package server

import (
	"fmt"
	"strings"
)

func determinePlatform(author string) (platform, error) {
	if strings.HasPrefix(author, "did:") {
		return Bluesky, nil
	}
	if strings.HasPrefix(author, "npub") {
		return Nostr, nil
	}
	if strings.HasPrefix(author, "@") {
		if strings.Count(author, "@") > 1 {
			return ActivityPub, nil
		}

		if strings.Contains(author, ".") {
			return Bluesky, nil
		}

		return Twitter, nil
	}
	if len(author) == 64 {
		isHex := true
		for _, c := range author {
			if (c < '0' || c > '9') && (c < 'a' || c > 'f') && (c < 'A' || c > 'F') {
				isHex = false
				break
			}
		}
		if isHex {
			return Nostr, nil
		}
	}

	if strings.Contains(author, ".") {
		return Bluesky, nil
	}

	return -1, fmt.Errorf("unknown author format: %s", author)
}