import { useEffect, useState } from 'react';
import { useParams } from 'react-router-dom';
import Typography from 'antd/es/typography';
import Card from 'antd/es/card';
import Upload from 'antd/es/upload';
import Button from 'antd/es/button';
import Input from 'antd/es/input';
import Alert from 'antd/es/alert';
import Spin from 'antd/es/spin';
import Space from 'antd/es/space';
import Checkbox from 'antd/es/checkbox';
import { UploadOutlined } from '@ant-design/icons';
import type { UploadFile } from 'antd/es/upload/interface';
import { fetchIntakeLink, submitItem } from './intakeApi';
import type { LinkState } from './intakeApi';

const { Title, Paragraph } = Typography;
const { TextArea } = Input;

/**
 * Where someone with no account sends in photos of one item (#222).
 *
 * The three types the server will accept, and the same per-request cap. Listed
 * here so the file picker offers exactly what will be taken and the count is
 * bounded before anything is uploaded — but the server checks both again,
 * because everything on this page is under the sender's control.
 */
const ACCEPT = 'image/jpeg,image/png,image/webp';
const MAX_IMAGES = 6;

export default function Submit() {
  const { token = '' } = useParams();
  const [state, setState] = useState<LinkState>({ kind: 'unusable' });
  const [checking, setChecking] = useState(true);
  const [files, setFiles] = useState<UploadFile[]>([]);
  const [note, setNote] = useState('');
  // Ticked by default. Most items look better cut out, and a submitter who
  // wants their kitchen table in the photograph can say so — the reverse
  // default would mean almost nobody got it.
  const [removeBackground, setRemoveBackground] = useState(true);
  const [sending, setSending] = useState(false);
  const [sent, setSent] = useState(false);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    let cancelled = false;
    void fetchIntakeLink(token).then((result) => {
      // The token can change if the URL does, and a late response from the
      // previous one would otherwise overwrite the current answer.
      if (cancelled) return;
      setState(result);
      setChecking(false);
    });
    return () => {
      cancelled = true;
    };
  }, [token]);

  async function send() {
    setSending(true);
    setError(null);

    const result = await submitItem(
      token,
      // originFileObj is what antd hands back for a file it did not upload
      // itself; beforeUpload returning false is what keeps them here. flatMap
      // rather than map-then-filter because a type predicate cannot narrow to
      // File here — antd's RcFile extends it, so the predicate would widen.
      files.flatMap((f) => (f.originFileObj ? [f.originFileObj] : [])),
      note,
      removeBackground
    );

    setSending(false);
    if (result.ok) {
      setSent(true);
      return;
    }
    setError(result.error);
  }

  if (checking) {
    return (
      <div style={{ maxWidth: 640, margin: '48px auto', padding: '0 16px', textAlign: 'center' }}>
        <Spin />
      </div>
    );
  }

  // Kept apart from the state below on purpose. The two need opposite
  // reactions — wait a moment, versus go and ask for a different link — so
  // telling a throttled sender their link was dead would send them to fetch a
  // replacement that could not have helped.
  if (state.kind === 'throttled') {
    return (
      <div style={{ maxWidth: 640, margin: '48px auto', padding: '0 16px' }}>
        <Card>
          <Title level={3}>Too many requests just now</Title>
          <Paragraph>
            Your link is fine — this page has just been asked for too many times from your
            connection. Wait a minute and reload.
          </Paragraph>
        </Card>
      </div>
    );
  }

  // One state for unknown, revoked and used-up alike, matching the server's
  // single 404. Saying which it was would tell a stranger whether a link they
  // guessed at exists.
  if (state.kind === 'unusable') {
    return (
      <div style={{ maxWidth: 640, margin: '48px auto', padding: '0 16px' }}>
        <Card>
          <Title level={3}>This link is not active</Title>
          <Paragraph>
            It may have been turned off, or already used as many times as it was meant for. Ask
            whoever sent it to you for a new one.
          </Paragraph>
        </Card>
      </div>
    );
  }

  if (sent) {
    return (
      <div style={{ maxWidth: 640, margin: '48px auto', padding: '0 16px' }}>
        <Card>
          <Title level={3}>Thank you — it arrived</Title>
          <Paragraph>
            Somebody will look at your photos and write it up. Nothing is listed for sale until they
            have.
          </Paragraph>
          <Button
            onClick={() => {
              setFiles([]);
              setNote('');
              setRemoveBackground(true);
              setSent(false);
            }}
          >
            Send another item
          </Button>
        </Card>
      </div>
    );
  }

  return (
    <div style={{ maxWidth: 640, margin: '48px auto', padding: '0 16px' }}>
      <Card>
        <Title level={3}>Send in an item</Title>
        <Paragraph>
          Photos of one item, and anything you know about it. Send each item separately.
        </Paragraph>

        <Space direction="vertical" size="middle" style={{ width: '100%' }}>
          <Upload
            accept={ACCEPT}
            multiple
            listType="picture"
            maxCount={MAX_IMAGES}
            fileList={files}
            // Returning false stops antd uploading each file the moment it is
            // picked; they are sent together by `send` instead, which is what
            // makes this one request the server can accept or refuse as a unit.
            beforeUpload={() => false}
            onChange={({ fileList }) => setFiles(fileList)}
          >
            <Button icon={<UploadOutlined />}>Choose photos</Button>
          </Upload>

          <TextArea
            rows={4}
            value={note}
            onChange={(e) => setNote(e.target.value)}
            aria-label="Anything you know about this item"
            placeholder="What is it, what is it made of, how big, what condition, where did it come from? Anything you know helps — a photo cannot show any of it."
          />

          {state.kind === 'usable' && state.link.backgroundRemoval && (
            <Checkbox
              checked={removeBackground}
              onChange={(e) => setRemoveBackground(e.target.checked)}
            >
              {/* Described by what it does, not by how. Nobody sending in a
                  vase knows what a cut-out or an alpha channel is. */}
              Remove the background from my photos
            </Checkbox>
          )}

          {error && <Alert type="error" message={error} showIcon />}

          <Button type="primary" onClick={send} loading={sending} disabled={files.length === 0}>
            Send
          </Button>
        </Space>
      </Card>
    </div>
  );
}