at-container-registry/pkg/atproto/resolver.go

package atproto

import (
	"context"
	"fmt"

	"github.com/bluesky-social/indigo/atproto/syntax"
)

// ResolveDIDToPDS resolves a DID to its PDS endpoint.
// Uses the shared identity directory with 8h cache TTL.
func ResolveDIDToPDS(ctx context.Context, did string) (string, error) {
	directory := GetDirectory()
	didParsed, err := syntax.ParseDID(did)
	if err != nil {
		return "", fmt.Errorf("invalid DID: %w", err)
	}

	ident, err := directory.LookupDID(ctx, didParsed)
	if err != nil {
		return "", fmt.Errorf("failed to resolve DID: %w", err)
	}

	pdsEndpoint := ident.PDSEndpoint()
	if pdsEndpoint == "" {
		return "", fmt.Errorf("no PDS endpoint found for DID")
	}

	return pdsEndpoint, nil
}

// ResolveIdentity resolves an ATProto identifier (handle or DID) to DID, handle, and PDS endpoint.
// Uses the shared identity directory with 8h cache TTL.
//
// If the handle is invalid (handle.invalid), it returns the DID as the handle for display purposes.
// Returns: did, handle, pdsEndpoint, error
func ResolveIdentity(ctx context.Context, identifier string) (string, string, string, error) {
	directory := GetDirectory()
	atID, err := syntax.ParseAtIdentifier(identifier)
	if err != nil {
		return "", "", "", fmt.Errorf("invalid identifier %q: %w", identifier, err)
	}

	ident, err := directory.Lookup(ctx, *atID)
	if err != nil {
		return "", "", "", fmt.Errorf("failed to resolve identity %q: %w", identifier, err)
	}

	did := ident.DID.String()
	handle := ident.Handle.String()
	pdsEndpoint := ident.PDSEndpoint()

	// If handle is invalid, use DID as display name
	if handle == "handle.invalid" || handle == "" {
		handle = did
	}

	// PDS endpoint is required for XRPC calls
	if pdsEndpoint == "" {
		return "", "", "", fmt.Errorf("no PDS endpoint found for identifier %q", identifier)
	}

	return did, handle, pdsEndpoint, nil
}

// ResolveHandleToDID resolves a handle or DID to just the DID.
// Uses the shared identity directory with 8h cache TTL.
// This is useful when you only need the DID and don't care about handle/PDS.
func ResolveHandleToDID(ctx context.Context, identifier string) (string, error) {
	directory := GetDirectory()
	atID, err := syntax.ParseAtIdentifier(identifier)
	if err != nil {
		return "", fmt.Errorf("invalid identifier: %w", err)
	}

	ident, err := directory.Lookup(ctx, *atID)
	if err != nil {
		return "", err
	}

	return ident.DID.String(), nil
}