//
// Advent of Code 2018 "Day 1: Chronal Calibration"
//

import Foundation

class Chronal {
    fileprivate var adjustments: [Int] = []
    let startingFreq = 0

    // Supply filename for input ex: '/home/peterr/AOC2018/Sources/AOC2018/data/day01.txt'
    init(withFile filename: String) {
        let adjString = Tools.readFile(fromPath: filename)
        var adjustmentArray: [String] = []
        adjustmentArray = adjString.components(separatedBy: "\n")
        adjustments = []
        for val in adjustmentArray {
            if let intVal = Int(val) {
                adjustments.append(intVal)
            }
        }
    }

    // Supply test data in the form of a String
    init(withString adjString: String) {
        var adjustmentArray: [String] = []
        adjustmentArray = adjString.components(separatedBy: ", ")
        adjustments = []
        for val in adjustmentArray {
            if let intVal = Int(val) {
                adjustments.append(intVal)
            }
        }
    }

    // Apply all the adjustments that this class was initialized with
    // Return the resulting frequency as an Optional (nil => no adjustments)
    func applyAdjustments() -> Int? {
        var retVal: Int?
        if adjustments.count > 0 {
            var  sum = 0
            for val in adjustments {
                sum += val
            }
            retVal = sum
        }
        return retVal
    }

    func repeatedAjustmentUntilTwice() -> Int {
        var retVal = -1
        if adjustments.count > 0 {
            var usedFreqs = [Int: Int]()
            var sum = 0
            usedFreqs[sum] = 1
            var noRepeats = true
            repeat {
                for val in adjustments {
                    sum += val
                    if usedFreqs[sum] != nil {
                        retVal = sum
                        noRepeats = false
                        break
                    } else {
                        usedFreqs[sum] = 1
                    }
                }
            } while noRepeats
        }
        return retVal
    }
}

class Day01: AOCDay {
    lazy var tests: (() -> ()) = day01Tests
    lazy var final: (() -> ()) = day01Final

    func testInitWithFile() {
        let chrona = Chronal(withFile: "/home/peterr/AOC2018/Sources/AOC2018/data/day01.txt")
        XCTAssertEqual(test: "testInitWithFile", withExpression: (chrona.adjustments.count == 990))
        if chrona.adjustments.count == 990 {
            XCTAssertEqual(test: "testInitWithFile index[10]", withExpression: (chrona.adjustments[10] == -17))
            XCTAssertEqual(test: "testInitWithFile index[989]", withExpression: (chrona.adjustments[989] == 124726))
        }
    }

    // +1, +1, +1 results in  3
    // +1, +1, -2 results in  0
    // -1, -2, -3 results in -6
    func testInitWithString() {
        var chrona = Chronal(withString: "+1, +1, +1")
        XCTAssertEqual(test: "testInitWithString", withExpression: (chrona.adjustments.count == 3))
        if chrona.adjustments.count == 3 {
            XCTAssertEqual(test: "testInitWithString index[1]", withExpression: (chrona.adjustments[1] == 1))
        }
        chrona = Chronal(withString: "+1, +1, -2")
        XCTAssertEqual(test: "testInitWithString", withExpression: (chrona.adjustments.count == 3))
        if chrona.adjustments.count == 3 {
            XCTAssertEqual(test: "testInitWithString index[1]", withExpression: (chrona.adjustments[1] == 1))
        }
        chrona = Chronal(withString: "-1, -2, -3")
        XCTAssertEqual(test: "testInitWithString", withExpression: (chrona.adjustments.count == 3))
        if chrona.adjustments.count == 3 {
            XCTAssertEqual(test: "testInitWithString index[1]", withExpression: (chrona.adjustments[1] == -2))
        }
    }

    func testApplyAdjustments() {
        var chrona = Chronal(withString: "+1, +1, +1")
        var val = chrona.applyAdjustments()
        XCTAssertEqual(test: "testApplyAdjustments", withExpression: (val == 3))
        chrona = Chronal(withString: "+1, +1, -2")
        val = chrona.applyAdjustments()
        XCTAssertEqual(test: "testApplyAdjustments", withExpression: (val == 0))
        chrona = Chronal(withString: "-1, -2, -3")
        val = chrona.applyAdjustments()
        XCTAssertEqual(test: "testApplyAdjustments", withExpression: (val == -6))
   }

    // +1, -1 first reaches 0 twice.
    // +3, +3, +4, -2, -4 first reaches 10 twice.
    // -6, +3, +8, +5, -6 first reaches 5 twice.
    // +7, +7, -2, -7, -4 first reaches 14 twice.

   func testRepeatedAjustmentUntilTwice() {
        var chrona = Chronal(withString: "+1, -1")
        var val = chrona.repeatedAjustmentUntilTwice()
        XCTAssertEqual(test: "testRepeatedAjustmentUntilTwice", withExpression: (val == 0))
        chrona = Chronal(withString: "+3, +3, +4, -2, -4")
        val = chrona.repeatedAjustmentUntilTwice()
        XCTAssertEqual(test: "testRepeatedAjustmentUntilTwice", withExpression: (val == 10))
        chrona = Chronal(withString: "-6, +3, +8, +5, -6")
        val = chrona.repeatedAjustmentUntilTwice()
        XCTAssertEqual(test: "testRepeatedAjustmentUntilTwice", withExpression: (val == 5))
        chrona = Chronal(withString: "+7, +7, -2, -7, -4")
        val = chrona.repeatedAjustmentUntilTwice()
        XCTAssertEqual(test: "testRepeatedAjustmentUntilTwice", withExpression: (val == 14))
   }

    func day01Tests() {
        testInitWithFile()
        testInitWithString()
        testApplyAdjustments()
        testRepeatedAjustmentUntilTwice()
    }

    func day01Final() {
        let chrona = Chronal(withFile: "/home/peterr/AOC2018/Sources/AOC2018/data/day01.txt")
        if let val = chrona.applyAdjustments() {
            print("Answer to part 1 is: \(val)")
        }
        let twice = chrona.repeatedAjustmentUntilTwice()
        print("Answer to part 2 is: \(twice)")
    }
}