require(stringr)

# Replace characters messing up JSON validation (\,\n,^)
correctJSON <- function(string) {
  string <- gsub('\\\\\\\\\\"(\\w)', '\\1' , string)
  string <- gsub('\\\\\\\\\\" ', ' ', string)
  string <- gsub("\\\\{2,}", "", string)
  string <- str_replace_all(string, pattern = "[^[:print:]]", replacement = " ")
  string <- str_replace_all(string, pattern = "&..;", replacement = " ")
  string <- str_replace_all(string, pattern = perl('\\\\(?![tn"])'), replacement = " ")
  return(string)
}

insertRow <- function(existingDF, newrow, r) {
  r <- as.numeric(nrow(existingDF)) + 1
  existingDF <- rbind(existingDF,newrow)
  existingDF <- existingDF[order(c(1:(nrow(existingDF)-1),r-0.5)),]
  row.names(existingDF) <- 1:nrow(existingDF)
  return(existingDF)  
}

convertLogical0 <- function(var) {
  if(is.integer(var) && length(var) == 0) {
    var <- 0
  }
  return(var)
}

smartPatternMatch <- function(string, pattern, chars) {
  if(chars < 5) {
    found <- agrep(pattern, string, max.distance = list(all = 0), ignore.case = TRUE, fixed = FALSE)
  }
  else if(chars > 7) {
    found <- agrep(pattern, string, max.distance = list(all = 2), ignore.case = TRUE, fixed = FALSE)
  }
  else {
    found <- agrep(pattern, string, max.distance = list(all = 1), ignore.case = TRUE, fixed = FALSE)
  }
  found <- convertLogical0(found)
  return(found)
}

## ERROR HANDLING

# Check for empty API returns (0 or 1 or 2)
errorEmptyAPI <- function(df) {
  status <- length(df)
  if(status == 0) {
    if(error < 3) {
      cat("[WARNING] Empty API result. Trying again.\n")
      returncode <- 1
    }
    else {
      cat("[WARNING] 3x empty API result. Aborting now.\n")
      returncode <- 2
    } 
  }
  else {
    returncode <- 0
  }
  return(returncode)
}

# Check if API output contains error fields (0 or 2)
errorErrorColumn <- function(df) {
  status <- "error" %in% names(df)
  if(status) {
    cat("[WARNING] Error in API request:", df$error[1],"\n")
    returncode <- 2
  }
  else {
    returncode <- 0
  }
  return(returncode)
}

# Check if error codes exist (i.e. 34 or 88)
errorCheckCode <- function(df) {
  status <- "errors" %in% names(df)
  if(status) {
    cat("[WARNING] Error in API request:", df$errors[1,1],"\n")
    code <- df$errors[1,2]
  }
  else {
    code <- 0
  }
  return(code)
}

# Handle code 88: rate limit exceeded (wait time)
errorCode88 <- function() {
  rate_api_url <- "https://api.twitter.com/1.1/application/rate_limit_status.json"
  rate_query <- c(resources="statuses")
  resettime <- fromJSON(twitter_api_call(rate_api_url, rate_query, api_params))
  resettime <- resettime$resources$statuses$`/statuses/user_timeline`$reset
  curtime <- as.numeric(as.POSIXct(Sys.time()))
  wait <- round(resettime - curtime + 10)
  cat("[INFO] Rate limit is exceeded. Now waiting",wait,"seconds.\n")
  return(wait)
}

# Handle code 34: Page does not exist (1 or 2)
errorCode34 <- function() {
  if(error > 2) {
    cat("[WARNING] 3x Not existing page. Aborting now.\n")
    returncode <- 2
  }
  else {
    returncode <- 1
  }
  return(returncode)
}