//
//  PhotoLibraryWriter.swift
//  Focale
//
//  Author: Simon-Pierre Boucher
//  Contact: contact@spboucher.ai
//
//  Writes captures into the system photo library via PHAssetCreationRequest.
//  No parallel library, no private sandbox (CLAUDE.md §4). The user can
//  uninstall tomorrow and lose nothing.
//

import Foundation
import Photos

actor PhotoLibraryWriter {

    /// PhotoKit runs change blocks on its own queue; this box carries the
    /// created identifier out of the @Sendable block without giving the
    /// block any actor isolation (a Swift 6 runtime crash otherwise).
    private final class IdentifierBox: @unchecked Sendable {
        var value: String?
    }

    /// Saves a capture and returns the new asset's localIdentifier —
    /// the key the whole index is built on.
    func save(_ photo: CapturedPhoto) async throws -> String {
        let box = IdentifierBox()
        let change: @Sendable () -> Void = {
            let request = PHAssetCreationRequest.forAsset()
            if let processed = photo.processedData {
                request.addResource(with: .photo, data: processed, options: nil)
                if let raw = photo.rawData {
                    let options = PHAssetResourceCreationOptions()
                    request.addResource(with: .alternatePhoto, data: raw, options: options)
                }
            } else if let raw = photo.rawData {
                request.addResource(with: .photo, data: raw, options: nil)
            }
            box.value = request.placeholderForCreatedAsset?.localIdentifier
        }
        try await PHPhotoLibrary.shared().performChanges(change)

        guard let localIdentifier = box.value else { throw CaptureError.captureFailed }
        return localIdentifier
    }
}