import type { CallableQAItem } from "./types";

export type ChatRole = "assistant" | "user";

export type ChatMessage = {
  id: string;
  role: ChatRole;
  content: string;
  source?: string;
  boundary?: string;
  feedback?: "liked" | "disliked";
  createdAt: string;
};

export type ChatSession = {
  id: string;
  title: string;
  preview: string;
  messages: ChatMessage[];
  updatedAt: string;
  questionCount: number;
};

export type SuggestedQuestion = {
  id: string;
  text: string;
  tags: string[];
};

export const suggestedQuestions: SuggestedQuestion[] = [
  {
    id: "parent-child-emotion",
    text: "孩子一写作业就发脾气，我怎么接住他的情绪？",
    tags: ["亲子关系", "情绪"]
  },
  {
    id: "self-growth",
    text: "我知道要行动，但总是拖延，应该先从哪里开始？",
    tags: ["个人成长", "行动力"]
  },
  {
    id: "marriage-talk",
    text: "伴侣不愿意沟通，我怎么表达才不容易吵起来？",
    tags: ["婚姻关系", "沟通"]
  }
];

export const initialMessages: ChatMessage[] = [
  {
    id: "welcome",
    role: "assistant",
    content:
      "你好，我是千问千答助手。你可以把最近遇到的亲子、关系、情绪或行动问题发给我，我会优先基于已审核的答疑资产给你一个可落地的回应。",
    boundary: "当前为 H5 体验版，一期免登录试用；问答答案只读取后端可调用库。",
    createdAt: "09:30"
  }
];

export function createEmptySession(): ChatSession {
  return {
    id: `session-${Date.now()}`,
    title: "新的问答",
    preview: "还没有开始提问",
    messages: initialMessages,
    updatedAt: new Date().toISOString(),
    questionCount: 0
  };
}

export function summarizeSession(sessionId: string, messages: ChatMessage[]): ChatSession {
  const userMessages = messages.filter((message) => message.role === "user");
  const lastMessage = [...messages].reverse().find((message) => message.role === "assistant" || message.role === "user");
  const firstQuestion = userMessages[0]?.content;

  return {
    id: sessionId,
    title: firstQuestion ? firstQuestion.slice(0, 24) : "新的问答",
    preview: lastMessage?.content.slice(0, 42) ?? "还没有开始提问",
    messages,
    updatedAt: new Date().toISOString(),
    questionCount: userMessages.length
  };
}

function scoreQuestion(question: string, qa: CallableQAItem): number {
  const haystack = [
    qa.standard_question,
    qa.standard_answer,
    qa.primary_topic,
    qa.course_stage,
    ...qa.problem_tags,
    ...qa.similar_questions
  ].join(" ");
  return Array.from(new Set(question.trim().split(""))).reduce((score, char) => {
    if (!char.trim()) return score;
    return haystack.includes(char) ? score + 1 : score;
  }, 0);
}

export function findQaAnswer(question: string, qaItems: CallableQAItem[]) {
  if (qaItems.length === 0) {
    return null;
  }
  const [best] = [...qaItems].sort((left, right) => scoreQuestion(question, right) - scoreQuestion(question, left));
  return best ?? null;
}