dchain/desktop/src/sections/wallet/SendModal.tsx

// SendModal — a focused little dialog for Transfer tx's. Accepts a
// hex pub, DC-address, or @username and resolves to the Ed25519 pub
// before submitting. Validates amount against balance + min fee.

import React, { useEffect, useMemo, useState } from 'react';
import { useStore } from '@/lib/store';
import { getBalance, resolveAccount } from '@/lib/api';
import { buildTransferTx, submitTx, humanizeTxError } from '@/lib/tx';

const MIN_FEE_UT = 1_000;

function parseAmountT(s: string): number | null {
  const n = parseFloat(s);
  if (!Number.isFinite(n) || n <= 0) return null;
  return Math.round(n * 1_000_000);
}

export function SendModal({
  onClose, onSent,
}: {
  onClose: () => void;
  onSent: () => void;
}): React.ReactElement {
  const keyFile = useStore(s => s.keyFile);

  const [toInput, setToInput] = useState('');
  const [amount,  setAmount]  = useState('');
  const [memo,    setMemo]    = useState('');
  const [busy,    setBusy]    = useState(false);
  const [err,     setErr]     = useState<string | null>(null);
  const [balance, setBalance] = useState<number | null>(null);

  useEffect(() => {
    if (!keyFile) return;
    getBalance(keyFile.pub_key).then(setBalance).catch(() => setBalance(null));
  }, [keyFile]);

  const amountUT = useMemo(() => parseAmountT(amount), [amount]);
  const totalUT  = amountUT === null ? null : amountUT + MIN_FEE_UT;

  const canSend = !!keyFile && !busy && amountUT !== null
                && balance !== null && totalUT !== null && balance >= totalUT
                && toInput.trim().length > 0;

  const submit = async () => {
    if (!keyFile || !canSend || amountUT === null) return;
    setBusy(true); setErr(null);
    try {
      const to = await resolveAccount(toInput);
      if (!to) throw new Error('Can\'t resolve recipient');
      if (to === keyFile.pub_key) throw new Error('Refusing self-transfer');
      const tx = buildTransferTx({
        from:    keyFile.pub_key,
        to,
        amount:  amountUT,
        fee:     MIN_FEE_UT,
        privKey: keyFile.priv_key,
        memo:    memo.trim() || undefined,
      });
      await submitTx(tx);
      onSent();
      onClose();
    } catch (e) {
      setErr(humanizeTxError(e));
    } finally {
      setBusy(false);
    }
  };

  return (
    <Backdrop onClose={busy ? () => {} : onClose}>
      <div style={{
        width: '100%', maxWidth: 460, padding: 20, borderRadius: 16,
        background: '#0a0a0a', border: '1px solid #1f1f1f',
      }}>
        <Header title="Send" onClose={onClose} busy={busy} />
        <div style={{ display: 'flex', flexDirection: 'column', gap: 12 }}>
          <Field label="To" hint="@username, DC-address or hex pubkey">
            <input
              value={toInput}
              onChange={e => setToInput(e.target.value)}
              placeholder="@alice or DC… or <hex>"
              spellCheck={false}
              autoFocus
              style={inputStyle}
            />
          </Field>
          <Field label="Amount (T)">
            <input
              value={amount}
              onChange={e => setAmount(e.target.value)}
              placeholder="0.0"
              inputMode="decimal"
              style={inputStyle}
            />
            <div style={{ color: '#6a6a6a', fontSize: 11, marginTop: 4 }}>
              Balance: {balance === null ? '…' : `${(balance / 1_000_000).toLocaleString(undefined, { maximumFractionDigits: 6 })} T`}
              {amountUT !== null && (
                <> · Fee: {(MIN_FEE_UT / 1_000_000).toFixed(6)} T</>
              )}
            </div>
          </Field>
          <Field label="Memo (optional)">
            <input
              value={memo}
              onChange={e => setMemo(e.target.value)}
              placeholder="Invoice #42"
              style={inputStyle}
            />
          </Field>
        </div>

        {err && (
          <div style={{
            marginTop: 12, padding: 10, borderRadius: 8,
            background: '#2a1414', color: '#ff9b9b', fontSize: 12,
          }}>{err}</div>
        )}

        <div style={{
          marginTop: 16, display: 'flex', justifyContent: 'flex-end', gap: 10,
        }}>
          <button
            onClick={onClose}
            disabled={busy}
            style={secondaryBtnStyle(busy)}
          >Cancel</button>
          <button
            onClick={submit}
            disabled={!canSend}
            style={primaryBtnStyle(!canSend)}
          >{busy ? '…' : 'Send'}</button>
        </div>
      </div>
    </Backdrop>
  );
}

// ─── Shared modal primitives used by Send/Receive ────────────────────────

function Backdrop({ children, onClose }: { children: React.ReactNode; onClose: () => void }) {
  return (
    <div
      onClick={onClose}
      style={{
        position: 'fixed', inset: 0, zIndex: 20,
        background: 'rgba(0,0,0,0.7)',
        display: 'flex', alignItems: 'center', justifyContent: 'center',
        padding: 24,
      }}
    >
      <div onClick={e => e.stopPropagation()} style={{ width: '100%', display: 'flex', justifyContent: 'center' }}>
        {children}
      </div>
    </div>
  );
}

function Header({ title, onClose, busy }: {
  title: string; onClose: () => void; busy: boolean;
}) {
  return (
    <div style={{
      display: 'flex', alignItems: 'center', justifyContent: 'space-between',
      marginBottom: 14,
    }}>
      <div style={{ color: '#fff', fontSize: 16, fontWeight: 700 }}>{title}</div>
      <button
        onClick={onClose}
        disabled={busy}
        style={{
          background: 'transparent', border: 'none',
          color: '#8b8b8b', fontSize: 20, cursor: 'pointer',
        }}
      >×</button>
    </div>
  );
}

function Field({ label, hint, children }: {
  label: string; hint?: string; children: React.ReactNode;
}) {
  return (
    <div>
      <div style={{
        color: '#8b8b8b', fontSize: 11, fontWeight: 700,
        letterSpacing: 1, textTransform: 'uppercase', marginBottom: 6,
      }}>{label}</div>
      {children}
      {hint && (
        <div style={{ color: '#6a6a6a', fontSize: 11, marginTop: 4 }}>{hint}</div>
      )}
    </div>
  );
}

const inputStyle: React.CSSProperties = {
  width: '100%', boxSizing: 'border-box',
  background: '#000', border: '1px solid #1f1f1f',
  borderRadius: 8, padding: '10px 12px',
  color: '#fff', fontSize: 13, fontFamily: 'inherit',
  outline: 'none',
};

const primaryBtnStyle = (disabled: boolean): React.CSSProperties => ({
  padding: '9px 18px', borderRadius: 999, border: 'none',
  background: '#1d9bf0', color: '#fff',
  fontSize: 13, fontWeight: 700,
  cursor: disabled ? 'default' : 'pointer',
  opacity: disabled ? 0.5 : 1,
});
const secondaryBtnStyle = (disabled: boolean): React.CSSProperties => ({
  padding: '9px 14px', borderRadius: 999,
  background: 'transparent', border: '1px solid #1f1f1f',
  color: '#8b8b8b', fontSize: 13, fontWeight: 700,
  cursor: disabled ? 'default' : 'pointer',
});

export { Backdrop, Header, Field, inputStyle, primaryBtnStyle, secondaryBtnStyle };