// PR-A4 command registry + appSidebar placements (HOST_PLUGIN_UI_SPEC §4/§5).
// The host keeps a static command registry per installed plugin and renders
// placements from declared `menus` data only — it never scans workbenches to
// invent entries. Executing a command re-resolves the workbench reference and
// opens the plugin workbench with a host-authored context: the plugin payload
// rides under `context.plugin`, while workbenchId/restored/surface are
// injected here and can never be supplied by the plugin (§11 ownership).
import { onScopeDispose, ref, shallowRef, watch } from "vue";
import { useI18n } from "vue-i18n";
import * as api from "@/lib/backend/api";
import { uuid } from "@/lib/common/utils";
import { activatePluginDockEntry, addPluginDockEntry, findReusableDockEntry } from "@/lib/plugins/pluginBottomDock";
import { createFrontendPluginRegistry, evaluatePluginCommandConditions, type FrontendPluginRegistry } from "@/lib/plugins/frontendPlugin";
import { useQueryStore } from "@/stores/queryStore";
import type { PluginCommandContribution, PluginConditionContextKeys } from "@/types/database";

export interface PluginToolbarCommandEntry {
  pluginId: string;
  pluginName: string;
  commandId: string;
  label: string;
  description?: string;
  icon?: string;
}

export interface PluginCommandExecutionResult {
  error?: string;
}

/**
 * §5.4 re-validate enablement right before execution (against the current context snapshot; the surface key follows
 * presentation).
 */
export function executePluginCommand(registry: FrontendPluginRegistry, queryStore: ReturnType<typeof useQueryStore>, pluginId: string, commandId: string): PluginCommandExecutionResult {
  const command = registry.findCommand(pluginId, commandId)?.contribution;
  if (!command) return { error: `Unknown command '${pluginId}.${commandId}'` };
  const action = command.action;
  if (action.type !== "open-workbench") return { error: `Command '${pluginId}.${commandId}' has an unsupported action` };
  const workbench = registry.findWorkbench(pluginId, action.workbench);
  if (!workbench) return { error: `Command '${pluginId}.${commandId}' references missing workbench '${action.workbench}'` };
  // §5.4 re-validate enablement right before execution (against the current context snapshot; the surface key follows
  // presentation).
  const commandContextKeys: PluginConditionContextKeys = { surface: action.presentation === "panel" ? "panel" : "tab", "connection.state": "none", readOnly: false };
  if (!evaluatePluginCommandConditions(command.enablement?.all, commandContextKeys)) {
    return { error: `Command '${pluginId}.${commandId}' is disabled by enablement` };
  }
  // presentation: panel -> adds an entry to the global bottom dock (§8.3); tab (default)
  // -> opens a workbench tab.
  if (action.presentation === "panel") {
    // §4.1: singleton (default) re-activates the existing panel instance
    // (reuse key = pluginId + commandId + presentation + instance_key);
    // reuse:"new" always spawns one. The dock "+" menu bypasses this path by
    // design — it is the explicit multi-open affordance.
    if (action.reuse !== "new") {
      const existing = findReusableDockEntry(pluginId, command.id, action.instance_key);
      if (existing) {
        activatePluginDockEntry(existing.id);
        return {};
      }
    }
    addPluginDockEntry({
      pluginId,
      workbenchContributionId: action.workbench,
      kind: "command",
      commandId: command.id,
      instanceKey: action.instance_key,
      title: command.label,
      icon: command.icon,
      commandContext: action.context ?? {},
    });
    return {};
  }
  // Host-authored context: rebuilt from action.context — plugin-supplied reserved fields
  // (workbenchId/restored/surface) never pass through; the workbenchId is generated by the host.
  const context = {
    ...(action.context ?? {}),
    workbenchId: uuid(),
    restored: false,
    surface: "tab",
  };
  // singleton (default) reuses the existing instance tab; new forces a fresh one.
  queryStore.openPluginWorkbench(pluginId, action.workbench, {
    commandId: command.id,
    title: command.label,
    context,
    forceNew: action.reuse === "new",
  });
  return {};
}

export function usePluginToolbarCommands() {
  const { locale } = useI18n();
  const entries = ref<PluginToolbarCommandEntry[]>([]);
  // shallowRef: the registry is a class instance with private fields — a deep ref's UnwrapRef would break
  // nominal type (TS expands it into a plain structural object, making it unassignable).
  const registry = shallowRef<FrontendPluginRegistry | null>(null);

  async function refresh() {
    try {
      const installedPlugins = await api.listPlugins();
      const nextRegistry = createFrontendPluginRegistry(installedPlugins, locale.value);
      entries.value = nextRegistry.listToolbarMenuCommands().map(({ plugin, command }: { plugin: { manifest: { id: string; name: string } }; command: PluginCommandContribution }) => ({
        pluginId: plugin.manifest.id,
        pluginName: plugin.manifest.name,
        commandId: command.id,
        label: command.label,
        description: command.description,
        icon: command.icon,
      }));
      registry.value = nextRegistry;
    } catch (cause) {
      console.warn("[DBX][plugin:toolbar-entries]", cause);
      entries.value = [];
      registry.value = null;
    }
  }

  function open(entry: PluginToolbarCommandEntry): PluginCommandExecutionResult {
    if (!registry.value) return { error: "Plugin registry is not ready" };
    // Lazy store access: pinia is only needed when an entry is actually clicked (mount-time has no store dependency;
    // plain host tests need no Pinia).
    return executePluginCommand(registry.value, useQueryStore(), entry.pluginId, entry.commandId);
  }

  watch(locale, () => void refresh());
  // Refresh entries on plugin install/uninstall/replace (plugin center broadcasts dbx:plugins-changed) or window focus so they match the installed-plugin list.
  // refresh entries so they match the installed-plugin list.
  const onPluginsChanged = () => void refresh();
  window.addEventListener("dbx:plugins-changed", onPluginsChanged);
  window.addEventListener("focus", onPluginsChanged);
  onScopeDispose(() => {
    window.removeEventListener("dbx:plugins-changed", onPluginsChanged);
    window.removeEventListener("focus", onPluginsChanged);
  });
  void refresh();

  return { entries, refresh, open };
}