/**
 * Intelligence Layer - LocalStorage Compactor Fallback
 *
 * Provides rule-based compaction for browser/dev environment.
 */

import type { CompactableMessage, CompactionResult, CompactionCheck, CompactionConfig } from '../intelligence-backend';

export const fallbackCompactor = {
  async estimateTokens(text: string): Promise<number> {
    // Simple heuristic: ~4 chars per token for English, ~1.5 for CJK
    const cjkChars = (text.match(/[\u4e00-\u9fff\u3040-\u30ff]/g) ?? []).length;
    const otherChars = text.length - cjkChars;
    return Math.ceil(cjkChars * 1.5 + otherChars / 4);
  },

  async estimateMessagesTokens(messages: CompactableMessage[]): Promise<number> {
    let total = 0;
    for (const m of messages) {
      total += await fallbackCompactor.estimateTokens(m.content);
    }
    return total;
  },

  async checkThreshold(
    messages: CompactableMessage[],
    config?: CompactionConfig
  ): Promise<CompactionCheck> {
    const threshold = config?.soft_threshold_tokens ?? 15000;
    const currentTokens = await fallbackCompactor.estimateMessagesTokens(messages);

    return {
      should_compact: currentTokens >= threshold,
      current_tokens: currentTokens,
      threshold,
      urgency: currentTokens >= (config?.hard_threshold_tokens ?? 20000) ? 'hard' :
               currentTokens >= threshold ? 'soft' : 'none',
    };
  },

  async compact(
    messages: CompactableMessage[],
    _agentId: string,
    _conversationId?: string,
    config?: CompactionConfig
  ): Promise<CompactionResult> {
    // Simple rule-based compaction: keep last N messages
    const keepRecent = config?.keep_recent_messages ?? 10;
    const retained = messages.slice(-keepRecent);

    return {
      compacted_messages: retained,
      summary: `[Compacted ${messages.length - retained.length} earlier messages]`,
      original_count: messages.length,
      retained_count: retained.length,
      flushed_memories: 0,
      tokens_before_compaction: await fallbackCompactor.estimateMessagesTokens(messages),
      tokens_after_compaction: await fallbackCompactor.estimateMessagesTokens(retained),
    };
  },
};