src/lib/documents/storage.ts

Linked repository file from this build.

import { z } from "zod";
import { RuleError } from "@/lib/errors";

export const MAX_PDF_BYTES = 10 * 1024 * 1024;

export interface DocumentStorage {
  put(file: File): Promise<string>;
  url(key: string): string;
}

export async function validatePdf(file: File): Promise<void> {
  if (file.size > MAX_PDF_BYTES) throw new RuleError("PDF must be 10 MB or smaller.");
  if (!file.size) throw new RuleError("The PDF is empty.");
  if (
    !file.name.toLowerCase().endsWith(".pdf") ||
    (file.type !== "application/pdf" && file.type !== "")
  )
    throw new RuleError("Select a PDF file.");
  if (new TextDecoder().decode(await file.slice(0, 5).arrayBuffer()) !== "%PDF-")
    throw new RuleError("The file does not have a PDF header.");
}

/** Upload through the configured server adapter. Review metadata stays in Postgres. */
export function createDocumentStorage(): DocumentStorage {
  return {
    async put(file) {
      await validatePdf(file);
      const start = await fetch("/api/documents", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ name: file.name, size: file.size }),
      });
      const upload = await readUploadResponse(start, uploadStartSchema);
      if (upload.mode === "local") {
        const form = new FormData();
        form.append("file", file);
        return (
          await readUploadResponse(
            await fetch("/api/documents", { method: "POST", body: form }),
            uploadCompleteSchema,
          )
        ).key;
      }
      const form = new FormData();
      for (const [name, value] of Object.entries(upload.fields)) form.append(name, value);
      form.append("file", file);
      const uploaded = await fetch(upload.url, { method: "POST", body: form, credentials: "omit" });
      if (!uploaded.ok) throw new RuleError("Unable to upload PDF. Try again.");
      const completed = await fetch("/api/documents", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ uploadId: upload.uploadId }),
      });
      return (await readUploadResponse(completed, uploadCompleteSchema)).key;
    },
    url(key) {
      return `/api/documents/${key}`;
    },
  };
}

const uploadStartSchema = z.discriminatedUnion("mode", [
  z.object({ mode: z.literal("local") }),
  z.object({
    mode: z.literal("neon"),
    uploadId: z.uuid(),
    url: z.url(),
    fields: z.record(z.string(), z.string()),
  }),
]);
const uploadCompleteSchema = z.object({ key: z.uuid() });

async function readUploadResponse<T>(response: Response, schema: z.ZodType<T>): Promise<T> {
  const data: unknown = await response.json().catch(() => null);
  if (!response.ok) {
    const error = z.object({ error: z.string() }).safeParse(data);
    throw new RuleError(error.success ? error.data.error : "Unable to save PDF. Try again.");
  }
  const parsed = schema.safeParse(data);
  if (!parsed.success) throw new RuleError("Invalid upload response. Try again.");
  return parsed.data;
}