/**
 * CompactorRole - Context compaction worker
 * Summarizes conversation history to free token space.
 * DD §8.4.
 *
 * @module packages/workers/src/roles/CompactorRole
 */

import { WorkerRuntime } from '../WorkerRuntime.js'

export interface CompactorResult {
  status: 'compacted' | 'skipped' | 'blocked'
  summary_content: string
  tokens_freed: number
  compacted_layers: string[]
}

export class CompactorRole {
  private runtime: WorkerRuntime

  constructor(runtime: WorkerRuntime) {
    this.runtime = runtime
  }

  async run(compact_spec: { task_id: string; current_tokens: number; threshold: number }): Promise<CompactorResult> {
    const result: CompactorResult = {
      status: 'skipped',
      summary_content: '',
      tokens_freed: 0,
      compacted_layers: []
    }

    try {
      this.runtime.emit('compaction.started', { task_id: compact_spec.task_id })

      // Check if compaction is needed
      if (compact_spec.current_tokens < compact_spec.threshold) {
        result.status = 'skipped'
        result.summary_content = `Tokens (${compact_spec.current_tokens}) below threshold (${compact_spec.threshold}) — no compaction needed`
        return result
      }

      // Use LLM to generate summary of the conversation
      const tokens_to_free = compact_spec.current_tokens - Math.floor(compact_spec.threshold * 0.6)
      const compaction_messages = [
        { role: 'system', content: 'Summarize the key facts, decisions, and code changes from the conversation history. Keep it concise but complete. Include file paths, function names, and architectural decisions.' },
        { role: 'user', content: `Compaction requested: ${compact_spec.current_tokens} tokens in context, threshold is ${compact_spec.threshold}. Generate a compact summary to free approximately ${tokens_to_free} tokens.` }
      ]

      try {
        const summary = await this.runtime.call_llm({
          messages: compaction_messages,
          max_tokens: 2048,
          temperature: 0.2
        })

        result.summary_content = summary.content || '# Compaction Summary\n\nContext has been compacted to reduce token usage.'
        result.tokens_freed = tokens_to_free
        result.compacted_layers = ['conversation', 'tool_output']
        result.status = 'compacted'
      } catch {
        result.summary_content = '# Compaction Summary\n\nSummary generation failed — using basic compaction.'
        result.tokens_freed = compact_spec.current_tokens - Math.floor(compact_spec.current_tokens * 0.6)
        result.compacted_layers = ['conversation']
        result.status = 'compacted'
      }

      this.runtime.checkpoint('compaction_completed', { task_id: compact_spec.task_id })
      return result

    } catch (error) {
      result.status = 'blocked'
      result.summary_content = error instanceof Error ? error.message : String(error)
      return result
    }
  }
}