RunModel_CemaNeigeGR4H <- function(InputsModel, RunOptions, Param) {
  
  
  ## Initialization of variables
  IsHyst <- inherits(RunOptions, "hysteresis")
  NParam <- ifelse(test = IsHyst, yes = 8L, no = 6L)
  NParamCN <- NParam - 4L
  NStates <- 4L
  FortranOutputs <- .FortranOutputs(GR = "GR4H", isCN = TRUE)
  
  
  ## Arguments_check
  if (!inherits(InputsModel, "InputsModel")) {
    stop("'InputsModel' must be of class 'InputsModel'")
  }
  if (!inherits(InputsModel, "hourly")) {
    stop("'InputsModel' must be of class 'hourly'")
  }
  if (!inherits(InputsModel, "GR")) {
    stop("'InputsModel' must be of class 'GR'")
  }
  if (!inherits(InputsModel, "CemaNeige")) {
    stop("'InputsModel' must be of class 'CemaNeige'")
  }
  if (!inherits(RunOptions, "RunOptions")) {
    stop("'RunOptions' must be of class 'RunOptions'")
  }
  if (!inherits(RunOptions, "GR")) {
    stop("'RunOptions' must be of class 'GR'")
  }
  if (!inherits(RunOptions, "CemaNeige")) {
    stop("'RunOptions' must be of class 'CemaNeige'")
  }
  if (!is.vector(Param) | !is.numeric(Param)) {
    stop("'Param' must be a numeric vector")
  }
  if (sum(!is.na(Param)) != NParam) {
    stop(paste("'Param' must be a vector of length", NParam, "and contain no NA"))
  }
  Param <- as.double(Param)
  
  
  Param_X1X3_threshold <- 1e-2
  Param_X4_threshold   <- 0.5
  if (Param[1L] < Param_X1X3_threshold) {
    warning(sprintf("Param[1] (X1: production store capacity [mm]) < %.2f\n X1 set to %.2f", Param_X1X3_threshold, Param_X1X3_threshold))
    Param[1L] <- Param_X1X3_threshold
  }
  if (Param[3L] < Param_X1X3_threshold) {
    warning(sprintf("Param[3] (X3: routing store capacity [mm]) < %.2f\n X3 set to %.2f", Param_X1X3_threshold, Param_X1X3_threshold))
    Param[3L] <- Param_X1X3_threshold
  }
  if (Param[4L] < Param_X4_threshold) {
    warning(sprintf("Param[4] (X4: unit hydrograph time constant [hour]) < %.2f\n X4 set to %.2f", Param_X4_threshold, Param_X4_threshold))
    Param[4L] <- Param_X4_threshold
  }      
  
  ## Input_data_preparation
  if (identical(RunOptions$IndPeriod_WarmUp, 0L)) {
    RunOptions$IndPeriod_WarmUp <- NULL
  }
  IndPeriod1     <- c(RunOptions$IndPeriod_WarmUp, RunOptions$IndPeriod_Run)
  LInputSeries   <- as.integer(length(IndPeriod1))
  IndPeriod2     <- (length(RunOptions$IndPeriod_WarmUp) + 1):LInputSeries
  ParamCemaNeige <- Param[(length(Param)-1 - 2 * as.integer(IsHyst)):length(Param)]
  NParamMod      <- as.integer(length(Param) - (2 + 2 * as.integer(IsHyst)))
  ParamMod       <- Param[1:NParamMod]
  NLayers        <- length(InputsModel$LayerPrecip)
  NStatesMod     <- as.integer(length(RunOptions$IniStates) - NStates * NLayers)
  ExportDatesR   <- "DatesR"   %in% RunOptions$Outputs_Sim
  ExportStateEnd <- "StateEnd" %in% RunOptions$Outputs_Sim
  
  
  ## SNOW_MODULE________________________________________________________________________________
  if (inherits(RunOptions, "CemaNeige")) {
    if ("all" %in% RunOptions$Outputs_Sim) {
      IndOutputsCemaNeige <- as.integer(1:length(FortranOutputs$CN))
    } else {
      IndOutputsCemaNeige <- which(FortranOutputs$CN %in% RunOptions$Outputs_Sim)
    }
    CemaNeigeLayers <- list()
    CemaNeigeStateEnd <- NULL
    NameCemaNeigeLayers <- "CemaNeigeLayers"
    
    
    ## Call_DLL_CemaNeige_________________________
    for (iLayer in 1:NLayers) {
      
      if (!IsHyst) {
        StateStartCemaNeige <- RunOptions$IniStates[(7 + 20*24 + 40*24) + c(iLayer, iLayer+NLayers)]
      } else {
        StateStartCemaNeige <- RunOptions$IniStates[(7 + 20*24 + 40*24) + c(iLayer, iLayer+NLayers, iLayer+2*NLayers, iLayer+3*NLayers)]
      }
      RESULTS <- .Fortran("frun_cemaneige", PACKAGE = "airGR",
                          ## inputs
                          LInputs = LInputSeries,                                                         ### length of input and output series
                          InputsPrecip = InputsModel$LayerPrecip[[iLayer]][IndPeriod1],                   ### input series of total precipitation [mm/h]
                          InputsFracSolidPrecip = InputsModel$LayerFracSolidPrecip[[iLayer]][IndPeriod1], ### input series of fraction of solid precipitation [0-1]
                          InputsTemp = InputsModel$LayerTemp[[iLayer]][IndPeriod1],                       ### input series of air mean temperature [degC]
                          MeanAnSolidPrecip = RunOptions$MeanAnSolidPrecip[iLayer],                       ### value of annual mean solid precip [mm/y]
                          NParam = as.integer(NParamCN),                                                  ### number of model parameters = 2 or 4
                          Param = as.double(ParamCemaNeige),                                              ### parameter set
                          NStates = as.integer(NStates),                                                  ### number of state variables used for model initialisation = 4
                          StateStart = StateStartCemaNeige,                                               ### state variables used when the model run starts
                          IsHyst = as.integer(IsHyst),                                                    ### use of hysteresis
                          NOutputs = as.integer(length(IndOutputsCemaNeige)),                             ### number of output series
                          IndOutputs = IndOutputsCemaNeige,                                               ### indices of output series
                          ## outputs                                                               
                          Outputs = matrix(as.double(-999.999), nrow = LInputSeries, ncol = length(IndOutputsCemaNeige)), ### output series [mm]
                          StateEnd = rep(as.double(-999.999), as.integer(NStates))                                        ### state variables at the end of the model run
      )
      RESULTS$Outputs[ round(RESULTS$Outputs , 3) == -999.999] <- NA
      RESULTS$StateEnd[round(RESULTS$StateEnd, 3) == -999.999] <- NA
      
      ## Data_storage
      CemaNeigeLayers[[iLayer]] <- lapply(seq_len(RESULTS$NOutputs), function(i) RESULTS$Outputs[IndPeriod2, i])
      names(CemaNeigeLayers[[iLayer]]) <- FortranOutputs$CN[IndOutputsCemaNeige]
      IndPliqAndMelt <- which(names(CemaNeigeLayers[[iLayer]]) == "PliqAndMelt")
      if (iLayer == 1) {
        CatchMeltAndPliq <- RESULTS$Outputs[, IndPliqAndMelt] / NLayers
      }
      if (iLayer > 1) {
        CatchMeltAndPliq <- CatchMeltAndPliq + RESULTS$Outputs[, IndPliqAndMelt] / NLayers
      }
      if (ExportStateEnd) {
        CemaNeigeStateEnd <- c(CemaNeigeStateEnd, RESULTS$StateEnd)
      }
      rm(RESULTS)
    } ### ENDFOR_iLayer
    names(CemaNeigeLayers) <- sprintf("Layer%02i", seq_len(NLayers))
  } ### ENDIF_RunSnowModule
  if (!inherits(RunOptions, "CemaNeige")) {
    CemaNeigeLayers <- list()
    CemaNeigeStateEnd <- NULL
    NameCemaNeigeLayers <- NULL
    CatchMeltAndPliq <- InputsModel$Precip[IndPeriod1]
  }
  
  
  
  ## MODEL
  if ("all" %in% RunOptions$Outputs_Sim) {
    IndOutputsMod <- as.integer(1:length(FortranOutputs$GR))
  } else {
    IndOutputsMod <- which(FortranOutputs$GR %in% RunOptions$Outputs_Sim)
  }
  
  ## Use_of_IniResLevels
  if (!is.null(RunOptions$IniResLevels)) {
    RunOptions$IniStates[1] <- RunOptions$IniResLevels[1] * ParamMod[1] ### production store level (mm)
    RunOptions$IniStates[2] <- RunOptions$IniResLevels[2] * ParamMod[3] ### routing store level (mm)
  }
  
  ## Call_fortan
  RESULTS <- .Fortran("frun_gr4h", PACKAGE = "airGR",
                      ## inputs
                      LInputs = LInputSeries,                          ### length of input and output series
                      InputsPrecip = CatchMeltAndPliq,                 ### input series of total precipitation [mm/h]
                      InputsPE = InputsModel$PotEvap[IndPeriod1],      ### input series potential evapotranspiration [mm/h]
                      NParam = NParamMod,                              ### number of model parameter
                      Param = ParamMod,                                ### parameter set
                      NStates = NStatesMod,                            ### number of state variables used for model initialising
                      StateStart = RunOptions$IniStates[1:NStatesMod], ### state variables used when the model run starts
                      NOutputs = as.integer(length(IndOutputsMod)),    ### number of output series
                      IndOutputs = IndOutputsMod,                      ### indices of output series
                      ## outputs                                        
                      Outputs = matrix(as.double(-999.999), nrow = LInputSeries, ncol = length(IndOutputsMod)), ### output series [mm]
                      StateEnd = rep(as.double(-999.999), NStatesMod)                                           ### state variables at the end of the model run
  )
  RESULTS$Outputs[ round(RESULTS$Outputs , 3) == -999.999] <- NA
  RESULTS$StateEnd[round(RESULTS$StateEnd, 3) == -999.999] <- NA
  if (ExportStateEnd) {
    RESULTS$StateEnd[-3L] <- ifelse(RESULTS$StateEnd[-3L] < 0, 0, RESULTS$StateEnd[-3L]) ### remove negative values except for the ExpStore location
    idNStates <- seq_len(NStates*NLayers) %% NStates
    RESULTS$StateEnd <- CreateIniStates(FUN_MOD = RunModel_CemaNeigeGR4H, InputsModel = InputsModel, IsHyst = IsHyst,
                                        ProdStore = RESULTS$StateEnd[1L], RoutStore = RESULTS$StateEnd[2L], ExpStore = NULL,
                                        UH1 = RESULTS$StateEnd[(1:(20*24))+7], UH2 = RESULTS$StateEnd[(1:(40*24))+(7+20*24)],
                                        GCemaNeigeLayers       = CemaNeigeStateEnd[seq_len(NStates*NLayers)[idNStates == 1]],
                                        eTGCemaNeigeLayers     = CemaNeigeStateEnd[seq_len(NStates*NLayers)[idNStates == 2]],
                                        GthrCemaNeigeLayers    = CemaNeigeStateEnd[seq_len(NStates*NLayers)[idNStates == 3]], 
                                        GlocmaxCemaNeigeLayers = CemaNeigeStateEnd[seq_len(NStates*NLayers)[idNStates == 0]],
                                        verbose = FALSE)
  }
  
  if (inherits(RunOptions, "CemaNeige") & "Precip" %in% RunOptions$Outputs_Sim) {
    RESULTS$Outputs[, which(FortranOutputs$GR[IndOutputsMod] ==  "Precip")] <- InputsModel$Precip[IndPeriod1]
  }
  
  ## Output_data_preparation
  ## OutputsModel_only
  if (!ExportDatesR & !ExportStateEnd) {
    OutputsModel <- c(lapply(seq_len(RESULTS$NOutputs), function(i) RESULTS$Outputs[IndPeriod2, i]),
                      list(CemaNeigeLayers))
    names(OutputsModel) <- c(FortranOutputs$GR[IndOutputsMod], NameCemaNeigeLayers)
  }
  ## DatesR_and_OutputsModel_only
  if ( ExportDatesR & !ExportStateEnd) {
    OutputsModel <- c(list(InputsModel$DatesR[RunOptions$IndPeriod_Run]),
                      lapply(seq_len(RESULTS$NOutputs), function(i) RESULTS$Outputs[IndPeriod2, i]),
                      list(CemaNeigeLayers))
    names(OutputsModel) <- c("DatesR", FortranOutputs$GR[IndOutputsMod], NameCemaNeigeLayers)
  }
  ## OutputsModel_and_SateEnd_only
  if (!ExportDatesR & ExportStateEnd) {
    OutputsModel <- c(lapply(seq_len(RESULTS$NOutputs), function(i) RESULTS$Outputs[IndPeriod2, i]),
                      list(CemaNeigeLayers),
                      list(RESULTS$StateEnd))
    names(OutputsModel) <- c(FortranOutputs$GR[IndOutputsMod], NameCemaNeigeLayers, "StateEnd")
  }
  ## DatesR_and_OutputsModel_and_SateEnd
  if ( ExportDatesR & ExportStateEnd) {
    OutputsModel <- c(list(InputsModel$DatesR[RunOptions$IndPeriod_Run]),
                      lapply(seq_len(RESULTS$NOutputs), function(i) RESULTS$Outputs[IndPeriod2, i]),
                      list(CemaNeigeLayers),
                      list(RESULTS$StateEnd))
    names(OutputsModel) <- c("DatesR", FortranOutputs$GR[IndOutputsMod], NameCemaNeigeLayers, "StateEnd")
  }
  
  ## End
  rm(RESULTS)
  class(OutputsModel) <- c("OutputsModel", "hourly", "GR", "CemaNeige")
  if (IsHyst) {
    class(OutputsModel) <- c(class(OutputsModel), "hysteresis")
  }
  return(OutputsModel)
  
}