"use client";

import { Icon } from "@/components/icons";
import { Field, Notice, TextInput, cx } from "@/components/ui";
import { evaluateContrast } from "@/lib/qr/contrast";
import {
  COLOR_PRESETS,
  EC_LEVELS,
  EC_LEVEL_LABELS,
  MAX_SIZE,
  MIN_SIZE,
  type EcLevel,
  type QrDesign,
} from "@/lib/qr/design";

const HEX_INPUT = /^#[0-9a-fA-F]{6}$/;

function ColorField({
  label,
  value,
  onChange,
  id,
}: {
  label: string;
  value: string;
  onChange: (value: string) => void;
  id: string;
}) {
  const valid = HEX_INPUT.test(value);

  return (
    <Field
      label={label}
      htmlFor={id}
      error={valid ? null : "Bitte im Format #RRGGBB angeben."}
    >
      <div className="flex items-center gap-2">
        <input
          type="color"
          aria-label={`${label} auswählen`}
          value={valid ? value : "#000000"}
          onChange={(event) => onChange(event.target.value.toUpperCase())}
          className="size-10 shrink-0 cursor-pointer rounded-lg border border-slate-300 bg-surface p-1"
        />
        <TextInput
          id={id}
          value={value}
          invalid={!valid}
          spellCheck={false}
          maxLength={7}
          onChange={(event) => {
            const next = event.target.value.trim();
            onChange(next.startsWith("#") ? next.toUpperCase() : `#${next.toUpperCase()}`);
          }}
          className="font-mono uppercase"
        />
      </div>
    </Field>
  );
}

export function DesignPanel({
  design,
  onChange,
}: {
  design: QrDesign;
  onChange: (design: QrDesign) => void;
}) {
  const patch = (changes: Partial<QrDesign>) => onChange({ ...design, ...changes });
  const contrast = evaluateContrast(design.fgColor, design.bgColor);

  return (
    <div className="space-y-5">
      <div className="grid grid-cols-1 gap-4 sm:grid-cols-2">
        <ColorField
          id="fg-color"
          label="Vordergrund"
          value={design.fgColor}
          onChange={(fgColor) => patch({ fgColor })}
        />
        <ColorField
          id="bg-color"
          label="Hintergrund"
          value={design.bgColor}
          onChange={(bgColor) => patch({ bgColor })}
        />
      </div>

      <div className="flex flex-wrap items-center gap-2">
        {COLOR_PRESETS.map((preset) => (
          <button
            key={preset.label}
            type="button"
            title={preset.label}
            onClick={() =>
              patch({ fgColor: preset.fgColor, bgColor: preset.bgColor })
            }
            className="flex items-center gap-2 rounded-lg border border-slate-300 bg-surface py-1 pr-2.5 pl-1.5 text-xs font-medium text-slate-700 transition-colors hover:bg-slate-50"
          >
            <span
              className="size-4 rounded border border-slate-300"
              style={{
                background: `linear-gradient(135deg, ${preset.fgColor} 50%, ${preset.bgColor} 50%)`,
              }}
            />
            {preset.label}
          </button>
        ))}
        <button
          type="button"
          onClick={() =>
            patch({ fgColor: design.bgColor, bgColor: design.fgColor })
          }
          className="rounded-lg border border-slate-300 bg-surface px-2.5 py-1 text-xs font-medium text-slate-700 transition-colors hover:bg-slate-50"
        >
          Farben tauschen
        </button>
      </div>

      {contrast.message ? (
        <Notice tone={contrast.verdict === "schlecht" ? "error" : "warning"}>
          <span className="flex gap-2">
            <Icon name="warning" className="mt-0.5 size-4 shrink-0" />
            <span>
              {contrast.message}
              <span className="mt-0.5 block text-xs opacity-80">
                Kontrastverhältnis: {contrast.ratio.toFixed(1)} : 1
              </span>
            </span>
          </span>
        </Notice>
      ) : null}

      <Field
        label={`Größe: ${design.size} × ${design.size} px`}
        htmlFor="qr-size"
        hint={`Zwischen ${MIN_SIZE} und ${MAX_SIZE} px. Gilt für den PNG-Download; das SVG skaliert verlustfrei.`}
      >
        <div className="flex items-center gap-3">
          <input
            id="qr-size"
            type="range"
            min={MIN_SIZE}
            max={MAX_SIZE}
            step={32}
            value={design.size}
            onChange={(event) => patch({ size: Number(event.target.value) })}
            className="h-2 w-full cursor-pointer appearance-none rounded-full bg-slate-200 accent-indigo-600"
          />
          <input
            type="number"
            aria-label="Größe in Pixeln"
            min={MIN_SIZE}
            max={MAX_SIZE}
            value={design.size}
            onChange={(event) => {
              const raw = Number(event.target.value);
              if (Number.isNaN(raw)) return;
              patch({ size: Math.min(MAX_SIZE, Math.max(MIN_SIZE, Math.round(raw))) });
            }}
            className="w-24 shrink-0 rounded-lg border border-slate-300 bg-surface px-2.5 py-2 text-sm tabular-nums shadow-sm"
          />
        </div>
      </Field>

      <Field
        label="Fehlerkorrektur"
        hint={EC_LEVEL_LABELS[design.ecLevel]}
      >
        <div
          role="radiogroup"
          aria-label="Fehlerkorrektur-Level"
          className="grid grid-cols-4 gap-2"
        >
          {EC_LEVELS.map((level: EcLevel) => (
            <button
              key={level}
              type="button"
              role="radio"
              aria-checked={design.ecLevel === level}
              onClick={() => patch({ ecLevel: level })}
              className={cx(
                "rounded-lg border py-2 text-sm font-medium transition-colors",
                design.ecLevel === level
                  ? "border-indigo-600 bg-accent-soft text-accent-soft-fg"
                  : "border-slate-300 bg-surface text-slate-600 hover:bg-slate-50",
              )}
            >
              {level}
            </button>
          ))}
        </div>
      </Field>

      <Field
        label={`Rand: ${design.margin} Module`}
        htmlFor="qr-margin"
        hint="Die weiße Ruhezone rundherum. Weniger als 4 Module können das Scannen erschweren."
      >
        <input
          id="qr-margin"
          type="range"
          min={0}
          max={16}
          step={1}
          value={design.margin}
          onChange={(event) => patch({ margin: Number(event.target.value) })}
          className="h-2 w-full cursor-pointer appearance-none rounded-full bg-slate-200 accent-indigo-600"
        />
      </Field>
    </div>
  );
}