AssignmentParser.swift

/*
Copyright (c) 2021 Mike Bobiney

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

//
// Output the diff between an existing and new array of Assignment strings
//

import Foundation

enum Status: String, Decodable {
    case assigned       = "Assigned"
    case submited       = "Submitted"
    case graded         = "Graded"
    case returned       = "Returned"
    case addressable    = "Addressable"
    case notFound       = "NotFound"
}

struct Assignment {
    var id:Int
    var title:String
    var status:Status
}

func parseAssignments(_ array: [String]) -> [Assignment] {
    var retArray = [Assignment]()
    array.forEach {
        let arr = $0.split(separator: "_")
        let a = Assignment.init(
            id: Int(arr[0]) ?? 0, 
            title: String(arr[1]), 
            status: Status(rawValue: String(arr[2])) ?? Status.notFound
        )
        retArray.append(a)
    }
    return retArray
}

func assignmentOutput(existing: [Assignment], new: [Assignment]) -> [String] {
    var stringOutput = [String]()

    // Find max id
    let max = (existing+new).max(by: { (a, b) in a.id < b.id })!.id

    var reservedExisting = [Assignment?](repeating: nil, count: max)
    existing.enumerated().forEach { (index, obj) in reservedExisting[obj.id-1] = obj }

    var reservedNew = [Assignment?](repeating: nil, count: max)
    new.enumerated().forEach { (index, obj) in reservedNew[obj.id-1] = obj }

    (0..<max).forEach { (index) in 

        let padded:Assignment = .init(id: index, title: "", status: .notFound)
        let safeExisting = reservedExisting[index] ?? padded
        let safeNew = reservedNew[index] ?? padded
        
        // append only if status differs
        if safeExisting.status != safeNew.status {
            let underscoreOutput = comparisonString(a: safeExisting, b: safeNew).replacingOccurrences(of: " ", with: "_")
            stringOutput.append(underscoreOutput)
        }
    }
    return stringOutput
}

func comparisonString(a:Assignment, b:Assignment) -> String {
    if a.status == .notFound {
        return "\(b.title) was added and it was \(b.status.rawValue.lowercased())."
    } else if b.status == .notFound {
        return "\(a.title) was removed."
    } else {
        return "\(a.title) was \(b.status.rawValue.lowercased())."
    }
}



//====================================================================================================

// Test Cases Set 1

// #1
//let existing = parseAssignments(["1_FirstHomework_Assigned"])
//let new = parseAssignments(["1_FirstHomework_Submitted"])
//print(assignmentOutput(existing:existing, new:new))

// Output
// ["FirstHomework_was_submitted."]

// #2
//let existing = parseAssignments(["1_FirstHomework_Submitted", "2_SecondHomework_Assigned"])
//let new = parseAssignments(["1_GRADEDFirsthomework_Graded", "2_SecondHomework_Submitted"])
//print(assignmentOutput(existing:existing, new:new))

// Output
// ["FirstHomework_was_graded.", "SecondHomework_was_submitted."]

// #3
//let existing = parseAssignments(["1_FirstHomework_Submitted"])
//let new = parseAssignments(["1_FirstHomework_Submitted", "2_SecondHomework_Assigned"])
//print(assignmentOutput(existing:existing, new:new))

// Output
// ["SecondHomework_was_added_and_it_was_assigned."]



//====================================================================================================

// Test Cases Set 2

// #1
//let existing = parseAssignments(["1_FirstHomework_Graded","2_SecondHomework_Assigned"])
//let new = parseAssignments(["1_FirstHomework_Graded"])
//print(assignmentOutput(existing:existing, new:new))

// Output
// ["SecondHomework_was_removed."]

// #2
//let existing = parseAssignments(["1_FirstHomework_Assigned","2_SecondHomework_Assigned","3_ThirdHomework_Assigned"])
//let new = parseAssignments(["3_ThirdHomework_Submitted","1_FirstHomework_Graded","2_SecondHomework_Returned"])
//print(assignmentOutput(existing:existing, new:new))

// Output
//["FirstHomework_was_graded.", "SecondHomework_was_returned.", "ThirdHomework_was_submitted."]

// #3
//let existing = parseAssignments(["1_FirstHomework_Assigned","2_SecondHomework_Assigned","3_ThirdHomework_Assigned"])
//let new = parseAssignments(["1_FirstHomework_Assigned","3_ThirdHomework_Assigned"])
//print(assignmentOutput(existing:existing, new:new))

// Output
// ["SecondHomework_was_removed."]

// #4
//let existing = parseAssignments(["1_FirstHomework_Assigned"])
//let new = parseAssignments(["1_FirstHomework_Submitted"])
//print(assignmentOutput(existing:existing, new:new))

// Output
// ["FirstHomework_was_submitted."]

// #5
//let existing = parseAssignments(["1_FirstHomework_Assigned","2_SecondHomework_Assigned","3_ThirdHomework_Assigned"])
//let new = parseAssignments(["4_FourthHomework_Assigned","5_FifthHomework_Addressable","6_SixthHomework_Assigned"])
//print(assignmentOutput(existing:existing, new:new))

// Output
// ["FirstHomework_was_removed.", "SecondHomework_was_removed.", "ThirdHomework_was_removed.", "FourthHomework_was_added_and_it_was_assigned.", "FifthHomework_was_added_and_it_was_addressable.", "SixthHomework_was_added_and_it_was_assigned."]