#!/bin/awk -f
#!/opt/busybox/awk -f

# Copyright 2022 - 2023 Paul Hänsch
# 
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
# 
# THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
# SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
# IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

function sh_escape(arg){
  return "'" gensub(/'/, "'\"'\"'", "g", arg) "'";
}

function argsplit(line, args, LOCAL, c, n, ctx) {
  ctx="space"; n=0;

  while ( length(line) > 0 ) {
    c = substr(line, 1, 1);
    line = substr(line, 2);
    if (ctx == "space" )
           if (c ~ /[ \t]/) ctx = "space";
      else if (c ~ /\\/) { n++; ctx = "escbare"; }
      else if (c ~ /"/)  { n++; ctx = "dquot"; }
      else if (c ~ /'/)  { n++; ctx = "squot"; }
      else   { n++; args[n] = c; ctx = "bare"; }
    else if (ctx == "bare")
           if (c ~ /[ \t]/) ctx = "space";
      else if (c ~ /\\/)  ctx = "escbare";
      else if (c ~ /"/)   ctx = "dquot";
      else if (c ~ /'/)   ctx = "squot";
      else args[n] = args[n] c;
    else if (ctx == "dquot")
           if (c ~ /"/)  ctx = "bare";
      else if (c ~ /\\/) ctx = "escdquot";
      else args[n] = args[n] c;
    else if (ctx == "squot")
      if (c ~ /'/)  ctx = "bare";
      else args[n] = args[n] c;
    else if (ctx == "escbare") {
      args[n] = args[n] c;
      ctx = "bare";
    }
    else if (ctx == "escdquot") {
      args[n] = args[n] c;
      ctx = "dquot";
    }
  }
} 

function HTML ( text ) {
  gsub( /&/,  "\\&",  text );
  gsub( /</,  "\\&lt;",   text );
  gsub( />/,  "\\&gt;",   text );
  gsub( /"/,  "\\&quot;", text );
  gsub( /'/,  "\\&#x27;", text );
  gsub( /\\/, "\\&#x5C;", text );
  return text;
}

function macro(call, LOCAL, line, args) {
  argsplit(call, args);
  call="";

  for (n = 1; n in args; n++) call = call sh_escape(args[n]) " ";

  if (args[1] in MACROS) {
    printf "%s", file | sh_escape(ENVIRON["MD_MACROS"]) "/" call;
    close(sh_escape(ENVIRON["MD_MACROS"]) "/" call);
  } else {
    printf "%s", HTML("<<" call ">>");
  }
}

function unhtml ( text ) {
  gsub( /&lt;/, "<", text);
  gsub( /&gt;/, ">", text);
  gsub( /&quot;/, "\"", text);
  gsub( /&#x27;/, "'", text);
  gsub( /&#x5c;/, "\\", text);
  gsub( /&amp;/, "\\&", text);
  return text;
}

function findmacro(line, LOCAL, st, len, pre, post) {
  if ( match(line, /<code class="macro">[^\n]*<\/code>/) ) {
    match(line, /<code class="macro">/); pre = substr( line, 1, RSTART - 1 );
    line = substr( line, RSTART + RLENGTH);
    match( line, /<\/code>/); post = substr(line, RSTART + RLENGTH);
    line = substr(line, 1, RSTART - 1);

    printf "%s", pre; macro( unhtml(line) ); findmacro( post );
  } else {
    printf "%s", line;
  }
}

BEGIN {
  if (ENVIRON["MD_MACROS"]) {
    AllowMacros = "true";
    "cd " sh_escape(ENVIRON["MD_MACROS"]) "; printf '%s/' *" |getline macro_list;
    split(macro_list, MACROS, "/");
    for (n in MACROS) { MACROS[MACROS[n]] = ""; delete MACROS[n]; }
    delete MACROS[""];

    file = ""; while ( getline ) { file = file $0 "\n"; }
    findmacro( file );
  }
}