DownloadVideosCommand.swift

import Command
import Console
import Crypto
import Fluent
import FluentSQLite

struct DownloadVideosCommand: Command, Service {
    var arguments: [CommandArgument] { return [] }
    var options: [CommandOption] { return [] }
    var help: [String] { return [] }

    func run(using ctx: CommandContext) throws -> Future<Void> {
        return ctx.container.withPooledConnection(to: .sqlite) { db in
            return Video
                .query(on: db)
                .group(.or) { or in
                    // 0 = not processed
                    or.filter(\Video.status == 0)
                    // 1 = processing attempted but failed
                    or.filter(\Video.status == 1)
                }
                .all()
                .flatMap { videos in
                    let downloadTasks = videos.map { video in
                        return Process.asyncExecute(
                            "youtube-dl",
                            ["-x", "--audio-format", "mp3", video.url],
                            on: ctx.container) { output in
                                switch output {
                                case .stdout(let data), .stderr(let data):
                                    if let string = String(data: data, encoding: .utf8) {
                                        print(string)
                                    }
                                }
                            }.flatMap { returnCode -> Future<Video> in
                                switch returnCode {
                                case 0:
                                    // 2 = success, never process again
                                    video.status = 2
                                default:
                                    // 1 = processing attempted but failed
                                    video.status = 1
                                }

                                return video.save(on: db)
                            }
                    }

                    return downloadTasks
                        .flatten(on: ctx.container)
                        .transform(to: ())
                }
        }
    }
}

DownloadVideosCommand_Sync.swift

import Command
import Console
import Crypto
import Fluent
import FluentSQLite

struct DownloadVideosCommand: Command, Service {
    var arguments: [CommandArgument] { return [] }
    var options: [CommandOption] { return [] }
    var help: [String] { return [] }

    func run(using ctx: CommandContext) throws -> Future<Void> {
        return ctx.container.withPooledConnection(to: .sqlite) { db in
            return Video
                .query(on: db)
                .group(.or) { or in
                    or.filter(\Video.status == 0)
                    or.filter(\Video.status == 1)
                }
                .all()
                .flatMap { videos in
                    let downloadTasks: [LazyFuture<Void>] = videos.map { video in
                        return {
                            return Process.asyncExecute(
                                "youtube-dl",
                                ["-x", "--audio-format", "mp3", video.url],
                                on: ctx.container) { output in
                                    switch output {
                                    case .stdout(let data), .stderr(let data):
                                        if let string = String(data: data, encoding: .utf8) {
                                            print(string)
                                        }
                                    }
                                }.flatMap { returnCode -> Future<Video> in
                                    switch returnCode {
                                    case 0:
                                        video.status = 2
                                    default:
                                        video.status = 1
                                    }

                                    return video.save(on: db)
                                }.transform(to: ())
                        }
                    }

                    return downloadTasks
                        .syncFlatten(on: ctx.container)
                        .transform(to: ())
                }
        }
    }
}