Rota.playground

import Foundation

// Update these fields
let nextRetroDate = "01/01/2021"

let team = [
    "Name 1",
    "Name 2",
    "Name 3"
]

struct RetroRota {
    
    let nextRetroDate: String

    let team: [String]

    let sprintLengthInWeeks: Int = 2
    
    func generate() {
        generateRota(for: team, from: nextRetroDate)
    }
    
    // Function to convert date from string on format dd/mm/YYYY to Date
    private func getDate(from string: String) -> Date {
        
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "dd/MM/yyyy"
        
        let date = dateFormatter.date(from: string)
        
        assert(date != nil, "Cannot convert date, needs to be input as dd/mm/YYYY format")
        
        return date!
        
    }

    // Function to produce an array of specific size with dates at fortnightly intervals
    private func getFortnights(from start: Date, count: Int) -> [Date] {

        var result = [start]
        
        for i in 0..<(count-1) {
            let current = result[i]
            let next = Calendar.current.date(byAdding: .weekOfYear, value: sprintLengthInWeeks, to: current)
            assert(next != nil, "Cannot create next date")
            result.append(next!)
        }
        
        return result
       
    }

    // Function to convert a date into a string with format dd/mm/YYYY
    private func getString(from date: Date) -> String {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "dd/MM/yyyy"
        return dateFormatter.string(from: date)
    }

    // Function to generate random rota with dates and output as string
    @discardableResult
    private func generateRota(for team: [String], from dateString: String) -> String {

        // Randomly shuffle team array
        let retroRota = team.shuffled()

        // Create correct number of dates
        let date = getDate(from: dateString)
        let dates = getFortnights(from: date, count: retroRota.count).compactMap { getString(from: $0) }
        
        assert(retroRota.count == dates.count, "Expected dates and retroRota arrays to be same size")
        
        // Generate string to output
        var string = "*Date // Chair *\n"

        for (index, date) in dates.enumerated() {
            string += "\(date) // \(retroRota[index])\n"
        }
        
        print(string)
        return string

    }
}

// Generate rota and print
RetroRota(nextRetroDate: nextRetroDate, team: team).generate()