//go:build linux

package host

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

	"github.com/carlosframework/platform/internal/hostbox"
	"github.com/carlosframework/platform/internal/hostclaim"
	"github.com/carlosframework/platform/internal/hostguard"
	"github.com/carlosframework/platform/internal/instancefs"
	"github.com/carlosframework/platform/internal/provision"
	"golang.org/x/sys/unix"
)

// servingParkStateDirectory accepts only root installation and root inventory
// snapshots. The root handler reads both locally under host authority;
// this function is not a transport decoder and accepts no registry row.
func servingParkStateDirectory(data string, o hostclaim.Observed, installation hostguard.RootInstallation, in hostbox.StopInventory, revision uint64, actor hostbox.Actor) (servingArtifactDirectory, error) {
	var zero servingArtifactDirectory
	current, err := servingWriterIdentity(o, actor.Box, actor.Region)
	if err != nil {
		return zero, err
	}
	if !filepath.IsAbs(data) || filepath.Clean(data) != data || strings.ContainsAny(current.Host, "/\\\x00") || current.Host == "." || current.Host == ".." {
		return zero, hostbox.ErrChanged
	}
	h := o.Claim.Holder
	if h.Family != "instance" || installation.Migration == 0 || installation.Empty || installation.Host != current.Host || installation.Incarnation != current.Incarnation || installation.Stamp == 0 || installation.Stamp > current.Stamp || installation.Account != h.Account || installation.App != h.App || installation.Record != h.Key || installation.Box != actor.Box || installation.Enrollment != actor.Enrollment || actor.Enrollment == "" || actor.Revision == 0 || actor.Binding == "" || revision == 0 || installation.InventoryRevision != revision {
		return zero, hostbox.ErrChanged
	}
	if installation.Stamp != current.Stamp {
		if _, err := servingPredecessor(o.Claim, current, installation.Stamp, ""); err != nil {
			return zero, err
		}
	}
	if !in.Complete || in.Host != installation.Host || in.Incarnation != installation.Incarnation || in.InstallationStamp != installation.Stamp || in.Box != actor.Box || in.Enrollment != actor.Enrollment || in.DirectoryRevision != actor.Binding {
		return zero, hostbox.ErrTypedInventory
	}
	relative := filepath.ToSlash(filepath.Join("instances", provision.InstanceID(current.Host)))
	sum := sha256.Sum256([]byte(fmt.Sprintf("%s\x00%s\x00%d\x00%s", in.Host, in.Incarnation, in.InstallationStamp, in.Box)))
	owner := hex.EncodeToString(sum[:])
	var selected hostbox.StopInventoryEntry
	for _, entry := range in.Entries {
		if entry.Kind != "path" || entry.ManagedRoot != "data" || entry.RelativePath != relative {
			continue
		}
		if selected.ArtifactID != "" || entry.ArtifactID == "" || entry.Ownership != owner || entry.Materialization != "materialized" || entry.Type != unix.S_IFDIR || entry.Device == 0 || entry.Inode == 0 {
			return zero, hostbox.ErrTypedInventory
		}
		selected = entry
	}
	if selected.ArtifactID == "" {
		return zero, hostbox.ErrTypedInventory
	}
	dir, err := instancefs.OpenDirBeneath(data, relative)
	if err != nil {
		return zero, err
	}
	defer dir.Close()
	id, err := servingParkDirID(dir)
	if err != nil {
		return zero, err
	}
	if id.Device != selected.Device || id.Inode != selected.Inode {
		return zero, hostbox.ErrChanged
	}
	return id, nil
}