package secrets

import (
	"context"
	"encoding/base64"
	"fmt"
)

// SessionStorage keeps the MTProto session in OpenBao and never on disk.
//
// gotd's own FileStorage would put a full-account credential in the working
// directory, where it outlives the run, gets committed by accident, and is
// readable by anything on the box. The session can do everything the operator
// account can do, so it is held exactly where the bot token is.
type SessionStorage struct {
	Store *Store
}

const sessionField = "session_b64"

func (s SessionStorage) LoadSession(ctx context.Context) ([]byte, error) {
	fields, found, err := s.Store.Get(ctx, KeyOperatorSession)
	if err != nil {
		return nil, err
	}
	if !found || fields[sessionField] == "" {
		// gotd treats a nil session as "not authenticated yet", which is the
		// correct reading of an empty path.
		return nil, nil
	}
	raw, err := base64.StdEncoding.DecodeString(fields[sessionField])
	if err != nil {
		return nil, fmt.Errorf("stored session at %s is not decodable; re-run "+
			"`provision session bootstrap`", s.Store.Ref(KeyOperatorSession))
	}
	return raw, nil
}

func (s SessionStorage) StoreSession(ctx context.Context, data []byte) error {
	return s.Store.Put(ctx, KeyOperatorSession, map[string]string{
		sessionField: base64.StdEncoding.EncodeToString(data),
	})
}

// AppCredentials are issued by my.telegram.org and cannot be provisioned; see
// docs/seeding-runbook.md step 2.
type AppCredentials struct {
	AppID   int
	AppHash string
}