// lambdas/settings/index.js
// User settings CRUD — stores config (dynamo, edi, company) and invCounter per user

const { GetCommand, PutCommand } = require("@aws-sdk/lib-dynamodb");
const { getDocClient, TABLES, ok, notFound, badRequest, serverError, parseBody, handler } = require("@ledgerflow/shared");

const TABLE = () => TABLES.SETTINGS;

// Default config shape (mirrors frontend defaults)
const DEFAULT_CONFIG = {
  dynamo: { region: "us-east-1", table: "", key: "", secret: "", fields: { poNumber: "po_number", vendor: "vendor_name", amount: "total_amount", status: "status", issueDate: "issue_date", dueDate: "due_date" }, connected: false },
  edi: { region: "us-east-1", partnershipId: "", key: "", secret: "", senderId: "", receiverId: "", transformerId: "", connected: false },
  company: { name: "", taxId: "", terms: "Net 30", currency: "USD", invPrefix: "INV-", taxRate: 0 },
};

async function getSettings(event, user) {
  const doc = getDocClient();
  const result = await doc.send(new GetCommand({ TableName: TABLE(), Key: { userId: user.userId } }));
  if (!result.Item) {
    return ok({ config: DEFAULT_CONFIG, invCounter: 1 });
  }
  return ok({ config: result.Item.config, invCounter: result.Item.invCounter });
}

async function putSettings(event, user) {
  const body = parseBody(event);
  if (!body.config && body.invCounter === undefined) {
    return badRequest("Request body must include config and/or invCounter");
  }

  const doc = getDocClient();

  // Merge with existing settings so partial updates work
  const existing = await doc.send(new GetCommand({ TableName: TABLE(), Key: { userId: user.userId } }));
  const current = existing.Item || { config: DEFAULT_CONFIG, invCounter: 1 };

  const item = {
    userId: user.userId,
    config: body.config !== undefined ? body.config : current.config,
    invCounter: body.invCounter !== undefined ? body.invCounter : current.invCounter,
    updatedAt: new Date().toISOString(),
  };

  await doc.send(new PutCommand({ TableName: TABLE(), Item: item }));
  return ok({ config: item.config, invCounter: item.invCounter });
}

// ── Router ────────────────────────────────────────────────────────────────────

exports.handler = handler(async (event, context, user) => {
  if (!user) return { statusCode: 401, body: "Unauthorized" };

  const method = event.requestContext?.http?.method || event.httpMethod;

  switch (method) {
    case "GET":    return getSettings(event, user);
    case "PUT":    return putSettings(event, user);
    default:       return badRequest(`Method ${method} not allowed on /settings`);
  }
});