package cache

import (
	"crypto/sha256"
	"fmt"
	"io"
	"os"
)

// HashFile computes the SHA-256 hex digest of the file at path.
func HashFile(path string) (string, error) {
	f, err := os.Open(path)
	if err != nil {
		return "", err
	}
	defer f.Close()
	h := sha256.New()
	if _, err := io.Copy(h, f); err != nil {
		return "", err
	}
	return fmt.Sprintf("%x", h.Sum(nil)), nil
}

// AnalysisKey builds a cache key for FFF or SLA analysis.
// Format: "<endpoint>:<filehash>:scale=<scale>"
// scale uses %.6g so "1.50" and "1.5" map to the same key.
func AnalysisKey(endpoint, fileHash string, scale float64) string {
	return fmt.Sprintf("%s:%s:scale=%.6g", endpoint, fileHash, scale)
}

// ThumbnailKey builds a cache key for thumbnail generation.
func ThumbnailKey(fileHash string) string {
	return "thumbnail:" + fileHash
}