#![no_main]

use libfuzzer_sys::fuzz_target;
use dagx::{task, DagRunner};
use std::sync::Arc;

fuzz_target!(|data: &[u8]| {
    if data.is_empty() || data.len() > 50 {
        return;
    }

    let rt = tokio::runtime::Runtime::new().unwrap();

    // Test concurrent task execution
    struct SlowTask { val: i32, delay_ms: u64 }
    #[task]
    impl SlowTask {
        async fn run(&self) -> i32 {
            tokio::time::sleep(tokio::time::Duration::from_millis(self.delay_ms)).await;
            self.val
        }
    }

    struct FastTask { val: i32 }
    #[task]
    impl FastTask {
        async fn run(&self) -> i32 { self.val }
    }

    // Test concurrent independent tasks
    {
        let dag = DagRunner::new();

        // Create multiple independent tasks
        let num_tasks = (data[0] % 5 + 1) as usize;
        let mut tasks = Vec::new();

        for i in 0..num_tasks {
            let val = data.get(i).copied().unwrap_or(0) as i32;
            let delay = (val.abs() as u64 % 10) + 1;

            let task = dag.add_task(SlowTask { val, delay_ms: delay });
            tasks.push((task, val));
        }

        if rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).is_ok() {
            // Verify all tasks completed with correct values
            for (handle, expected) in tasks {
                if let Ok(result) = dag.get(handle) {
                    assert_eq!(result, expected);
                }
            }
        }
    }

    // Test concurrent dependent tasks
    {
        let dag = DagRunner::new();

        let source = dag.add_task(FastTask { val: data[0] as i32 });

        // Create multiple tasks that depend on source
        struct AddOne;
        #[task]
        impl AddOne {
            async fn run(input: &i32) -> i32 {
                input.wrapping_add(1)
            }
        }

        struct AddTwo;
        #[task]
        impl AddTwo {
            async fn run(input: &i32) -> i32 {
                input.wrapping_add(2)
            }
        }

        struct AddThree;
        #[task]
        impl AddThree {
            async fn run(input: &i32) -> i32 {
                input.wrapping_add(3)
            }
        }

        let t1 = dag.add_task(AddOne).depends_on(&source);
        let t2 = dag.add_task(AddTwo).depends_on(&source);
        let t3 = dag.add_task(AddThree).depends_on(&source);

        if rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).is_ok() {
            let base = data[0] as i32;
            if let Ok(r1) = dag.get(t1) {
                assert_eq!(r1, base.wrapping_add(1));
            }
            if let Ok(r2) = dag.get(t2) {
                assert_eq!(r2, base.wrapping_add(2));
            }
            if let Ok(r3) = dag.get(t3) {
                assert_eq!(r3, base.wrapping_add(3));
            }
        }
    }

    // Test Arc sharing across concurrent tasks
    {
        let dag = Arc::new(DagRunner::new());

        struct SharedTask { val: i32 }
        #[task]
        impl SharedTask {
            async fn run(&self) -> i32 { self.val }
        }

        let task = dag.add_task(SharedTask { val: data[0] as i32 });
        let task_copy = task;

        let dag1 = Arc::clone(&dag);
        let dag2 = Arc::clone(&dag);

        if rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).is_ok() {
            // Multiple threads can access result
            if let Ok(r1) = dag1.get(task_copy) {
                if let Ok(r2) = dag2.get(task_copy) {
                    assert_eq!(r1, r2);
                    assert_eq!(r1, data[0] as i32);
                }
            }
        }
    }
});