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

# CASAN H6 — live alert dispatch (D1).
# Pushes AgentOps alerts to a real HTTP webhook (Slack/Teams/PagerDuty-style
# endpoint) instead of only appending to a local log file. Undelivered alerts
# are queued to a dead-letter file so no alert is silently lost.
#
# Usage:
#   alert-dispatch.sh <alert-json-file>      dispatch one alert (JSON object)
#   alert-dispatch.sh --flush-deadletter     retry alerts that failed delivery
#
# Env:
#   CASAN_ALERT_WEBHOOK          webhook URL (required to dispatch)
#   CASAN_ALERT_STRICT=1         delivery failure => exit 1 (fail-loud); default warn
#   CASAN_ALERT_DEDUP_WINDOW_S   suppress same service/step/type within N s (default 300)
#   CASAN_AGENTOPS_DIR           state dir override (default .specify/agentops)
#
# Greppable outputs:
#   ALERT_DISPATCHED | ALERT_DEDUP_SUPPRESSED | ALERT_DELIVERY_FAILED |
#   ALERT_DEADLETTER_FLUSHED | ALERT_WEBHOOK_UNSET

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/casan-paths.sh"
PROJECT_ROOT="$CASAN_APP_ROOT"
AGENTOPS_DIR="${CASAN_AGENTOPS_DIR:-$CASAN_HARNESS_ROOT/agentops}"
STATE="$AGENTOPS_DIR/alert-dispatch-state.jsonl"
DEADLETTER="$AGENTOPS_DIR/alert-deadletter.jsonl"
WEBHOOK="${CASAN_ALERT_WEBHOOK:-}"
STRICT="${CASAN_ALERT_STRICT:-0}"
DEDUP_S="${CASAN_ALERT_DEDUP_WINDOW_S:-300}"
mkdir -p "$AGENTOPS_DIR"

post_payload() { # <json-payload> — 0 = delivered
  curl -sS -m 5 --retry 2 --retry-delay 1 \
    -H 'Content-Type: application/json' \
    -d "$1" "$WEBHOOK" >/dev/null 2>&1
}

if [[ "${1:-}" == "--flush-deadletter" ]]; then
  if [[ -z "$WEBHOOK" ]]; then
    echo "ALERT_WEBHOOK_UNSET cannot flush dead-letter queue" >&2
    exit 1
  fi
  if [[ ! -s "$DEADLETTER" ]]; then
    echo "ALERT_DEADLETTER_FLUSHED redelivered=0 remaining=0"
    exit 0
  fi
  TMP="$DEADLETTER.tmp"
  : > "$TMP"
  sent=0; kept=0
  while IFS= read -r line; do
    [[ -z "$line" ]] && continue
    if post_payload "$line"; then
      sent=$((sent + 1))
    else
      printf '%s\n' "$line" >> "$TMP"
      kept=$((kept + 1))
    fi
  done < "$DEADLETTER"
  mv "$TMP" "$DEADLETTER"
  echo "ALERT_DEADLETTER_FLUSHED redelivered=$sent remaining=$kept"
  [[ "$kept" -eq 0 ]] || exit 1
  exit 0
fi

ALERT_FILE="${1:-}"
if [[ -z "$ALERT_FILE" || ! -f "$ALERT_FILE" ]]; then
  echo "Usage: alert-dispatch.sh <alert-json-file> | --flush-deadletter" >&2
  exit 64
fi

if [[ -z "$WEBHOOK" ]]; then
  echo "ALERT_WEBHOOK_UNSET alert not dispatched (set CASAN_ALERT_WEBHOOK)" >&2
  [[ "$STRICT" == "1" ]] && exit 1
  exit 0
fi

# Normalize the alert, decide severity, and apply the dedup window.
DECISION="$(python - "$ALERT_FILE" "$STATE" "$DEDUP_S" <<'PY'
import json, sys, time

alert_path, state_path, window = sys.argv[1], sys.argv[2], int(sys.argv[3])
alert = json.load(open(alert_path, encoding="utf-8"))
body = alert.get("body", {}) if isinstance(alert.get("body"), dict) else {}
resource = alert.get("resource", {}) if isinstance(alert.get("resource"), dict) else {}
atype = body.get("alert.type") or alert.get("alert_type") or "unknown"
step = body.get("step.name") or alert.get("step") or "unknown"
service = resource.get("service.name") or alert.get("agent") or "unknown"
critical = {"execution-failed", "circuit-open", "cost-spike", "token-overuse", "audit-gap"}
severity = "CRITICAL" if atype in critical else "WARN"
key = f"{service}/{step}/{atype}"
now = int(time.time())
last = None
try:
    with open(state_path, encoding="utf-8") as fh:
        for line in fh:
            line = line.strip()
            if not line:
                continue
            rec = json.loads(line)
            if rec.get("key") == key:
                last = rec.get("ts")
except OSError:
    pass
if last is not None and now - last < window:
    print("SUPPRESS " + key)
    raise SystemExit(0)
payload = json.dumps({
    "source": "casan-agentops",
    "severity": severity,
    "alert_type": atype,
    "step": step,
    "service": service,
    "dedup_key": key,
    "alert": alert,
})
with open(state_path, "a", encoding="utf-8") as fh:
    fh.write(json.dumps({"key": key, "ts": now}) + "\n")
print("SEND " + payload)
PY
)"

case "$DECISION" in
  SUPPRESS*)
    echo "ALERT_DEDUP_SUPPRESSED key=${DECISION#SUPPRESS } window_s=$DEDUP_S"
    exit 0
    ;;
  SEND*)
    PAYLOAD="${DECISION#SEND }"
    ;;
  *)
    echo "ALERT_DISPATCH_ERROR unparsable alert file: $ALERT_FILE" >&2
    exit 1
    ;;
esac

if post_payload "$PAYLOAD"; then
  echo "ALERT_DISPATCHED webhook=$WEBHOOK"
  exit 0
fi

printf '%s\n' "$PAYLOAD" >> "$DEADLETTER"
echo "ALERT_DELIVERY_FAILED queued=dead-letter webhook=$WEBHOOK" >&2
[[ "$STRICT" == "1" ]] && exit 1
exit 0