import { type NavConfig, type NavEntry, config } from './config'

function _extendConfig(config1: NavConfig, config2: NavConfig): NavConfig {
  // Helper function to merge two NavEntry objects
  function mergeEntries(entry1: NavEntry, entry2: NavEntry): NavEntry {
    if ('items' in entry1 && 'items' in entry2) {
      // If both entries are NavParent objects, merge their items
      return {
        label: entry1.label,
        items: _extendConfig(entry1.items, entry2.items),
      }
    }
    // Otherwise, override with the new entry
    return entry2
  }

  // Create a record to merge configs by label
  const newConfig: Record<string, NavEntry> = {}

  // Start with the original config
  for (const entry of config1) {
    newConfig[entry.label] = { ...entry }
  }

  // Merge entries from the second config
  for (const entry of config2) {
    if (newConfig[entry.label]) {
      const mergedEntry = mergeEntries(newConfig[entry.label] ?? entry, entry)
      newConfig[entry.label] = { ...newConfig[entry.label], ...mergedEntry }
    } else {
      newConfig[entry.label] = { ...newConfig[entry.label], ...entry }
    }
  }

  // Convert the map back to an array
  return Object.values(newConfig)
}

/**
 * Allows developers to manipulate the contents of the VerticalNavBar.
 *
 * When the entry is a NavParent:
 * - if a NavParent with the same label exists, their items will be merged recursively.
 * - otherwise, a new parent category will be added.
 *
 * When the entry is a NavItem:
 * - if a NavItem with the same label exists, its config is overriden.
 * - otherwise, a new item will be added to the parent.
 * @param extraNavConfig a list with new or updated entries
 */
export function extendConfig(extraNavConfig: NavConfig) {
  return _extendConfig(config, extraNavConfig)
}