// Package ports defines the stable interfaces that connect Game Master
// use cases to external state and external services.
package ports

import (
	"context"
	"fmt"
	"strings"
	"time"

	"galaxy/gamemaster/internal/domain/runtime"
)

//go:generate go run go.uber.org/mock/mockgen -destination=../adapters/mocks/mock_runtimerecordstore.go -package=mocks galaxy/gamemaster/internal/ports RuntimeRecordStore

// RuntimeRecordStore stores runtime records and exposes the operations
// used by the service layer (Stages 13+) and the workers (Stages 15-18).
// Adapters must preserve domain semantics:
//
//   - Get returns runtime.ErrNotFound when no record exists for gameID.
//   - Insert installs a fresh record and returns runtime.ErrConflict
//     when a row already exists.
//   - UpdateStatus applies one transition through a compare-and-swap
//     guard on the stored status and returns runtime.ErrConflict on a
//     stale CAS.
//   - UpdateScheduling mutates `next_generation_at`, `skip_next_tick`,
//     and `current_turn` together; the destination status is unaffected.
//   - UpdateImage rotates `current_image_ref` and
//     `current_engine_version` under a compare-and-swap guard on the
//     stored status and returns runtime.ErrConflict on a stale CAS.
//   - UpdateEngineHealth rotates the `engine_health` column without
//     touching status. The call applies from any status (including
//     stopped and finished) so late-arriving health observations still
//     bookkeep correctly. Returns runtime.ErrNotFound when no row
//     matches.
//   - Delete removes the record identified by gameID. The call is
//     idempotent: it returns nil even when no row matches.
//   - ListDueRunning returns every running record with
//     `next_generation_at <= now`.
//   - ListByStatus returns every record currently indexed under status.
//   - List returns every record ordered by `created_at` descending. Used
//     by the `internalListRuntimes` REST handler when no status filter
//     is supplied.
type RuntimeRecordStore interface {
	// Get returns the record identified by gameID. It returns
	// runtime.ErrNotFound when no record exists.
	Get(ctx context.Context, gameID string) (runtime.RuntimeRecord, error)

	// Insert installs record into the store. It returns
	// runtime.ErrConflict when a row already exists for record.GameID.
	Insert(ctx context.Context, record runtime.RuntimeRecord) error

	// UpdateStatus applies one status transition in a compare-and-swap
	// fashion. The adapter must first call runtime.Transition to reject
	// invalid pairs without touching the store, then verify that the
	// stored status equals input.ExpectedFrom. Optional fields on the
	// input (CurrentImageRef, CurrentEngineVersion, EngineHealthSummary)
	// are persisted only when non-nil.
	UpdateStatus(ctx context.Context, input UpdateStatusInput) error

	// UpdateScheduling mutates the scheduling columns
	// (`next_generation_at`, `skip_next_tick`, `current_turn`) of the
	// record identified by input.GameID. The store does not validate
	// the runtime status; callers issue UpdateScheduling alongside an
	// UpdateStatus when the destination status changes.
	UpdateScheduling(ctx context.Context, input UpdateSchedulingInput) error

	// UpdateImage rotates `current_image_ref` and
	// `current_engine_version` of the record identified by
	// input.GameID under a compare-and-swap guard on the stored status.
	// The destination status is unchanged. Used by the admin patch
	// flow (Stage 17) where the runtime stays `running` while the
	// engine container is recreated by Runtime Manager with a new
	// image. Returns runtime.ErrNotFound when no row matches and
	// runtime.ErrConflict when the stored status differs from
	// input.ExpectedStatus.
	UpdateImage(ctx context.Context, input UpdateImageInput) error

	// UpdateEngineHealth rotates the `engine_health` column of the
	// record identified by input.GameID without touching status. Used
	// by the runtime:health_events consumer (Stage 18) when an
	// observation should refresh the summary regardless of the current
	// runtime status (including stopped and finished, so late-arriving
	// events still bookkeep correctly). Returns runtime.ErrNotFound
	// when no row matches.
	UpdateEngineHealth(ctx context.Context, input UpdateEngineHealthInput) error

	// Delete removes the record identified by gameID. The call is
	// idempotent: it returns nil even when no row matches. Used by the
	// register-runtime rollback path (Stage 13) when the engine
	// /admin/init call or any later setup step fails after the row has
	// been installed with status=starting.
	Delete(ctx context.Context, gameID string) error

	// ListDueRunning returns every record whose status is `running`
	// and whose `next_generation_at <= now`. The order is
	// adapter-defined; callers may reorder as needed.
	ListDueRunning(ctx context.Context, now time.Time) ([]runtime.RuntimeRecord, error)

	// ListByStatus returns every record currently indexed under status.
	// The order is adapter-defined; callers may reorder as needed.
	ListByStatus(ctx context.Context, status runtime.Status) ([]runtime.RuntimeRecord, error)

	// List returns every record in the store, ordered by `created_at`
	// descending. Used by the `internalListRuntimes` REST handler when no
	// status filter is supplied.
	List(ctx context.Context) ([]runtime.RuntimeRecord, error)
}

// UpdateStatusInput stores the arguments required to apply one status
// transition through a RuntimeRecordStore. The optional fields are
// pointers so the adapter can distinguish «leave alone» from «write
// the zero value».
type UpdateStatusInput struct {
	// GameID identifies the record to mutate.
	GameID string

	// ExpectedFrom stores the status the caller believes the record
	// currently has. A mismatch results in runtime.ErrConflict.
	ExpectedFrom runtime.Status

	// To stores the destination status.
	To runtime.Status

	// Now stores the wall-clock used to derive the lifecycle timestamps
	// (started_at, stopped_at, finished_at, updated_at) according to
	// To.
	Now time.Time

	// EngineHealthSummary is the new value of the `engine_health`
	// column. Nil leaves the column unchanged.
	EngineHealthSummary *string

	// CurrentImageRef is the new value of the `current_image_ref`
	// column. Nil leaves the column unchanged. Used by the patch flow
	// (Stage 17) when the image reference rotates together with the
	// status update.
	CurrentImageRef *string

	// CurrentEngineVersion is the new value of the
	// `current_engine_version` column. Nil leaves the column unchanged.
	// Used by the patch flow when the engine version rotates together
	// with the status update.
	CurrentEngineVersion *string
}

// Validate reports whether input contains a structurally valid status
// transition request. Adapters call Validate before touching the store.
func (input UpdateStatusInput) Validate() error {
	if strings.TrimSpace(input.GameID) == "" {
		return fmt.Errorf("update runtime status: game id must not be empty")
	}
	if !input.ExpectedFrom.IsKnown() {
		return fmt.Errorf(
			"update runtime status: expected from status %q is unsupported",
			input.ExpectedFrom,
		)
	}
	if !input.To.IsKnown() {
		return fmt.Errorf(
			"update runtime status: to status %q is unsupported",
			input.To,
		)
	}
	if err := runtime.Transition(input.ExpectedFrom, input.To); err != nil {
		return fmt.Errorf("update runtime status: %w", err)
	}
	if input.Now.IsZero() {
		return fmt.Errorf("update runtime status: now must not be zero")
	}
	if input.CurrentImageRef != nil && strings.TrimSpace(*input.CurrentImageRef) == "" {
		return fmt.Errorf(
			"update runtime status: current image ref must not be empty when set",
		)
	}
	if input.CurrentEngineVersion != nil && strings.TrimSpace(*input.CurrentEngineVersion) == "" {
		return fmt.Errorf(
			"update runtime status: current engine version must not be empty when set",
		)
	}
	return nil
}

// UpdateSchedulingInput stores the arguments required to mutate the
// scheduling columns of one runtime record. The status enum is
// deliberately absent: scheduling and status updates are independent
// operations and the service layer composes them when both must change.
type UpdateSchedulingInput struct {
	// GameID identifies the record to mutate.
	GameID string

	// NextGenerationAt is the new value of the column. Nil writes SQL
	// NULL (used to clear the tick when the runtime leaves running).
	NextGenerationAt *time.Time

	// SkipNextTick is the new value of the column. The store overwrites
	// the column unconditionally.
	SkipNextTick bool

	// CurrentTurn is the new value of the column. Must be non-negative.
	CurrentTurn int

	// Now stores the wall-clock used to refresh `updated_at`.
	Now time.Time
}

// Validate reports whether input contains structurally valid scheduling
// arguments. Adapters call Validate before touching the store.
func (input UpdateSchedulingInput) Validate() error {
	if strings.TrimSpace(input.GameID) == "" {
		return fmt.Errorf("update runtime scheduling: game id must not be empty")
	}
	if input.CurrentTurn < 0 {
		return fmt.Errorf("update runtime scheduling: current turn must not be negative")
	}
	if input.NextGenerationAt != nil && input.NextGenerationAt.IsZero() {
		return fmt.Errorf(
			"update runtime scheduling: next generation at must not be zero when set",
		)
	}
	if input.Now.IsZero() {
		return fmt.Errorf("update runtime scheduling: now must not be zero")
	}
	return nil
}

// UpdateImageInput stores the arguments required to rotate the engine
// image reference and version of one runtime record without changing
// its status. The store applies a compare-and-swap guard on
// `(game_id, status)` so callers can reject the update if the runtime
// has drifted out of the expected status.
type UpdateImageInput struct {
	// GameID identifies the record to mutate.
	GameID string

	// ExpectedStatus stores the status the caller believes the record
	// currently has. A mismatch results in runtime.ErrConflict.
	ExpectedStatus runtime.Status

	// CurrentImageRef stores the new value of the
	// `current_image_ref` column. Must not be empty.
	CurrentImageRef string

	// CurrentEngineVersion stores the new value of the
	// `current_engine_version` column. Must not be empty.
	CurrentEngineVersion string

	// Now stores the wall-clock used to refresh `updated_at`.
	Now time.Time
}

// Validate reports whether input contains structurally valid image
// rotation arguments. Adapters call Validate before touching the store.
func (input UpdateImageInput) Validate() error {
	if strings.TrimSpace(input.GameID) == "" {
		return fmt.Errorf("update runtime image: game id must not be empty")
	}
	if !input.ExpectedStatus.IsKnown() {
		return fmt.Errorf(
			"update runtime image: expected status %q is unsupported",
			input.ExpectedStatus,
		)
	}
	if strings.TrimSpace(input.CurrentImageRef) == "" {
		return fmt.Errorf("update runtime image: current image ref must not be empty")
	}
	if strings.TrimSpace(input.CurrentEngineVersion) == "" {
		return fmt.Errorf("update runtime image: current engine version must not be empty")
	}
	if input.Now.IsZero() {
		return fmt.Errorf("update runtime image: now must not be zero")
	}
	return nil
}

// UpdateEngineHealthInput stores the arguments required to rotate the
// `engine_health` column of one runtime record without touching its
// status. The store performs no compare-and-swap so callers can apply
// the update from any runtime status (including stopped and finished)
// to keep the summary current for late-arriving runtime:health_events.
type UpdateEngineHealthInput struct {
	// GameID identifies the record to mutate.
	GameID string

	// EngineHealthSummary stores the new value of the `engine_health`
	// column. The summary is a free-form short string drawn from the
	// vocabulary documented in
	// `gamemaster/README.md §Persistence Layout` and produced by the
	// Stage 18 consumer.
	EngineHealthSummary string

	// Now stores the wall-clock used to refresh `updated_at`.
	Now time.Time
}

// Validate reports whether input carries structurally valid arguments
// for an engine-health update. Adapters call Validate before touching
// the store.
func (input UpdateEngineHealthInput) Validate() error {
	if strings.TrimSpace(input.GameID) == "" {
		return fmt.Errorf("update runtime engine health: game id must not be empty")
	}
	if input.Now.IsZero() {
		return fmt.Errorf("update runtime engine health: now must not be zero")
	}
	return nil
}