#!/usr/bin/env python3

# This script constructs a Markdown file (on standard output) that constitutes
# an index of all web-rendered pages of Dex examples, documentation, and
# libraries.

# The rendered HTML of the index is meant to be placed at the root of the Dex
# page tree, so that relative links work.

# The script accepts three arguments:
# - One argument containing a space-separated list of documentation files
# - One argument containing a space-separated list of example files
# - One argument containing a space-separated list of library files

# TODO: Right now, the indexing script requires every file to have a single
# title, identified by having a "'# <title>" line in the Dex source.  We should
# detect when a file lacks such a title and fail loudly, instead of just
# omitting that file from the index.

import re
import sys

def file_block(files):
  for fname in files:
    if fname.startswith("doc/"):
      link_name = fname[len("doc/"):-len(".dx")]
    else:
      link_name = fname[:-len(".dx")]
    with open(fname, 'r') as f:
      line = f.readline()
      title = re.match(r"' *# ?(.*)", line)
      if title:
        print(f"- [{fname}]({link_name}.html) {title.group(1)}")
      else:
        raise ValueError(f"First line of file {fname} was not a title (top-level Markdown heading)")

def main():
  docs, examples, libraries = sys.argv[1:4]

  print("# InDex"); print("")

  print("## Documentation"); print("")

  file_block(docs.split())

  print(""); print("## Examples"); print("")

  file_block(examples.split())

  print(""); print("## Libraries"); print("")

  print("- [lib/prelude.dx](lib/prelude.html): The Dex Prelude (automatically imported)")

  file_block(libraries.split())


if __name__ == '__main__':
  main()