Day07.swift

import Foundation
import Tools

final class Day07Solver: DaySolver {
	let dayNumber: Int = 7

	struct Input {
		let program: [Int]
	}

	func solvePart1(withInput input: Input) -> Int {
		let intcode = IntcodeProcessor()

		let permutations = [0, 1, 2, 3, 4].permutations

		var maxThrusterSignal = 0

		for permutation in permutations {
			var currentInput = 0

			for phaseSetting in permutation {
				currentInput = intcode.executeProgram(input.program, input: [phaseSetting, currentInput]).output.last!
			}

			maxThrusterSignal = max(maxThrusterSignal, currentInput)
		}

		return maxThrusterSignal
	}

	func solvePart2(withInput input: Input) -> Int {
		let permutations = [5, 6, 7, 8, 9].permutations

		var maxThrusterSignal = 0

		for permutation in permutations {
			let amplifiers: [IntcodeProcessor] = [
				IntcodeProcessor(),
				IntcodeProcessor(),
				IntcodeProcessor(),
				IntcodeProcessor(),
				IntcodeProcessor(),
			]

			var currentInput = 0
			var iteration = 0

			iterationLoop: while true {
				for (amplifierIndex, phaseSetting) in permutation.enumerated() {
					if iteration == 0 {
						guard let newCurrentInput = amplifiers[amplifierIndex].executeProgramTillOutput(input.program, input: [phaseSetting, currentInput]) else {
							fatalError()
						}

						currentInput = newCurrentInput
					} else {
						if let newCurrentInput = amplifiers[amplifierIndex].continueProgramTillOutput(input: [currentInput]) {
							currentInput = newCurrentInput
						} else {
							break iterationLoop
						}
					}

					maxThrusterSignal = max(maxThrusterSignal, currentInput)
				}

				iteration += 1
			}
		}

		return maxThrusterSignal
	}

	func parseInput(rawString: String) -> Input {
		return .init(program: rawString.parseCommaSeparatedInts())
	}
}