import { DiffLine } from "./diffApi";

// Reine Funktion (Akzeptanzkriterium 3: Sprung zur naechsten Aenderung
// moeglich) -- unabhaengig vom DOM testbar, dieselbe Struktur wie
// virtualization.ts.
export function findNextChangeIndex(lines: DiffLine[], afterIndex: number): number {
  for (let i = afterIndex + 1; i < lines.length; i++) {
    if (lines[i].op !== "equal") {
      return i;
    }
  }
  return -1;
}

export function findPreviousChangeIndex(lines: DiffLine[], beforeIndex: number): number {
  for (let i = beforeIndex - 1; i >= 0; i--) {
    if (lines[i].op !== "equal") {
      return i;
    }
  }
  return -1;
}

export function countChanges(lines: DiffLine[]): number {
  return lines.filter((l) => l.op !== "equal").length;
}