	// Resize if width exceeds 800px
	bounds := img.Bounds()
	w := bounds.Dx()
	h := bounds.Dy()
	maxW := 800
	if w > maxW {
		h = h * maxW / w
		if h < 1 {
			h = 1
		}
		w = maxW
		// Simple resize using standard library
		scaled := image.NewRGBA(image.Rect(0, 0, w, h))
		for y := 0; y < h; y++ {
			for x := 0; x < w; x++ {
				srcX := x * bounds.Dx() / w
				srcY := y * bounds.Dy() / h
				scaled.Set(x, y, img.At(srcX, srcY))
			}
		}
		img = scaled
	}

	var buf bytes.Buffer
	err = jpeg.Encode(&buf, img, &jpeg.Options{Quality: 80})
	if err != nil {
		return nil, fmt.Errorf("cannot encode JPEG: %v", err)
	}

	log.Printf("[I] image compressed: %s %dx%d, %d -> %d bytes", format, bounds.Dx(), bounds.Dy(), len(data), buf.Len())
	return buf.Bytes(), nil
}

// GET /api/themes/featured?limit=6

func ValidateAlthemeFile(data []byte) (map[string]interface{}, error) {
	reader, err := zip.NewReader(bytes.NewReader(data), int64(len(data)))
	if err != nil {
		return nil, fmt.Errorf("invalid zip file: %v", err)
	}

	var hasInfoJSON, hasThemeQSS bool
	var info map[string]interface{}

	for _, f := range reader.File {
		if f.Name == "info.json" {
			hasInfoJSON = true
			rc, err := f.Open()
			if err != nil {
				return nil, fmt.Errorf("cannot open info.json: %v", err)
			}
			decoder := json.NewDecoder(rc)
			if err := decoder.Decode(&info); err != nil {
				rc.Close()
				return nil, fmt.Errorf("invalid info.json: %v", err)
			}
			rc.Close()
		}
		if f.Name == "theme.qss" {
			hasThemeQSS = true
		}
	}

	if !hasInfoJSON {
		return nil, fmt.Errorf("missing info.json in .altheme file")
	}
	if !hasThemeQSS {
		return nil, fmt.Errorf("missing theme.qss in .altheme file")
	}

	required := []string{"name", "author", "need_theme", "brief"}
	for _, key := range required {
		if _, ok := info[key]; !ok {
			return nil, fmt.Errorf("info.json missing required key: %s", key)
		}
	}

	return info, nil
}

// buildInfoJSON constructs the info.json map from a Theme DB record.
// It merges Brief and Description with a newline separator into the "brief" field.

func BuildInfoJSON(theme themes_model.Theme) map[string]interface{} {
	brief := theme.Brief
	if theme.Description != "" {
		brief = brief + "\n" + theme.Description
	}
	return map[string]interface{}{
		"qss":                "theme.qss",
		"name":               theme.Name,
		"author":             theme.Author,
		"need_theme":         theme.NeedTheme,
		"brief":              brief,
		"version":            theme.Version,
		"compatible_version": theme.CompatVersion,
	}
}

// createAlthemeArchive creates a .altheme ZIP archive in memory
// containing theme.qss (from qssData) and info.json (from info map).

func CreateAlthemeArchive(qssData []byte, info map[string]interface{}) ([]byte, error) {
	var buf bytes.Buffer
	w := zip.NewWriter(&buf)

	// Add theme.qss
	qssWriter, err := w.Create("theme.qss")
	if err != nil {
		return nil, fmt.Errorf("cannot create theme.qss in archive: %v", err)
	}
	if _, err := qssWriter.Write(qssData); err != nil {
		return nil, fmt.Errorf("cannot write theme.qss to archive: %v", err)
	}

	// Add info.json
	infoWriter, err := w.Create("info.json")
	if err != nil {
		return nil, fmt.Errorf("cannot create info.json in archive: %v", err)
	}
	infoBytes, err := json.MarshalIndent(info, "", "  ")
	if err != nil {
		return nil, fmt.Errorf("cannot marshal info.json: %v", err)
	}
	if _, err := infoWriter.Write(infoBytes); err != nil {
		return nil, fmt.Errorf("cannot write info.json to archive: %v", err)
	}

	if err := w.Close(); err != nil {
		return nil, fmt.Errorf("cannot close archive: %v", err)
	}

	return buf.Bytes(), nil
}

// extractQSSFromAltheme reads an existing .altheme ZIP file from disk
// and returns the raw bytes of its theme.qss entry.

func ExtractQSSFromAltheme(filePath string) ([]byte, error) {
	data, err := os.ReadFile(filePath)
	if err != nil {
		return nil, fmt.Errorf("cannot read .altheme file: %v", err)
	}
	reader, err := zip.NewReader(bytes.NewReader(data), int64(len(data)))
	if err != nil {
		return nil, fmt.Errorf("cannot open .altheme as zip: %v", err)
	}
	for _, f := range reader.File {
		if f.Name == "theme.qss" {
			rc, err := f.Open()
			if err != nil {
				return nil, fmt.Errorf("cannot open theme.qss in archive: %v", err)
			}
			defer rc.Close()
			return io.ReadAll(rc)
		}
	}
	return nil, fmt.Errorf("theme.qss not found in .altheme archive")
}