#!/usr/bin/env Rscript

local({
  p = commandArgs(TRUE)
  if (length(p) == 0L || any(c('-h', '--help') %in% p)) {
    message('usage: knit input [input2 input3] [-n] [-o output output2 output3]
    -h, --help        to print help messages
    -n, --no-convert  do not convert tex to pdf, markdown to html, etc
    -o                output filename(s) for knit()')
    q('no')
  }

  library(knitr)
  o = match('-o', p)
  if (is.na(o)) output = NA else {
    output = tail(p, length(p) - o)
    p = head(p, o - 1L)
  }
  nc = c('-n', '--no-convert')
  knit_fun = if (any(nc %in% p)) {
    p = setdiff(p, nc)
    knit
  } else {
    if (length(p) == 0L) stop('no input file provided')
    if (grepl('\\.(R|S)(nw|tex)$', p[1])) {
      function(x, ...) knit2pdf(x, ..., clean = TRUE)
    } else {
      if (grepl('\\.R(md|markdown)$', p[1])) knit2html else knit
    }
  }

  mapply(knit_fun, p, output = output, MoreArgs = list(envir = globalenv()))
})