// SPDX-FileCopyrightText: Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
// SPDX-License-Identifier: Apache-2.0

use anyhow::Error;
use async_stream::stream;
use dynamo_llm::{
    http::service::{metrics::Endpoint, service_v2::HttpService},
    model_card::ModelDeploymentCard,
    preprocessor::LLMMetricAnnotation,
    protocols::{
        Annotated,
        openai::chat_completions::{
            NvCreateChatCompletionRequest, NvCreateChatCompletionStreamResponse,
        },
    },
};
use dynamo_runtime::metrics::prometheus_names::frontend_service::METRICS_PREFIX_ENV;
use dynamo_runtime::{
    CancellationToken,
    pipeline::{
        AsyncEngine, AsyncEngineContextProvider, ManyOut, ResponseStream, SingleIn, async_trait,
    },
};
use std::{sync::Arc, time::Duration};

#[path = "common/ports.rs"]
mod ports;
use ports::get_random_port;

// Mock engine for testing metrics
struct MockModelEngine {}

#[async_trait]
impl
    AsyncEngine<
        SingleIn<NvCreateChatCompletionRequest>,
        ManyOut<Annotated<NvCreateChatCompletionStreamResponse>>,
        Error,
    > for MockModelEngine
{
    async fn generate(
        &self,
        request: SingleIn<NvCreateChatCompletionRequest>,
    ) -> Result<ManyOut<Annotated<NvCreateChatCompletionStreamResponse>>, Error> {
        let (request, context) = request.transfer(());
        let ctx = context.context();

        let mut generator = request.response_generator(ctx.id().to_string());

        let stream = stream! {
            // Simulate some processing time
            tokio::time::sleep(std::time::Duration::from_millis(10)).await;

            // Generate 5 response chunks with LLMMetricAnnotation so that
            // output_sequence_tokens is properly recorded (the histogram only
            // records when osl > 0, which requires the annotation to be present).
            for i in 0..5 {
                let output = generator.create_choice(i, Some(format!("Mock response {i}")), None, None);
                let mut annotated = Annotated::from_data(output);
                let metrics = LLMMetricAnnotation {
                    input_tokens: 5,
                    output_tokens: (i + 1) as usize,
                    chunk_tokens: 1,
                    cached_tokens: None,
                    prefill_worker_id: None,
                    prefill_dp_rank: None,
                    prefill_worker_type: None,
                    decode_worker_id: None,
                    decode_dp_rank: None,
                    decode_worker_type: None,
                    tokenize_latency: None,
                    detokenize_total_latency: None,
                    detokenize_count: None,
                };
                if let Ok(ann) = metrics.to_annotation::<NvCreateChatCompletionStreamResponse>() {
                    annotated.event = ann.event;
                    annotated.comment = ann.comment;
                }
                yield annotated;
            }
        };

        Ok(ResponseStream::new(Box::pin(stream), ctx))
    }
}

#[tokio::test]
async fn test_metrics_prefix_default() {
    // Test default prefix when no env var is set
    temp_env::async_with_vars([(METRICS_PREFIX_ENV, None::<&str>)], async {
        let port = get_random_port().await;
        let service = HttpService::builder().port(port).build().unwrap();
        let token = CancellationToken::new();
        let handle = service.spawn(token.clone()).await;
        wait_for_metrics_ready(port).await;

        // Populate labeled metrics
        let state = service.state_clone();
        {
            let _guard = state.metrics_clone().create_inflight_guard(
                "test-model",
                Endpoint::ChatCompletions,
                false,
                "",
            );
        }

        let body = reqwest::get(format!("http://localhost:{}/metrics", port))
            .await
            .unwrap()
            .text()
            .await
            .unwrap();

        // Assert metrics that are actually present in the default configuration
        assert!(body.contains("dynamo_frontend_requests_total"));
        assert!(body.contains("dynamo_frontend_inflight_requests"));
        assert!(body.contains("dynamo_frontend_request_duration_seconds"));
        assert!(body.contains("dynamo_frontend_disconnected_clients"));

        token.cancel();
        let _ = handle.await;
    })
    .await;
}

#[tokio::test]
async fn test_metrics_prefix_custom() {
    // Test custom prefix override via environment variable
    temp_env::async_with_vars([(METRICS_PREFIX_ENV, Some("custom_prefix"))], async {
        let port = get_random_port().await;
        let service = HttpService::builder().port(port).build().unwrap();
        let token = CancellationToken::new();
        let handle = service.spawn(token.clone()).await;
        wait_for_metrics_ready(port).await;

        // Populate labeled metrics
        let state = service.state_clone();
        {
            let _guard = state.metrics_clone().create_inflight_guard(
                "test-model",
                Endpoint::ChatCompletions,
                true,
                "",
            );
        }

        let body = reqwest::get(format!("http://localhost:{}/metrics", port))
            .await
            .unwrap()
            .text()
            .await
            .unwrap();
        assert!(body.contains("custom_prefix_requests_total"));
        assert!(!body.contains("dynamo_frontend_requests_total"));

        token.cancel();
        let _ = handle.await;
    })
    .await;
}

#[tokio::test]
async fn test_metrics_prefix_sanitized() {
    // Test that invalid prefix characters are sanitized
    temp_env::async_with_vars([(METRICS_PREFIX_ENV, Some("nv-llm/http service"))], async {
        let port = get_random_port().await;
        let service = HttpService::builder().port(port).build().unwrap();
        let token = CancellationToken::new();
        let handle = service.spawn(token.clone()).await;
        wait_for_metrics_ready(port).await;

        let state = service.state_clone();
        {
            let _guard = state.metrics_clone().create_inflight_guard(
                "test-model",
                Endpoint::ChatCompletions,
                true,
                "",
            );
        }

        let body = reqwest::get(format!("http://localhost:{}/metrics", port))
            .await
            .unwrap()
            .text()
            .await
            .unwrap();
        assert!(body.contains("nv_llm_http_service_requests_total"));
        assert!(!body.contains("dynamo_frontend_requests_total"));

        token.cancel();
        let _ = handle.await;
    })
    .await;
}

// Poll /metrics until ready or timeout
async fn wait_for_metrics_ready(port: u16) {
    let url = format!("http://localhost:{}/metrics", port);
    let start = tokio::time::Instant::now();
    let timeout = Duration::from_secs(5);
    loop {
        if start.elapsed() > timeout {
            panic!("Timed out waiting for metrics endpoint at {}", url);
        }
        match reqwest::get(&url).await {
            Ok(resp) if resp.status().is_success() => break,
            _ => tokio::time::sleep(Duration::from_millis(50)).await,
        }
    }
}

#[tokio::test]
async fn test_metrics_with_mock_model() {
    // Test metrics collection with a mock model serving requests
    // Ensure we use the default prefix
    temp_env::async_with_vars([(METRICS_PREFIX_ENV, None::<&str>)], async {
        let port = get_random_port().await;
        let service = HttpService::builder()
            .port(port)
            .enable_chat_endpoints(true)
            .build()
            .unwrap();

        let state = service.state_clone();
        let manager = state.manager();

        // Start the HTTP service
        let token = CancellationToken::new();
        let cancel_token = token.clone();
        let task = tokio::spawn(async move { service.run(token.clone()).await });

        // Add mock model engine
        let card = ModelDeploymentCard::with_name_only("mockmodel");
        let mock_engine = Arc::new(MockModelEngine {});
        manager
            .add_chat_completions_model("mockmodel", card.mdcsum(), mock_engine)
            .unwrap();

        // Wait for service to be ready
        wait_for_metrics_ready(port).await;

        let client = reqwest::Client::new();

        // Create a chat completion request
        let message = dynamo_protocols::types::ChatCompletionRequestMessage::User(
            dynamo_protocols::types::ChatCompletionRequestUserMessage {
                content: dynamo_protocols::types::ChatCompletionRequestUserMessageContent::Text(
                    "Hello, mock model!".to_string(),
                ),
                name: None,
            },
        );

        let request = dynamo_protocols::types::CreateChatCompletionRequestArgs::default()
            .model("mockmodel")
            .messages(vec![message])
            .max_tokens(50u32)
            .stream(true)
            .build()
            .expect("Failed to build request");

        // Make the request to the HTTP service
        let response = client
            .post(format!("http://localhost:{}/v1/chat/completions", port))
            .json(&request)
            .send()
            .await
            .unwrap();

        assert!(
            response.status().is_success(),
            "Request failed: {:?}",
            response
        );

        // Consume the response stream to complete the request
        let _response_body = response.bytes().await.unwrap();

        // Give some time for metrics to be updated
        tokio::time::sleep(Duration::from_millis(100)).await;

        // Fetch and verify metrics
        let metrics_response = client
            .get(format!("http://localhost:{}/metrics", port))
            .send()
            .await
            .unwrap();

        assert!(metrics_response.status().is_success());
        let metrics_body = metrics_response.text().await.unwrap();

        println!("=== METRICS WITH MOCK MODEL ===");
        println!("{}", metrics_body);
        println!("=== END METRICS ===");

        // Assert that key metrics are present with the mockmodel
        assert!(metrics_body.contains("dynamo_frontend_requests_total"));
        assert!(metrics_body.contains("model=\"mockmodel\""));
        assert!(metrics_body.contains("dynamo_frontend_inflight_requests"));
        assert!(metrics_body.contains("dynamo_frontend_request_duration_seconds"));
        assert!(metrics_body.contains("dynamo_frontend_output_sequence_tokens"));
        assert!(metrics_body.contains("dynamo_frontend_queued_requests"));

        // Verify specific request counter incremented
        assert!(metrics_body.contains("endpoint=\"chat_completions\""));
        assert!(metrics_body.contains("request_type=\"stream\""));
        assert!(metrics_body.contains("status=\"success\""));

        // Clean up
        cancel_token.cancel();
        task.await.unwrap().unwrap();
    })
    .await;
}

// Integration tests that require distributed runtime with etcd
#[cfg(feature = "integration")]
mod integration_tests {
    use super::*;
    use dynamo_llm::{
        discovery::ModelWatcher, engines::make_echo_engine, entrypoint::EngineConfig,
        local_model::LocalModelBuilder, namespace::NamespaceFilter,
    };
    use dynamo_runtime::DistributedRuntime;
    use dynamo_runtime::discovery::DiscoveryQuery;
    use std::sync::Arc;

    #[tokio::test]
    #[ignore = "Requires etcd and distributed runtime"]
    async fn test_metrics_with_mdc_registration() {
        // Integration test for metrics collection with full MDC registration (like real model servers)
        let port = get_random_port().await;

        // Create distributed runtime (required for MDC registration)
        let runtime = dynamo_runtime::Runtime::from_settings().unwrap();
        let distributed_runtime = DistributedRuntime::from_settings(runtime.clone())
            .await
            .unwrap();

        // Create LocalModel with realistic configuration for testing
        let mut local_model = LocalModelBuilder::default()
            .model_name(Some("test-mdc-model".to_string()))
            .build()
            .await
            .unwrap();

        // Create EngineConfig with EchoEngine
        let engine_config = EngineConfig::InProcessText {
            engine: make_echo_engine(),
            model: Box::new(local_model.clone()),
        };

        let service = HttpService::builder()
            .port(port)
            .enable_chat_endpoints(true)
            .build()
            .unwrap();

        // Set up model watcher to discover models via discovery interface (like production)
        // This is crucial for the polling task to find model entries

        let model_watcher = ModelWatcher::new(
            distributed_runtime.clone(),
            service.state().manager_clone(),
            dynamo_llm::entrypoint::RouterConfig::default(),
            0,    // migration_limit
            None, // migration_max_seq_len
            None,
            None,
            service.state().metrics_clone(),
        );
        // Start watching for model registrations via discovery interface
        let discovery = distributed_runtime.discovery();
        let discovery_stream = discovery
            .list_and_watch(
                DiscoveryQuery::AllModels,
                Some(distributed_runtime.primary_token()),
            )
            .await
            .unwrap();

        // Spawn watcher task to discover models
        let _watcher_task = tokio::spawn(async move {
            Arc::new(model_watcher)
                .watch(discovery_stream, NamespaceFilter::Global)
                .await;
        });

        let EngineConfig::InProcessText { engine, model, .. } = engine_config else {
            panic!("Expected InProcessText config");
        };

        let card = local_model.card().clone();
        let engine = Arc::new(dynamo_llm::engines::StreamingEngineAdapter::new(engine));
        let manager = service.model_manager();
        manager
            .add_chat_completions_model(model.service_name(), card.mdcsum(), engine.clone())
            .unwrap();

        // Now do the proper MDC registration via LocalModel::attach()
        // Create a component and endpoint for proper registration
        let namespace = distributed_runtime.namespace("test-namespace").unwrap();
        let test_component = namespace.component("test-mdc-component").unwrap();
        let test_endpoint = test_component.endpoint("test-mdc-endpoint");

        // This will store the MDC in key-value store for discovery
        local_model
            .attach(
                &test_endpoint,
                dynamo_llm::model_type::ModelType::Chat,
                dynamo_llm::model_type::ModelInput::Text,
                None,
            )
            .await
            .unwrap();

        // Manually save the model card and update metrics
        // This simulates what the ModelWatcher polling task would do in production
        let _ = manager.save_model_card("test-mdc-key", card.clone());

        if let Err(e) = service
            .state()
            .metrics_clone()
            .update_metrics_from_mdc(&card)
        {
            tracing::debug!(
                model = %card.display_name,
                error = %e,
                "Failed to update MDC metrics in test"
            );
        }

        // Start the HTTP service
        let token = CancellationToken::new();
        let cancel_token = token.clone();
        let service_for_task = service.clone();
        let task = tokio::spawn(async move { service_for_task.run(token.clone()).await });

        // Wait for service to be ready
        wait_for_metrics_ready(port).await;

        // Give a bit more time for background metrics collection
        tokio::time::sleep(Duration::from_secs(5)).await;

        let client = reqwest::Client::new();

        // Create a chat completion request
        let message = dynamo_protocols::types::ChatCompletionRequestMessage::User(
            dynamo_protocols::types::ChatCompletionRequestUserMessage {
                content: dynamo_protocols::types::ChatCompletionRequestUserMessageContent::Text(
                    "Hello, MDC model!".to_string(),
                ),
                name: None,
            },
        );

        let request = dynamo_protocols::types::CreateChatCompletionRequestArgs::default()
            .model(model.service_name())
            .messages(vec![message])
            .max_tokens(50u32)
            .stream(true)
            .build()
            .expect("Failed to build request");

        // Make the request to the HTTP service
        let response = client
            .post(format!("http://localhost:{}/v1/chat/completions", port))
            .json(&request)
            .send()
            .await
            .unwrap();

        assert!(
            response.status().is_success(),
            "Request failed: {:?}",
            response
        );

        // Consume the response stream to complete the request
        let _response_body = response.bytes().await.unwrap();

        // Wait for the fast polling interval (50ms) for MDC metrics
        tokio::time::sleep(Duration::from_millis(50)).await;

        // Fetch and verify metrics
        let metrics_response = client
            .get(format!("http://localhost:{}/metrics", port))
            .send()
            .await
            .unwrap();

        assert!(metrics_response.status().is_success());
        let metrics_body = metrics_response.text().await.unwrap();

        println!("=== METRICS WITH FULL MDC REGISTRATION ===");
        println!("{}", metrics_body);
        println!("=== END METRICS ===");

        // Assert basic metrics are present (using service_name from the model)
        let model_name = model.service_name();
        assert!(metrics_body.contains("dynamo_frontend_requests_total"));
        assert!(metrics_body.contains(&format!("model=\"{}\"", model_name)));
        assert!(metrics_body.contains("dynamo_frontend_inflight_requests"));
        assert!(metrics_body.contains("dynamo_frontend_request_duration_seconds"));
        assert!(metrics_body.contains("dynamo_frontend_output_sequence_tokens"));
        assert!(metrics_body.contains("dynamo_frontend_queued_requests"));

        // Assert MDC-based model configuration metrics are present
        // These MUST be present for the test to pass
        assert!(
            metrics_body.contains("dynamo_frontend_model_context_length"),
            "MDC metrics not found! Metrics body: {}",
            metrics_body
        );

        assert!(metrics_body.contains("dynamo_frontend_model_kv_cache_block_size"));
        assert!(metrics_body.contains("dynamo_frontend_model_migration_limit"));

        // Note: The following metrics are not present in this test because they require
        // actual inference engines (vllm/sglang/trtllm *.py) with real runtime configurations:
        // - dynamo_frontend_model_total_kv_blocks (requires actual KV cache from real engines)
        // - dynamo_frontend_model_max_num_seqs (requires actual batching config from real engines)
        // - dynamo_frontend_model_max_num_batched_tokens (requires actual batching config from real engines)

        // Verify specific request counter incremented
        assert!(metrics_body.contains("endpoint=\"chat_completions\""));
        assert!(metrics_body.contains("request_type=\"stream\""));
        assert!(metrics_body.contains("status=\"success\""));

        // etcd lease will ensure we everything is deleted from etcd

        // Now test the complete lifecycle: remove the model from etcd
        // We don't need to cleanup model manager because it's local to this test

        /*
        // Clean up
        // Remove the model using the cleaner ModelWatcher approach
        if let Some(etcd_client) = distributed_runtime.etcd_client() {
            // Use ModelWatcher to find and remove the model (following ModelWatcher::handle_delete pattern)
            let watcher = ModelWatcher::new(
                distributed_runtime.clone(),
                service.state().manager_clone(),
                dynamo_llm::entrypoint::RouterConfig::default(),
                0, // migration_limit
                None,
                service.state().metrics_clone(),
            );

            // Get all model entries for our test model
            let model_entries = watcher.entries_for_model("test-mdc-model").await.unwrap();

            if !model_entries.is_empty() {
                // For each model entry, we need to find its etcd key and remove it
                // This follows the same pattern as ModelWatcher::handle_delete
                for model_entry in model_entries {
                    // Find the etcd key for this specific model entry
                    // etcd keys follow pattern: "models/{UUID}"
                    // Example: "models/11dff335-316d-4c9f-8229-88ad8e8dac5e"
                    let kvs = etcd_client.kv_get_prefix("models").await.unwrap();

                    // Find the key by matching ModelEntry JSON structure:
                    // {
                    //   "name": "test-mdc-model",
                    //   "endpoint": { "namespace": "...", "component": "...", "name": "..." },
                    //   "model_type": "Chat",
                    //   "runtime_config": { ... },
                    //   "model_input": "Text"
                    // }
                    let key = kvs
                        .iter()
                        .find(|kv| {
                            serde_json::from_slice::<ModelEntry>(kv.value())
                                .map(|entry| {
                                    entry.name == model_entry.name
                                        && entry.endpoint_id == model_entry.endpoint_id
                                })
                                .unwrap_or(false)
                        })
                        .map(|kv| kv.key_str().unwrap().to_string());

                    if let Some(key) = key {
                        // Remove from ModelManager first (this returns the ModelEntry)
                        if let Some(_removed_card) = manager.remove_model_card(&key) {
                            // Remove entire model (following ModelWatcher::handle_delete pattern)
                            manager.remove_model(&model_entry.name);

                            // Then delete from etcd
                            etcd_client.kv_delete(key.as_str(), None).await.unwrap();
                        }
                    }
                }
            }
        }
        */

        cancel_token.cancel();
        task.await.unwrap().unwrap();
    }
}
