// KBDB 基本盤 API client — 唯一對外通道（API-as-Wall）
//
// 鐵律：插件不碰表、零 SQL。所有讀寫只透過基本盤 HTTP API（arcrun/kbdb）。
// 這裡只發 fetch，絕無 .prepare / D1。base URL 由 KBDB_BASE_URL env var 注入（可留空於本地測試以 mock 替代）。
//
// 對齊基本盤真實契約（讀 arcrun/kbdb/src 2026-06-14）：
//   欄位用 entry_type / owner_id（非 type / user_id）；回應包在 { success, ... }。

export type BaseEntry = {
  id: string;
  content: string | null;
  entry_type: string;
  owner_id: string | null;
  parent_id?: string | null;
  page_name?: string | null;
  created_at?: number;
  updated_at?: number;
};

export type BaseRecord = {
  record_id: string;
  template: string;
  values: Record<string, string>;
};

export type CreateEntryInput = {
  content: string | null;
  entry_type: string;
  owner_id?: string;
  parent_id?: string;
  page_name?: string;
};

/** 基本盤 API client。所有方法 = 一個 HTTP 呼叫，零 SQL。 */
export class KbdbClient {
  constructor(
    private readonly baseUrl: string,
    private readonly token?: string,
  ) {
    if (!baseUrl) {
      throw new Error('KBDB_BASE_URL 未設定：插件需指向基本盤 API（不可直連 D1）');
    }
  }

  private async req<T>(method: string, path: string, body?: unknown): Promise<T> {
    const headers: Record<string, string> = { 'Content-Type': 'application/json' };
    if (this.token) headers['Authorization'] = `Bearer ${this.token}`;

    const res = await fetch(this.baseUrl.replace(/\/$/, '') + path, {
      method,
      headers,
      body: body === undefined ? undefined : JSON.stringify(body),
    });

    const json = (await res.json().catch(() => null)) as any;
    if (!res.ok || (json && json.success === false)) {
      const msg = json?.error ?? `${res.status} ${res.statusText}`;
      throw new Error(`[kbdb-base] ${method} ${path}: ${msg}`);
    }
    return json as T;
  }

  // --- entries ---

  async createEntry(input: CreateEntryInput): Promise<BaseEntry> {
    const { entry } = await this.req<{ entry: BaseEntry }>('POST', '/entries', input);
    return entry;
  }

  async getEntry(id: string): Promise<BaseEntry | null> {
    try {
      const { entry } = await this.req<{ entry: BaseEntry }>('GET', `/entries/${encodeURIComponent(id)}`);
      return entry;
    } catch {
      return null;
    }
  }

  async listEntries(filters: {
    entry_type?: string;
    owner_id?: string;
    parent_id?: string;
    page_name?: string;
    limit?: number;
    offset?: number;
  } = {}): Promise<BaseEntry[]> {
    const { entries } = await this.req<{ entries: BaseEntry[] }>('GET', '/entries' + qs(filters));
    return entries ?? [];
  }

  /** 基本盤 D1 LIKE keyword 搜尋（語意搜尋屬 optional embed 模組，base 沒有）。 */
  async searchEntries(q: string, owner_id?: string): Promise<BaseEntry[]> {
    const { entries } = await this.req<{ entries: BaseEntry[] }>(
      'GET',
      '/entries/search' + qs({ q, owner_id }),
    );
    return entries ?? [];
  }

  async updateEntry(id: string, patch: Partial<CreateEntryInput>): Promise<BaseEntry | null> {
    try {
      const { entry } = await this.req<{ entry: BaseEntry }>('PATCH', `/entries/${encodeURIComponent(id)}`, patch);
      return entry;
    } catch {
      return null;
    }
  }

  async deleteEntry(id: string): Promise<void> {
    await this.req('DELETE', `/entries/${encodeURIComponent(id)}`);
  }

  // --- templates（= 替代建表；插件要新類型只能建 template） ---

  async ensureTemplate(name: string, slots: string[], description?: string): Promise<void> {
    const existing = await this.req<{ id?: string; slots?: string[] } | { error: string }>(
      'GET',
      `/templates/${encodeURIComponent(name)}`,
    ).catch(() => null);

    // 全新 template → 建。
    if (!existing || !(existing as any).id) {
      await this.req('POST', '/templates', { name, slots, description, created_by: 'kbdb-graph' });
      return;
    }

    // 既有 template → 補缺 slot（不 early-return；否則 seed 後新增的 slot 永遠進不來）。
    // 走 base PATCH /templates/:id 增 slot；既有環境免另跑遷移腳本即收斂。
    const have = new Set((existing as any).slots ?? []);
    const missing = slots.filter((s) => !have.has(s));
    if (missing.length === 0) return;
    await this.req('PATCH', `/templates/${encodeURIComponent((existing as any).id)}`, {
      slots: [...have, ...missing],
    });
  }

  // --- records（= template 實例，填 slot） ---

  async createRecord(template: string, values: Record<string, string>, owner_id?: string): Promise<string> {
    const { record } = await this.req<{ record: { record_id: string } }>('POST', '/records', {
      template,
      values,
      owner_id,
    });
    return record.record_id;
  }

  async getRecord(recordId: string): Promise<BaseRecord | null> {
    try {
      const { record } = await this.req<{ record: BaseRecord }>('GET', `/records/${encodeURIComponent(recordId)}`);
      return record;
    } catch {
      return null;
    }
  }

  /** 翻 record 的 slot 值（base PATCH /records/:id）。deprecate（翻 status）與 rollback 都靠它。 */
  async updateRecord(recordId: string, values: Record<string, string>): Promise<void> {
    await this.req('PATCH', `/records/${encodeURIComponent(recordId)}`, { values });
  }

  async listRecordsByTemplate(template: string, owner_id?: string): Promise<BaseRecord[]> {
    const { records } = await this.req<{ records: BaseRecord[] }>(
      'GET',
      `/records/by-template/${encodeURIComponent(template)}` + qs({ owner_id }),
    );
    return records ?? [];
  }
}

function qs(params: Record<string, string | number | undefined>): string {
  const parts = Object.entries(params)
    .filter(([, v]) => v !== undefined && v !== '')
    .map(([k, v]) => `${encodeURIComponent(k)}=${encodeURIComponent(String(v))}`);
  return parts.length ? `?${parts.join('&')}` : '';
}

/** 從 Bindings 建 client。KBDB_BASE_URL 未設時拋錯（不准 fallback 直連 D1）。 */
export function makeKbdbClient(env: { KBDB_BASE_URL?: string; KBDB_INTERNAL_TOKEN?: string }): KbdbClient {
  return new KbdbClient(env.KBDB_BASE_URL ?? '', env.KBDB_INTERNAL_TOKEN);
}