package artifact

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"mime"
	"net/http"
	"os"
	"path/filepath"
	"strings"
)

// TaskStyleReference is the style-only reference used as Image 2 for RIFT
// generation. Custom style assets live below <ARTIFACT_DIR>/_styles; an empty
// task reference resolves to the bundled default image.
type TaskStyleReference struct {
	Bytes       []byte `json:"-"`
	Name        string `json:"name"`
	ContentType string `json:"content_type"`
	Custom      bool   `json:"custom"`
	SHA256      string `json:"sha256"`
}

func styleContentType(name string, b []byte) string {
	ct := http.DetectContentType(b)
	if ct == "application/octet-stream" {
		if ext := filepath.Ext(name); ext != "" {
			if v := mime.TypeByExtension(ext); v != "" {
				ct = v
			}
		}
	}
	return strings.Split(ct, ";")[0]
}

func (w *Worker) loadStyleReference(ref string) (TaskStyleReference, error) {
	ref = strings.TrimSpace(ref)
	if ref == "" {
		b := DefaultStyleReferenceJPEG()
		h := sha256.Sum256(b)
		return TaskStyleReference{
			Bytes:       b,
			Name:        "default_style_reference.jpg",
			ContentType: "image/jpeg",
			Custom:      false,
			SHA256:      hex.EncodeToString(h[:]),
		}, nil
	}
	if filepath.Base(ref) != ref || strings.ContainsAny(ref, `/\\`) {
		return TaskStyleReference{}, fmt.Errorf("invalid task style reference %q", ref)
	}
	p := filepath.Join(w.dir, "_styles", ref)
	b, err := os.ReadFile(p)
	if err != nil {
		return TaskStyleReference{}, fmt.Errorf("read task style reference %q: %w", ref, err)
	}
	if len(b) < 128 {
		return TaskStyleReference{}, fmt.Errorf("task style reference %q is empty or invalid", ref)
	}
	h := sha256.Sum256(b)
	return TaskStyleReference{
		Bytes:       b,
		Name:        ref,
		ContentType: styleContentType(ref, b),
		Custom:      true,
		SHA256:      hex.EncodeToString(h[:]),
	}, nil
}

// TaskStyleReference reads the configured style for a task. It is used by the
// UI preview endpoints and intentionally returns the bundled default when the
// task has no custom style assigned.
func (w *Worker) TaskStyleReference(ctx context.Context, taskID string) (TaskStyleReference, error) {
	var ref string
	if err := w.db.QueryRowContext(ctx, `SELECT nft_style_reference FROM tasks WHERE id=?`, taskID).Scan(&ref); err != nil {
		return TaskStyleReference{}, err
	}
	return w.loadStyleReference(ref)
}