import Foundation
import AVFoundation

struct LocalTrack: Identifiable, Hashable {
    let id: UUID
    let url: URL
    let displayName: String
    let duration: TimeInterval

    static func libraryDirectory() -> URL {
        let docs = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
        let dir = docs.appendingPathComponent("RunPlus", isDirectory: true)
        if !FileManager.default.fileExists(atPath: dir.path) {
            try? FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
        }
        return dir
    }

    static func loadLibrary() async -> [LocalTrack] {
        let dir = libraryDirectory()
        let urls = (try? FileManager.default.contentsOfDirectory(at: dir, includingPropertiesForKeys: nil)) ?? []
        var tracks: [LocalTrack] = []
        for url in urls {
            let asset = AVURLAsset(url: url)
            let duration = (try? await asset.load(.duration).seconds) ?? 0
            let track = LocalTrack(
                id: UUID(uuidString: url.deletingPathExtension().lastPathComponent) ?? UUID(),
                url: url,
                displayName: url.deletingPathExtension().lastPathComponent,
                duration: duration
            )
            tracks.append(track)
        }
        return tracks.sorted { $0.displayName.lowercased() < $1.displayName.lowercased() }
    }

    static func importTrack(from url: URL) async throws -> LocalTrack {
        let dir = libraryDirectory()
        let id = UUID()
        let dest = dir.appendingPathComponent("\(id.uuidString).mp3")
        let didStart = url.startAccessingSecurityScopedResource()
        defer {
            if didStart { url.stopAccessingSecurityScopedResource() }
        }
        try FileManager.default.copyItem(at: url, to: dest)
        let duration = (try? await AVURLAsset(url: dest).load(.duration).seconds) ?? 0
        return LocalTrack(
            id: id,
            url: dest,
            displayName: url.deletingPathExtension().lastPathComponent,
            duration: duration
        )
    }

    static func importReceivedTrack(from url: URL, trackID: String, displayName: String) async throws -> LocalTrack {
        let dir = libraryDirectory()
        let dest = dir.appendingPathComponent("\(trackID).mp3")
        if FileManager.default.fileExists(atPath: dest.path) {
            try FileManager.default.removeItem(at: dest)
        }
        try FileManager.default.moveItem(at: url, to: dest)
        let duration = (try? await AVURLAsset(url: dest).load(.duration).seconds) ?? 0
        return LocalTrack(
            id: UUID(uuidString: trackID) ?? UUID(),
            url: dest,
            displayName: displayName,
            duration: duration
        )
    }
}