package storage

import (
	"context"
	"encoding/json"
	"errors"
)

// ErrNoSuchDelayedEvent is returned for a delay ID that is unknown, belongs
// to someone else, or is no longer scheduled.
var ErrNoSuchDelayedEvent = errors.New("no such delayed event")

// DelayedEvent is an event a client asked to have sent later (MSC4140).
//
// While it is scheduled FinalisedAtMS is zero. Once it has been sent or
// cancelled it is kept for a while with its outcome, so a client that comes
// back can find out what became of it.
type DelayedEvent struct {
	DelayID  string
	UserID   string
	DeviceID string
	RoomID   string
	Type     string

	// StateKey is nil for a timeline event.
	StateKey *string
	Content  json.RawMessage

	// DelayMS is the delay the client asked for. A restart counts it again
	// from now.
	DelayMS int64

	// RunningSinceMS is when the delay was last (re)started, and SendAtMS
	// when it runs out: RunningSinceMS + DelayMS.
	RunningSinceMS int64
	SendAtMS       int64

	// The outcome, once finalised: Outcome is "send" or "cancel", Reason
	// "delay", "action" or "error". EventID is the event that was sent,
	// and Error the Matrix error that stopped it.
	FinalisedAtMS int64
	Outcome       string
	Reason        string
	EventID       string
	Error         json.RawMessage
}

// DelayedEventStore keeps the delayed events of every user.
type DelayedEventStore interface {
	// InsertDelayedEvent schedules an event.
	InsertDelayedEvent(ctx context.Context, e DelayedEvent) error

	// DelayedEvent returns one of userID's events, scheduled or finalised.
	DelayedEvent(ctx context.Context, userID, delayID string) (DelayedEvent, error)

	// ScheduledDelayedEvent returns a scheduled event whoever owns it: the
	// action endpoints are addressed by the delay ID alone.
	ScheduledDelayedEvent(ctx context.Context, delayID string) (DelayedEvent, error)

	// DelayedEvents lists userID's events, scheduled ones first by when
	// they are due, then finalised ones newest first.
	DelayedEvents(ctx context.Context, userID string) ([]DelayedEvent, error)

	// CountScheduledDelayedEvents counts userID's scheduled events.
	CountScheduledDelayedEvents(ctx context.Context, userID string) (int, error)

	// RestartDelayedEvent starts a scheduled event's delay again from nowMS.
	// It returns ErrNoSuchDelayedEvent if the event is not scheduled.
	RestartDelayedEvent(ctx context.Context, delayID string, nowMS int64) error

	// FinaliseDelayedEvent records what became of a scheduled event. It
	// returns ErrNoSuchDelayedEvent if the event was already finalised,
	// which is how two racing finalisers are told apart: only one of them
	// gets to send.
	FinaliseDelayedEvent(ctx context.Context, e DelayedEvent) error

	// DueDelayedEvents returns up to limit scheduled events whose delay
	// has run out at nowMS, the earliest first.
	DueDelayedEvents(ctx context.Context, nowMS int64, limit int) ([]DelayedEvent, error)

	// NextDelayedEventDue reports when the next scheduled event is due,
	// and false when nothing is scheduled.
	NextDelayedEventDue(ctx context.Context) (int64, bool, error)

	// ScheduledDelayedStateEvents lists the scheduled state events for one
	// piece of room state, of every user.
	ScheduledDelayedStateEvents(ctx context.Context, roomID, eventType, stateKey string) ([]DelayedEvent, error)

	// PurgeFinalisedDelayedEvents forgets the events finalised before
	// beforeMS.
	PurgeFinalisedDelayedEvents(ctx context.Context, beforeMS int64) error
}

// ErrNoSuchOpenIDToken is returned for an OpenID token that is unknown or
// has expired.
var ErrNoSuchOpenIDToken = errors.New("no such OpenID token")

// OpenIDTokenStore keeps the OpenID tokens users hand to third parties, so
// those can find out who the user is (and nothing more) from this server.
type OpenIDTokenStore interface {
	// InsertOpenIDToken stores a token by its hash.
	InsertOpenIDToken(ctx context.Context, tokenHash, userID string, expiresAtMS int64) error

	// OpenIDTokenUser returns the user a token was issued to, or
	// ErrNoSuchOpenIDToken once it has expired at nowMS.
	OpenIDTokenUser(ctx context.Context, tokenHash string, nowMS int64) (string, error)

	// PurgeOpenIDTokens forgets tokens that expired before beforeMS.
	PurgeOpenIDTokens(ctx context.Context, beforeMS int64) error
}