import Foundation

/// Non-drop-frame timecode. Frame count + fps.
public struct Timecode: Sendable, Equatable, CustomStringConvertible {
    public var frames: Int
    public var fps: Int

    public init(frames: Int, fps: Int) {
        self.frames = frames
        self.fps = fps
    }

    /// Parse HH:MM:SS:FF.
    public static func parse(_ s: String, fps: Int) -> Timecode? {
        let parts = s.split(separator: ":")
        guard parts.count == 4,
              let h = Int(parts[0]), let m = Int(parts[1]),
              let sec = Int(parts[2]), let f = Int(parts[3]),
              m < 60, sec < 60, f < fps else { return nil }
        return Timecode(frames: ((h * 3600 + m * 60 + sec) * fps) + f, fps: fps)
    }

    public var description: String {
        let totalSeconds = frames / fps
        let f = frames % fps
        let h = totalSeconds / 3600
        let m = (totalSeconds % 3600) / 60
        let s = totalSeconds % 60
        return String(format: "%02d:%02d:%02d:%02d", h, m, s, f)
    }

    public static func + (l: Timecode, r: Timecode) -> Timecode {
        Timecode(frames: l.frames + r.frames, fps: l.fps)
    }

    public static func - (l: Timecode, r: Timecode) -> Timecode {
        Timecode(frames: max(0, l.frames - r.frames), fps: l.fps)
    }
}