import { useEffect, useState } from "react";

export interface NumberFieldProps {
  label: string;
  value: number;
  onChange: (v: number) => void;
  /** Display = value * scale (e.g. 1000 to show metres as millimetres) */
  scale?: number;
  unit?: string;
  step?: number;
  min?: number;
  max?: number;
  integer?: boolean;
  invalid?: boolean;
  disabled?: boolean;
  title?: string;
}

/** A numeric input that tolerates partial typing and commits parsed values. */
export function NumberField(props: NumberFieldProps) {
  const {
    label,
    value,
    onChange,
    scale = 1,
    unit,
    step,
    min,
    max,
    integer,
    invalid,
    disabled,
    title,
  } = props;
  const shown = formatShown(value * scale);
  const [text, setText] = useState(shown);
  useEffect(() => {
    // Sync from outside unless the text already means the same number
    if (Number(text) * 1 !== value * scale) setText(shown);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [value, scale]);
  return (
    <div className={`pl-field${disabled ? " pl-disabled" : ""}`} title={title}>
      <label>{label}</label>
      <input
        type="number"
        className={invalid ? "pl-invalid" : undefined}
        value={text}
        step={step ?? (integer ? 1 : "any")}
        min={min}
        max={max}
        disabled={disabled}
        onChange={(e) => {
          setText(e.target.value);
          const n = Number(e.target.value);
          if (e.target.value.trim() === "" || !Number.isFinite(n)) return;
          onChange(integer ? Math.round(n) : n / scale);
        }}
        onBlur={() => setText(shown)}
      />
      <span className="pl-unit">{unit ?? ""}</span>
    </div>
  );
}

function formatShown(x: number): string {
  if (!Number.isFinite(x)) return "";
  const r = Number(x.toPrecision(10));
  return String(r);
}