import { getLastRenderableEventId } from "#/hooks/chat/model-command-event-anchor";
import { useModelStore, SeededSwitch } from "#/stores/model-store";
import {
  getStoredConversationMetadata,
  mergeStoredConversationMetadata,
} from "#/api/conversation-metadata-store";
import { OpenHandsEvent } from "#/types/agent-server/core";
import { isSwitchLLMObservationEvent } from "#/types/agent-server/type-guards";
import { shouldRenderEvent } from "#/components/conversation-events/chat/event-content-helpers/should-render-event";

export function recordModelSwitchMessage(
  conversationId: string,
  profileName: string,
  anchorEventId: string | null = getLastRenderableEventId(),
) {
  useModelStore
    .getState()
    .recordSwitch(conversationId, anchorEventId, profileName);
}

/**
 * The active-profile stamp for a conversation: the optimistic in-memory entry
 * (read first by the chat-input pill) plus the persisted per-conversation
 * `active_profile` metadata (survives reloads, round-tripped onto the
 * conversation by the agent-server adapter — issue #1082). Every path that
 * learns of a successful switch — the user `/model` mutation, the live
 * WebSocket handler, and the history seed below — must write through this one
 * function so the live and reload paths can't drift.
 *
 * `stampedAt` is persisted alongside the profile so the history seed can tell
 * a stale observation apart from a newer manual switch (see below). The live
 * WebSocket handler passes the observation's own (server) timestamp; the user
 * `/model` mutation has no event and defaults to the client clock.
 */
export function stampActiveLlmProfile(
  conversationId: string,
  profileName: string,
  stampedAt: string = new Date().toISOString(),
) {
  useModelStore.getState().setActiveProfile(conversationId, profileName);

  // Merge rather than replace: the stamp only owns these two fields, and the
  // record carries others it must not drop — the attached workspace mode
  // (#15520), the plugins snapshot behind the in-conversation plugins view,
  // and the local planner conversation id. Enumerating them here meant every
  // new field had to remember to opt in.
  mergeStoredConversationMetadata(conversationId, {
    active_profile: profileName,
    stamped_at: stampedAt,
  });
}

/**
 * Rebuilds the inline "Switched to" messages for a conversation from its loaded
 * history.
 *
 * The live messages live in an in-memory store written only by the WebSocket
 * handler and the user `/model` action. Existing conversations load via REST
 * history, which bypasses that handler, so without this replay no past agent
 * switches would render after a reload (the SwitchLLMObservation events are
 * also hidden as cards by `shouldRenderEvent`).
 *
 * `uiEvents` MUST be the event store's `uiEvents` (the same list the renderer
 * and the live `getLastRenderableEventId()` use) — NOT the raw history. The
 * renderer anchors a message after an event only if that event's id is in
 * `uiEvents.filter(shouldRenderEvent)`, and `uiEvents` differs from raw history:
 * actions are replaced by their observations and `ThinkObservation` /
 * `FinishObservation` are dropped. Anchoring off raw history would point at ids
 * that never mount (e.g. a dropped `ThinkObservation`), orphaning the message.
 *
 * Each successful switch is anchored to the last renderable event before it,
 * matching where the live handler would have placed it. Idempotent: entries are
 * keyed by the observation event id, so re-seeding on every reload is a no-op.
 *
 * Also re-derives the active-profile stamp from the latest successful
 * SwitchLLM observation. The stamp is otherwise written only by the live
 * WebSocket handler and the user `/model` mutation, so a switch that fired
 * while the socket was down would never be stamped — after a reload the pill
 * showed the stale profile while the panel showed the server's true model.
 *
 * The re-stamp is gated on the stored `stamped_at`: manual `/model` switches
 * go through REST and leave NO observation in history, so an unconditional
 * re-stamp would roll a newer manual switch back to an older tool switch.
 * The seed therefore only stamps when there is no existing stamp, the stamp
 * predates this field (legacy — treated as older than any observation so it
 * still gets repaired), or the latest observation is strictly newer.
 * Observation timestamps are server-generated while `stamped_at` from the
 * mutation path is client-generated, so the cross-clock comparison is a
 * heuristic — acceptable here since the alternative is a silent rollback.
 */
export function seedModelSwitchesFromHistory(
  conversationId: string,
  uiEvents: OpenHandsEvent[],
) {
  const switches: SeededSwitch[] = [];
  let lastRenderableId: string | null = null;
  let latestSwitch: { profileName: string; timestamp: string } | null = null;

  for (const event of uiEvents) {
    if (isSwitchLLMObservationEvent(event) && !event.observation.is_error) {
      switches.push({
        id: `history-switch:${event.id}`,
        anchorEventId: lastRenderableId,
        profileName: event.observation.profile_name,
      });
      latestSwitch = {
        profileName: event.observation.profile_name,
        timestamp: event.timestamp,
      };
    }
    if (shouldRenderEvent(event)) {
      lastRenderableId = String(event.id);
    }
  }

  if (switches.length > 0) {
    useModelStore.getState().seedSwitches(conversationId, switches);
  }

  if (latestSwitch) {
    const { profileName, timestamp } = latestSwitch;
    const stored = getStoredConversationMetadata(conversationId);
    const stampedAt = stored?.active_profile ? stored.stamped_at : null;
    if (!stampedAt || Date.parse(timestamp) > Date.parse(stampedAt)) {
      // Stamp with the observation's own timestamp so re-seeding the same
      // history on the next reload is a no-op (strictly-newer never matches).
      stampActiveLlmProfile(conversationId, profileName, timestamp);
    }
  }
}