#!/bin/bash
# Exit codes: 0 healthy, 1 degraded, 2 unhealthy/invalid invocation.

set -uo pipefail

GOCHAT_HOST="${GOCHAT_HOST:-localhost}"
GOCHAT_PORT="${GOCHAT_PORT:-3000}"
GOCHAT_METRICS_PORT="${GOCHAT_METRICS_PORT:-${GOCHAT_PORT}}"
TIMEOUT="${TIMEOUT:-5}"
FULL_CHECK=false
JSON_OUTPUT=false
RESULTS=()
CRITICAL_FAIL=0
DEGRADED_FAIL=0

for arg in "$@"; do
  [[ "${arg}" == "--json" ]] && JSON_OUTPUT=true
done

usage_error() {
  if [[ "${JSON_OUTPUT}" == "true" ]]; then
    printf '{"error":"%s","checks":[],"summary":{"critical_failures":1,"degraded_failures":0}}\n' "$1"
  else
    printf 'health_check: %s\n' "$1" >&2
  fi
  exit 2
}

while [[ $# -gt 0 ]]; do
  case "$1" in
    --full) FULL_CHECK=true; shift ;;
    --json) JSON_OUTPUT=true; shift ;;
    --timeout)
      [[ $# -ge 2 && "$2" =~ ^[1-9][0-9]*$ ]] || usage_error "--timeout requires a positive integer"
      TIMEOUT="$2"
      shift 2
      ;;
    --help)
      if [[ "${JSON_OUTPUT}" == "true" ]]; then
        printf '{"usage":"health_check.sh [--full] [--json] [--timeout SECONDS]"}\n'
      else
        printf 'Usage: %s [--full] [--json] [--timeout SECONDS]\n' "$0"
      fi
      exit 0
      ;;
    *) usage_error "unknown option" ;;
  esac
done

BASE_URL="http://${GOCHAT_HOST}:${GOCHAT_PORT}"
METRICS_URL="http://${GOCHAT_HOST}:${GOCHAT_METRICS_PORT}"

check_result() {
  local name="$1" status="$2" detail="$3"
  RESULTS+=("${name}|${status}|${detail}")
  [[ "${status}" == "CRITICAL_FAIL" ]] && CRITICAL_FAIL=$((CRITICAL_FAIL + 1))
  [[ "${status}" == "DEGRADED" ]] && DEGRADED_FAIL=$((DEGRADED_FAIL + 1))
}

check_url() {
  local name="$1" severity="$2" url="$3" ok_detail="$4" fail_detail="$5"
  if curl -fsS --max-time "${TIMEOUT}" -o /dev/null "${url}"; then
    check_result "${name}" "OK" "${ok_detail}"
  else
    check_result "${name}" "${severity}" "${fail_detail}"
  fi
}

check_url "liveness" "CRITICAL_FAIL" "${BASE_URL}/live" "process is alive" "liveness endpoint unreachable"
check_url "readiness" "CRITICAL_FAIL" "${BASE_URL}/ready" "dependencies are ready" "readiness endpoint failed"

if [[ "${FULL_CHECK}" == "true" ]]; then
  check_url "database" "CRITICAL_FAIL" "${BASE_URL}/health?check=database" "database is healthy" "database check failed"
  check_url "redis" "CRITICAL_FAIL" "${BASE_URL}/health?check=redis" "redis is healthy" "redis check failed"
else
  check_result "database" "SKIPPED" "not in full mode"
  check_result "redis" "SKIPPED" "not in full mode"
fi

check_url "metrics" "DEGRADED" "${METRICS_URL}/metrics" "metrics endpoint is responding" "metrics endpoint unreachable"

if [[ "${JSON_OUTPUT}" == "true" ]]; then
  printf '{"checks":['
  for i in "${!RESULTS[@]}"; do
    IFS='|' read -r name status detail <<< "${RESULTS[$i]}"
    [[ $i -gt 0 ]] && printf ','
    printf '{"name":"%s","status":"%s","detail":"%s"}' "${name}" "${status}" "${detail}"
  done
  printf '],"summary":{"critical_failures":%d,"degraded_failures":%d}}\n' "${CRITICAL_FAIL}" "${DEGRADED_FAIL}"
else
  printf '=== GoChat Health Check Report ===\n'
  for result in "${RESULTS[@]}"; do
    IFS='|' read -r name status detail <<< "${result}"
    printf '  %s: %s — %s\n' "${name}" "${status}" "${detail}"
  done
  printf 'Critical failures: %d | Degraded: %d\n' "${CRITICAL_FAIL}" "${DEGRADED_FAIL}"
fi

if [[ ${CRITICAL_FAIL} -gt 0 ]]; then
  exit 2
elif [[ ${DEGRADED_FAIL} -gt 0 ]]; then
  exit 1
fi