#!/usr/bin/env bash
# Summarize Rust compiler errors into a clean, readable log.
# Prefers cargo JSON + jq; falls back to sed/awk parser if jq is unavailable.
# Output file: /tmp/cargo_errors_only.log (override with OUT env var)

set -euo pipefail

OUT=${OUT:-/tmp/cargo_errors_only.log}
PROJECT_ROOT=$(git rev-parse --show-toplevel 2>/dev/null || echo "")
if [[ -n "$PROJECT_ROOT" ]]; then
  cd "$PROJECT_ROOT"
fi

# Ensure colorless output from cargo to avoid ANSI in fallback
export CARGO_TERM_COLOR=never

# Function: JSON mode (best)
run_json_mode() {
  # Capture cargo's exit code from the first command in the pipeline
  set +e
  set +o pipefail
  cargo check --message-format=json -q "$@" 2>/dev/null \
    | jq -r 'select(.reason=="compiler-message" and .message.level=="error") | .message.rendered' \
    | tee "$OUT"
  local cargo_status=${PIPESTATUS[0]}
  set -o pipefail
  set -e
  return "$cargo_status"
}

# Function: Fallback parser (no jq required)
run_fallback_mode() {
  # We intentionally capture stderr (diagnostics) and stdout
  set +e
  set +o pipefail
  cargo check -q "$@" 2>&1 \
    | sed -r 's/\x1B\[[0-9;]*[mK]//g' \
    | awk '
      BEGIN{inerr=0}
      /^warning:/{inerr=0; next}
      /^error(\[|:)/{inerr=1}
      # Drop cargo/rustc warning summaries while still inside an error block
      inerr && /[0-9]+ warnings? emitted/ {next}
      inerr{print}
    ' \
    | tee "$OUT"
  local cargo_status=${PIPESTATUS[0]}
  set -o pipefail
  set -e
  return "$cargo_status"
}

status=0
if command -v jq >/dev/null 2>&1; then
  if ! run_json_mode "$@"; then
    status=$?
  fi
else
  echo "INFO: jq not found; using fallback parser (install jq for best results)." >&2
  if ! run_fallback_mode "$@"; then
    status=$?
  fi
fi

exit "$status"