//! Property-based testing for the dagx crate.
//! Uses proptest to generate random test cases and verify invariants.

use dagx::DagRunner;
use proptest::prelude::*;
use std::collections::HashMap;

// Re-export task macro for use in tests
use dagx::task;

// Strategy for generating various types
fn arb_string() -> impl Strategy<Value = String> {
    prop::string::string_regex("[a-zA-Z0-9]{0,100}").unwrap()
}

fn arb_vec() -> impl Strategy<Value = Vec<i32>> {
    prop::collection::vec(any::<i32>(), 0..100)
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: Single task execution preserves value
    ///
    /// Verifies: Output matches input for identity tasks
    /// Strategy: Random i32 values
    #[test]
    fn prop_single_task_preserves_value(value: i32) {
        struct IdentityTask { val: i32 }
        #[task]
        impl IdentityTask {
            async fn run(&self) -> i32 { self.val }
        }

        let dag = DagRunner::new();
        let task = dag.add_task(IdentityTask { val: value });

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        assert_eq!(dag.get(task).unwrap(), value);
    }
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: Linear dependency chain maintains computation
    ///
    /// Verifies: Values flow correctly through chain
    /// Strategy: Random starting value with fixed operations
    #[test]
    fn prop_linear_chain_correctness(start: i32) {
        struct Source { val: i32 }
        #[task]
        impl Source {
            async fn run(&self) -> i32 { self.val }
        }

        struct AddOne;
        #[task]
        impl AddOne {
            async fn run(input: &i32) -> i32 {
                input.wrapping_add(1)
            }
        }

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

        let dag = DagRunner::new();
        let source = dag.add_task(Source { val: start });
        let add_one = dag.add_task(AddOne).depends_on(&source);
        let double = dag.add_task(Double).depends_on(&add_one);

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        let expected = start.wrapping_add(1).wrapping_mul(2);
        assert_eq!(dag.get(double).unwrap(), expected);
    }
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: Fan-out delivers same value to all dependents
    ///
    /// Verifies: All dependent tasks receive identical input
    /// Strategy: Random source value with multiple computations
    #[test]
    fn prop_fan_out_delivers_same_value(value: i32) {
        struct Source { val: i32 }
        #[task]
        impl Source {
            async fn run(&self) -> i32 { self.val }
        }

        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 dag = DagRunner::new();
        let source = dag.add_task(Source { val: value });
        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);

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        assert_eq!(dag.get(t1).unwrap(), value.wrapping_add(1));
        assert_eq!(dag.get(t2).unwrap(), value.wrapping_add(2));
        assert_eq!(dag.get(t3).unwrap(), value.wrapping_add(3));
    }
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: Diamond pattern computes correctly
    ///
    /// Verifies: Fork and join operations maintain correctness
    /// Strategy: Random base value through diamond computation
    #[test]
    fn prop_diamond_pattern_correctness(base: i32) {
        struct Source { val: i32 }
        #[task]
        impl Source {
            async fn run(&self) -> i32 { self.val }
        }

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

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

        struct Merge;
        #[task]
        impl Merge {
            async fn run(left: &i32, right: &i32) -> i32 {
                left.wrapping_add(*right)
            }
        }

        let dag = DagRunner::new();
        let source = dag.add_task(Source { val: base });
        let left = dag.add_task(Left).depends_on(&source);
        let right = dag.add_task(Right).depends_on(&source);
        let merge = dag.add_task(Merge).depends_on((&left, &right));

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        let expected = base.wrapping_mul(2).wrapping_add(base.wrapping_mul(3));
        assert_eq!(dag.get(merge).unwrap(), expected);
    }
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: String data preserved through DAG
    ///
    /// Verifies: Non-trivial types flow correctly
    /// Strategy: Random strings with transformations
    #[test]
    fn prop_string_data_preserved(s in arb_string()) {
        struct StringSource { val: String }
        #[task]
        impl StringSource {
            async fn run(&self) -> String { self.val.clone() }
        }

        struct Uppercase;
        #[task]
        impl Uppercase {
            async fn run(input: &String) -> String {
                input.to_uppercase()
            }
        }

        struct Lowercase;
        #[task]
        impl Lowercase {
            async fn run(input: &String) -> String {
                input.to_lowercase()
            }
        }

        let dag = DagRunner::new();
        let source = dag.add_task(StringSource { val: s.clone() });
        let upper = dag.add_task(Uppercase).depends_on(&source);
        let lower = dag.add_task(Lowercase).depends_on(&source);

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        assert_eq!(dag.get(upper).unwrap(), s.to_uppercase());
        assert_eq!(dag.get(lower).unwrap(), s.to_lowercase());
    }
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: Vec operations maintain length and contents
    ///
    /// Verifies: Collection types work correctly in DAG
    /// Strategy: Random Vec<i32> with transformations
    #[test]
    fn prop_vec_operations_correct(vec in arb_vec()) {
        struct VecSource { data: Vec<i32> }
        #[task]
        impl VecSource {
            async fn run(&self) -> Vec<i32> { self.data.clone() }
        }

        struct Sum;
        #[task]
        impl Sum {
            async fn run(input: &Vec<i32>) -> i32 {
                input.iter().fold(0i32, |acc, &x| acc.wrapping_add(x))
            }
        }

        struct Len;
        #[task]
        impl Len {
            async fn run(input: &Vec<i32>) -> usize {
                input.len()
            }
        }

        let dag = DagRunner::new();
        let source = dag.add_task(VecSource { data: vec.clone() });
        let sum = dag.add_task(Sum).depends_on(&source);
        let len = dag.add_task(Len).depends_on(&source);

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        let expected_sum = vec.iter().fold(0i32, |acc, &x| acc.wrapping_add(x));
        assert_eq!(dag.get(sum).unwrap(), expected_sum);
        assert_eq!(dag.get(len).unwrap(), vec.len());
    }
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: Option<T> values preserved correctly
    ///
    /// Verifies: Both Some and None variants handled properly
    /// Strategy: Random Option<i32> values
    #[test]
    fn prop_option_handling(opt in prop::option::of(any::<i32>())) {
        struct OptionSource { val: Option<i32> }
        #[task]
        impl OptionSource {
            async fn run(&self) -> Option<i32> { self.val }
        }

        struct MapOption;
        #[task]
        impl MapOption {
            async fn run(input: &Option<i32>) -> Option<i32> {
                input.map(|x| x.wrapping_mul(2))
            }
        }

        let dag = DagRunner::new();
        let source = dag.add_task(OptionSource { val: opt });
        let mapped = dag.add_task(MapOption).depends_on(&source);

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        let expected = opt.map(|x| x.wrapping_mul(2));
        assert_eq!(dag.get(mapped).unwrap(), expected);
    }
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: Result<T, E> values preserved correctly
    ///
    /// Verifies: Both Ok and Err variants handled properly
    /// Strategy: Random Result<i32, String> values
    #[test]
    fn prop_result_handling(
        result in prop::result::maybe_ok(any::<i32>(), arb_string())
    ) {
        struct ResultSource { val: Result<i32, String> }
        #[task]
        impl ResultSource {
            async fn run(&self) -> Result<i32, String> { self.val.clone() }
        }

        struct MapResult;
        #[task]
        impl MapResult {
            async fn run(input: &Result<i32, String>) -> Result<i32, String> {
                input.as_ref().map(|&x| x.wrapping_add(1)).map_err(|e| e.clone())
            }
        }

        let dag = DagRunner::new();
        let source = dag.add_task(ResultSource { val: result.clone() });
        let mapped = dag.add_task(MapResult).depends_on(&source);

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        let expected = result.map(|x| x.wrapping_add(1));
        assert_eq!(dag.get(mapped).unwrap(), expected);
    }
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: HashMap structure preserved through DAG
    ///
    /// Verifies: Complex types maintain structure
    /// Strategy: Random HashMap with string keys and i32 values
    #[test]
    fn prop_hashmap_preservation(
        data in prop::collection::hash_map(arb_string(), any::<i32>(), 0..20)
    ) {
        struct MapSource { data: HashMap<String, i32> }
        #[task]
        impl MapSource {
            async fn run(&self) -> HashMap<String, i32> { self.data.clone() }
        }

        struct MapLen;
        #[task]
        impl MapLen {
            async fn run(input: &HashMap<String, i32>) -> usize {
                input.len()
            }
        }

        let dag = DagRunner::new();
        let source = dag.add_task(MapSource { data: data.clone() });
        let len = dag.add_task(MapLen).depends_on(&source);

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        let result_map = dag.get(source).unwrap();
        assert_eq!(result_map.len(), data.len());
        for (k, v) in &data {
            assert_eq!(result_map.get(k), Some(v));
        }

        assert_eq!(dag.get(len).unwrap(), data.len());
    }
}

// Custom struct for testing
#[derive(Clone, Debug, PartialEq)]
struct CustomData {
    id: i32,
    name: String,
    values: Vec<i32>,
}

// Strategy for generating CustomData
fn arb_custom_data() -> impl Strategy<Value = CustomData> {
    (any::<i32>(), arb_string(), arb_vec())
        .prop_map(|(id, name, values)| CustomData { id, name, values })
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: Custom structs preserved through DAG
    ///
    /// Verifies: User-defined types work correctly
    /// Strategy: Random custom struct instances
    #[test]
    fn prop_custom_struct_preservation(custom in arb_custom_data()) {
        struct CustomSource { data: CustomData }
        #[task]
        impl CustomSource {
            async fn run(&self) -> CustomData { self.data.clone() }
        }

        struct ExtractId;
        #[task]
        impl ExtractId {
            async fn run(input: &CustomData) -> i32 {
                input.id
            }
        }

        let dag = DagRunner::new();
        let source = dag.add_task(CustomSource { data: custom.clone() });
        let id = dag.add_task(ExtractId).depends_on(&source);

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        let result = dag.get(source).unwrap();
        assert_eq!(result, custom);
        assert_eq!(dag.get(id).unwrap(), custom.id);
    }
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(256))]

    /// Property: Multiple independent DAGs are isolated
    ///
    /// Verifies: DAG instances don't interfere with each other
    /// Strategy: Two random values in separate DAGs
    #[test]
    fn prop_dag_isolation(value1: i32, value2: i32) {
        struct Source { val: i32 }
        #[task]
        impl Source {
            async fn run(&self) -> i32 { self.val }
        }

        let dag1 = DagRunner::new();
        let dag2 = DagRunner::new();

        let task1 = dag1.add_task(Source { val: value1 });
        let task2 = dag2.add_task(Source { val: value2 });

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag1.run(|fut| { tokio::spawn(fut); }).await.unwrap();
            dag2.run(|fut| { tokio::spawn(fut); }).await.unwrap();
        });

        assert_eq!(dag1.get(task1).unwrap(), value1);
        assert_eq!(dag2.get(task2).unwrap(), value2);
    }
}

proptest! {
    #![proptest_config(ProptestConfig::with_cases(128))]

    /// Property: N independent tasks all execute correctly
    ///
    /// Verifies: Concurrent execution scales correctly
    /// Strategy: Variable task count (1-20) with unique values
    #[test]
    fn prop_concurrent_independent_tasks(count in 1usize..20) {
        struct IndependentTask { val: i32 }
        #[task]
        impl IndependentTask {
            async fn run(&self) -> i32 { self.val }
        }

        let dag = DagRunner::new();
        let mut tasks = Vec::new();

        for i in 0..count {
            let task = dag.add_task(IndependentTask { val: i as i32 });
            tasks.push((task, i as i32));
        }

        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            dag.run(|fut| { tokio::spawn(fut); }).await
        }).unwrap();

        for (handle, expected) in tasks {
            assert_eq!(dag.get(handle).unwrap(), expected);
        }
    }
}