package domain

import (
	"crypto/sha256"
	"fmt"
)

type AllocationManifest struct {
	AllocationID string
	MatchID      string
	ServerID     string
	Region       string
	Build        string
	Protocol     int
	Transport    string
	RosterDigest string
}

type Assignment struct {
	Allocation Allocation
	Manifest   AllocationManifest
	Endpoint   string
}

var ErrManifestRejected = fmt.Errorf("allocation manifest rejected")

// VerifyAssignment is the assignment-ready gate. A Ready/Allocated process
// has no client-facing endpoint until its signed manifest, allocator binding,
// and hosted endpoint all pass this check.
func VerifyAssignment(allocation Allocation, manifest AllocationManifest, endpoint string, signature []byte, verify func([]byte, []byte) bool) (Assignment, error) {
	if allocation.State != ServerAllocated || allocation.AllocationID == "" || allocation.MatchID == "" || allocation.ServerID == "" || endpoint == "" || len(signature) == 0 || verify == nil {
		return Assignment{}, ErrManifestRejected
	}
	if manifest.AllocationID != allocation.AllocationID || manifest.MatchID != allocation.MatchID || manifest.ServerID != allocation.ServerID || manifest.Region != allocation.Region || manifest.Build != allocation.Build || manifest.Protocol != allocation.Protocol || manifest.Transport != allocation.Transport || manifest.RosterDigest == "" {
		return Assignment{}, ErrManifestRejected
	}
	if !verify(manifestBytes(manifest), signature) {
		return Assignment{}, ErrManifestRejected
	}
	return Assignment{Allocation: allocation, Manifest: manifest, Endpoint: endpoint}, nil
}

func manifestBytes(manifest AllocationManifest) []byte {
	canonical := fmt.Sprintf("%s\x00%s\x00%s\x00%s\x00%s\x00%d\x00%s\x00%s", manifest.AllocationID, manifest.MatchID, manifest.ServerID, manifest.Region, manifest.Build, manifest.Protocol, manifest.Transport, manifest.RosterDigest)
	return []byte(canonical)
}

func ManifestDigest(manifest AllocationManifest) [32]byte {
	return sha256.Sum256(manifestBytes(manifest))
}

// AssignmentParticipant is the durable roster row the allocator turns into one
// signed join authorisation. It lives here rather than in the store so the
// allocator can consume it through an interface without depending on the
// persistence package.
type AssignmentParticipant struct {
	PlayerID string
	SteamID  string
	Slot     int
	Team     int
}