package api

import (
	"context"
	"database/sql"
	"fmt"
	"time"

	"github.com/cosmic-clash/cosmic-clash/server/domain"
	"github.com/cosmic-clash/cosmic-clash/server/store"
	"github.com/cosmic-clash/cosmic-clash/server/workload"
)

// AssignmentProviderFromStore adapts the durable player-scoped assignment
// projection to the HTTP boundary. The store query filters expiry and binds
// both match and player; the API still performs its response-shape checks.
func AssignmentProviderFromStore(db *sql.DB) AssignmentProvider {
	return func(ctx context.Context, playerID, matchID string, now time.Time) (AssignmentView, error) {
		assignment, err := store.GetAssignment(ctx, db, playerID, matchID, now)
		if err != nil {
			return AssignmentView{}, err
		}
		return AssignmentView{
			MatchID:           assignment.MatchID,
			ServerID:          assignment.ServerID,
			PlayerID:          assignment.PlayerID,
			Slot:              assignment.Slot,
			ExpiresAt:         assignment.ExpiresAt,
			ProtocolVersion:   assignment.ProtocolVersion,
			Transport:         assignment.Transport,
			JoinAuthorisation: assignment.JoinAuthorisation,
			Endpoint:          assignment.Endpoint,
			Revision:          assignment.Revision,
		}, nil
	}
}

type postgresProposalBackend struct{ db *sql.DB }

func (p postgresProposalBackend) Get(ctx context.Context, playerID, proposalID string, now time.Time) (domain.Proposal, error) {
	return store.GetProposal(ctx, p.db, playerID, proposalID, now)
}

func (p postgresProposalBackend) Respond(ctx context.Context, playerID, proposalID, idempotencyKey string, accept bool, expectedRevision uint64, now time.Time) (domain.Proposal, error) {
	return store.RespondToProposal(ctx, p.db, playerID, proposalID, idempotencyKey, accept, expectedRevision, now)
}

func ProposalProviderFromStore(db *sql.DB) ProposalBackend {
	return postgresProposalBackend{db: db}
}

// ProposalPromoterFromStore turns a durably accepted proposal into its exact
// matcher-selected ALLOCATING match. The store chooses a deterministic match
// ID so an API retry after a transient failure cannot duplicate the match.
func ProposalPromoterFromStore(db *sql.DB) ProposalPromoter {
	return ProposalPromoterFunc(func(ctx context.Context, proposal domain.Proposal, now time.Time) error {
		if proposal.State != domain.Accepted {
			return domain.ErrIllegalTransition
		}
		return store.PromoteStoredAcceptedProposal(ctx, db, proposal.ProposalID, now)
	})
}

type postgresServerRegistrar struct{ db *sql.DB }

func (p postgresServerRegistrar) RegisterServer(ctx context.Context, binding domain.WorkloadBinding, protocol int, assignmentReady bool, idempotencyKey string, now time.Time) error {
	return store.AdvanceServerRegistration(ctx, p.db, binding, protocol, assignmentReady, idempotencyKey, now)
}

func ServerRegistrarFromStore(db *sql.DB) ServerRegistrar {
	if db == nil {
		return nil
	}
	return postgresServerRegistrar{db: db}
}

type postgresServerShutdowner struct{ db *sql.DB }

func (p postgresServerShutdowner) ShutdownServer(ctx context.Context, binding domain.WorkloadBinding, reason, idempotencyKey string, now time.Time) error {
	return store.RecordServerShutdown(ctx, p.db, binding, reason, idempotencyKey, now)
}

func ServerShutdownerFromStore(db *sql.DB) ServerShutdowner {
	if db == nil {
		return nil
	}
	return postgresServerShutdowner{db: db}
}

type postgresServerConnections struct{ db *sql.DB }

func (p postgresServerConnections) RecordPlayerConnected(ctx context.Context, binding domain.WorkloadBinding, playerID, idempotencyKey string, now time.Time) error {
	return store.RecordPlayerConnected(ctx, p.db, binding, playerID, idempotencyKey, now)
}

func ServerConnectionsFromStore(db *sql.DB) ServerConnectionRecorder {
	if db == nil {
		return nil
	}
	return postgresServerConnections{db: db}
}

// WorkloadVerifierFromSignedToken builds WorkloadVerify from a control-plane
// -owned signed token instead of a Kubernetes-projected JWT (see
// workload/signed_token.go for why: it needs no live cluster to verify).
// secret must be kept out of source control (env var in cmd/control-plane);
// an empty secret returns nil so a misconfigured deployment fails the same
// way an unwired verifier already does today (503, not a silent bypass).
func WorkloadVerifierFromSignedToken(secret []byte, db *sql.DB) WorkloadVerifier {
	if len(secret) == 0 || db == nil {
		return nil
	}
	return func(token string, now time.Time) (domain.WorkloadBinding, error) {
		claims, err := workload.ParseSignedWorkloadToken(secret, token, now)
		if err != nil {
			return domain.WorkloadBinding{}, err
		}
		// WorkloadVerifier has no context parameter (see its type in
		// service.go) so the durable lookup below cannot inherit the
		// caller's request context; bound it locally instead of running
		// unbounded against context.Background().
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		// The token only names allocation_id (see signed_token.go for why);
		// match_id/server_id come from the durable allocator record, never
		// from the caller, so a token can never claim a pairing that wasn't
		// actually, durably allocated.
		matchID, serverID, ok, err := store.AllocationBindingByAllocationID(ctx, db, claims.AllocationID)
		if err != nil {
			return domain.WorkloadBinding{}, err
		}
		if !ok {
			return domain.WorkloadBinding{}, fmt.Errorf("signed workload token names an allocation that is no longer valid")
		}
		return domain.WorkloadBinding{
			AllocationID: claims.AllocationID,
			MatchID:      matchID,
			ServerID:     serverID,
		}, nil
	}
}