"use client";
// Uploading a product (or a new revision of one): the hub gives an upload token, then the browser sends the file to
// the catalog itself, so files never pass through the website's server.
import { useRouter } from "next/navigation";
import { useState } from "react";
import { ErrorText } from "@/components/forms";
import { Button } from "@/components/ui/button";
import { Field, FieldDescription, FieldGroup, FieldLabel } from "@/components/ui/field";
import { Input } from "@/components/ui/input";
import { NativeSelect, NativeSelectOption } from "@/components/ui/native-select";
import { Textarea } from "@/components/ui/textarea";
import { startUpload } from "@/app/products/actions";

type Option = { id: string; name: string };

/** Sends form to url with the token, reporting progress; resolves with the catalog's status and JSON answer. */
function send(url: string, token: string, form: FormData, progress: (fraction: number) => void) {
  return new Promise<{ status: number; body: unknown }>((resolve, reject) => {
    const xhr = new XMLHttpRequest();
    xhr.open("POST", url);
    xhr.setRequestHeader("Authorization", `Bearer ${token}`);
    xhr.upload.onprogress = (e) => e.lengthComputable && progress(e.loaded / e.total);
    xhr.onload = () => {
      let body: unknown = null;
      try {
        body = JSON.parse(xhr.responseText);
      } catch {}
      resolve({ status: xhr.status, body });
    };
    xhr.onerror = () => reject(new Error("network"));
    xhr.send(form);
  });
}

export function UploadForm({ catalogs, product }: { catalogs: Option[]; product?: string }) {
  const router = useRouter();
  const [error, setError] = useState("");
  const [progress, setProgress] = useState<number | null>(null);

  async function submit(form: FormData) {
    setError("");
    setProgress(0);
    const start = await startUpload(String(form.get("catalog")), product);
    if ("error" in start) {
      setError(start.error);
      setProgress(null);
      return;
    }
    const body = new FormData();
    body.set("file", form.get("file") as File);
    body.set("notes", String(form.get("notes") ?? ""));
    try {
      const answer = await send(start.url, start.token, body, setProgress);
      const value = answer.body as { product?: unknown; message?: unknown } | null;
      if (answer.status === 201 && typeof value?.product === "string") {
        router.push(`/products/${value.product}`);
        router.refresh();
        return;
      }
      setError(
        typeof value?.message === "string" && value.message
          ? value.message
          : `The catalog refused the upload (${answer.status}).`,
      );
    } catch {
      setError("Couldn't reach the catalog. Try again in a moment.");
    }
    setProgress(null);
  }

  const busy = progress !== null;
  return (
    <form
      onSubmit={(e) => {
        e.preventDefault();
        void submit(new FormData(e.currentTarget));
      }}
    >
      <FieldGroup>
        <Field>
          <FieldLabel htmlFor="catalog">Catalog</FieldLabel>
          <NativeSelect id="catalog" name="catalog" required className="w-full max-w-sm">
            {catalogs.map((c) => (
              <NativeSelectOption key={c.id} value={c.id}>
                {c.name}
              </NativeSelectOption>
            ))}
          </NativeSelect>
        </Field>
        <Field>
          <FieldLabel htmlFor="file">File</FieldLabel>
          <Input id="file" name="file" type="file" accept=".chkn,.zip" required className="max-w-sm" />
          <FieldDescription>A Create Mode .chkn, or a zip of the product&apos;s files.</FieldDescription>
        </Field>
        <Field>
          <FieldLabel htmlFor="notes">{product ? "What changed" : "Notes"}</FieldLabel>
          <Textarea id="notes" name="notes" required={!!product} maxLength={4000} rows={3} />
        </Field>
        <div className="flex items-center gap-3">
          <Button type="submit" disabled={busy}>
            {busy ? "Uploading…" : "Upload"}
          </Button>
          {busy && (
            <div
              className="h-1.5 w-40 overflow-hidden rounded-full bg-muted"
              role="progressbar"
              aria-valuemin={0}
              aria-valuemax={100}
              aria-valuenow={Math.round(progress * 100)}
            >
              <div className="h-full bg-foreground transition-[width]" style={{ width: `${progress * 100}%` }} />
            </div>
          )}
        </div>
        {error && <ErrorText>{error}</ErrorText>}
      </FieldGroup>
    </form>
  );
}