// kbclient.ts — TypeScript HTTP client for HarborForge.Backend KB
// REST routes. Mirrors HarborForge.PlexumPlugin/internal/kbclient.
// Routes verified against app/api/routers/knowledge.py:
//
//   GET /knowledge-bases[?project=<code>]    list KBs
//   GET /knowledge-bases/{id|code}/topics    list topics in a KB
//   GET /knowledge-bases/{id|code}/tree      full hierarchy
//   GET /knowledge-facts/{id}                single fact
//
// Auth: per-agent HF token (looked up via secret-mgr by caller; this
// client takes a pre-resolved token string). Cross-runtime parity
// note: Plexum client uses plugin-level APIKey from config because
// the Plexum SDK can't reach secret-mgr; openclaw side has agent
// context so we go per-agent here.

export interface KBSummary {
  id: number;
  knowledge_base_code: string;
  title: string;
  description: string;
}

export interface TopicSummary {
  id: number;
  topic: string;
  description: string;
}

export interface FactSummary {
  id: number;
  topic_id: number;
  topic_slug: string;
  title: string;
  snippet: string;
}

export interface Fact {
  id: number;
  kb_code: string;
  topic_slug: string;
  content: string;
}

interface TreeNode {
  id: number;
  topic?: string;
  category?: string;
  title?: string;
  content?: string;
  categories?: TreeNode[];
  facts?: TreeNode[];
}

interface KBTree {
  knowledge_base_code: string;
  topics: TreeNode[];
}

export class KBClient {
  private readonly baseUrl: string;
  private readonly token: string;

  constructor(baseUrl: string, token: string) {
    this.baseUrl = baseUrl.replace(/\/$/, '');
    this.token = token;
  }

  async listKBs(projectCode?: string): Promise<KBSummary[]> {
    let path = '/knowledge-bases';
    if (projectCode) path += '?project=' + encodeURIComponent(projectCode);
    return this.get<KBSummary[]>(path);
  }

  async listTopics(kbCode: string): Promise<TopicSummary[]> {
    if (!kbCode) throw new Error('kbclient: kb-code required');
    return this.get<TopicSummary[]>('/knowledge-bases/' + encodeURIComponent(kbCode) + '/topics');
  }

  /** ListFacts pulls the tree once + flattens facts under topic-ids client-side. */
  async listFacts(kbCode: string, topicIds: number[]): Promise<FactSummary[]> {
    if (!kbCode) throw new Error('kbclient: kb-code required');
    if (!topicIds || topicIds.length === 0) throw new Error('kbclient: topic-ids required');
    const tree = await this.get<KBTree>('/knowledge-bases/' + encodeURIComponent(kbCode) + '/tree');
    const wantTopic = new Set(topicIds);
    const out: FactSummary[] = [];
    for (const topic of tree.topics || []) {
      if (!wantTopic.has(topic.id)) continue;
      this.walkFactsInto(out, topic.id, topic.topic || '', topic.categories || [], topic.facts || []);
    }
    return out;
  }

  private walkFactsInto(
    out: FactSummary[],
    topicId: number,
    topicSlug: string,
    cats: TreeNode[],
    facts: TreeNode[],
  ): void {
    for (const f of facts) {
      out.push({
        id: f.id,
        topic_id: topicId,
        topic_slug: topicSlug,
        title: f.title || '',
        snippet: snippet(f.content || '', 120),
      });
    }
    for (const c of cats) {
      this.walkFactsInto(out, topicId, topicSlug, c.categories || [], c.facts || []);
    }
  }

  /** GetFacts pulls each fact's full body. Backend has no batch route. */
  async getFacts(kbCode: string, factIds: number[]): Promise<Fact[]> {
    if (!kbCode) throw new Error('kbclient: kb-code required');
    const out: Fact[] = [];
    for (const id of factIds) {
      try {
        const node = await this.get<{ id: number; title: string; content: string; topic: string }>(
          '/knowledge-facts/' + id,
        );
        out.push({
          id: node.id,
          kb_code: kbCode,
          topic_slug: node.topic || '',
          content: node.content || '',
        });
      } catch (err: any) {
        if (err?.code === 404) continue; // skip missing
        throw err;
      }
    }
    return out;
  }

  private async get<T>(p: string): Promise<T> {
    const res = await fetch(this.baseUrl + p, {
      method: 'GET',
      headers: {
        Accept: 'application/json',
        ...(this.token ? { Authorization: 'Bearer ' + this.token } : {}),
      },
    });
    if (res.status === 404) {
      const e: any = new Error(`GET ${p}: 404 not found`);
      e.code = 404;
      throw e;
    }
    if (!res.ok) {
      const body = await res.text().catch(() => '');
      throw new Error(`GET ${p}: HTTP ${res.status}: ${truncate(body, 200)}`);
    }
    if (res.status === 204) return undefined as T;
    return (await res.json()) as T;
  }
}

function snippet(s: string, n: number): string {
  s = s.trim();
  return s.length <= n ? s : s.slice(0, n) + '...';
}

function truncate(s: string, n: number): string {
  return s.length > n ? s.slice(0, n) + '...' : s;
}