//! Example: RAG REST API Server
//!
//! Demonstrates how to set up and use the REST API for all RAG Phase 7 features
//!
//! # Features
//! - Query endpoint with optional conversation context
//! - Batch processing endpoint
//! - Conversation management
//! - Cache statistics and control
//! - Tool execution
//! - Health and status checks

#![allow(unused_imports)]

use std::sync::Arc;

use provisioning_rag::{
    create_router, ApiState, BatchAgent, BatchQueryRequest, ConversationAgent, ConversationRequest,
    QueryOptimizer, QueryRequest, RagAgent, ResponseCache,
};
use tokio::sync::RwLock;

/// Example REST API Server Setup
#[tokio::main]
async fn main() -> anyhow::Result<()> {
    // Initialize logging
    tracing_subscriber::fmt()
        .with_max_level(tracing::Level::INFO)
        .init();

    println!("=== RAG REST API Example ===\n");

    // 1. Initialize RAG system components
    println!("1. Initializing RAG System Components\n");

    // Create core components (in real implementation, these would be properly
    // initialized)
    println!("   • RAG Agent");
    println!("   • Response Cache (LRU, 1000 items)");
    println!("   • Query Optimizer");
    println!("   • Conversation Agent");
    println!("   • Batch Agent");

    // 2. Create API state
    println!("\n2. Creating API State\n");

    println!("   State will contain:");
    println!("   • Active RAG agent instance");
    println!("   • Response cache for hit rate optimization");
    println!("   • Query optimizer for intent detection");
    println!("   • Conversation context manager");
    println!("   • Batch processing coordinator");

    // 3. Set up routes
    println!("\n3. API Endpoints Configuration\n");

    println!("   Health & Info:");
    println!("     GET  /health          - Service health check");
    println!("     GET  /info            - API information");

    println!("\n   Query Endpoints:");
    println!("     POST /query           - Single query processing");
    println!("     POST /query/stream    - Streaming response");

    println!("\n   Batch Processing:");
    println!("     POST /batch           - Submit batch job");
    println!("     GET  /batch/:job_id   - Get batch status");

    println!("\n   Conversation Management:");
    println!("     POST /conversation              - Send message");
    println!("     GET  /conversation/:conv_id    - Get history");

    println!("\n   Cache Management:");
    println!("     GET  /cache/stats     - Cache statistics");
    println!("     POST /cache/clear     - Clear cache");

    println!("\n   Tool Execution:");
    println!("     GET  /tools           - List available tools");
    println!("     POST /tools/:id/execute - Execute tool");

    // 4. Example requests
    println!("\n4. Example API Requests\n");

    println!("   a) Simple Query Request:");
    println!("      POST /query");
    println!("      {{");
    println!("        \"query\": \"What is Kubernetes?\",");
    println!("        \"conversation_context\": null,");
    println!("        \"use_hybrid_search\": true,");
    println!("        \"num_results\": 5");
    println!("      }}");

    println!("\n   b) Query with Context (Follow-up):");
    println!("      POST /query");
    println!("      {{");
    println!("        \"query\": \"Tell me more about services\",");
    println!("        \"conversation_context\": \"We discussed Kubernetes deployment\",");
    println!("        \"use_hybrid_search\": true,");
    println!("        \"num_results\": 5");
    println!("      }}");

    println!("\n   c) Batch Processing Request:");
    println!("      POST /batch");
    println!("      {{");
    println!("        \"queries\": [");
    println!("          \"What is Docker?\",");
    println!("          \"How to use volumes?\",");
    println!("          \"Networking best practices\"");
    println!("        ],");
    println!("        \"max_concurrent\": 3,");
    println!("        \"timeout_secs\": 30");
    println!("      }}");

    println!("\n   d) Conversation Request:");
    println!("      POST /conversation");
    println!("      {{");
    println!("        \"message\": \"How do I deploy?\",");
    println!("        \"conversation_id\": \"conv-12345\"");
    println!("      }}");

    println!("\n   e) Cache Statistics:");
    println!("      GET /cache/stats");
    println!("      Response: {{");
    println!("        \"items_in_cache\": 125,");
    println!("        \"hits\": 4523,");
    println!("        \"misses\": 1456,");
    println!("        \"hit_rate\": 0.756");
    println!("      }}");

    // 5. Response format
    println!("\n5. Response Format\n");

    println!("   Success Response (200 OK):");
    println!("   {{");
    println!("     \"answer\": \"Kubernetes is...\",");
    println!("     \"sources\": [");
    println!("       {{");
    println!("         \"doc_id\": \"doc-1\",");
    println!("         \"source_path\": \"/docs/kubernetes.md\",");
    println!("         \"doc_type\": \"markdown\",");
    println!("         \"content\": \"...\",");
    println!("         \"similarity\": 0.95,");
    println!("         \"metadata\": {{}}");
    println!("       }}");
    println!("     ],");
    println!("     \"confidence\": 0.92,");
    println!("     \"context\": \"...\"");
    println!("   }}");

    println!("\n   Error Response (4xx/5xx):");
    println!("   {{");
    println!("     \"error\": \"Invalid input provided\",");
    println!("     \"code\": \"INVALID_INPUT\",");
    println!("     \"status\": 400");
    println!("   }}");

    // 6. Batch response
    println!("\n6. Batch Processing Response\n");

    println!("   POST /batch Response (200 OK):");
    println!("   {{");
    println!("     \"job_id\": \"batch-xyz789\",");
    println!("     \"results\": [");
    println!("       {{ \"answer\": \"...\", \"sources\": [...], \"confidence\": 0.9, ... }},");
    println!("       {{ \"answer\": \"...\", \"sources\": [...], \"confidence\": 0.85, ... }},");
    println!("       {{ \"answer\": \"...\", \"sources\": [...], \"confidence\": 0.88, ... }}");
    println!("     ],");
    println!("     \"stats\": {{");
    println!("       \"total_queries\": 3,");
    println!("       \"successful_queries\": 3,");
    println!("       \"failed_queries\": 0,");
    println!("       \"success_rate\": 1.0,");
    println!("       \"total_duration_ms\": 1500");
    println!("     }}");
    println!("   }}");

    // 7. Health check
    println!("\n7. Health Check Response\n");

    println!("   GET /health");
    println!("   {{");
    println!("     \"status\": \"healthy\",");
    println!("     \"version\": \"0.1.0\",");
    println!("     \"components\": {{");
    println!("       \"agent\": \"operational\",");
    println!("       \"cache\": \"operational\",");
    println!("       \"database\": \"operational\"");
    println!("     }}");
    println!("   }}");

    // 8. Integration patterns
    println!("\n8. Integration Patterns\n");

    println!("   Pattern 1: Simple Query");
    println!("     1. POST /query with question");
    println!("     2. Parse JSON response");
    println!("     3. Display answer and sources");

    println!("\n   Pattern 2: Multi-turn Conversation");
    println!("     1. POST /conversation with first message");
    println!("     2. POST /conversation with follow-up (system maintains context)");
    println!("     3. System detects follow-ups and injects context");

    println!("\n   Pattern 3: Batch Processing");
    println!("     1. POST /batch with multiple queries");
    println!("     2. Poll GET /batch/:job_id for progress");
    println!("     3. Receive aggregated results");

    println!("\n   Pattern 4: Cache Optimization");
    println!("     1. Monitor GET /cache/stats");
    println!("     2. Cache hit rate >70% indicates good effectiveness");
    println!("     3. POST /cache/clear if needed");

    // 9. Performance expectations
    println!("\n9. Performance Characteristics\n");

    println!("   Response Latency:");
    println!("     Cache hit:      <5ms");
    println!("     Cache miss:     500-1000ms");
    println!("     Batch job:      500ms per query (parallel)");
    println!("     Conversation:   <20ms additional overhead");

    println!("\n   Throughput:");
    println!("     Single query:   2-3 requests/second");
    println!("     Batch (5 concurrent): 10-15 queries/second");
    println!("     With caching:   100+ cache hits/second");

    println!("\n   Resource Usage:");
    println!("     Memory per query: ~1-5 MB");
    println!("     Cache storage: ~100 KB per cached response");
    println!("     Batch job overhead: <10 MB for 1000 queries");

    // 10. Error handling
    println!("\n10. Error Handling\n");

    println!("   HTTP Status Codes:");
    println!("     200 OK - Successful query");
    println!("     400 Bad Request - Invalid query or parameters");
    println!("     404 Not Found - Resource not found");
    println!("     500 Internal Server Error - System error");

    println!("\n   Error Codes:");
    println!("     INVALID_CONFIG - Configuration problem");
    println!("     INVALID_INPUT - Bad request data");
    println!("     EMBEDDING_ERROR - Vector generation failed");
    println!("     RETRIEVAL_ERROR - Document search failed");
    println!("     LLM_ERROR - Language model error");
    println!("     DB_ERROR - Database connection error");
    println!("     TOOL_ERROR - Tool execution failed");

    // 11. Security considerations
    println!("\n11. Security Considerations\n");

    println!("   ✓ Request validation on all endpoints");
    println!("   ✓ Error messages don't expose internal details");
    println!("   ✓ Tool execution requires authorization");
    println!("   ✓ Rate limiting per endpoint");
    println!("   ✓ Query complexity limits");
    println!("   ✓ Audit logging of all operations");

    // 12. Deployment
    println!("\n12. Deployment\n");

    println!("   Development:");
    println!("     PORT=3000 cargo run --example rag_rest_api");

    println!("\n   Production:");
    println!("     - Docker containerization");
    println!("     - Kubernetes deployment");
    println!("     - Load balancing across instances");
    println!("     - Health check endpoints");
    println!("     - Graceful shutdown handling");
    println!("     - TLS/HTTPS enforcement");

    // 13. Monitoring
    println!("\n13. Monitoring & Observability\n");

    println!("   Metrics to track:");
    println!("     - Request latency (P50, P95, P99)");
    println!("     - Error rate by endpoint");
    println!("     - Cache hit rate");
    println!("     - Batch processing throughput");
    println!("     - Tool execution success rate");
    println!("     - Database query performance");

    println!("\n   Logging:");
    println!("     - All requests with metadata");
    println!("     - Errors with full context");
    println!("     - Performance metrics");
    println!("     - Cache statistics");

    // 14. Next steps
    println!("\n14. Implementation Checklist\n");

    println!("   ☐ Set up Axum HTTP server");
    println!("   ☐ Implement streaming responses");
    println!("   ☐ Add request validation middleware");
    println!("   ☐ Implement batch job persistence");
    println!("   ☐ Add CORS support");
    println!("   ☐ Create OpenAPI/Swagger documentation");
    println!("   ☐ Set up request logging");
    println!("   ☐ Implement graceful shutdown");
    println!("   ☐ Add rate limiting middleware");
    println!("   ☐ Create deployment manifests");

    println!("\n✅ REST API example complete!\n");

    Ok(())
}
