package contract

import (
	"context"
	"time"
)

// RunReader is the HTTP lookup boundary. Fall back to archive only when the
// live reader returns ErrNotFound, not on transient live storage failures.
type RunReader interface {
	GetRun(ctx context.Context, runID string) (RunView, error)
}

type RunListFilter struct {
	SyncKind SyncKind
	Limit    int
}

type RunList struct {
	Items []RunView `json:"items"`
	Total int       `json:"total"`
}

type RunLister interface {
	ListRuns(ctx context.Context, filter RunListFilter) (RunList, error)
}

type LiveRunReader interface {
	GetRunMeta(ctx context.Context, runID string) (RunMeta, error)
}

type ArchivedRunReader interface {
	GetArchivedRun(ctx context.Context, runID string) (RunArchive, error)
}

type RoundStatsReader interface {
	GetRoundStats(ctx context.Context, runID string) ([]RoundStats, error)
}

// FailurePager returns live details only. An archived summary without live
// details returns ErrFailureDetailsUnavailable, never a misleading empty page.
// Items must serialize as [] on empty pages; NextCursor alone signals EOF.
type FailurePager interface {
	ListFailures(ctx context.Context, runID string, page PageRequest) (FailurePage, error)
}

type ReplayRequester interface {
	RequestReplay(ctx context.Context, request ReplayRequest) (ReplayAccepted, error)
}

type ActionReader interface {
	GetReplayAction(ctx context.Context, actionID string) (ReplayAction, error)
}

// ArchiveWorkDiscovery returns pending/retryable work from a durable index.
// Terminal run registration must not depend on an in-memory notification.
type ArchiveWorkDiscovery interface {
	ListArchiveWork(ctx context.Context, page PageRequest) (ArchiveWorkPage, error)
}

// RegisterArchiveWork idempotently schedules a terminal run/version. Since the
// index can occupy another Redis slot, callers must reconcile registration
// after a crash between completing the run and updating the index.
type ArchiveWorkRegistrar interface {
	RegisterArchiveWork(ctx context.Context, work ArchiveWork) error
}

type ArchiveWorkLoader interface {
	LoadArchiveWork(ctx context.Context, work ArchiveWork) (RunArchive, error)
}

// ArchiveRegistrar conditionally records a durable publication against the
// work version. Repeating the same receipt is a no-op; a different version or
// conflicting receipt returns ErrConflict. Failure retains discoverable work.
type ArchiveRegistrar interface {
	RegisterArchive(ctx context.Context, work ArchiveWork, receipt ArchiveReceipt) error
	RegisterArchiveFailure(ctx context.Context, work ArchiveWork, message string) error
}

// ReplayActionCreator atomically reserves (sourceRunId, idempotencyKey) with
// its fingerprint and action. Same key/request returns the original action
// regardless of candidate IDs; different request returns ErrConflict. The
// candidate starts accepted and fixes the target ID before any target writes.
type ReplayActionCreator interface {
	GetOrCreateReplayAction(ctx context.Context, request ReplayRequest, candidate ReplayAction) (ReplayActionCreation, error)
}

// Discovery includes accepted, processing, cleanup_pending and receipt_pending
// actions after crashes. Completed/needs_attention actions require no automatic
// work. Lease acquisition, not listing, chooses an exclusive owner.
type ReplayWorkDiscovery interface {
	ListReplayWork(ctx context.Context, page PageRequest) (ReplayActionPage, error)
}

type ReplayLeaseStore interface {
	AcquireReplayLease(ctx context.Context, actionID, owner string, ttl time.Duration) (ReplayLease, error)
	RenewReplayLease(ctx context.Context, lease ReplayLease, ttl time.Duration) (ReplayLease, error)
	ReleaseReplayLease(ctx context.Context, lease ReplayLease) error
}

// All updates are fenced and compare ExpectedRevision. Expired/replaced leases
// return ErrLeaseLost; revision conflicts return ErrConflict. Implementations
// reject progress regression and preserve immutable action identity.
type ReplayProgressStore interface {
	UpdateReplayAction(ctx context.Context, update ReplayActionUpdate) (ReplayAction, error)
}

// The implementation must preserve scan continuity while source entries are
// cleaned. This can use a durable selection/snapshot; deleting records must not
// make a later cursor skip an unprocessed failure. Tokens are bound to actionID.
type ReplayFailurePager interface {
	ListReplayFailures(ctx context.Context, actionID string, page PageRequest) (FailureRecordPage, error)
}

// TargetRunCreator is idempotent: retrying the same target preserves counters;
// incompatible source/operation/month/cycle returns ErrConflict. Replay targets
// are distinct runs and must not mutate the source's historical FailedCount.
type TargetRunCreator interface {
	EnsureTargetRun(ctx context.Context, meta RunMeta) (RunMeta, error)
}

// TargetEnqueueResult distinguishes a durable duplicate from a rejected write.
// A zero NewlyEnqueued count alone is never sufficient evidence for cleanup.
// Every input TaskID must be durably present on nil error; otherwise return an
// error and let the caller safely retry the identical batch. Both counts are
// unique task counts, and their sum equals the number of distinct input IDs.
type TargetEnqueueResult struct {
	NewlyEnqueued  int64
	AlreadyPresent int64
}

type TargetRunEnqueuer interface {
	// Tasks must match the target run and channel and use stable logical IDs.
	EnqueueTargetBatch(ctx context.Context, lease ReplayLease, runID, chanKey string, tasks []Task, nextExecuteAt time.Time) (TargetEnqueueResult, error)
	MarkTargetProducerDone(ctx context.Context, lease ReplayLease, runID string) error
}

// Cleanup is idempotent and conditional on the lease, exact source versions,
// and durable evidence of target acceptance. It changes pending failures only,
// never historical failedCount. Conflicts must remain visible for attention.
// Source keys and action/target keys may occupy different Redis Cluster slots;
// implementations need recoverable receipts, not cross-slot Lua assumptions.
type ReplayFailureCleaner interface {
	CleanupReplayFailures(ctx context.Context, cleanup ReplayCleanup) (ReplayCleanupResult, error)
}