export function Diff({ diff }: { diff: string }) {
  const lines = diff.replace(/\n+$/, "").split("\n");
  return (
    <div className="diff">
      {lines.map((l, i) => {
        let cls = "";
        if (l.startsWith("+++") || l.startsWith("---")) cls = "meta";
        else if (l.startsWith("@@")) cls = "hunk";
        else if (l.startsWith("+")) cls = "add";
        else if (l.startsWith("-")) cls = "del";
        return (
          <div key={i} className={cls}>
            {l || " "}
          </div>
        );
      })}
    </div>
  );
}

/** Split a unified diff into its file header and hunks (at "@@" lines). */
export function splitHunks(diff: string): { header: string[]; hunks: string[][] } {
  const lines = diff.replace(/\n+$/, "").split("\n");
  const header: string[] = [];
  const hunks: string[][] = [];
  for (const l of lines) {
    if (l.startsWith("@@")) hunks.push([l]);
    else if (hunks.length) hunks[hunks.length - 1].push(l);
    else header.push(l);
  }
  return { header, hunks };
}

/** Diff with a checkbox per hunk (review a change piece by piece). */
export function HunkDiff({ diff, selected, onToggle }: { diff: string; selected: boolean[]; onToggle: (i: number) => void }) {
  const { header, hunks } = splitHunks(diff);
  return (
    <div className="diff hunk-diff">
      {header.map((l, i) => (
        <div key={`h${i}`} className="meta">
          {l}
        </div>
      ))}
      {hunks.map((h, i) => (
        <div key={i} className={`hunk-block ${selected[i] ? "" : "off"}`}>
          <label className="hunk-head">
            <input type="checkbox" checked={!!selected[i]} onChange={() => onToggle(i)} />
            <span>{h[0]}</span>
          </label>
          {h.slice(1).map((l, j) => (
            <div key={j} className={l.startsWith("+") ? "add" : l.startsWith("-") ? "del" : ""}>
              {l || " "}
            </div>
          ))}
        </div>
      ))}
    </div>
  );
}