//! Tests for single dependencies and basic dependency data flow

use crate::common::task_fn;
use dagx::{DagResult, DagRunner, TaskHandle};
use futures::FutureExt;

#[tokio::test]
async fn test_single_dependency() -> DagResult<()> {
    let dag = DagRunner::new();

    let source = dag.add_task(task_fn(|_: ()| async { 42 }));
    let dependent = dag
        .add_task(task_fn(|x: i32| async move { x + 1 }))
        .depends_on(source);

    dag.run(|fut| tokio::spawn(fut).map(Result::unwrap)).await?;

    assert_eq!(dag.get(dependent)?, 43);
    Ok(())
}

#[tokio::test]
async fn test_dependency_data_flow() -> DagResult<()> {
    // Test that data flows correctly through dependencies
    let dag = DagRunner::new();

    let source: TaskHandle<_> = dag
        .add_task(task_fn(|_: ()| async { vec![1, 2, 3, 4, 5] }))
        .into();

    let sum = dag
        .add_task(task_fn(|v: Vec<i32>| async move { v.iter().sum::<i32>() }))
        .depends_on(source);

    let product = dag
        .add_task(task_fn(
            |v: Vec<i32>| async move { v.iter().product::<i32>() },
        ))
        .depends_on(source);

    let final_result = dag
        .add_task(task_fn(|(s, p): (i32, i32)| async move { s + p }))
        .depends_on((&sum, &product));

    dag.run(|fut| tokio::spawn(fut).map(Result::unwrap)).await?;

    // Note: sum and product are not sinks (final_result depends on them)
    // Only final_result is a sink and can be retrieved
    assert_eq!(dag.get(final_result)?, 135); // 15+120

    Ok(())
}

#[tokio::test]
async fn test_dependencies_with_different_types() -> DagResult<()> {
    // Test that dependencies with different types work correctly
    let dag = DagRunner::new();

    let int_source = dag.add_task(task_fn(|_: ()| async { 42 }));
    let string_source = dag.add_task(task_fn(|_: ()| async { "hello".to_string() }));
    let bool_source = dag.add_task(task_fn(|_: ()| async { true }));

    let combined = dag
        .add_task(task_fn(|(i, s, b): (i32, String, bool)| async move {
            format!("{}: {} ({})", s, i, b)
        }))
        .depends_on((int_source, string_source, bool_source));

    dag.run(|fut| tokio::spawn(fut).map(Result::unwrap)).await?;

    assert_eq!(dag.get(combined)?, "hello: 42 (true)");
    Ok(())
}

#[tokio::test]
async fn test_shared_dependencies() -> DagResult<()> {
    // Test that a single node can be a dependency for multiple downstream nodes
    let dag = DagRunner::new();

    let shared: TaskHandle<_> = dag.add_task(task_fn(|_: ()| async { 42 })).into();

    // Create 10 tasks that all depend on the shared node
    let dependents: Vec<_> = (0..10)
        .map(|i| {
            dag.add_task(task_fn(move |x: i32| async move { x * (i + 1) }))
                .depends_on(shared)
        })
        .collect();

    dag.run(|fut| tokio::spawn(fut).map(Result::unwrap)).await?;

    // Verify all dependents got the correct value from shared
    for (i, handle) in dependents.iter().enumerate() {
        assert_eq!(dag.get(handle)?, 42 * (i as i32 + 1));
    }

    Ok(())
}

#[tokio::test]
async fn test_multiple_source_nodes() -> DagResult<()> {
    // Test DAG with multiple source nodes (no dependencies)
    let dag = DagRunner::new();

    let sources: Vec<_> = (0..20)
        .map(|i| dag.add_task(task_fn(move |_: ()| async move { i * 10 })))
        .collect();

    dag.run(|fut| tokio::spawn(fut).map(Result::unwrap)).await?;

    for (i, source) in sources.into_iter().enumerate() {
        assert_eq!(dag.get(source)?, i as i32 * 10);
    }

    Ok(())
}