// TDD: RED phase - Write tests first for core traits
use nalgebra::Vector3;
use rtx_cfd::error::CfdResult;
use rtx_cfd::traits::{CfdSolver, FluidField, MeshEntity};

// Mock implementations for testing
#[derive(Debug)]
struct MockField {
    values: Vec<f64>,
}

impl FluidField for MockField {
    type Scalar = f64;
    type Vector = Vector3<f64>;

    fn get_velocity(&self, index: usize) -> CfdResult<Self::Vector> {
        if index < self.values.len() / 3 {
            Ok(Vector3::new(
                self.values[index * 3],
                self.values[index * 3 + 1],
                self.values[index * 3 + 2],
            ))
        } else {
            Err(rtx_cfd::error::CfdError::MeshError(
                "Index out of bounds".to_string(),
            ))
        }
    }

    fn set_velocity(&mut self, index: usize, velocity: Self::Vector) -> CfdResult<()> {
        if index < self.values.len() / 3 {
            self.values[index * 3] = velocity.x;
            self.values[index * 3 + 1] = velocity.y;
            self.values[index * 3 + 2] = velocity.z;
            Ok(())
        } else {
            Err(rtx_cfd::error::CfdError::MeshError(
                "Index out of bounds".to_string(),
            ))
        }
    }

    fn get_pressure(&self, index: usize) -> CfdResult<Self::Scalar> {
        if index < self.values.len() {
            Ok(self.values[index])
        } else {
            Err(rtx_cfd::error::CfdError::MeshError(
                "Index out of bounds".to_string(),
            ))
        }
    }

    fn set_pressure(&mut self, index: usize, pressure: Self::Scalar) -> CfdResult<()> {
        if index < self.values.len() {
            self.values[index] = pressure;
            Ok(())
        } else {
            Err(rtx_cfd::error::CfdError::MeshError(
                "Index out of bounds".to_string(),
            ))
        }
    }

    fn node_count(&self) -> usize {
        self.values.len() / 3
    }
}

#[derive(Debug)]
struct MockSolver;

impl CfdSolver for MockSolver {
    type Field = MockField;

    fn solve_step(&mut self, _field: &mut Self::Field, _dt: f64) -> CfdResult<f64> {
        // Mock solver that just returns a fake residual
        Ok(1e-6)
    }

    fn is_converged(&self, residual: f64, tolerance: f64) -> bool {
        residual < tolerance
    }

    fn get_iteration_count(&self) -> usize {
        0
    }

    fn reset(&mut self) -> CfdResult<()> {
        Ok(())
    }
}

#[derive(Debug)]
struct MockMeshEntity {
    id: usize,
    vertices: Vec<usize>,
}

impl MeshEntity for MockMeshEntity {
    fn id(&self) -> usize {
        self.id
    }

    fn vertex_count(&self) -> usize {
        self.vertices.len()
    }

    fn vertex_indices(&self) -> &[usize] {
        &self.vertices
    }

    fn volume(&self) -> f64 {
        1.0 // Mock volume
    }

    fn centroid(&self) -> Vector3<f64> {
        Vector3::new(0.0, 0.0, 0.0) // Mock centroid
    }
}

#[test]
fn test_fluid_field_velocity_operations() {
    let mut field = MockField {
        values: vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0],
    };

    // Test getting velocity
    let velocity = field.get_velocity(0).unwrap();
    assert_eq!(velocity, Vector3::new(1.0, 2.0, 3.0));

    let velocity = field.get_velocity(1).unwrap();
    assert_eq!(velocity, Vector3::new(4.0, 5.0, 6.0));

    // Test setting velocity
    field
        .set_velocity(0, Vector3::new(10.0, 20.0, 30.0))
        .unwrap();
    let new_velocity = field.get_velocity(0).unwrap();
    assert_eq!(new_velocity, Vector3::new(10.0, 20.0, 30.0));
}

#[test]
fn test_fluid_field_pressure_operations() {
    let mut field = MockField {
        values: vec![1.0, 2.0, 3.0],
    };

    // Test getting pressure
    let pressure = field.get_pressure(0).unwrap();
    assert_eq!(pressure, 1.0);

    // Test setting pressure
    field.set_pressure(1, 100.0).unwrap();
    let new_pressure = field.get_pressure(1).unwrap();
    assert_eq!(new_pressure, 100.0);
}

#[test]
fn test_fluid_field_bounds_checking() {
    let field = MockField {
        values: vec![1.0, 2.0, 3.0],
    };

    // Test out of bounds access
    assert!(field.get_velocity(10).is_err());
    assert!(field.get_pressure(10).is_err());
}

#[test]
fn test_cfd_solver_interface() {
    let mut solver = MockSolver;
    let mut field = MockField {
        values: vec![0.0; 6],
    };

    // Test solver step
    let residual = solver.solve_step(&mut field, 0.01).unwrap();
    assert_eq!(residual, 1e-6);

    // Test convergence checking
    assert!(solver.is_converged(1e-7, 1e-6));
    assert!(!solver.is_converged(1e-5, 1e-6));

    // Test iteration count
    assert_eq!(solver.get_iteration_count(), 0);

    // Test reset
    assert!(solver.reset().is_ok());
}

#[test]
fn test_mesh_entity_interface() {
    let entity = MockMeshEntity {
        id: 42,
        vertices: vec![0, 1, 2, 3],
    };

    assert_eq!(entity.id(), 42);
    assert_eq!(entity.vertex_count(), 4);
    assert_eq!(entity.vertex_indices(), &[0, 1, 2, 3]);
    assert_eq!(entity.volume(), 1.0);
    assert_eq!(entity.centroid(), Vector3::new(0.0, 0.0, 0.0));
}

#[test]
fn test_field_node_count() {
    let field = MockField {
        values: vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0],
    };
    assert_eq!(field.node_count(), 3);
}