//! Integration tests for Prometheus remote_write ingestion endpoint
//!
//! These tests verify the end-to-end functionality of the ingestion service,
//! including HTTP handling, snappy compression, and protobuf encoding.

use axum::body::Body;
use axum::http::{Request, StatusCode};
use metricstor_api::prometheus::{Label, Sample, TimeSeries, WriteRequest};
use prost::Message;
use snap::raw::Encoder as SnappyEncoder;
use std::collections::HashMap;
use std::sync::Arc;
use tokio::sync::RwLock;
use tower::ServiceExt; // For oneshot

use metricstor_server::query::QueryableStorage;

/// Helper function to create shared storage for tests
fn create_shared_storage() -> Arc<RwLock<QueryableStorage>> {
    Arc::new(RwLock::new(QueryableStorage {
        series: HashMap::new(),
        label_index: HashMap::new(),
    }))
}

/// Helper function to create a valid WriteRequest
fn create_test_write_request() -> WriteRequest {
    WriteRequest {
        timeseries: vec![TimeSeries {
            labels: vec![
                Label {
                    name: "__name__".to_string(),
                    value: "test_metric".to_string(),
                },
                Label {
                    name: "job".to_string(),
                    value: "test".to_string(),
                },
                Label {
                    name: "instance".to_string(),
                    value: "localhost:9090".to_string(),
                },
            ],
            samples: vec![
                Sample {
                    value: 42.0,
                    timestamp: 1234567890000,
                },
                Sample {
                    value: 43.0,
                    timestamp: 1234567891000,
                },
            ],
        }],
    }
}

/// Helper function to encode and compress a WriteRequest
fn encode_and_compress(request: &WriteRequest) -> Vec<u8> {
    // Encode to protobuf
    let mut buf = Vec::new();
    request.encode(&mut buf).unwrap();

    // Compress with snappy
    let mut encoder = SnappyEncoder::new();
    encoder.compress_vec(&buf).unwrap()
}

#[tokio::test]
async fn test_remote_write_valid_request() {
    // Create a valid WriteRequest
    let write_request = create_test_write_request();

    // Encode and compress
    let compressed = encode_and_compress(&write_request);

    // Create HTTP request
    let request = Request::builder()
        .method("POST")
        .uri("/api/v1/write")
        .header("Content-Type", "application/x-protobuf")
        .header("Content-Encoding", "snappy")
        .body(Body::from(compressed))
        .unwrap();

    // Create service and send request
    let service = metricstor_server::ingestion::IngestionService::new(create_shared_storage());
    let app = service.router();

    let response = app.oneshot(request).await.unwrap();

    // Should return 204 No Content on success
    assert_eq!(response.status(), StatusCode::NO_CONTENT);
}

#[tokio::test]
async fn test_remote_write_missing_name_label() {
    // Create WriteRequest without __name__ label
    let write_request = WriteRequest {
        timeseries: vec![TimeSeries {
            labels: vec![Label {
                name: "job".to_string(),
                value: "test".to_string(),
            }],
            samples: vec![Sample {
                value: 42.0,
                timestamp: 1234567890000,
            }],
        }],
    };

    let compressed = encode_and_compress(&write_request);

    let request = Request::builder()
        .method("POST")
        .uri("/api/v1/write")
        .body(Body::from(compressed))
        .unwrap();

    let service = metricstor_server::ingestion::IngestionService::new(create_shared_storage());
    let app = service.router();

    let response = app.oneshot(request).await.unwrap();

    // Should return 400 Bad Request for invalid labels
    assert_eq!(response.status(), StatusCode::BAD_REQUEST);
}

#[tokio::test]
async fn test_remote_write_invalid_label_name() {
    // Create WriteRequest with invalid label name (starts with digit)
    let write_request = WriteRequest {
        timeseries: vec![TimeSeries {
            labels: vec![
                Label {
                    name: "__name__".to_string(),
                    value: "test_metric".to_string(),
                },
                Label {
                    name: "123invalid".to_string(), // Invalid: starts with digit
                    value: "value".to_string(),
                },
            ],
            samples: vec![Sample {
                value: 42.0,
                timestamp: 1234567890000,
            }],
        }],
    };

    let compressed = encode_and_compress(&write_request);

    let request = Request::builder()
        .method("POST")
        .uri("/api/v1/write")
        .body(Body::from(compressed))
        .unwrap();

    let service = metricstor_server::ingestion::IngestionService::new(create_shared_storage());
    let app = service.router();

    let response = app.oneshot(request).await.unwrap();

    // Should return 400 Bad Request for invalid label name
    assert_eq!(response.status(), StatusCode::BAD_REQUEST);
}

#[tokio::test]
async fn test_remote_write_invalid_protobuf() {
    // Send invalid protobuf data (but properly snappy-compressed)
    let invalid_data = b"this is not valid protobuf data";

    let mut encoder = SnappyEncoder::new();
    let compressed = encoder.compress_vec(invalid_data).unwrap();

    let request = Request::builder()
        .method("POST")
        .uri("/api/v1/write")
        .body(Body::from(compressed))
        .unwrap();

    let service = metricstor_server::ingestion::IngestionService::new(create_shared_storage());
    let app = service.router();

    let response = app.oneshot(request).await.unwrap();

    // Should return 400 Bad Request for invalid protobuf
    assert_eq!(response.status(), StatusCode::BAD_REQUEST);
}

#[tokio::test]
async fn test_remote_write_invalid_snappy() {
    // Send data that's not snappy-compressed
    let invalid_data = b"not snappy compressed data";

    let request = Request::builder()
        .method("POST")
        .uri("/api/v1/write")
        .body(Body::from(invalid_data.to_vec()))
        .unwrap();

    let service = metricstor_server::ingestion::IngestionService::new(create_shared_storage());
    let app = service.router();

    let response = app.oneshot(request).await.unwrap();

    // Should return 400 Bad Request for invalid snappy compression
    assert_eq!(response.status(), StatusCode::BAD_REQUEST);
}

#[tokio::test]
async fn test_remote_write_multiple_series() {
    // Create WriteRequest with multiple time series
    let write_request = WriteRequest {
        timeseries: vec![
            TimeSeries {
                labels: vec![
                    Label {
                        name: "__name__".to_string(),
                        value: "http_requests_total".to_string(),
                    },
                    Label {
                        name: "method".to_string(),
                        value: "GET".to_string(),
                    },
                ],
                samples: vec![Sample {
                    value: 100.0,
                    timestamp: 1234567890000,
                }],
            },
            TimeSeries {
                labels: vec![
                    Label {
                        name: "__name__".to_string(),
                        value: "http_requests_total".to_string(),
                    },
                    Label {
                        name: "method".to_string(),
                        value: "POST".to_string(),
                    },
                ],
                samples: vec![Sample {
                    value: 50.0,
                    timestamp: 1234567890000,
                }],
            },
        ],
    };

    let compressed = encode_and_compress(&write_request);

    let request = Request::builder()
        .method("POST")
        .uri("/api/v1/write")
        .body(Body::from(compressed))
        .unwrap();

    let service = metricstor_server::ingestion::IngestionService::new(create_shared_storage());
    let app = service.router();

    let response = app.oneshot(request).await.unwrap();

    // Should return 204 No Content on success
    assert_eq!(response.status(), StatusCode::NO_CONTENT);
}

#[tokio::test]
async fn test_remote_write_nan_value() {
    // Create WriteRequest with NaN value (should be rejected)
    let write_request = WriteRequest {
        timeseries: vec![TimeSeries {
            labels: vec![
                Label {
                    name: "__name__".to_string(),
                    value: "test_metric".to_string(),
                },
            ],
            samples: vec![Sample {
                value: f64::NAN, // Invalid value
                timestamp: 1234567890000,
            }],
        }],
    };

    let compressed = encode_and_compress(&write_request);

    let request = Request::builder()
        .method("POST")
        .uri("/api/v1/write")
        .body(Body::from(compressed))
        .unwrap();

    let service = metricstor_server::ingestion::IngestionService::new(create_shared_storage());
    let app = service.router();

    let response = app.oneshot(request).await.unwrap();

    // NaN values are filtered out, but request still succeeds
    // (just with 0 samples ingested)
    assert_eq!(response.status(), StatusCode::NO_CONTENT);
}

#[tokio::test]
async fn test_buffer_stats() {
    let service = metricstor_server::ingestion::IngestionService::new(create_shared_storage());

    // Initially buffer should be empty
    let (samples, series) = service.storage_stats().await;
    assert_eq!(samples, 0);
    assert_eq!(series, 0);

    // Send a write request
    let write_request = create_test_write_request();
    let compressed = encode_and_compress(&write_request);

    let request = Request::builder()
        .method("POST")
        .uri("/api/v1/write")
        .body(Body::from(compressed))
        .unwrap();

    let app = service.clone().router();
    let response = app.oneshot(request).await.unwrap();
    assert_eq!(response.status(), StatusCode::NO_CONTENT);

    // Buffer should now contain samples
    let (samples, series) = service.storage_stats().await;
    assert_eq!(samples, 2); // 2 samples in the test request
    assert_eq!(series, 1);  // 1 time series
}