//! Unit tests for task module

use crate::task::{task_fn, Task, TaskInput};
use std::any::Any;
use std::future::Future;
use std::pin::Pin;
use std::sync::Arc;

// Test the task_fn function and TaskFn struct
#[tokio::test]
async fn test_task_fn_creation_and_execution() {
    // Test line 111 in task.rs - Task implementation for TaskFn

    // Create a simple task function
    let task = task_fn::<i32, _, _>(|input: &i32| input * 2);

    // Test the Task trait implementation
    let result = task
        .run(TaskInput::new(
            [Arc::new(42) as Arc<dyn Any + Send + Sync + 'static>].iter(),
        ))
        .await;
    assert_eq!(result, 84);
}

#[tokio::test]
async fn test_task_fn_with_unit_input() {
    // Test task_fn with unit input
    let task = task_fn::<(), _, _>(|_: ()| 100);

    let result = task
        .run(TaskInput::new(
            [Arc::new(()) as Arc<dyn Any + Send + Sync + 'static>].iter(),
        ))
        .await;
    assert_eq!(result, 100);
}

#[tokio::test]
async fn test_task_fn_with_tuple_input() {
    // Test task_fn with tuple input
    let task = task_fn::<(i32, i32), _, _>(|(a, b): (&i32, &i32)| a + b);

    let result = task
        .run(TaskInput::new(
            [
                Arc::new(10) as Arc<dyn Any + Send + Sync + 'static>,
                Arc::new(20) as Arc<dyn Any + Send + Sync + 'static>,
            ]
            .iter(),
        ))
        .await;
    assert_eq!(result, 30);
}

#[tokio::test]
async fn test_task_fn_with_string_input() {
    // Test task_fn with String input
    let task = task_fn::<String, _, _>(|input: &String| input.len());

    let test_string = String::from("hello");
    let result = task
        .run(TaskInput::new(
            [Arc::new(test_string) as Arc<dyn Any + Send + Sync + 'static>].iter(),
        ))
        .await;
    assert_eq!(result, 5);
}

#[tokio::test]
async fn test_task_fn_with_complex_output() {
    // Test task_fn with complex output type
    let task = task_fn::<i32, _, _>(|&input: &i32| vec![input, input * 2, input * 3]);

    let result = task
        .run(TaskInput::new(
            [Arc::new(5) as Arc<dyn Any + Send + Sync + 'static>].iter(),
        ))
        .await;
    assert_eq!(result, vec![5, 10, 15]);
}

#[tokio::test]
async fn test_task_fn_stateful_closure() {
    // Test that task_fn can capture state
    let multiplier = 3;
    let task = task_fn::<i32, _, _>(move |input: &i32| input * multiplier);

    let result = task
        .run(TaskInput::new(
            [Arc::new(7) as Arc<dyn Any + Send + Sync + 'static>].iter(),
        ))
        .await;
    assert_eq!(result, 21);
}

// Test custom Task implementation
struct CustomTask {
    state: i32,
}

impl Task for CustomTask {
    type Input = (i32,);
    type Output = i32;

    #[allow(refining_impl_trait)]
    fn run(
        mut self,
        input: TaskInput<'_, Self::Input>,
    ) -> Pin<Box<dyn Future<Output = Self::Output> + Send + '_>> {
        Box::pin(async move {
            self.state += input.next().0;
            self.state
        })
    }
}

#[tokio::test]
async fn test_custom_task_implementation() {
    let task = CustomTask { state: 10 };

    let result1 = task
        .run(TaskInput::new(
            [Arc::new(5) as Arc<dyn Any + Send + Sync + 'static>].iter(),
        ))
        .await;
    assert_eq!(result1, 15);

    // Can't call run again since task was consumed
    // This demonstrates the ownership model
}

// Test that Task trait bounds are correct
fn assert_task_bounds<T: Task>() {
    // This function just checks that T implements Task with the right bounds
    fn assert_send<T: Send>() {}

    // These should compile if bounds are correct
    assert_send::<T>();
    assert_send::<T::Input>();
    assert_send::<T::Output>();
}

#[test]
fn test_task_trait_bounds() {
    // Verify that our test tasks meet the Task trait bounds
    assert_task_bounds::<CustomTask>();

    // We can't directly test TaskFn because it's a private type and needs a concrete closure type,
    // but the fact that task_fn works in the tests above proves it's correct
}

#[tokio::test]
async fn test_task_fn_single_call() {
    // Test that task_fn works (can only call once due to ownership)
    let task = task_fn::<i32, _, _>(|x: &i32| x + 1);

    assert_eq!(
        task.run(TaskInput::new(
            [Arc::new(1) as Arc<dyn Any + Send + Sync + 'static>].iter()
        ))
        .await,
        2
    );
}

#[tokio::test]
async fn test_task_fn_with_result_type() {
    // Test task_fn returning Result
    let task = task_fn::<i32, _, _>(|&x: &i32| {
        if x > 0 {
            Ok(x * 2)
        } else {
            Err("negative input")
        }
    });

    assert_eq!(
        task.run(TaskInput::new(
            [Arc::new(5) as Arc<dyn Any + Send + Sync + 'static>].iter()
        ))
        .await,
        Ok(10)
    );
}

#[tokio::test]
async fn test_task_fn_with_option_type() {
    // Test task_fn returning Option
    let task = task_fn::<i32, _, _>(|&x: &i32| if x > 0 { Some(x * 2) } else { None });

    assert_eq!(
        task.run(TaskInput::new(
            [Arc::new(5) as Arc<dyn Any + Send + Sync + 'static>].iter()
        ))
        .await,
        Some(10)
    );
}

#[tokio::test]
async fn test_task_fn_explicit_trait_call() {
    // Test explicit Task trait method call to cover line 121

    let task = task_fn::<i32, _, _>(|x: &i32| x * 3);

    // Explicitly call the Task trait's run method
    let result = Task::run(
        task,
        TaskInput::new([Arc::new(10) as Arc<dyn Any + Send + Sync + 'static>].iter()),
    )
    .await;
    assert_eq!(result, 30);
}