import { isManagerRequest, managerForbidden } from "../../../lib/user-auth";
import { runInBackground } from "../../../lib/background";
import {
  parseResourceImportFile,
  RESOURCE_IMPORT_MAX_BYTES,
  RESOURCE_IMPORT_MAX_ROWS,
  resourceImportMissingFields,
  type ResourceImportRow,
} from "../../../lib/resource-import";
import {
  analyzeRows,
  enrichRows,
  loadAccounts,
  mergeExistingFields,
  writeAnalyzedRows,
  RESOURCE_IMPORT_SYNC_ENRICH_ROWS,
  type AnalyzedRow,
  type AccountRow,
} from "../../../lib/resource-write";

const RESOURCE_IMPORT_PREVIEW_ROWS = 100;

function summarize(rows: AnalyzedRow[]) {
  return {
    total: rows.length,
    create: rows.filter((row) => row.action === "create").length,
    update: rows.filter((row) => row.action === "update").length,
    error: rows.filter((row) => row.action === "error").length,
  };
}

function previewAnalyzedRows(rows: AnalyzedRow[]) {
  const errorRows = rows.filter((row) => row.action === "error");
  if (errorRows.length === 0) {
    return rows.slice(0, RESOURCE_IMPORT_PREVIEW_ROWS);
  }
  const importableRows = rows.filter((row) => row.action !== "error");
  return [
    ...errorRows.slice(0, RESOURCE_IMPORT_PREVIEW_ROWS),
    ...importableRows.slice(
      0,
      Math.max(0, RESOURCE_IMPORT_PREVIEW_ROWS - errorRows.length),
    ),
  ];
}

function deferredEnrichmentCount(rows: ResourceImportRow[]) {
  return rows.filter(
    (row) =>
      row.errors.length === 0 &&
      row.profileUrl &&
      resourceImportMissingFields(row).length > 0,
  ).length;
}

async function enrichImportedRowsInBackground(rows: ResourceImportRow[]) {
  const accounts = await loadAccounts();
  const baselineRows = mergeExistingFields(rows, accounts.results);
  const missingRows = baselineRows.filter(
    (row) =>
      row.errors.length === 0 &&
      row.profileUrl &&
      resourceImportMissingFields(row).length > 0,
  );
  if (missingRows.length === 0) return;
  const enriched = await enrichRows(missingRows, accounts.results);
  const latestAccounts = await loadAccounts();
  const analyzed = analyzeRows(enriched, latestAccounts.results).filter(
    (row) => row.action !== "error",
  );
  await writeAnalyzedRows(analyzed);
}

export async function POST(request: Request) {
  if (!(await isManagerRequest(request))) return managerForbidden();
  try {
    const form = await request.formData();
    const file = form.get("file");
    const mode = String(form.get("mode") ?? "preview");
    if (!(file instanceof File)) {
      return Response.json({ error: "请选择需要导入的 Excel 文件" }, { status: 400 });
    }
    if (file.size <= 0 || file.size > RESOURCE_IMPORT_MAX_BYTES) {
      return Response.json({ error: "文件不能为空，且不能超过 20MB" }, { status: 400 });
    }
    const rows = parseResourceImportFile(file.name, new Uint8Array(await file.arrayBuffer()));
    const accounts = await loadAccounts();
    const accountRows: AccountRow[] = accounts.results;
    const shouldEnrichSynchronously = rows.length <= RESOURCE_IMPORT_SYNC_ENRICH_ROWS;
    const preparedRows = shouldEnrichSynchronously
      ? await enrichRows(rows, accountRows)
      : mergeExistingFields(rows, accountRows);
    const analyzed = analyzeRows(preparedRows, accountRows);
    const summary = summarize(analyzed);
    const importableRows = analyzed.filter((row) => row.action !== "error");
    const importableRowNumbers = new Set(
      importableRows.map((row) => row.rowNumber),
    );
    const importablePreparedRows = preparedRows.filter((row) =>
      importableRowNumbers.has(row.rowNumber),
    );
    const deferredEnrichment = shouldEnrichSynchronously
      ? 0
      : deferredEnrichmentCount(importablePreparedRows);
    if (mode !== "commit") {
      return Response.json({
        summary,
        rows: previewAnalyzedRows(analyzed).map((row) => ({
          rowNumber: row.rowNumber,
          platform: row.platform,
          nickname: row.nickname,
          publicAccountId: row.publicAccountId,
          profileUrl: row.profileUrl,
          ipLocation: row.ipLocation,
          followers: row.followers,
          gender: row.gender,
          bio: row.bio,
          tags: row.tags,
          cooperationSource: row.cooperationSource,
          action: row.action,
          errors: row.errors,
        })),
        truncated: analyzed.length > RESOURCE_IMPORT_PREVIEW_ROWS,
        deferredEnrichment,
        maxRows: RESOURCE_IMPORT_MAX_ROWS,
      });
    }
    if (importableRows.length === 0) {
      return Response.json(
        { error: "没有可导入的有效账号，请修正异常数据后重新上传", summary },
        { status: 400 },
      );
    }
    await writeAnalyzedRows(importableRows);
    if (deferredEnrichment > 0) {
      const importableSourceRows = rows.filter((row) =>
        importableRowNumbers.has(row.rowNumber),
      );
      runInBackground(
        enrichImportedRowsInBackground(importableSourceRows),
        "bulk resource profile enrichment",
      );
    }
    return Response.json({
      summary,
      deferredEnrichment,
      message: `已导入 ${summary.create} 个新账号，更新 ${summary.update} 个已有账号${
        summary.error > 0 ? `；跳过 ${summary.error} 条异常数据` : ""
      }${
        deferredEnrichment > 0
          ? `；${deferredEnrichment} 个账号的缺失公开资料将在后台补全`
          : ""
      }`,
    });
  } catch (error) {
    const message = error instanceof Error ? error.message : "导入失败";
    return Response.json({ error: message }, { status: 400 });
  }
}