#!/usr/bin/env bash
# arity.sh — check call arity against the runtime's OWN declarations.
#
# codegen.el carried builtin_arity(): 344 lines, 300 entries, of which 243 were
# an exact duplicate of el_runtime.h. Measured drift between them was zero --
# the duplicate had been maintained correctly -- but 199 functions the runtime
# declares had NO entry, so calling them with the wrong argument count produced
# no El-level diagnostic at all. The table was not wrong, it was 40% incomplete.
#
# Deriving from the header fixes the coverage and makes drift impossible.
set -uo pipefail
REL="${1:?usage: arity.sh <relations-file> [runtime-header]}"
HDR="${2:-$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)/runtime/el_runtime.h}"
[ -f "$REL" ] || exit 0
[ -f "$HDR" ] || { echo "no header: $HDR" >&2; exit 0; }

SIG=$(mktemp); trap 'rm -f "$SIG"' EXIT
# Declarations may span lines, so join continuations before parsing. Reading
# only the first line silently yields 0 params, and a checker that reports the
# wrong expected count is worse than no checker at all.
sed 's://.*::' "$HDR" | tr '\n' ' ' | sed 's:/\*[^*]*\*/: :g; s/;/;\n/g' | awk '
  /el_val_t[[:space:]]+[a-z0-9_]+[[:space:]]*\(/ {
    line=$0
    match(line, /el_val_t[[:space:]]+[a-z0-9_]+/); name=substr(line,RSTART,RLENGTH)
    sub(/el_val_t[[:space:]]+/,"",name)
    match(line, /\(.*\)/); params=substr(line,RSTART+1,RLENGTH-2)
    gsub(/^[[:space:]]+|[[:space:]]+$/,"",params)
    if (params=="void" || params=="") n=0
    else { n=1; for(i=1;i<=length(params);i++) if(substr(params,i,1)==",") n++ }
    if (line ~ /\.\.\./) n=-1
    print name, n
  }' | sort -u > "$SIG"

V=0
while read -r callee _ rest; do
    [ "${rest#arity:}" = "$rest" ] && continue
    actual="${rest#arity:}"
    expected=$(awk -v n="$callee" '$1==n {print $2; exit}' "$SIG")
    # 60 of 500 runtime decls carry a __ prefix: El's `println` is C's
    # `__println`. codegen owns that mapping and its table carried BOTH keys.
    # One rule covers every one of them.
    [ -n "$expected" ] || expected=$(awk -v n="__$callee" '$1==n {print $2; exit}' "$SIG")
    [ -n "$expected" ] || continue          # not a runtime builtin
    [ "$expected" = "-1" ] && continue      # variadic
    if [ "$actual" != "$expected" ]; then
        printf "arity error: '%s' takes %s arguments, called with %s\n" "$callee" "$expected" "$actual"
        V=$((V+1))
    fi
done < <(sort -u "$REL")

[ "$V" -eq 0 ] && echo "arity: clean ($(wc -l < "$SIG" | tr -d ' ') signatures from the header)"
exit "$V"