import { MAX_ITEMS } from "../constants.ts";
import { normalizeSearch } from "../identity.ts";
import type { HelpState, IndexedItem, ResourceKind } from "../types.ts";
import { mergeItem } from "./migrate.ts";

export function sortItems(a: IndexedItem, b: IndexedItem): number {
  if ((a.pinned ? 1 : 0) !== (b.pinned ? 1 : 0)) return (b.pinned ? 1 : 0) - (a.pinned ? 1 : 0);
  if ((a.useCount ?? 0) !== (b.useCount ?? 0)) return (b.useCount ?? 0) - (a.useCount ?? 0);
  if ((a.lastUsedAt ?? 0) !== (b.lastUsedAt ?? 0)) return (b.lastUsedAt ?? 0) - (a.lastUsedAt ?? 0);
  return (a.displayName ?? a.name).localeCompare(b.displayName ?? b.name);
}

export function upsertItem(state: HelpState, item: IndexedItem): IndexedItem {
  const merged = mergeItem(state.items[item.key], item);
  state.items[item.key] = merged;
  return merged;
}

export function recordUsage(state: HelpState, key: string, now = Date.now()): void {
  const item = state.items[key];
  if (!item) return;
  item.useCount = (item.useCount ?? 0) + 1;
  item.lastUsedAt = now;
  item.lastSeenAt = now;
}

export function recordUsageByName(state: HelpState, kind: ResourceKind, name: string, now = Date.now()): void {
  const matches = Object.values(state.items).filter((item) => item.kind === kind && (item.name === name || item.displayName === name));
  if (matches.length === 0) return;
  const target = [...matches].sort(sortItems)[0];
  if (!target) return;
  recordUsage(state, target.key, now);
}

export function findMatches(state: HelpState, query: string): IndexedItem[] {
  const normalizedQuery = normalizeSearch(query);
  if (!normalizedQuery) return [];
  return Object.values(state.items)
    .filter((item) => normalizeSearch([item.name, item.displayName, item.description, item.sourceLabel, item.packageName, item.sourceRef, item.kind].join(" ")).includes(normalizedQuery))
    .sort(sortItems);
}

export function pruneState(state: HelpState): void {
  const items = Object.values(state.items);
  if (items.length <= MAX_ITEMS) return;

  const removable = items
    .filter((item) => !item.pinned)
    .sort((a, b) => {
      if ((a.useCount ?? 0) !== (b.useCount ?? 0)) {
        return (a.useCount ?? 0) - (b.useCount ?? 0);
      }
      return (a.lastUsedAt ?? 0) - (b.lastUsedAt ?? 0);
    });

  while (Object.keys(state.items).length > MAX_ITEMS && removable.length > 0) {
    const victim = removable.shift();
    if (victim) delete state.items[victim.key];
  }
}