/**
 * 경영성과 대시보드: 엑셀 업로드 파싱·스냅샷 저장·최신 페이로드 조회
 */
const fs = require("fs");
const path = require("path");

function loadXlsx() {
  try {
    return require("xlsx");
  } catch {
    return null;
  }
}

const ROOT = path.join(__dirname, "..");
const DEFAULT_PAYLOAD_PATH = path.join(ROOT, "data", "mgmt-perf-default-payload.json");
const FILE_STATE_PATH = path.join(ROOT, "data", "mgmt-perf-last-state.json");

function loadDefaultPayload() {
  const raw = fs.readFileSync(DEFAULT_PAYLOAD_PATH, "utf8");
  return JSON.parse(raw);
}

/**
 * 매출일보 시트를 읽어 기본 페이로드에 메타를 덧붙입니다. (집계 치환은 추후 확장)
 * @param {Buffer} buffer
 * @param {object} defaultPayload
 */
function buildPayloadFromWorkbook(buffer, defaultPayload) {
  const XLSX = loadXlsx();
  if (!XLSX) {
    const payload = JSON.parse(JSON.stringify(defaultPayload));
    payload._uploadMeta = {
      sheets: [],
      primarySheet: null,
      rowCount: 0,
      importedAt: new Date().toISOString(),
      note: "npm 패키지 `xlsx`가 없어 엑셀을 파싱하지 못했습니다. 프로젝트 루트에서 `npm install` 후 서버를 재시작하세요.",
    };
    return payload;
  }
  const wb = XLSX.read(buffer, { type: "buffer", cellDates: true });
  const names = wb.SheetNames || [];
  const sheetName = names.includes("매출일보") ? "매출일보" : names[0];
  const ws = wb.Sheets[sheetName];
  const matrix = XLSX.utils.sheet_to_json(ws, { header: 1, defval: "" });
  const nonEmptyRows = matrix.filter((r) => Array.isArray(r) && r.some((c) => c !== "" && c != null));
  const payload = JSON.parse(JSON.stringify(defaultPayload));
  payload._uploadMeta = {
    sheets: names,
    primarySheet: sheetName,
    rowCount: nonEmptyRows.length,
    importedAt: new Date().toISOString(),
    note:
      "매출일보 행 수·시트명만 반영했습니다. 차트 수치를 엑셀 집계로 치환하려면 별도 매핑 로직이 필요합니다.",
  };
  return payload;
}

/**
 * @param {import("pg").Pool | null} pgPool
 * @param {{ userEmail: string | null, originalFilename: string, filePath: string, fiscalYear: number, quarter: number, payload: object }} row
 */
async function saveUploadAndSnapshot(pgPool, row) {
  const { userEmail, originalFilename, filePath, fiscalYear, quarter, payload } = row;
  const stat = fs.statSync(filePath);
  if (!pgPool) {
    fs.writeFileSync(
      FILE_STATE_PATH,
      JSON.stringify(
        {
          payload,
          meta: {
            originalFilename,
            fiscalYear,
            quarter,
            savedAt: new Date().toISOString(),
            fileSize: stat.size,
          },
        },
        null,
        2
      ),
      "utf8"
    );
    return { id: null, fileBacked: true };
  }
  const ins = await pgPool.query(
    `INSERT INTO mgmt_perf_uploads (user_email, original_filename, fiscal_year, quarter, file_path, file_size, parse_status)
     VALUES ($1,$2,$3,$4,$5,$6,'ok')
     RETURNING id`,
    [userEmail || null, originalFilename, fiscalYear, quarter, filePath, stat.size]
  );
  const uploadId = ins.rows[0].id;
  await pgPool.query(`INSERT INTO mgmt_perf_snapshots (upload_id, payload) VALUES ($1, $2::jsonb)`, [
    uploadId,
    JSON.stringify(payload),
  ]);
  return { id: uploadId, fileBacked: false };
}

/**
 * @param {import("pg").Pool | null} pgPool
 */
async function getLatestPayloadRow(pgPool) {
  if (pgPool) {
    const r = await pgPool.query(`
      SELECT s.payload, u.fiscal_year, u.quarter, u.original_filename, u.created_at
      FROM mgmt_perf_snapshots s
      JOIN mgmt_perf_uploads u ON u.id = s.upload_id
      ORDER BY u.created_at DESC
      LIMIT 1
    `);
    if (r.rows[0]) {
      const row = r.rows[0];
      return {
        payload: row.payload,
        fiscal_year: row.fiscal_year,
        quarter: row.quarter,
        original_filename: row.original_filename,
        created_at: row.created_at,
      };
    }
  }
  try {
    const j = JSON.parse(fs.readFileSync(FILE_STATE_PATH, "utf8"));
    return {
      payload: j.payload,
      fiscal_year: j.meta?.fiscalYear,
      quarter: j.meta?.quarter,
      original_filename: j.meta?.originalFilename,
      created_at: j.meta?.savedAt ? new Date(j.meta.savedAt) : null,
    };
  } catch {
    return {
      payload: loadDefaultPayload(),
      fiscal_year: new Date().getFullYear(),
      quarter: 1,
      original_filename: null,
      created_at: null,
    };
  }
}

/**
 * @param {import("pg").Pool | null} pgPool
 * @param {number} [limit=20]
 */
async function listUploads(pgPool, limit = 20) {
  if (!pgPool) {
    try {
      const j = JSON.parse(fs.readFileSync(FILE_STATE_PATH, "utf8"));
      return [
        {
          id: "file",
          original_filename: j.meta?.originalFilename,
          fiscal_year: j.meta?.fiscalYear,
          quarter: j.meta?.quarter,
          created_at: j.meta?.savedAt,
          parse_status: "ok",
        },
      ];
    } catch {
      return [];
    }
  }
  const r = await pgPool.query(
    `SELECT id, original_filename, fiscal_year, quarter, parse_status, created_at
     FROM mgmt_perf_uploads
     ORDER BY created_at DESC
     LIMIT $1`,
    [limit]
  );
  return r.rows;
}

module.exports = {
  loadDefaultPayload,
  buildPayloadFromWorkbook,
  saveUploadAndSnapshot,
  getLatestPayloadRow,
  listUploads,
  FILE_STATE_PATH,
};