package hostops

import (
	"context"
	"encoding/json"
	"errors"
	"os"

	"github.com/carlosframework/platform/internal/provision"
	"github.com/carlosframework/platform/internal/release"
)

func sequenceError(err error) error {
	if errors.Is(err, provision.ErrRecordSequence) {
		return ErrIdentity
	}
	if errors.Is(err, provision.ErrRecordSequenceExhausted) {
		return ErrPending
	}
	return err
}

func recordSequence(body []byte) (map[string]json.RawMessage, uint64, error) {
	fields, seq, err := provision.RecordSequence(body)
	return fields, seq, sequenceError(err)
}

func advanceRecordSequence(before, body []byte) ([]byte, error) {
	next, err := provision.AdvanceRecordSequence(before, body)
	return next, sequenceError(err)
}

// This claim-only boundary delegates encoding to provision, including when
// an upstream typed writer has already prepared the same conditional Put.
func putSequencedRecord(ctx context.Context, raw release.Store, key string, body []byte, etag string) (string, error) {
	before, seen, err := raw.Get(ctx, key)
	if errors.Is(err, os.ErrNotExist) {
		if etag != "" {
			return "", release.ErrCASConflict
		}
		before, seen = []byte(`{}`), ""
	} else if err != nil {
		return "", err
	}
	if seen != etag {
		return "", release.ErrCASConflict
	}
	MarkAppMutationIssued(ctx)
	tag, _, err := provision.WriteRecord(provision.WithRecordSequence(ctx), raw, key, before, body, etag)
	return tag, sequenceError(err)
}