/**
 * SDKAgent: SDK query loop handler
 *
 * Responsibility:
 * - Spawn Claude subprocess via Agent SDK
 * - Run event-driven query loop (no polling)
 * - Process SDK responses (observations, summaries)
 * - Sync to database and Chroma
 */

import { execSync } from 'child_process';
import { homedir } from 'os';
import path from 'path';
import { existsSync, readFileSync } from 'fs';
import { DatabaseManager } from './DatabaseManager.js';
import { SessionManager } from './SessionManager.js';
import { logger } from '../../utils/logger.js';
import { parseObservations, parseSummary } from '../../sdk/parser.js';
import { buildInitPrompt, buildObservationPrompt, buildSummaryPrompt } from '../../sdk/prompts.js';
import type { ActiveSession, SDKUserMessage, PendingMessage } from '../worker-types.js';

// Import Agent SDK (assumes it's installed)
// @ts-ignore - Agent SDK types may not be available
import { query } from '@anthropic-ai/claude-agent-sdk';

export class SDKAgent {
  private dbManager: DatabaseManager;
  private sessionManager: SessionManager;

  constructor(dbManager: DatabaseManager, sessionManager: SessionManager) {
    this.dbManager = dbManager;
    this.sessionManager = sessionManager;
  }

  /**
   * Start SDK agent for a session (event-driven, no polling)
   */
  async startSession(session: ActiveSession): Promise<void> {
    try {
      // Find Claude executable
      const claudePath = this.findClaudeExecutable();

      // Get model ID and disallowed tools
      const modelId = this.getModelId();
      const disallowedTools = ['Bash']; // Prevent infinite loops

      // Create message generator (event-driven)
      const messageGenerator = this.createMessageGenerator(session);

      // Run Agent SDK query loop
      const queryResult = query({
        prompt: messageGenerator,
        options: {
          model: modelId,
          disallowedTools,
          abortController: session.abortController,
          pathToClaudeCodeExecutable: claudePath
        }
      });

      // Process SDK messages
      for await (const message of queryResult) {
        // Handle assistant messages
        if (message.type === 'assistant') {
          const content = message.message.content;
          const textContent = Array.isArray(content)
            ? content.filter((c: any) => c.type === 'text').map((c: any) => c.text).join('\n')
            : typeof content === 'string' ? content : '';

          const responseSize = textContent.length;
          logger.dataOut('SDK', `Response received (${responseSize} chars)`, {
            sessionId: session.sessionDbId,
            promptNumber: session.lastPromptNumber
          });

          // Parse and process response
          await this.processSDKResponse(session, textContent);
        }

        // Log result messages
        if (message.type === 'result' && message.subtype === 'success') {
          // Usage telemetry is captured at SDK level
        }
      }

      // Mark session complete
      const sessionDuration = Date.now() - session.startTime;
      logger.success('SDK', 'Agent completed', {
        sessionId: session.sessionDbId,
        duration: `${(sessionDuration / 1000).toFixed(1)}s`
      });

      this.dbManager.getSessionStore().markSessionCompleted(session.sessionDbId);

    } catch (error: any) {
      if (error.name === 'AbortError') {
        logger.warn('SDK', 'Agent aborted', { sessionId: session.sessionDbId });
      } else {
        logger.failure('SDK', 'Agent error', { sessionDbId: session.sessionDbId }, error);
      }
      throw error;
    } finally {
      // Cleanup
      this.sessionManager.deleteSession(session.sessionDbId).catch(() => {});
    }
  }

  /**
   * Create event-driven message generator (yields messages from SessionManager)
   */
  private async *createMessageGenerator(session: ActiveSession): AsyncIterableIterator<SDKUserMessage> {
    // Yield initial user prompt with context
    yield {
      type: 'user',
      message: {
        role: 'user',
        content: buildInitPrompt(session.project, session.claudeSessionId, session.userPrompt)
      },
      session_id: session.claudeSessionId,
      parent_tool_use_id: null,
      isSynthetic: true
    };

    // Consume pending messages from SessionManager (event-driven, no polling)
    for await (const message of this.sessionManager.getMessageIterator(session.sessionDbId)) {
      if (message.type === 'observation') {
        // Update last prompt number
        if (message.prompt_number !== undefined) {
          session.lastPromptNumber = message.prompt_number;
        }

        yield {
          type: 'user',
          message: {
            role: 'user',
            content: buildObservationPrompt({
              id: 0, // Not used in prompt
              tool_name: message.tool_name!,
              tool_input: JSON.stringify(message.tool_input),
              tool_output: JSON.stringify(message.tool_output),
              created_at_epoch: Date.now()
            })
          },
          session_id: session.claudeSessionId,
          parent_tool_use_id: null,
          isSynthetic: true
        };
      } else if (message.type === 'summarize') {
        yield {
          type: 'user',
          message: {
            role: 'user',
            content: buildSummaryPrompt({
              id: session.sessionDbId,
              sdk_session_id: session.sdkSessionId,
              project: session.project,
              user_prompt: session.userPrompt
            })
          },
          session_id: session.claudeSessionId,
          parent_tool_use_id: null,
          isSynthetic: true
        };
      }
    }
  }

  /**
   * Process SDK response text (parse XML, save to database, sync to Chroma)
   */
  private async processSDKResponse(session: ActiveSession, text: string): Promise<void> {
    // Parse observations
    const observations = parseObservations(text, session.claudeSessionId);

    // Store observations
    for (const obs of observations) {
      const { id: obsId, createdAtEpoch } = this.dbManager.getSessionStore().storeObservation(
        session.claudeSessionId,
        session.project,
        obs,
        session.lastPromptNumber
      );

      // Sync to Chroma (fire-and-forget)
      this.dbManager.getChromaSync().syncObservation(
        obsId,
        session.claudeSessionId,
        session.project,
        obs,
        session.lastPromptNumber,
        createdAtEpoch
      ).catch(() => {});

      logger.info('SDK', 'Observation saved', { obsId, type: obs.type });
    }

    // Parse summary
    const summary = parseSummary(text, session.sessionDbId);

    // Store summary
    if (summary) {
      const { id: summaryId, createdAtEpoch } = this.dbManager.getSessionStore().storeSummary(
        session.claudeSessionId,
        session.project,
        summary,
        session.lastPromptNumber
      );

      // Sync to Chroma (fire-and-forget)
      this.dbManager.getChromaSync().syncSummary(
        summaryId,
        session.claudeSessionId,
        session.project,
        summary,
        session.lastPromptNumber,
        createdAtEpoch
      ).catch(() => {});

      logger.info('SDK', 'Summary saved', { summaryId });
    }
  }

  // ============================================================================
  // Configuration Helpers
  // ============================================================================

  /**
   * Find Claude executable (inline, called once per session)
   */
  private findClaudeExecutable(): string {
    const claudePath = process.env.CLAUDE_CODE_PATH ||
      execSync(process.platform === 'win32' ? 'where claude' : 'which claude', { encoding: 'utf8' })
        .trim().split('\n')[0].trim();

    if (!claudePath) {
      throw new Error('Claude executable not found in PATH');
    }

    return claudePath;
  }

  /**
   * Get model ID from settings or environment
   */
  private getModelId(): string {
    try {
      const settingsPath = path.join(homedir(), '.claude-mem', 'settings.json');
      if (existsSync(settingsPath)) {
        const settings = JSON.parse(readFileSync(settingsPath, 'utf-8'));
        const modelId = settings.env?.CLAUDE_MEM_MODEL;
        if (modelId) return modelId;
      }
    } catch {
      // Fall through to env var or default
    }

    return process.env.CLAUDE_MEM_MODEL || 'claude-haiku-4-5';
  }
}