nudge_best_match.swift

func getOSVerProfile() throws -> OSVersionRequirement? {
    if Utils().demoModeEnabled() {
        return nil
    }
    
    guard
        let osRequirements = nudgeDefaults.object(forKey: "osVersionRequirements") as? [[String:AnyObject]]
    else {
        // Log missing key in nudgeDefaults
        return nil
    }
    
    let requirements = osRequirements.map(OSVersionRequirement.init)
    guard requirements.isEmpty else {
        // OSVersionRequirement.init should throw, otherwise we need another guard for .isEmpty
        // If requirements is empty, but osVersionRequirements was present, it's not clear what failed.
        // TODO: log something here
        return nil
        
    }
    
    // In order, find and return
    // first full version match
    // first major version match
    // explicitly stated "default" rule
    // maximum possible required version
    
    if let fullVersionMatch = requirements.first(where: { match in
        match.targetedOSVersionsRule != nil && match.targetedOSVersionsRule == currentOSVersion
    }) {
        return fullVersionMatch
    }
    
    if let majorVersionMatch = requirements.first(where: { match in
        match.targetedOSVersionsRule != nil && match.targetedOSVersionsRule == String(ProcessInfo().operatingSystemVersion.majorVersion)
    }) {
        return majorVersionMatch
    }
    
    if let defaultVersionMatch = requirements.first(where: {match in
        match.targetedOSVersionsRule != nil && match.targetedOSVersionsRule == "default"
    }) {
        return defaultVersionMatch
    }
    
    
    let maxVersionMatch = try requirements.max(by: {
        // Want to find max required version,
        // Unfortunately requiredMinimumOSVersion is a String instead of OSVersion, which is another little yaq to shave.
        
        let v0 = try OSVersion($0.requiredMinimumOSVersion!) // does it have to be optional?
        let v1 = try OSVersion($1.requiredMinimumOSVersion!)
        if v0.major != v1.major {
            return v0.major < v1.major
        }
        
        return v0.minor < v1.minor
    })
    
    
    return maxVersionMatch
}