name: Filter text
inputs:
- {name: Text}
- {name: Pattern, default: '.*'}
outputs:
- {name: Filtered text}
metadata:
  annotations:
    author: Alexey Volkov <alexey.volkov@ark-kun.com>
implementation:
  container:
    image: r-base:4.0.2
    command:
    - Rscript
    - -e
    - |
      args <- commandArgs(trailingOnly = TRUE)
      textPath <- args[1]
      pattern <- args[2]
      filteredTextPath <- args[3]

      dir.create(dirname(filteredTextPath), showWarnings = FALSE, recursive = TRUE)

      inputFile = file(textPath, "r")
      outputFile = file(filteredTextPath, "w")
      while ( TRUE ) {
          lines = readLines(inputFile, n = 1)
          if ( length(lines) == 0 ) {
              break
          }
          if ( grepl(pattern = pattern, lines) ) {
              writeLines(lines, outputFile)
          }
      }
      close(outputFile)
      close(inputFile)
    - {inputPath: Text}
    - {inputValue: Pattern}
    - {outputPath: Filtered text}