import { query, type Options, type SDKMessage } from '@anthropic-ai/claude-agent-sdk'
import type { SubagentBackend, SubagentInput, SubagentResult } from './types.js'

const DEFAULT_TIMEOUT_MS = 900_000

export class ClaudeBackend implements SubagentBackend {
  readonly name = 'claude'

  async run(input: SubagentInput): Promise<SubagentResult> {
    const start = Date.now()
    const ac = new AbortController()
    const timer = setTimeout(() => ac.abort(), input.timeoutMs ?? DEFAULT_TIMEOUT_MS)
    timer.unref()
    const options: Options = {
      model: 'claude-sonnet-4-6',
      permissionMode: 'bypassPermissions',
      maxTurns: 10,
      settingSources: [],
      abortController: ac,
    }
    const result: SubagentResult = { backend: this.name, text: '', durationMs: 0 }
    try {
      for await (const msg of query({ prompt: input.prompt, options }) as AsyncIterable<SDKMessage>) {
        if (msg.type === 'system' && msg.subtype === 'init') result.sessionId = msg.session_id
        if (msg.type === 'result') {
          if (msg.subtype === 'success') {
            result.text = msg.result
            result.durationMs = msg.duration_ms
            result.costUsd = msg.total_cost_usd
            result.inputTokens = msg.usage.input_tokens ?? 0
            result.outputTokens = msg.usage.output_tokens ?? 0
          } else {
            result.error = `claude: ${msg.subtype}`
          }
        }
        if (msg.type === 'assistant') {
          const content = (msg as { message?: { content?: Array<{ type: string }> } }).message?.content
          if (Array.isArray(content)) {
            result.toolCallsUsed = (result.toolCallsUsed ?? 0) + content.filter(c => c.type === 'tool_use').length
          }
        }
      }
    } catch (err) {
      result.error = err instanceof Error ? err.message : String(err)
    } finally {
      clearTimeout(timer)
    }
    if (result.durationMs === 0) result.durationMs = Date.now() - start
    return result
  }
}