package host

import (
	"context"
	"crypto/rand"
	"encoding/hex"
	"encoding/json"
	"errors"
	"github.com/carlosframework/platform/internal/rootparticipation"
	"os"
)

type rootFloorAuthorization struct {
	Identity   rootFloorIdentity
	Generation uint64
	Nonce      string
}

// Only an offline root caller with the checked private store may issue this
// capability. No production caller is installed until migration has full history.
func (f rootMovesFloors) authorizeReconstruction(ctx context.Context) (*rootFloorAuthorization, error) {
	unlock, err := f.private.Lock(ctx, "floor.lock")
	if err != nil {
		return nil, err
	}
	defer unlock()
	generation := uint64(1)
	old, err := f.record(rootFloorAccepted)
	if err == nil {
		generation = old.Generation + 1
	} else if !errors.Is(err, os.ErrNotExist) {
		return nil, err
	}
	var nonce [32]byte
	if _, err := rand.Read(nonce[:]); err != nil {
		return nil, err
	}
	token := rootFloorAuthorization{Identity: f.identity, Generation: generation, Nonce: hex.EncodeToString(nonce[:])}
	raw, _ := json.Marshal(token)
	if err := f.private.Write("reconstruction-token.json", raw); err != nil {
		return nil, err
	}
	return &token, nil
}
func (f rootMovesFloors) authorizedReconstruction(token *rootFloorAuthorization, generation uint64) bool {
	if token == nil || token.Identity != f.identity || token.Generation != generation || len(token.Nonce) != 64 {
		return false
	}
	raw, err := f.private.Read("reconstruction-token.json")
	if err != nil {
		return false
	}
	var retained rootFloorAuthorization
	return rootparticipation.Decode(raw, &retained) == nil && retained == *token
}