feat: add twitch graphql streamer resolution

internal/twitch/service.go

@@ -0,0 +1,108 @@
+// service.go defines the Twitch domain lookups the rewritten app currently needs.
+// It wraps the lower-level GraphQL client with small typed methods for the viewer
+// identity and configured streamer resolution used to populate the terminal UI.
+package twitch
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"parasocial/internal/gql"
+)
+
+// GQLClient is the minimal GraphQL interface the Twitch service depends on.
+type GQLClient interface {
+	Do(context.Context, gql.Request, any) error
+}
+
+// Service exposes the Twitch lookups the current app needs.
+type Service struct {
+	GQL GQLClient
+}
+
+// Viewer is the authenticated Twitch account.
+type Viewer struct {
+	ID    string
+	Login string
+}
+
+// Channel is the resolved Twitch channel identity for one streamer login.
+type Channel struct {
+	ID    string
+	Login string
+}
+
+// StreamerStatus describes one row's resolution state in the UI.
+type StreamerStatus string
+
+const (
+	StreamerLoading StreamerStatus = "loading"
+	StreamerReady   StreamerStatus = "ready"
+	StreamerError   StreamerStatus = "error"
+)
+
+// StreamerEntry is the UI-facing state for one configured streamer.
+type StreamerEntry struct {
+	ConfigLogin string
+	Login       string
+	ChannelID   string
+	Status      StreamerStatus
+	Error       string
+}
+
+// ErrStreamerNotFound is returned when Twitch has no channel for the requested login.
+var ErrStreamerNotFound = errors.New("streamer does not exist")
+
+// LoadingStreamerEntries seeds UI state from the normalized config logins.
+func LoadingStreamerEntries(logins []string) []StreamerEntry {
+	entries := make([]StreamerEntry, 0, len(logins))
+	for _, login := range logins {
+		entries = append(entries, StreamerEntry{
+			ConfigLogin: login,
+			Status:      StreamerLoading,
+		})
+	}
+	return entries
+}
+
+// CurrentUser resolves the authenticated viewer through Twitch GraphQL.
+func (s *Service) CurrentUser(ctx context.Context) (*Viewer, error) {
+	var data struct {
+		CurrentUser *struct {
+			ID    string `json:"id"`
+			Login string `json:"login"`
+		} `json:"currentUser"`
+	}
+	if err := s.GQL.Do(ctx, gql.CurrentUser(), &data); err != nil {
+		return nil, err
+	}
+	if data.CurrentUser == nil || data.CurrentUser.ID == "" || data.CurrentUser.Login == "" {
+		return nil, fmt.Errorf("current user response missing id or login")
+	}
+	return &Viewer{
+		ID:    data.CurrentUser.ID,
+		Login: data.CurrentUser.Login,
+	}, nil
+}
+
+// ResolveStreamer resolves a configured streamer login into canonical Twitch identity.
+func (s *Service) ResolveStreamer(ctx context.Context, login string) (*Channel, error) {
+	var data struct {
+		User *struct {
+			ID    string `json:"id"`
+			Login string `json:"login"`
+		} `json:"user"`
+	}
+	if err := s.GQL.Do(ctx, gql.GetIDFromLogin(login), &data); err != nil {
+		return nil, err
+	}
+	if data.User == nil || data.User.ID == "" {
+		return nil, fmt.Errorf("%w: %s", ErrStreamerNotFound, login)
+	}
+	resolvedLogin := data.User.Login
+	if resolvedLogin == "" {
+		resolvedLogin = login
+	}
+	return &Channel{ID: data.User.ID, Login: resolvedLogin}, nil
+}