#' PLCOm2012 risk prediction model for lung cancer

#'

#' @param age a vector of patient's age

#' @param race categorical variable of patient's race or ethnic group (White, Black, Hispanic,

#' Asian, American Indian, Alaskan Native, Native Hawaiian, Pacific Islander)

#' @param education education was measured in six ordinal levels: less than high-school graduate (level 1),

#' high-school graduate (level 2), some training after high school (level 3), some college (level 4),

#' college graduate (level 5), and postgraduate or professional degree (level 6)

#' @param bmi a vector of patient's body mass index, per 1 unit of increase

#' @param copd binary variable of chronic obstructive pulmonary disease (yes as 1 or no as 0)

#' @param cancer_hist binary variable of patient's cancer history (yes as 1 or no as 0)

#' @param family_hist_lung_cancer binary variable of patient's family history of lung cancer (yes as 1 or no as 0)

#' @param smoking_status binary variable of patient's smoking status (current as 1 or former as 0)

#' @param smoking_intensity a vector of the number cigarettes patient smokes per day

#' @param duration_smoking a vector of patient's duration of smoking, per 1-yr increase

#' @param smoking_quit_time a vector of patient's smoking quit time, per 1-yr increase

#'

#' @return prob patient's 6-year probability of lung-cancer

#' @export

#'

#' @examples

#'plcom2012(age=62, race='White', education=4, bmi=27, copd=0, cancer_hist=0,

#'family_hist_lung_cancer=0, smoking_status=0, smoking_intensity=80,

#'duration_smoking=27, smoking_quit_time=10)

plcom2012 <- function(age, race, education, bmi, copd, cancer_hist, family_hist_lung_cancer, smoking_status, smoking_intensity, duration_smoking,

                      smoking_quit_time) {

  race <- tolower(race)

  if (race == "white" | race == "american indian" | race == "alaskan native" | race == 1) {

    model <- 0.0778868 * (age - 62) - 0.0812744 * (education - 4) - 0.0274194 * (bmi - 27) + 0.3553063 * copd + 0.4589971 * cancer_hist +

      0.587185 * family_hist_lung_cancer + 0.2597431 * smoking_status - 1.822606 * ((smoking_intensity/10)^(-1) - 0.4021541613) + 0.0317321 *

      (duration_smoking - 27) - 0.0308572 * (smoking_quit_time - 10) - 4.532506

  }

  if (race == "black" | race == 2) {

    model <- 0.0778868 * (age - 62) - 0.0812744 * (education - 4) - 0.0274194 * (bmi - 27) + 0.3553063 * copd + 0.4589971 * cancer_hist +

      0.587185 * family_hist_lung_cancer + 0.2597431 * smoking_status - 1.822606 * ((smoking_intensity/10)^(-1) - 0.4021541613) + 0.0317321 *

      (duration_smoking - 27) - 0.0308572 * (smoking_quit_time - 10) - 4.532506 + 0.3944778

  }

  if (race == "hispanic" | race == 3) {

    model <- 0.0778868 * (age - 62) - 0.0812744 * (education - 4) - 0.0274194 * (bmi - 27) + 0.3553063 * copd + 0.4589971 * cancer_hist +

      0.587185 * family_hist_lung_cancer + 0.2597431 * smoking_status - 1.822606 * ((smoking_intensity/10)^(-1) - 0.4021541613) + 0.0317321 *

      (duration_smoking - 27) - 0.0308572 * (smoking_quit_time - 10) - 4.532506 - 0.7434744

  }

  if (race == "asian" | race == 4) {

    model <- 0.0778868 * (age - 62) - 0.0812744 * (education - 4) - 0.0274194 * (bmi - 27) + 0.3553063 * copd + 0.4589971 * cancer_hist +

      0.587185 * family_hist_lung_cancer + 0.2597431 * smoking_status - 1.822606 * ((smoking_intensity/10)^(-1) - 0.4021541613) + 0.0317321 *

      (duration_smoking - 27) - 0.0308572 * (smoking_quit_time - 10) - 4.532506 - 0.466585

  }

  if (race == "native hawaiian" | race == "pacific islander" | race == 5) {

    model <- 0.0778868 * (age - 62) - 0.0812744 * (education - 4) - 0.0274194 * (bmi - 27) + 0.3553063 * copd + 0.4589971 * cancer_hist +

      0.587185 * family_hist_lung_cancer + 0.2597431 * smoking_status - 1.822606 * ((smoking_intensity/10)^(-1) - 0.4021541613) + 0.0317321 *

      (duration_smoking - 27) - 0.0308572 * (smoking_quit_time - 10) - 4.532506 + 1.027152

  }

  prob <- exp(model)/(1 + exp(model))

  results <- list()

  results$prob <- prob

  return(results)

}