// A recorded playback session, replayed through the sink call by call: the playlists with their
// receipts, the objects the player received, its observations, its end. The bundle the sink
// signs at the end must verify as the stream's owner verifies it, and state what was recorded.
import Foundation
import WaiSink

enum Replay {
    static func run(path: String) throws -> Bool {
        let doc = try JSONSerialization.jsonObject(with: Data(contentsOf: URL(fileURLWithPath: path))) as! [String: Any]
        let objects = doc["objects"] as! [String: String]
        func bytes(_ name: Any?) -> Data? { (name as? String).map { hex(objects[$0]!) } }
        let sink = try WaiSink(configJSON: doc["config"] as! [String: Any], seed: hex(doc["seed"] as! String), startUs: (doc["start_us"] as! NSNumber).uint64Value)
        var bundle = Data()
        var verified = 0
        for d in doc["calls"] as! [[String: Any]] {
            let t = { (d["t_us"] as! NSNumber).uint64Value }
            switch d["call"] as! String {
            case "playlist":
                _ = try sink.playlist(url: d["url"] as! String, bytes: bytes(d["body"])!, receipt: bytes(d["receipt"]))
                verified += 1
            case "object":
                _ = try sink.object(meta: d["meta"] as! [String: Any], bytes: bytes(d["body"])!)
                verified += 1
            case "event": try sink.event(d["name"] as! String, atUs: t())
            case "observe": _ = try sink.observe(d["obs"] as! [String: Any])
            case "end": bundle = try sink.end(WaiSink.Ended(rawValue: d["ended"] as! String)!, atUs: t())
            default: break
            }
        }
        let out = try WaiSink.verifyBundle(bundle, owner: hex(doc["owner"] as! String), channels: doc["channels"] as! [String])
        let want = doc["outcome"] as! [String: Any]
        let ok = out["outcome"] as? String == "accept" && out["digest"] as? String == want["digest"] as? String
        print("replay: \(verified) playlists and objects through the sink; the bundle \(ok ? "verifies" : "does NOT verify") as its owner verifies it (\(out["outcome"] ?? "?"), \(out["presented_ms"] ?? "?") ms presented)")
        return ok
    }

    static func hex(_ s: String) -> Data {
        var d = Data(capacity: s.count / 2)
        var i = s.startIndex
        while i < s.endIndex {
            let j = s.index(i, offsetBy: 2)
            d.append(UInt8(s[i..<j], radix: 16)!)
            i = j
        }
        return d
    }
}