import { STATE_VERSION } from "../constants.ts";
import { canonicalName, compactSourceRef, displayName, makeItemKey } from "../identity.ts";
import type { HelpState, IndexedItem, LegacyHelpState, ResourceKind, ResourceScope } from "../types.ts";

export function emptyState(): HelpState {
  return { version: STATE_VERSION, items: {} };
}

export function legacySourceFromKey(key: string | undefined): string | undefined {
  if (!key) return undefined;
  const first = key.indexOf(":");
  const last = key.lastIndexOf(":");
  if (first < 0 || last <= first) return undefined;
  return key.slice(first + 1, last);
}

function fallbackSourceLabel(kind: ResourceKind, sourceRef: string, scope?: ResourceScope): string {
  if (sourceRef === "builtin") return kind === "tool" ? "内置工具" : "内置";
  if (sourceRef === "sdk") return kind === "tool" ? "SDK 工具" : "SDK";
  if (sourceRef.startsWith("pkg:")) return `npm:${sourceRef.slice("pkg:".length)}`;
  if (sourceRef.startsWith("npm:")) return sourceRef;
  if (sourceRef.startsWith("mcp:")) return sourceRef === "mcp:gateway" ? "内置网关" : "MCP 服务器";
  if (sourceRef.startsWith("local:")) return scope === "project" ? "项目本地" : "本地包";
  return sourceRef;
}

export function mergeItem(existing: IndexedItem | undefined, next: IndexedItem): IndexedItem {
  if (!existing) return next;

  return {
    ...existing,
    ...next,
    description: next.description ?? existing.description,
    sourceLabel: next.sourceLabel || existing.sourceLabel,
    sourceRef: next.sourceRef || existing.sourceRef,
    useCount: Math.max(existing.useCount ?? 0, next.useCount ?? 0),
    lastUsedAt: Math.max(existing.lastUsedAt ?? 0, next.lastUsedAt ?? 0) || undefined,
    lastSeenAt: Math.max(existing.lastSeenAt ?? 0, next.lastSeenAt ?? 0) || undefined,
    pinned: Boolean(existing.pinned || next.pinned),
  };
}

export function normalizeRawItem(raw: Partial<IndexedItem> & { key?: string; kind?: ResourceKind; name?: string; source?: string }): IndexedItem | undefined {
  if (!raw.kind || !raw.name) return undefined;

  const sourceRef = compactSourceRef(raw.sourceRef ?? raw.source ?? legacySourceFromKey(raw.key) ?? raw.packageName ?? raw.sourceLabel);
  const name = canonicalName(raw.kind, raw.name);
  const key = makeItemKey(raw.kind, name, sourceRef);
  return {
    key,
    kind: raw.kind,
    name,
    displayName: raw.displayName ?? displayName(raw.kind, name),
    description: raw.description,
    sourceLabel: raw.sourceLabel || fallbackSourceLabel(raw.kind, sourceRef, raw.scope),
    sourceRef,
    scope: raw.scope,
    packageName: raw.packageName,
    useCount: raw.useCount ?? 0,
    lastUsedAt: raw.lastUsedAt,
    lastSeenAt: raw.lastSeenAt,
    pinned: raw.pinned,
  };
}

export function migrateState(state: LegacyHelpState | HelpState): HelpState {
  const items: Record<string, IndexedItem> = {};

  for (const raw of Object.values(state.items ?? {})) {
    const next = normalizeRawItem(raw);
    if (!next) continue;
    items[next.key] = mergeItem(items[next.key], next);
  }

  return {
    version: STATE_VERSION,
    items,
    lastRefresh: state.lastRefresh,
  };
}