import AppKit
import Darwin
import Foundation
import ShotdeckCore

extension AppModel: SendCapable {
    public func send(anchor: NSView?) async {
        guard !session.isEmpty, !isSending else { return }
        setSending(true)
        defer { setSending(false) }

        let workingSession = session
        let composer = self.composer
        // Live outbox (FolderSettings), not `paths.outbox` — Settings changes take effect.
        let outboxDir = outboxURL
        let sourceDir = paths.sessionDirectory(workingSession.id)
        let fileName = PDFComposer.fileName(for: workingSession)
        let finalURL = outboxDir.appendingPathComponent(fileName)
        // Same directory as the final target so the rename below is same-volume (atomic).
        let tempURL = outboxDir.appendingPathComponent(".shotdeck-\(UUID().uuidString).pdf")
        let title = "Shotdeck – \(DubaiTime.stamp(workingSession.createdAt))"

        do {
            // D-13: build off the main actor. Only Sendable values cross into the
            // detached task — never `anchor` (NSView is not Sendable).
            try await Task.detached(priority: .userInitiated) {
                _ = try composer.compose(
                    session: workingSession,
                    imageURL: { capture in sourceDir.appendingPathComponent(capture.fileName) },
                    title: title,
                    to: tempURL
                )
                // POSIX rename onto `finalURL` replaces any same-name file in one
                // directory operation; there is never a window where the PDF is gone.
                if Darwin.rename(tempURL.path, finalURL.path) != 0 {
                    throw ShotdeckError.pdfCompositionFailed(
                        reason: "could not publish the PDF: \(String(cString: strerror(errno)))"
                    )
                }
                try AtomicFile.fsyncDirectory(at: outboxDir)
            }.value

            // File exists on disk now — archive only after that (D-13). A later AirDrop
            // failure never deletes this file.
            guard FileManager.default.fileExists(atPath: finalURL.path) else {
                throw ShotdeckError.pdfCompositionFailed(reason: "the PDF was not written to disk")
            }
            _ = try await spool.archiveCurrent(pdfFileName: fileName)
            replaceSession(try await spool.currentSession())

            let pageWord = workingSession.captures.count == 1 ? "page" : "pages"
            setStatus("Sent — \(workingSession.captures.count) \(pageWord).")

            guard let anchor else {
                setStatus("PDF saved to \(outboxDisplayName). Open the panel to AirDrop it.")
                return
            }
            do {
                try Sharing.airDrop(fileURL: finalURL, from: anchor)
            } catch {
                setStatus(
                    "AirDrop is not available right now — the PDF is on your \(outboxDisplayName)."
                )
            }
        } catch {
            // Never unlink the published PDF, and never unlink `tempURL` either:
            // a rename failure would leave the complete document at the temp name.
            setStatus((error as? ShotdeckError)?.errorDescription ?? "The PDF could not be built.")
        }
    }
}