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

DEFAULT_CHANNEL="__NAGIENT_DEFAULT_CHANNEL__"
DEFAULT_UPDATE_BASE_URL="__NAGIENT_UPDATE_BASE_URL__"

NAGIENT_CHANNEL="${NAGIENT_CHANNEL:-$DEFAULT_CHANNEL}"
NAGIENT_HOME="${NAGIENT_HOME:-$HOME/.nagient}"
NAGIENT_UPDATE_BASE_URL="${NAGIENT_UPDATE_BASE_URL:-$DEFAULT_UPDATE_BASE_URL}"
NAGIENT_COMPOSE_FILE="${NAGIENT_HOME}/docker-compose.yml"
NAGIENT_ENV_FILE="${NAGIENT_HOME}/.env"
NAGIENT_CONFIG_FILE="${NAGIENT_HOME}/config.toml"
NAGIENT_RELEASES_DIR="${NAGIENT_HOME}/releases"
NAGIENT_BIN_DIR="${NAGIENT_HOME}/bin"

ensure_release_defaults() {
  if [ "$NAGIENT_UPDATE_BASE_URL" = "__NAGIENT_UPDATE_BASE_URL__" ]; then
    echo "NAGIENT_UPDATE_BASE_URL is not configured." >&2
    echo "Use a released installer asset or export NAGIENT_UPDATE_BASE_URL explicitly." >&2
    exit 1
  fi

  if [ "$NAGIENT_CHANNEL" = "__NAGIENT_DEFAULT_CHANNEL__" ]; then
    NAGIENT_CHANNEL="stable"
  fi
}

require_cmd() {
  if ! command -v "$1" >/dev/null 2>&1; then
    echo "Missing required command: $1" >&2
    exit 1
  fi
}

python_cmd() {
  if command -v python3 >/dev/null 2>&1; then
    echo "python3"
    return 0
  fi
  if command -v python >/dev/null 2>&1; then
    echo "python"
    return 0
  fi
  echo "Python 3 is required for manifest parsing." >&2
  exit 1
}

fetch_url() {
  local url="$1"
  if command -v curl >/dev/null 2>&1; then
    curl -fsSL "$url"
    return 0
  fi
  if command -v wget >/dev/null 2>&1; then
    wget -qO- "$url"
    return 0
  fi
  echo "Either curl or wget is required." >&2
  exit 1
}

json_field() {
  local field="$1"
  local payload_file="$2"
  "$(python_cmd)" - "$field" "$payload_file" <<'PY'
import json
import sys

field = sys.argv[1].split(".")
payload = json.loads(open(sys.argv[2], "r", encoding="utf-8").read())
current = payload
for chunk in field:
    current = current[chunk]
print(current)
PY
}

artifact_url() {
  local artifact_name="$1"
  local payload_file="$2"
  "$(python_cmd)" - "$artifact_name" "$payload_file" <<'PY'
import json
import sys

artifact_name = sys.argv[1]
payload = json.loads(open(sys.argv[2], "r", encoding="utf-8").read())
for artifact in payload.get("artifacts", []):
    if artifact.get("name") == artifact_name:
        print(artifact["url"])
        sys.exit(0)
raise SystemExit(f"Artifact not found: {artifact_name}")
PY
}

download_artifact() {
  local url="$1"
  local target="$2"
  mkdir -p "$(dirname "$target")"
  fetch_url "$url" >"$target"
  chmod +x "$target" || true
}

require_cmd docker
ensure_release_defaults
mkdir -p "$NAGIENT_HOME" "$NAGIENT_RELEASES_DIR" "$NAGIENT_BIN_DIR" "$NAGIENT_HOME/runtime"

channel_payload="$(mktemp)"
manifest_payload="$(mktemp)"
trap 'rm -f "$channel_payload" "$manifest_payload"' EXIT

fetch_url "${NAGIENT_UPDATE_BASE_URL%/}/channels/${NAGIENT_CHANNEL}.json" >"$channel_payload"
manifest_url="$(json_field manifest_url "$channel_payload")"
fetch_url "$manifest_url" >"$manifest_payload"

compose_url="$(json_field docker.compose_url "$manifest_payload")"
image="$(json_field docker.image "$manifest_payload")"
version="$(json_field version "$manifest_payload")"
update_url="$(artifact_url update.sh "$manifest_payload")"
uninstall_url="$(artifact_url uninstall.sh "$manifest_payload")"

download_artifact "$compose_url" "$NAGIENT_COMPOSE_FILE"
download_artifact "$update_url" "${NAGIENT_BIN_DIR}/nagient-update"
download_artifact "$uninstall_url" "${NAGIENT_BIN_DIR}/nagient-uninstall"
cp "$manifest_payload" "${NAGIENT_RELEASES_DIR}/current.json"
cp "$manifest_payload" "${NAGIENT_RELEASES_DIR}/${version}.json"

if [ ! -f "$NAGIENT_CONFIG_FILE" ]; then
  cat >"$NAGIENT_CONFIG_FILE" <<EOF
[updates]
channel = "${NAGIENT_CHANNEL}"
base_url = "${NAGIENT_UPDATE_BASE_URL}"

[runtime]
heartbeat_interval_seconds = 30

[docker]
project_name = "nagient"
EOF
fi

cat >"$NAGIENT_ENV_FILE" <<EOF
NAGIENT_IMAGE=${image}
NAGIENT_CHANNEL=${NAGIENT_CHANNEL}
NAGIENT_UPDATE_BASE_URL=${NAGIENT_UPDATE_BASE_URL}
NAGIENT_CONTAINER_NAME=nagient
NAGIENT_DOCKER_PROJECT_NAME=nagient
EOF

docker compose -f "$NAGIENT_COMPOSE_FILE" --env-file "$NAGIENT_ENV_FILE" pull
docker compose -f "$NAGIENT_COMPOSE_FILE" --env-file "$NAGIENT_ENV_FILE" up -d

echo "Nagient ${version} installed into ${NAGIENT_HOME}"
echo "Use ${NAGIENT_BIN_DIR}/nagient-update for future upgrades."