#==============================================================================================#
# FUNCTION: listFiles
# Function to search through a given folder, and return the paths of the ".xlsx" files present
# in that folder
#----------------------------------------------------------------------------------------------#
# PARAMETERS:
# inputFolder : String, path of the folder containing the input files
#----------------------------------------------------------------------------------------------#
# RETURNS:
# fileVector : String Vector, containing the relative paths of the files in the input folder
#==============================================================================================#

listFiles <- function(inputFolder){
  
  inputDirectory <- file.path(inputFolder)
  fileVector <- list.files(path = inputDirectory, pattern = "*.xlsx",
                           all.files = FALSE, full.names = TRUE)
  
  return(fileVector)
  
}

#==============================================================================================#
# FUNCTION: readTables
# Wrapper function to read tables across sheets and return them in a list
# NOTE: For a given file, the logic in this code will not change.
#----------------------------------------------------------------------------------------------#
# PARAMETERS:
# filePath : String, path of the folder containing the input files
#
# sheetNames : String Vector, names of the sheet in the file that contain the tables
#
# startRow : Integer, row from which the tables begin
#
# headerPresent : Boolean, denoting if the table has a header or not
#----------------------------------------------------------------------------------------------#
# RETURNS:
# propertyInfoSheets : Dataframe List, containing the dataframes of the tables from each sheet
#==============================================================================================#

readTables <- function(filePath, sheetNames, startRow, headerPresent){
  
  sheetTables <- list()
  for(i in seq_along(sheetNames)){
    
    sheetTables[[i]] <- read_xlsx(path = filePath, sheet = sheetNames[i],
                                       col_names = headerPresent,
                                       skip = startRow - 1)
    
  }
  
  return(sheetTables)
  
}

#==============================================================================================#
# FUNCTION: readTables
# Wrapper function to collate the tables present in a list into a single table
#----------------------------------------------------------------------------------------------#
# PARAMETERS:
# tableList : Dataframe List, containing the tables to be collated
#----------------------------------------------------------------------------------------------#
# RETURNS:
# collatedTable : Dataframe, collated from the given list
#==============================================================================================#

collateTables <- function(tableList){
  
  collatedDataFrame <- data.frame()
  
  for(i in seq_along(tableList)){
    
    if(i == 1){
      collatedDataFrame <- tableList[[i]]
    } else{
      collatedDataFrame <- as.data.frame(rbind(collatedDataFrame, tableList[[i]]))
    }
    
  }
  
  return(collatedDataFrame)
  
}

#==============================================================================================#
# FUNCTION: dropColumns
# Wrapper function to iterate through the tables in a sheet and retain only the required 
# columns
#----------------------------------------------------------------------------------------------#
# PARAMETERS:
# tableList : Dataframe List, containing the tables to be collated
#
# columnsToRetain : Character Vector, containing the columns to be retained from the tables
#----------------------------------------------------------------------------------------------#
# RETURNS:
# treatedTableList : Dataframe List, containing the tables to be collated with only the required
#                    columns
#==============================================================================================#

dropColumns <- function(tableList, columnsToRetain){
  
  for(i in seq_along(tableList)){
    tableList[[i]] <- tableList[[i]][, columnsToRetain]
  }
  
  return(tableList)
}