package host

import (
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"github.com/carlosframework/platform/internal/hostbox"
	"github.com/carlosframework/platform/internal/hostclaim"
	"github.com/carlosframework/platform/internal/hostevidence"
	"github.com/carlosframework/platform/internal/park"
	"strconv"
)

// A root-signed stop receipt is an alternative to the target's own release journal.
func (h claimCrossBoxHandover) recoveryStopReceipt(ctx context.Context, o hostclaim.Observed, p hostclaim.AdmissionRecord, key, digest string) error {
	raw, _, err := h.Evidence.Get(ctx, key)
	if err != nil {
		return err
	}
	sum := sha256.Sum256(raw)
	if hex.EncodeToString(sum[:]) != digest {
		return ErrClaimStopReceipt
	}
	var r StopReceipt
	if json.Unmarshal(raw, &r) != nil {
		return ErrClaimStopReceipt
	}
	canonical, err := json.Marshal(r)
	if err != nil || !bytes.Equal(raw, canonical) {
		return ErrClaimStopReceipt
	}
	c := o.Claim
	stamp, err := strconv.ParseUint(c.Op.Journal[hostclaim.JournalTargetStamp], 10, 64)
	if err != nil || stamp == 0 || r.V != 1 || r.Kind != "stopped" || r.Host != o.Host || r.Box != p.Box || r.OperationID != c.Op.ID ||
		r.Incarnation != c.Holder.Incarnation || r.WriterSession != p.Session || r.InstallationStamp != stamp ||
		!park.SameRegion(c.Op.Intent["home_region"], r.Region, c.Op.Intent["to"]) || r.Enrollment != c.Op.Intent["target_enrollment"] || r.Phase != hostclaim.PhaseReleasing ||
		key != stopEvidenceKey(o.Host, c.Op.ID, p.Box, r.ID) || r.FenceID == "" || r.ObligationID == "" || r.ClaimGen == 0 ||
		r.EvidenceAt.IsZero() || r.RequestLimitNS != int64(hostbox.RequestLimit) || len(r.CgroupIdentities) == 0 ||
		!stopDigest(r.InventorySHA256) || !stopDigest(r.LocalJournalSHA256) || !stopDigest(r.ProducerDrainDigest) {
		return ErrClaimStopReceipt
	}
	roster, err := h.Directory.Read(ctx)
	if err != nil {
		return err
	}
	box, ok := roster.Roster.Boxes[p.Box]
	if (c.Op.Intent["home_region"] != "" && !roster.Roster.MatchesHome(c.Op.Intent["home_region"])) || !ok || box.Enrollment != r.Enrollment || !park.SameRegion("", box.Region, r.Region) {
		return ErrClaimStopIdentity
	}
	sig, _, err := h.Evidence.Get(ctx, key+".sig")
	if err != nil {
		return err
	}
	return hostevidence.Verify(box.CensusPublicKey, key, raw, sig)
}