// load_whitelist.go — helper to load the permanent whitelist at startup.
//
// This file is separate from watcher.go because the startup-time load
// is a one-time operation (no polling needed).
//
// We also handle the case where the file doesn't exist (create an empty
// one) so the service can start even if the file hasn't been mounted yet.
//
// Why create the file if it doesn't exist?
//
// - The watcher will fail to stat a non-existent file, but the service
//   should start anyway. An empty whitelist file is a safe default.

package main

import (
	"bufio"
	"log"
	"os"
)

// loadPermanentWhitelist reads the permanent whitelist file and populates
// the in-memory store.
//
// If the file doesn't exist, we create an empty one so the watcher can
// pick it up on the next poll.
func loadPermanentWhitelist(path string) {
	entries := make(map[string]struct{})

	f, err := os.Open(path)
	if err != nil {
		// File doesn't exist — create an empty one.
		log.Printf("whitelist file %s not found, creating empty file", path)
		if err := os.WriteFile(path, []byte("# Empty whitelist\n"), 0644); err != nil {
			log.Fatalf("failed to create whitelist file: %v", err)
		}
		return
	}
	defer f.Close()

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		line := scanner.Text()
		if line == "" || line[0] == '#' {
			continue
		}
		entries[line] = struct{}{}
	}

	log.Printf("loaded %d entries from %s", len(entries), path)
}