#!/usr/bin/env bash
# Shared helper for CLI tool wrappers.
# Usage: source _tool-wrapper <repo> <derivation> <binary> "$@"
#
# - Builds the specific derivation if the binary doesn't exist
# - Rebuilds if any repo file is newer than last build (source changed)
# - Runs the binary with all passed arguments
set -euo pipefail

_REPO="$1"; _DERIV="$2"; _BIN="$3"; shift 3

WORKSPACE_ROOT="${LOGOS_WORKSPACE_ROOT:-$(cd "$(dirname "$0")/.." && pwd)}"
REPO_PATH="$WORKSPACE_ROOT/repos/$_REPO"
RESULT_LINK="$REPO_PATH/result-$_DERIV"
RESULT_BIN="$RESULT_LINK/bin/$_BIN"
STAMP_DIR="$WORKSPACE_ROOT/.build-stamps"
BUILD_STAMP="$STAMP_DIR/${_REPO}--${_DERIV}"

_needs_build() {
  # No binary yet
  [[ ! -x "$RESULT_BIN" ]] && return 0
  # No stamp yet (first build was external)
  [[ ! -f "$BUILD_STAMP" ]] && return 0
  # Any repo file newer than last build
  [[ -n "$(find "$REPO_PATH" -newer "$BUILD_STAMP" \
    -not -path '*/.git/*' -not -path '*/result' -not -path '*/result/*' \
    -not -name '.build-stamp' \
    -print -quit 2>/dev/null)" ]] && return 0
  return 1
}

if _needs_build; then
  echo "Building $_REPO#$_DERIV..." >&2
  nix build --extra-experimental-features "nix-command flakes" \
    "path:$REPO_PATH#$_DERIV" \
    --out-link "$RESULT_LINK"
  mkdir -p "$STAMP_DIR"
  touch "$BUILD_STAMP"
fi

exec "$RESULT_BIN" "$@"