"use client";
import * as React from "react";
import { Upload } from "lucide-react";
import { Button, type ButtonProps } from "@/components/ui/button";
import { toast } from "@/components/ui/toast";
import { errorMessage } from "@/lib/client/humanize";
import { ClientApiError } from "@/lib/client/api";
import { LIBRARY_ACCEPT } from "./format";
import type { PublicProjectFile } from "@/lib/client/types";

export const LIBRARY_MAX_BYTES = 10 * 1024 * 1024;

/** Uploads files one by one to the library (multipart, same limits as chat attachments). Returns saved files + errors. */
export async function uploadLibraryFiles(files: File[], projectId?: string | null, onProgress?: (done: number, total: number) => void): Promise<{ saved: PublicProjectFile[]; errors: { name: string; message: string }[] }> {
  const saved: PublicProjectFile[] = [];
  const errors: { name: string; message: string }[] = [];
  let done = 0;
  for (const f of files) {
    if (f.size > LIBRARY_MAX_BYTES) {
      errors.push({ name: f.name, message: "Larger than 10 MB" });
    } else {
      const form = new FormData();
      form.append("file", f);
      if (projectId) form.append("projectId", projectId);
      try {
        const res = await fetch("/api/library/files", { method: "POST", body: form, credentials: "same-origin" });
        if (!res.ok) {
          const body = (await res.json().catch(() => ({}))) as { error?: { code?: string; message?: string } };
          throw new ClientApiError(res.status, body.error?.code ?? "HTTP_ERROR", body.error?.message ?? `Upload failed (${res.status})`);
        }
        const body = (await res.json()) as { file: PublicProjectFile };
        saved.push(body.file);
      } catch (e) {
        errors.push({ name: f.name, message: errorMessage(e) });
      }
    }
    done += 1;
    onProgress?.(done, files.length);
  }
  return { saved, errors };
}

/** Summarises an upload batch in toasts. */
export function reportUpload(result: { saved: PublicProjectFile[]; errors: { name: string; message: string }[] }) {
  if (result.saved.length) toast.success(result.saved.length === 1 ? `Added “${result.saved[0].name}”` : `Added ${result.saved.length} files to the library`);
  for (const e of result.errors.slice(0, 3)) toast.error(`Could not upload ${e.name}`, e.message);
  if (result.errors.length > 3) toast.error(`${result.errors.length - 3} more files failed`);
}

export function UploadButton({ projectId, onUploaded, children, size = "md", variant = "primary", className, ...rest }: { projectId?: string | null; onUploaded?: (files: PublicProjectFile[]) => unknown } & Omit<ButtonProps, "onClick">) {
  const inputRef = React.useRef<HTMLInputElement>(null);
  const [busy, setBusy] = React.useState<{ done: number; total: number } | null>(null);

  const onFiles = async (list: FileList | null) => {
    const files = list ? Array.from(list) : [];
    if (!files.length) return;
    setBusy({ done: 0, total: files.length });
    try {
      const result = await uploadLibraryFiles(files, projectId, (done, total) => setBusy({ done, total }));
      reportUpload(result);
      if (result.saved.length) await onUploaded?.(result.saved);
    } finally {
      setBusy(null);
      if (inputRef.current) inputRef.current.value = "";
    }
  };

  return (
    <>
      <input ref={inputRef} type="file" multiple accept={LIBRARY_ACCEPT} className="sr-only" tabIndex={-1} aria-hidden onChange={(e) => void onFiles(e.target.files)} />
      <Button size={size} variant={variant} className={className} loading={Boolean(busy)} onClick={() => inputRef.current?.click()} {...rest}>
        {busy ? (
          <span>
            {busy.done}/{busy.total}
          </span>
        ) : (
          children ?? (
            <>
              <Upload /> Upload
            </>
          )
        )}
      </Button>
    </>
  );
}