package store

import (
	"context"
	"crypto/ed25519"
	"crypto/x509"
	"errors"
	"fmt"
)

// LoadOrCreateIdentity returns the master's private key, creating and
// storing one with generate on first start. Keeping it in Postgres means it
// survives container recreation and is covered by database backups; losing
// it would force every agent to be reconfigured with a new MASTER_KEY.
func (s *Store) LoadOrCreateIdentity(ctx context.Context, generate func() (ed25519.PrivateKey, error)) (ed25519.PrivateKey, error) {
	fresh, err := generate()
	if err != nil {
		return nil, err
	}
	der, err := x509.MarshalPKCS8PrivateKey(fresh)
	if err != nil {
		return nil, fmt.Errorf("marshal master key: %w", err)
	}
	if _, err := s.pool.Exec(ctx,
		`INSERT INTO master_identity (id, private_key) VALUES (1, $1) ON CONFLICT (id) DO NOTHING`, der,
	); err != nil {
		return nil, fmt.Errorf("store master key: %w", err)
	}
	var stored []byte
	if err := s.pool.QueryRow(ctx, `SELECT private_key FROM master_identity WHERE id = 1`).Scan(&stored); err != nil {
		return nil, fmt.Errorf("load master key: %w", err)
	}
	parsed, err := x509.ParsePKCS8PrivateKey(stored)
	if err != nil {
		return nil, fmt.Errorf("parse master key: %w", err)
	}
	key, ok := parsed.(ed25519.PrivateKey)
	if !ok {
		return nil, errors.New("stored master key is not ed25519")
	}
	return key, nil
}