//
//  File.swift
//  
//
//  Created by Shibo Lyu on 2022/5/20.
//

import Foundation

public struct RAColemanLiauIndexScorer: RAScorer {
  public static let requiresCommonMetrics: Set<RACommonMetric>? = [
    .wordCount,
    .characterCount,
    .sentenceCount
  ]

  public static let meta = RAScorerMeta(
    name: "Coleman–Liau Index",
    creator: "Meri Coleman & T. L. Liau",
    citation: "Coleman, M., & Liau, T. L. (1975). A computer readability formula designed for machine scoring. Journal of Applied Psychology, 60(2), 283."
  )

  public init() {}

  public func score(_ text: String, metrics: RACommonMetricsCalculator.Results?) -> Double {
    let wordCount = metrics![.wordCount]!

    let l = metrics![.characterCount]! * 100 / wordCount
    let s = metrics![.sentenceCount]! * 100 / wordCount

    let cloze = 141.8401 - (0.214590 * l) + (1.079812 * s)
    return (-27.4004 * cloze) + 23.06395
  }
}