package hostops

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"strings"

	"github.com/carlosframework/platform/internal/geoip"
)

// classifyGeoip reviews the whole control/geoip/ family, exactly, as operator
// platform state that holds no app record: the content-addressed database
// blobs, the pointer to the live one, and the feed's status file. Nothing
// else under the prefix is classified, and a body that is not what the
// publisher writes at that key is refused, so a stray write cannot ride the
// family. Deletes carry no body and are checked by key alone.
func classifyGeoip(t MutationTarget) (Classification, error) {
	deleting := t.Method != "Put"
	switch {
	case t.Key == geoip.PointerKey:
		if !deleting {
			if _, err := geoip.ParsePointer(t.After); err != nil {
				return Classification{}, fmt.Errorf("%w: %s: %v", ErrUnclassified, t.Key, err)
			}
		}
		return Classification{Family: "geoip-pointer", NonApp: "operator GeoIP pointer; names one platform database blob and holds no app record"}, nil
	case t.Key == geoip.FeedKey:
		if !deleting {
			if _, err := geoip.ParseFeedStatus(t.After); err != nil {
				return Classification{}, fmt.Errorf("%w: %s: %v", ErrUnclassified, t.Key, err)
			}
		}
		return Classification{Family: "geoip-feed", NonApp: "operator GeoIP feed status; holds no app record"}, nil
	case IsGeoipBlobKey(t.Key):
		// A streamed put has no body here (PutFrom): the publisher hashed it
		// while staging and a create-only put cannot replace an object. A
		// buffered one must hash to its own name.
		if !deleting && len(t.After) != 0 {
			sum := sha256.Sum256(t.After)
			if t.Key != geoip.BlobKey(hex.EncodeToString(sum[:])) {
				return Classification{}, fmt.Errorf("%w: %s: body does not hash to its name", ErrUnclassified, t.Key)
			}
		}
		return Classification{Family: "geoip-blob", NonApp: "operator GeoIP database blob, content-addressed by its sha256; holds no app record"}, nil
	}
	return Classification{}, fmt.Errorf("%w: %s", ErrUnclassified, t.Key)
}

// IsGeoipBlobKey is exactly control/geoip/<64 lower-case hex>.mmdb.
func IsGeoipBlobKey(key string) bool {
	rest, ok := strings.CutPrefix(key, geoip.Prefix)
	if !ok {
		return false
	}
	sha, ok := strings.CutSuffix(rest, ".mmdb")
	return ok && geoip.IsSHA256Hex(sha)
}