#!/bin/bash

set -eu
cd "$(dirname "$0")"
TMP=$(mktemp); trap 'rm -f "$TMP"' EXIT

check() { # DESCRIPTION RULES WORD EXPECTED_FINAL_STRING
  printf '%s\n' "$2" > "$TMP"
  got=$(python3 uts35.py "$TMP" "$3" | awk '/^ *[0-9]+ - /{w=$3} END{print w}')
  [ "$got" = "$4" ] || { echo "FAIL: $1 on $3 -> $got, want $4"; exit 1; }
  echo "ok: $1 on $3 -> $got"
}

# Collatz of 5 (5 -> 8 -> 4 -> 2 -> 1): halts at the word a
check "collatz" "$(cat collatz.txt)" aaaaa Ma
# a->b, b->a: each step removes two letters, appends one; 11 a's end as b
check "shrink " 'M a [ab] ([ab]*) > | M $1 b ;
M b [ab] ([ab]*) > | M $1 a ;' aaaaaaaaaaa Mb
# a->bbb, b->(empty): the word drains through empty productions
check "drain  " 'M a [ab] ([ab]*) > | M $1 b b b ;
M b [ab] ([ab]*) > | M $1 ;' aaaaaa Mb
# c has no production (halting symbol): aaa -> abc -> cbc, then stuck
check "haltsym" 'M a [abc] ([abc]*) > | M $1 b c ;
M b [abc] ([abc]*) > | M $1 a ;' aaa Mcbc

# The post's Collatz claim, step by step: each pass is one tag step;
# on a^7 the values appear as runs of a's.
cp collatz.txt "$TMP"
got=$(python3 uts35.py "$TMP" aaaaaaa | awk '
  /^ *[0-9]+ - / { w = $3; sub(/^M/, "", w)
            if (w != "" && w !~ /[^a]/ && length(w) != last)
              { printf "%s%s", sep, length(w); sep = " -> "; last = length(w) } }')
want="7 -> 11 -> 17 -> 26 -> 13 -> 20 -> 10 -> 5 -> 8 -> 4 -> 2 -> 1"
[ "$got" = "$want" ] || { echo "FAIL: milestones $got"; exit 1; }
echo "Collatz milestones on a^7: $got"
echo "all checks pass"