/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    This file contains the FilterUtilities class. FilterUtilities objects contain functions and data that is used by both the SimpleTunnel UI and the SimpleTunnel content filter providers.

*/

import Foundation

import NetworkExtension

/// Content Filter actions.

public enum FilterRuleAction : Int, CustomStringConvertible {

    case block = 1

    case allow = 2

    case needMoreRulesAndBlock = 3

    case needMoreRulesAndAllow = 4

    case needMoreRulesFromDataAndBlock = 5

    case needMoreRulesFromDataAndAllow = 6

    case examineData = 7

    case redirectToSafeURL = 8

    case remediate = 9

    public var description: String {

        switch self {

        case .block: return "Block"

        case .examineData: return "Examine Data"

        case .needMoreRulesAndAllow: return "Ask for more rules, then allow"

        case .needMoreRulesAndBlock: return "Ask for more rules, then block"

        case .needMoreRulesFromDataAndAllow: return "Ask for more rules, examine data, then allow"

        case .needMoreRulesFromDataAndBlock: return "Ask for more rules, examine data, then block"

        case .redirectToSafeURL: return "Redirect"

        case .remediate: return "Remediate"

        case .allow: return "Allow"

        }

    }

}

/// A class containing utility properties and functions for Content Filtering.

open class FilterUtilities {

    // MARK: Properties

    /// A reference to the SimpleTunnel user defaults.

    open static let defaults = UserDefaults(suiteName: "group.com.example.apple-samplecode.SimpleTunnel")

    // MARK: Initializers

    /// Get rule parameters for a flow from the SimpleTunnel user defaults.

    open class func getRule(_ flow: NEFilterFlow) -> (FilterRuleAction, String, [String: AnyObject]) {

        let hostname = FilterUtilities.getFlowHostname(flow)

        guard !hostname.isEmpty else { return (.allow, hostname, [:]) }

        guard let hostNameRule = (defaults?.object(forKey: "rules") as AnyObject).object(forKey: hostname) as? [String: AnyObject] else {

            simpleTunnelLog("\(hostname) is set for NO RULES")

            return (.allow, hostname, [:])

        }

        guard let ruleTypeInt = hostNameRule["kRule"] as? Int,

            let ruleType = FilterRuleAction(rawValue: ruleTypeInt)

            else { return (.allow, hostname, [:]) }

        return (ruleType, hostname, hostNameRule)

    }

    /// Get the hostname from a browser flow.

    open class func getFlowHostname(_ flow: NEFilterFlow) -> String {

        guard let browserFlow : NEFilterBrowserFlow = flow as? NEFilterBrowserFlow,

            let url = browserFlow.url,

            let hostname = url.host

            , flow is NEFilterBrowserFlow

            else { return "" }

        return hostname

    }

    /// Download a fresh set of rules from the rules server.

    open class func fetchRulesFromServer(_ serverAddress: String?) {

        simpleTunnelLog("fetch rules called")

        guard serverAddress != nil else { return }

        simpleTunnelLog("Fetching rules from \(serverAddress)")

        guard let infoURL = URL(string: "http://\(serverAddress!)/rules/") else { return }

        simpleTunnelLog("Rules url is \(infoURL)")

        let content: String

        do {

            content = try String(contentsOf: infoURL, encoding: String.Encoding.utf8)

        }

        catch {

            simpleTunnelLog("Failed to fetch the rules from \(infoURL)")

            return

        }

        let contentArray = content.components(separatedBy: "<br/>")

        simpleTunnelLog("Content array is \(contentArray)")

        var urlRules = [String: [String: AnyObject]]()

        for rule in contentArray {

            if rule.isEmpty {

                continue

            }

            let ruleArray = rule.components(separatedBy: " ")

            guard !ruleArray.isEmpty else { continue }

            var redirectKey = "SafeYes"

            var remediateKey = "Remediate1"

            var remediateButtonKey = "RemediateButton1"

            var actionString = "9"

            let urlString = ruleArray[0]

            let ruleArrayCount = ruleArray.count

            if ruleArrayCount > 1 {

                actionString = ruleArray[1]

            }

            if ruleArrayCount > 2 {

                redirectKey = ruleArray[2]

            }

            if ruleArrayCount > 3 {

                remediateKey = ruleArray[3]

            }

            if ruleArrayCount > 4 {

                remediateButtonKey = ruleArray[4]

            }

            urlRules[urlString] = [

                "kRule" : actionString as AnyObject,

                "kRedirectKey" : redirectKey as AnyObject,

                "kRemediateKey" : remediateKey as AnyObject,

                "kRemediateButtonKey" : remediateButtonKey as AnyObject,

            ]

        }

        defaults?.setValue(urlRules, forKey:"rules")

    }

}