#!/usr/bin/env bash
set -euo pipefail
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
SKILL_ROOT="$(dirname "$SCRIPT_DIR")"
source "$SCRIPT_DIR/_common.sh"

: "${INPUT_DIR:=}"
: "${INPUT_FILES:=}"
: "${EXCLUDES:=.git,node_modules,target,dist,outputs}"
: "${LABEL:=snapshot}"
: "${NODE_NAME:=node-a}"
: "${OUTPUT_DIR:=$SKILL_ROOT/outputs}"

build_file_list() {
  local out="$1"
  local find_args=()
  IFS=',' read -r -a ex <<< "$EXCLUDES"
  for pat in "${ex[@]}"; do [[ -n "$pat" ]] && find_args+=( -not -path "*/$pat/*" ); done

  if [[ -n "$INPUT_FILES" ]]; then
    : > "$out"
    IFS=',' read -r -a files <<< "$INPUT_FILES"
    for f in "${files[@]}"; do
      f="${f#"${f%%[![:space:]]*}"}"; f="${f%"${f##*[![:space:]]}"}"
      [[ -f "$f" ]] || die "Not a file: $f"
      echo "$f" >> "$out"
    done
  else
    (cd "$INPUT_DIR" && find . -type f "${find_args[@]}" | sed 's|^\./||') > "$out.rel"
    awk -v root="$INPUT_DIR" '{print root "/" $0}' "$out.rel" > "$out"
    rm -f "$out.rel"
  fi
  sort -u "$out" -o "$out"
}

main() {
  confirm_gate
  local hasher; hasher="$(pick_hasher)"
  mkdir -p "$OUTPUT_DIR/runs"
  local ts; ts="$(date -Iseconds | tr ':' '-')"
  local run_dir="$OUTPUT_DIR/runs/${NODE_NAME}_${LABEL}_${ts}"
  mkdir -p "$run_dir/levels"

  local files="$run_dir/files.txt"
  build_file_list "$files"
  local n; n="$(wc -l < "$files" | tr -d ' ')"
  [[ "$n" -gt 0 ]] || die "No files to hash."

  local leaf="$run_dir/leaf_hashes.txt"
  : > "$leaf"
  while IFS= read -r f; do
    h="$(hash_file "$hasher" "$f")"
    printf "%s  %s\n" "$h" "$f" >> "$leaf"
  done < "$files"
  sort "$leaf" -o "$leaf"

  awk '{print $1}' "$leaf" > "$run_dir/levels/level_0.txt"
  local level=0 cur="$run_dir/levels/level_0.txt"
  while true; do
    local count; count="$(wc -l < "$cur" | tr -d ' ')"
    [[ "$count" -le 1 ]] && break
    local next="$run_dir/levels/level_$((level+1)).txt"
    : > "$next"
    mapfile -t arr < "$cur"
    i=0
    while [[ $i -lt ${#arr[@]} ]]; do
      left="${arr[$i]}"
      if [[ $((i+1)) -lt ${#arr[@]} ]]; then right="${arr[$((i+1))]}"; else right="$left"; fi
      hash_pair_hex "$hasher" "$left" "$right" >> "$next"
      echo "" >> "$next"
      i=$((i+2))
    done
    grep -v '^$' "$next" > "$next.tmp" && mv "$next.tmp" "$next"
    level=$((level+1)); cur="$next"
  done

  root_hex="$(head -n 1 "$cur")"
  [[ -n "$root_hex" ]] || die "Failed to compute root."

  cat > "$run_dir/ROOT.txt" <<EOF
root_hex=$root_hex
hasher=BLAKE3
leaves=$n
label=$LABEL
node=$NODE_NAME
timestamp=$(date -Iseconds)
EOF

  cat > "$run_dir/PROOF.json" <<EOF
{
  "skill": "merkle-forest",
  "version": "1.0.0",
  "timestamp": "$(date -Iseconds)",
  "node": "$NODE_NAME",
  "label": "$LABEL",
  "hasher": "BLAKE3",
  "leaf_count": $n,
  "root_hex": "$root_hex",
  "artifacts": {"root":"ROOT.txt","proof":"PROOF.json","leaf_hashes":"leaf_hashes.txt"}
}
EOF

  echo "$run_dir" > "$OUTPUT_DIR/last_run_dir.txt"
  log_info "Run created: $run_dir"
  log_info "ROOT: $root_hex"
}
main "$@"