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

# CASAN Level 5 fallback runner.
# Usage:
#   model-fallback.sh <output-file> --primary '<cmd>' --fallback '<cmd>'

OUTPUT_FILE="${1:-}"
shift || true

PRIMARY_CMD=""
FALLBACK_CMD=""

while [[ "$#" -gt 0 ]]; do
  case "$1" in
    --primary)
      PRIMARY_CMD="${2:-}"
      shift 2
      ;;
    --fallback)
      FALLBACK_CMD="${2:-}"
      shift 2
      ;;
    *)
      echo "Unknown argument: $1" >&2
      exit 64
      ;;
  esac
done

if [[ -z "$OUTPUT_FILE" || -z "$PRIMARY_CMD" || -z "$FALLBACK_CMD" ]]; then
  echo "Usage: model-fallback.sh <output-file> --primary '<cmd>' --fallback '<cmd>'" >&2
  exit 64
fi

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/casan-paths.sh"
PROJECT_ROOT="$CASAN_APP_ROOT"
LOG_DIR="$CASAN_STATE_ROOT/logs/level5"
mkdir -p "$LOG_DIR" "$(dirname "$OUTPUT_FILE")"
FALLBACK_LOG="$LOG_DIR/fallback.jsonl"
TRACE_ID="$(uuidgen 2>/dev/null | tr '[:upper:]' '[:lower:]' || printf 'fallback-%s-%s' "$(date +%s)" "$$")"
TIMESTAMP="$(date -u +"%Y-%m-%dT%H:%M:%SZ")"

TMP_PRIMARY="$(mktemp)"
TMP_FALLBACK="$(mktemp)"

set +e
bash -c "$PRIMARY_CMD" > "$TMP_PRIMARY" 2>&1
PRIMARY_RC=$?
set -e

ROUTE="primary"
FINAL_RC="$PRIMARY_RC"
if [[ "$PRIMARY_RC" -eq 0 && -s "$TMP_PRIMARY" ]]; then
  cp "$TMP_PRIMARY" "$OUTPUT_FILE"
else
  ROUTE="fallback"
  set +e
  bash -c "$FALLBACK_CMD" > "$TMP_FALLBACK" 2>&1
  FALLBACK_RC=$?
  set -e
  FINAL_RC="$FALLBACK_RC"
  cp "$TMP_FALLBACK" "$OUTPUT_FILE"
fi

printf '{"timestamp":"%s","trace_id":"%s","harness":"L5-model-fallback","primary_exit":%s,"route":"%s","final_exit":%s,"output":"%s"}\n' \
  "$TIMESTAMP" "$TRACE_ID" "$PRIMARY_RC" "$ROUTE" "$FINAL_RC" "$OUTPUT_FILE" >> "$FALLBACK_LOG"

echo "FALLBACK_ROUTE route=$ROUTE primary_exit=$PRIMARY_RC final_exit=$FINAL_RC output=$OUTPUT_FILE"
exit "$FINAL_RC"