import Foundation

/// Shared helpers for `social.grain.gallery` records.
///
/// Deleting a gallery goes through `XRPCClient.deleteGallery`, not a plain
/// `deleteRecord` on the collection. A gallery is the head of a small graph:
/// photos, the gallery items linking them, exif records, and the account's
/// own favorites and comments on it. Deleting the gallery record on its own
/// leaves all of that orphaned in the repo while the UI, which promises
/// "this will permanently delete this gallery and all its photos", looks
/// like it worked. Every place a gallery is deleted routes through here, so
/// there is one decision to get wrong.
enum GalleryService {
    static let collection = "social.grain.gallery"

    /// Deletes a gallery and everything hanging off it, by full URI.
    static func delete(
        galleryUri: String,
        client: XRPCClient,
        auth: AuthContext
    ) async throws {
        let rkey = galleryUri.split(separator: "/").last.map(String.init) ?? ""
        try await client.deleteGallery(rkey: rkey, auth: auth)
    }

    /// Resolves credentials, deletes, and reports the outcome.
    ///
    /// Routing every caller through one endpoint fixed half the problem. The
    /// flow *around* it stayed copied out seven times, and all seven dropped the
    /// error: six removed the gallery from their local collection regardless, so
    /// a delete the server refused still looked like it worked until the next
    /// refresh brought the gallery back, and the seventh silently did nothing at
    /// all. Callers get a `Result` here because there is no sensible default for
    /// a failed delete — the screen has to say something.
    static func delete(
        galleryUri: String,
        client: XRPCClient,
        auth: AuthManager
    ) async -> Result<Void, Error> {
        guard let context = await auth.authContext() else {
            return .failure(GalleryDeleteError.notSignedIn)
        }
        do {
            try await delete(galleryUri: galleryUri, client: client, auth: context)
            return .success(())
        } catch {
            return .failure(error)
        }
    }
}

/// The one failure `GalleryService.delete` can hit before it reaches the network.
enum GalleryDeleteError: LocalizedError, Equatable {
    case notSignedIn

    var errorDescription: String? {
        switch self {
        case .notSignedIn: "You're signed out. Sign in and try again."
        }
    }
}