import type { ProjectContext, ProtocolVersion, Session, SessionContext } from "./protocol.js";

export class ProtocolParseError extends Error {
  constructor(message: string) {
    super(message);
    this.name = "ProtocolParseError";
  }
}

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}

function hasString(value: Record<string, unknown>, key: string): boolean {
  return typeof value[key] === "string" && value[key] !== "";
}

export function isProtocolVersion(value: unknown): value is ProtocolVersion {
  return isRecord(value) && ["major", "minor", "patch"].every(
    (key) => Number.isInteger(value[key]) && (value[key] as number) >= 0,
  );
}

export function isProjectContext(value: unknown): value is ProjectContext {
  return isRecord(value) && hasString(value, "server_id") && hasString(value, "project_id");
}

export function isSessionContext(value: unknown): value is SessionContext {
  return isProjectContext(value) && hasString(value, "session_id");
}

export function isSession(value: unknown): value is Session {
  if (!isRecord(value) || !isSessionContext(value)) return false;
  return hasString(value, "name")
    && hasString(value, "state")
    && hasString(value, "first_seen_at")
    && hasString(value, "last_active_at")
    && Array.isArray(value.tags)
    && value.tags.every((tag) => typeof tag === "string")
    && Array.isArray(value.capabilities)
    && value.capabilities.every((capability) => typeof capability === "string");
}

export function parseSession(value: unknown): Session {
  if (!isSession(value)) {
    throw new ProtocolParseError("无效的 Session：缺少上下文字段或标准字段类型错误");
  }
  return value;
}