import { element } from "./dom.js";
import { formatBytes } from "./format.js";

function withFreeSpace(label, destination) {
  if (!destination || destination.freeBytes < 0) return label;
  return `${label} - ${formatBytes(destination.freeBytes)} free`;
}

function destinationForPath(destinations, path) {
  return destinations.find((destination) => path === destination.path || path.startsWith(`${destination.path}/`));
}

function libraryGroups(destinations) {
  const groups = new Map();
  for (const destination of destinations) {
    if (!groups.has(destination.root)) {
      const group = document.createElement("optgroup");
      group.label = destination.root;
      groups.set(destination.root, group);
    }
    const option = element("option", "", withFreeSpace(destination.name, destination));
    option.value = destination.path;
    option.title = destination.path;
    groups.get(destination.root).append(option);
  }
  return [...groups.values()];
}

function pathGroup(label, paths, destinations) {
  const group = document.createElement("optgroup");
  group.label = label;
  for (const path of paths) {
    const option = element("option", "", withFreeSpace(path, destinationForPath(destinations, path)));
    option.value = path;
    option.title = path;
    group.append(option);
  }
  return group;
}

export function fillLibrarySelect(select, destinations, extras = {}) {
  const previousValue = select.value;
  const leadingOptions = [];
  if (extras.emptyLabel) {
    const emptyOption = element("option", "", extras.emptyLabel);
    emptyOption.value = "";
    leadingOptions.push(emptyOption);
  }
  if (extras.recentPaths && extras.recentPaths.length > 0) {
    leadingOptions.push(pathGroup("Recent", extras.recentPaths, destinations));
  }
  if (extras.savedPaths && extras.savedPaths.length > 0) {
    leadingOptions.push(pathGroup("Saved paths", extras.savedPaths, destinations));
  }

  select.replaceChildren(...leadingOptions, ...libraryGroups(destinations));
  const availableValues = [...select.options].map((option) => option.value);
  if (availableValues.includes(previousValue)) {
    select.value = previousValue;
  }
}