/**
 * Pure conversion and presentation helpers for the management UI.
 *
 * No function in this module performs I/O or changes backend state. Keeping
 * byte decoding here prevents React views from silently treating arbitrary
 * Component output as readable text.
 */

import { FileCode2, History, LayoutDashboard, Package, Server, Settings } from "lucide-react";
import { BackendCapability, BackendEvent, BackendService } from "./api";

export type View = "overview" | "services" | "instances" | "wit-packages" | "activity" | "settings";
export type ServiceStatus = "running" | "stopped" | "faulted";
export type EventTone = "success" | "warning" | "danger" | "neutral";

export type Service = {
  id: string;
  revision: string;
  description: string;
  artifact: string;
  status: ServiceStatus;
  updatedAt: string;
  memoryMb: number;
  fuel: string;
  deadlineMs: number;
  mailbox: number;
  maxInputKb: number;
  capabilities: BackendCapability[];
  calls: number;
  errors: number;
  latencyMs: number | null;
  active: boolean;
};

export type RuntimeEvent = {
  id: number;
  time: string;
  title: string;
  detail: string;
  tone: EventTone;
};

export type ConnectionState = "connecting" | "online" | "offline";

export const NAV_ITEMS: Array<{
  id: View;
  label: string;
  icon: typeof LayoutDashboard;
}> = [
  { id: "overview", label: "运行概览", icon: LayoutDashboard },
  { id: "services", label: "服务版本", icon: Package },
  { id: "instances", label: "运行实例", icon: Server },
  { id: "wit-packages", label: "WIT 包", icon: FileCode2 },
  { id: "activity", label: "调用记录", icon: History },
  { id: "settings", label: "运行设置", icon: Settings },
];

export const STATUS_META: Record<ServiceStatus, { label: string; className: string }> = {
  running: { label: "运行中", className: "status-running" },
  stopped: { label: "已停止", className: "status-stopped" },
  faulted: { label: "故障", className: "status-faulted" },
};

export function serviceKey(service: Pick<Service, "id" | "revision">) {
  return `${service.id}@${service.revision}`;
}

export function toService(service: BackendService, activeRevision?: string): Service {
  return {
    id: service.id,
    revision: service.revision,
    description: "Wasm Component",
    artifact: service.artifact.split(/[\\/]/).pop() ?? service.artifact,
    status: service.status,
    updatedAt: new Date(service.updated_at_ms).toLocaleString("zh-CN", {
      hour12: false,
    }),
    memoryMb: Math.round(service.limits.memory_bytes / 1024 / 1024),
    fuel: compactNumber(service.limits.fuel_per_call),
    deadlineMs: service.limits.deadline_ms,
    mailbox: service.limits.mailbox_capacity,
    maxInputKb: Math.round(service.limits.max_input_bytes / 1024),
    capabilities: service.capabilities,
    calls: service.calls,
    errors: service.errors,
    latencyMs: service.last_latency_ms,
    active: service.revision === activeRevision,
  };
}

export function toEvent(event: BackendEvent): RuntimeEvent {
  const identity =
    event.service_id && event.revision ? `${event.service_id}@${event.revision}` : "Wasmeld";
  const meta: Record<BackendEvent["kind"], { label: string; tone: EventTone }> = {
    registered: { label: "已注册", tone: "success" },
    unregistered: { label: "已注销", tone: "neutral" },
    deployed: { label: "部署切换", tone: "success" },
    started: { label: "已启动", tone: "success" },
    stopped: { label: "已停止", tone: "neutral" },
    invoked: { label: "调用完成", tone: "success" },
    failed: { label: "操作失败", tone: "danger" },
  };
  return {
    id: event.id,
    time: new Date(event.timestamp_ms).toLocaleTimeString("zh-CN", {
      hour12: false,
    }),
    title: `${identity} ${meta[event.kind].label}`,
    detail: event.message,
    tone: meta[event.kind].tone,
  };
}

export function compactNumber(value: number) {
  if (value >= 1_000_000) return `${value / 1_000_000}M`;
  if (value >= 1_000) return `${value / 1_000}K`;
  return value.toString();
}

export function formatDuration(milliseconds: number) {
  const totalSeconds = Math.floor(milliseconds / 1000);
  const hours = Math.floor(totalSeconds / 3600);
  const minutes = Math.floor((totalSeconds % 3600) / 60);
  const seconds = totalSeconds % 60;
  return hours > 0 ? `${hours}h ${minutes}m` : `${minutes}m ${seconds}s`;
}

export function formatApiHost(value: string) {
  try {
    return new URL(value).host;
  } catch {
    return value;
  }
}

export function parseInvocationInput(value: string, format: "utf8" | "hex") {
  if (format === "utf8") return new TextEncoder().encode(value);
  const compact = value.replace(/\s+/g, "");
  if (compact.length % 2 !== 0 || /[^0-9a-f]/i.test(compact)) {
    throw new Error("HEX 输入必须由成对的十六进制字符组成");
  }
  return Uint8Array.from(compact.match(/.{2}/g)?.map((byte) => Number.parseInt(byte, 16)) ?? []);
}

export function invocationInputSize(value: string, format: "utf8" | "hex") {
  try {
    return parseInvocationInput(value, format).byteLength;
  } catch {
    return 0;
  }
}

export type FormattedInvocationOutput = {
  text: string;
  format: "UTF-8" | "HEX" | "U64 LE";
  automatic: boolean;
};

export function formatHex(bytes: Uint8Array) {
  return Array.from(bytes, (byte) => byte.toString(16).padStart(2, "0")).join(" ");
}

export function decodeReadableUtf8(bytes: Uint8Array) {
  let text: string;
  try {
    text = new TextDecoder("utf-8", { fatal: true }).decode(bytes);
  } catch {
    return null;
  }

  // Valid UTF-8 can still contain terminal controls. Reject them so the output
  // panel cannot render invisible or misleading content; tab/newline/CR remain
  // useful for ordinary textual responses.
  for (const character of text) {
    const codePoint = character.codePointAt(0) ?? 0;
    const allowedWhitespace = codePoint === 0x09 || codePoint === 0x0a || codePoint === 0x0d;
    if ((codePoint < 0x20 && !allowedWhitespace) || codePoint === 0x7f) {
      return null;
    }
  }
  return text;
}

export function formatInvocationOutput(
  service: Service,
  output: Uint8Array,
  format: "utf8" | "hex",
) {
  // Counter is the one built-in example with a documented numeric wire
  // format. Other eight-byte services remain generic bytes and are not
  // guessed as integers.
  if (service.id === "counter" && output.byteLength === 8) {
    return {
      text: new DataView(output.buffer, output.byteOffset, output.byteLength)
        .getBigUint64(0, true)
        .toString(),
      format: "U64 LE",
      automatic: false,
    } satisfies FormattedInvocationOutput;
  }
  if (format === "hex") {
    return {
      text: formatHex(output) || "(empty)",
      format: "HEX",
      automatic: false,
    } satisfies FormattedInvocationOutput;
  }

  // UTF-8 decoding is fatal rather than replacement-based. If one byte is
  // invalid or contains a disallowed control, show the exact bytes as HEX.
  const text = decodeReadableUtf8(output);
  if (text !== null) {
    return {
      text: text || "(empty)",
      format: "UTF-8",
      automatic: false,
    } satisfies FormattedInvocationOutput;
  }
  return {
    text: formatHex(output),
    format: "HEX",
    automatic: true,
  } satisfies FormattedInvocationOutput;
}