import { createHash } from "node:crypto";
import type { RowDataPacket } from "mysql2";
import pool from "../../db.js";
import type {
  DemandGap,
  GapReason,
  GapStatus,
} from "../../../shared/assets/assistant.js";
// Store the unmet request and concise analysis context for product feedback, not full sessions or result rows.
let ready: Promise<void> | undefined;
const purge = () =>
  pool.query(
    "DELETE FROM bi_asset_ai_gaps WHERE last_seen < DATE_SUB(UTC_TIMESTAMP(), INTERVAL 90 DAY)",
  );
const SCHEMA = `CREATE TABLE IF NOT EXISTS bi_asset_ai_gaps (
 id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
 user_id VARCHAR(64) NOT NULL, fingerprint CHAR(64) NOT NULL,
 demand VARCHAR(600) NOT NULL, reason VARCHAR(24) NOT NULL, status VARCHAR(24) NOT NULL DEFAULT 'open',
 occurrences INT NOT NULL DEFAULT 1, first_seen DATETIME NOT NULL, last_seen DATETIME NOT NULL,
 UNIQUE KEY user_demand (user_id, fingerprint), KEY last_seen (last_seen)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4`;
async function ensure() {
  if (!ready)
    ready = (async () => {
      // Precreated production tables need no DDL permission.
      try {
        await pool.query("SELECT id FROM bi_asset_ai_gaps LIMIT 0");
      } catch (error) {
        if ((error as { code?: string }).code !== "ER_NO_SUCH_TABLE")
          throw error;
        await pool.query(SCHEMA);
      }
      await purge();
      setInterval(
        () => {
          void purge().catch(() =>
            console.warn("asset_ai_gap_retention_failed"),
          );
        },
        60 * 60 * 1000,
      ).unref();
    })().catch((error) => {
      ready = undefined;
      throw error;
    });
  await ready;
}
export const gapStore = {
  async record(userId: string, demand: string, reason: GapReason) {
    await ensure();
    const fingerprint = createHash("sha256")
      .update(reason + "|" + demand)
      .digest("hex");
    await pool.query(
      `INSERT INTO bi_asset_ai_gaps (user_id,fingerprint,demand,reason,first_seen,last_seen)
      VALUES (?,?,?,?,UTC_TIMESTAMP(),UTC_TIMESTAMP()) ON DUPLICATE KEY UPDATE
      occurrences=occurrences+1, last_seen=UTC_TIMESTAMP(), status=IF(status='resolved','open',status)`,
      [userId, fingerprint, demand, reason],
    );
  },
  async list(userId: string | null, options: { readOnly?: boolean } = {}): Promise<DemandGap[]> {
    if (!options.readOnly) {
      await ensure();
      await purge();
    }
    const [rows] = await pool.query<RowDataPacket[]>(
      `SELECT id,demand,reason,status,occurrences,
      DATE_FORMAT(first_seen,'%Y-%m-%dT%H:%i:%sZ') firstSeen, DATE_FORMAT(last_seen,'%Y-%m-%dT%H:%i:%sZ') lastSeen
      FROM bi_asset_ai_gaps WHERE ${userId ? "user_id = ? AND " : ""}last_seen >= DATE_SUB(UTC_TIMESTAMP(), INTERVAL 90 DAY) ORDER BY last_seen DESC LIMIT 200`,
      userId ? [userId] : [],
    );
    return rows as DemandGap[];
  },
  async update(id: number, status: GapStatus) {
    await ensure();
    await pool.query("UPDATE bi_asset_ai_gaps SET status=? WHERE id=?", [
      status,
      id,
    ]);
  },
};