#!/usr/bin/env bash
set -uo pipefail

# @describe Apply a patch to a file at the specified path.
# @option --path! The path of the file to apply to
# @option --contents! The patch to apply to the file
# @env LLM_OUTPUT=/dev/stdout The output path

ROOT_DIR="${LLM_ROOT_DIR:-$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)}"
OUT="${LLM_OUTPUT:-/dev/stdout}"

err() {
  echo "ERROR: $*" >> "$OUT"
  exit 0
}

main() {
  path="${argc_path:-}"
  patch="${argc_contents:-}"

  [[ -z "$path" ]] && err "missing --path"
  [[ -z "$patch" ]] && err "missing --contents"
  [[ ! -e "$path" ]] && err "file not found: $path"
  [[ ! -f "$path" ]] && err "not a regular file: $path"
  [[ ! -r "$path" ]] && err "file not readable: $path"

  new_contents=""
  if ! new_contents="$(awk -f "$ROOT_DIR/utils/patch.awk" "$path" <(printf "%s" "$patch") 2>/tmp/fs_patch.err)"; then
    msg="$(cat /tmp/fs_patch.err 2>/dev/null || true)"
    err "patch apply failed for $path: ${msg:-unknown error}"
  fi

  # Diff in Tool-Output schreiben (damit das LLM es sieht)
  printf "%s" "$new_contents" | git diff --no-index "$path" - >> "$OUT" 2>/dev/null || true

  # Guard kann “abbrechen” -> als ERROR ausgeben, aber exit 0
  if ! "$ROOT_DIR/utils/guard_operation.sh" "Apply changes?" >>"$OUT" 2>&1; then
    err "operation cancelled by user"
  fi

  if ! printf "%s" "$new_contents" > "$path" 2>/tmp/fs_patch_write.err; then
    msg="$(cat /tmp/fs_patch_write.err 2>/dev/null || true)"
    err "failed to write patched file $path: ${msg:-unknown error}"
  fi

  echo "The patch applied to: $path" >> "$OUT"
  exit 0
}

eval "$(argc --argc-eval "$0" "$@")"
main