package main

import (
	"crypto/rand"
	"crypto/subtle"
	"encoding/base64"
	"net/http"

	"github.com/go-chi/chi/v5"
)

// genDeletionToken returns a 32-char url-safe random token
func genDeletionToken() string {
	b := make([]byte, 24)
	rand.Read(b)
	return base64.RawURLEncoding.EncodeToString(b)
}

// maybeBurn marks a paste soft-deleted if burn_after_read is set.
// Returns true if this read consumed the paste.
func (s *Store) maybeBurn(row *PasteRow) bool {
	if !row.BurnAfterRead {
		return false
	}
	s.SoftDelete(row.ID)
	return true
}

func deletionTokenEqual(stored, given string) bool {
	return subtle.ConstantTimeCompare([]byte(stored), []byte(given)) == 1
}

// handleRedeemDeletion lets a holder of the deletion token hard-delete immediately.
// DELETE /api/pastes/{id}/redeem?token=...
func (a *apiServer) handleRedeemDeletion(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	token := r.URL.Query().Get("token")
	if token == "" {
		writeErr(w, 400, "token required")
		return
	}
	row, err := a.store.GetPaste(id)
	if err != nil || row == nil {
		writeErr(w, 404, "paste not found")
		return
	}
	if row.DeletionToken.String == "" || !deletionTokenEqual(row.DeletionToken.String, token) {
		writeErr(w, 403, "invalid token")
		return
	}
	// hard delete: pastes table row goes away entirely
	a.store.db.Exec(`DELETE FROM pastes WHERE id = ?`, row.ID)
	writeJSON(w, 200, map[string]string{"status": "deleted"})
}