use assert_matches::assert_matches;
use data_types::{ColumnType, PartitionTemplate, QueryPoolId, ShardIndex, TemplatePart, TopicId};
use dml::DmlOperation;
use hashbrown::HashMap;
use hyper::{Body, Request, StatusCode};
use iox_catalog::{interface::Catalog, mem::MemCatalog};
use metric::{Attributes, DurationHistogram, Metric, Registry, U64Counter};
use mutable_batch::MutableBatch;
use router::{
    dml_handlers::{
        Chain, DmlError, DmlHandlerChainExt, FanOutAdaptor, InstrumentationDecorator,
        NamespaceAutocreation, Partitioned, Partitioner, SchemaError, SchemaValidator,
        ShardedWriteBuffer, WriteSummaryAdapter,
    },
    namespace_cache::{MemoryNamespaceCache, ShardedCache},
    server::http::HttpDelegate,
    shard::Shard,
};
use sharder::JumpHash;
use std::{collections::BTreeSet, iter, string::String, sync::Arc};
use write_buffer::{
    core::WriteBufferWriting,
    mock::{MockBufferForWriting, MockBufferSharedState},
};

/// The topic catalog ID assigned by the namespace auto-creator in the
/// handler stack for namespaces it has not yet observed.
const TEST_TOPIC_ID: i64 = 1;

/// The query pool catalog ID assigned by the namespace auto-creator in the
/// handler stack for namespaces it has not yet observed.
const TEST_QUERY_POOL_ID: i64 = 1;

pub struct TestContext {
    delegate: HttpDelegateStack,
    catalog: Arc<dyn Catalog>,
    write_buffer_state: Arc<MockBufferSharedState>,
    metrics: Arc<Registry>,
}

// This mass of words is certainly a downside of chained handlers.
//
// Fortunately the compiler errors are very descriptive and updating this is
// relatively easy when something changes!
type HttpDelegateStack = HttpDelegate<
    InstrumentationDecorator<
        Chain<
            Chain<
                Chain<
                    NamespaceAutocreation<
                        Arc<ShardedCache<Arc<MemoryNamespaceCache>>>,
                        HashMap<String, MutableBatch>,
                    >,
                    SchemaValidator<Arc<ShardedCache<Arc<MemoryNamespaceCache>>>>,
                >,
                Partitioner,
            >,
            WriteSummaryAdapter<
                FanOutAdaptor<
                    ShardedWriteBuffer<JumpHash<Arc<Shard>>>,
                    Vec<Partitioned<HashMap<String, MutableBatch>>>,
                >,
            >,
        >,
    >,
>;

/// A [`router`] stack configured with the various DML handlers using mock
/// catalog / write buffer backends.
impl TestContext {
    pub fn new() -> Self {
        let metrics = Arc::new(metric::Registry::default());
        let time = iox_time::MockProvider::new(iox_time::Time::from_timestamp_millis(668563200000));

        let write_buffer = MockBufferForWriting::new(
            MockBufferSharedState::empty_with_n_shards(1.try_into().unwrap()),
            None,
            Arc::new(time),
        )
        .expect("failed to init mock write buffer");
        let write_buffer_state = write_buffer.state();
        let write_buffer: Arc<dyn WriteBufferWriting> = Arc::new(write_buffer);

        let shards: BTreeSet<_> = write_buffer.shard_indexes();
        let sharded_write_buffer = ShardedWriteBuffer::new(JumpHash::new(
            shards
                .into_iter()
                .map(|shard_index| Shard::new(shard_index, Arc::clone(&write_buffer), &metrics))
                .map(Arc::new),
        ));

        let catalog: Arc<dyn Catalog> = Arc::new(MemCatalog::new(Arc::clone(&metrics)));
        let ns_cache = Arc::new(ShardedCache::new(
            iter::repeat_with(|| Arc::new(MemoryNamespaceCache::default())).take(10),
        ));

        let ns_creator = NamespaceAutocreation::new(
            Arc::clone(&catalog),
            Arc::clone(&ns_cache),
            TopicId::new(TEST_TOPIC_ID),
            QueryPoolId::new(TEST_QUERY_POOL_ID),
            iox_catalog::INFINITE_RETENTION_POLICY.to_owned(),
        );

        let schema_validator = SchemaValidator::new(Arc::clone(&catalog), ns_cache, &*metrics);
        let partitioner = Partitioner::new(PartitionTemplate {
            parts: vec![TemplatePart::TimeFormat("%Y-%m-%d".to_owned())],
        });

        let handler_stack = ns_creator
            .and_then(schema_validator)
            .and_then(partitioner)
            .and_then(WriteSummaryAdapter::new(FanOutAdaptor::new(
                sharded_write_buffer,
            )));

        let handler_stack = InstrumentationDecorator::new("request", &*metrics, handler_stack);

        let delegate = HttpDelegate::new(1024, 100, Arc::new(handler_stack), &metrics);

        Self {
            delegate,
            catalog,
            write_buffer_state,
            metrics,
        }
    }

    /// Get a reference to the test context's delegate.
    pub fn delegate(&self) -> &HttpDelegateStack {
        &self.delegate
    }

    /// Get a reference to the test context's catalog.
    pub fn catalog(&self) -> &dyn Catalog {
        self.catalog.as_ref()
    }

    /// Get a reference to the test context's write buffer state.
    pub fn write_buffer_state(&self) -> &Arc<MockBufferSharedState> {
        &self.write_buffer_state
    }

    /// Get a reference to the test context's metrics.
    pub fn metrics(&self) -> &Registry {
        self.metrics.as_ref()
    }
}

impl Default for TestContext {
    fn default() -> Self {
        Self::new()
    }
}

#[tokio::test]
async fn test_write_ok() {
    let ctx = TestContext::new();

    let request = Request::builder()
        .uri("https://bananas.example/api/v2/write?org=bananas&bucket=test")
        .method("POST")
        .body(Body::from("platanos,tag1=A,tag2=B val=42i 123456"))
        .expect("failed to construct HTTP request");

    let response = ctx
        .delegate()
        .route(request)
        .await
        .expect("LP write request failed");

    assert_eq!(response.status(), StatusCode::NO_CONTENT);

    // Check the write buffer observed the correct write.
    let writes = ctx.write_buffer_state().get_messages(ShardIndex::new(0));
    assert_eq!(writes.len(), 1);
    assert_matches!(writes.as_slice(), [Ok(DmlOperation::Write(w))] => {
        assert_eq!(w.namespace(), "bananas_test");
        assert!(w.table("platanos").is_some());
    });

    // Ensure the catalog saw the namespace creation
    let ns = ctx
        .catalog()
        .repositories()
        .await
        .namespaces()
        .get_by_name("bananas_test")
        .await
        .expect("query should succeed")
        .expect("namespace not found");
    assert_eq!(ns.name, "bananas_test");
    assert_eq!(
        ns.retention_duration.as_deref(),
        Some(iox_catalog::INFINITE_RETENTION_POLICY)
    );
    assert_eq!(ns.topic_id, TopicId::new(TEST_TOPIC_ID));
    assert_eq!(ns.query_pool_id, QueryPoolId::new(TEST_QUERY_POOL_ID));

    // Ensure the metric instrumentation was hit
    let histogram = ctx
        .metrics()
        .get_instrument::<Metric<DurationHistogram>>("dml_handler_write_duration")
        .expect("failed to read metric")
        .get_observer(&Attributes::from(&[
            ("handler", "request"),
            ("result", "success"),
        ]))
        .expect("failed to get observer")
        .fetch();
    let hit_count = histogram.sample_count();
    assert_eq!(hit_count, 1);

    assert_eq!(
        ctx.metrics()
            .get_instrument::<Metric<U64Counter>>("http_write_lines_total")
            .expect("failed to read metric")
            .get_observer(&Attributes::from(&[]))
            .expect("failed to get observer")
            .fetch(),
        1
    );

    let histogram = ctx
        .metrics()
        .get_instrument::<Metric<DurationHistogram>>("shard_enqueue_duration")
        .expect("failed to read metric")
        .get_observer(&Attributes::from(&[
            ("kafka_partition", "0"),
            ("result", "success"),
        ]))
        .expect("failed to get observer")
        .fetch();
    let hit_count = histogram.sample_count();
    assert_eq!(hit_count, 1);
}

#[tokio::test]
async fn test_schema_conflict() {
    let ctx = TestContext::new();

    let request = Request::builder()
        .uri("https://bananas.example/api/v2/write?org=bananas&bucket=test")
        .method("POST")
        .body(Body::from("platanos,tag1=A,tag2=B val=42i 123456"))
        .expect("failed to construct HTTP request");

    let response = ctx
        .delegate()
        .route(request)
        .await
        .expect("LP write request failed");

    assert_eq!(response.status(), StatusCode::NO_CONTENT);

    let request = Request::builder()
        .uri("https://bananas.example/api/v2/write?org=bananas&bucket=test")
        .method("POST")
        .body(Body::from("platanos,tag1=A,tag2=B val=42.0 123457"))
        .expect("failed to construct HTTP request");

    let err = ctx
        .delegate()
        .route(request)
        .await
        .expect_err("LP write request should fail");

    assert_matches!(
        &err,
        router::server::http::Error::DmlHandler(
            DmlError::Schema(
                SchemaError::Conflict(
                    e
                )
            )
        ) => {
            assert_matches!(e.err(), iox_catalog::interface::Error::ColumnTypeMismatch {
                name,
                existing,
                new,
            } => {
                assert_eq!(name, "val");
                assert_eq!(*existing, ColumnType::I64);
                assert_eq!(*new, ColumnType::F64);
            });
        }
    );
    assert_eq!(err.as_status_code(), StatusCode::BAD_REQUEST);
}

#[tokio::test]
async fn test_schema_limit() {
    let ctx = TestContext::new();

    // Drive the creation of the namespace
    let request = Request::builder()
        .uri("https://bananas.example/api/v2/write?org=bananas&bucket=test")
        .method("POST")
        .body(Body::from("platanos,tag1=A,tag2=B val=42i 123456"))
        .expect("failed to construct HTTP request");
    let response = ctx
        .delegate()
        .route(request)
        .await
        .expect("LP write request failed");
    assert_eq!(response.status(), StatusCode::NO_CONTENT);

    // Update the table limit
    ctx.catalog()
        .repositories()
        .await
        .namespaces()
        .update_table_limit("bananas_test", 1)
        .await
        .expect("failed to update table limit");

    // Attempt to create another table
    let request = Request::builder()
        .uri("https://bananas.example/api/v2/write?org=bananas&bucket=test")
        .method("POST")
        .body(Body::from("platanos2,tag1=A,tag2=B val=42i 123456"))
        .expect("failed to construct HTTP request");
    let err = ctx
        .delegate()
        .route(request)
        .await
        .expect_err("LP write request should fail");

    assert_matches!(
        &err,
        router::server::http::Error::DmlHandler(
            DmlError::Schema(
                SchemaError::ServiceLimit(
                    iox_catalog::interface::Error::TableCreateLimitError {
                        table_name,
                        namespace_id,
                    }
                )
            )
        ) => {
            assert_eq!(table_name, "platanos2");
            assert_eq!(namespace_id.to_string(), "1");
        }
    );
    assert_eq!(err.as_status_code(), StatusCode::TOO_MANY_REQUESTS);
}