quantrs2-anneal 0.1.3

//! Property-based testing system

use super::{
    ApplicationError, ApplicationResult, ConstraintSpec, DensitySpec, Duration, GenerationStrategy,
    HashMap, Instant, InvariantScope, ProblemSpecification, ProblemType, PropertyTestResult,
    PropertyType, PropertyValue, TestExecutionResult,
};
use scirs2_core::random::{thread_rng, Rng};

/// Property-based testing system
#[derive(Debug)]
pub struct PropertyBasedTester {
    /// Property definitions
    pub properties: Vec<PropertyDefinition>,
    /// Test case generators
    pub generators: Vec<TestCaseGenerator>,
    /// Shrinking strategies
    pub shrinking_strategies: Vec<ShrinkingStrategy>,
    /// Execution statistics
    pub execution_stats: PropertyTestStats,
}

/// Property definition for testing
#[derive(Debug)]
pub struct PropertyDefinition {
    /// Property identifier
    pub id: String,
    /// Property description
    pub description: String,
    /// Property type
    pub property_type: PropertyType,
    /// Preconditions
    pub preconditions: Vec<Precondition>,
    /// Postconditions
    pub postconditions: Vec<Postcondition>,
    /// Invariants
    pub invariants: Vec<Invariant>,
}

/// Precondition for property
#[derive(Debug, Clone)]
pub struct Precondition {
    /// Condition identifier
    pub id: String,
    /// Condition expression
    pub expression: String,
    /// Condition parameters
    pub parameters: HashMap<String, f64>,
}

/// Postcondition for property
#[derive(Debug, Clone)]
pub struct Postcondition {
    /// Condition identifier
    pub id: String,
    /// Condition expression
    pub expression: String,
    /// Expected result
    pub expected_result: PropertyValue,
    /// Tolerance
    pub tolerance: f64,
}

/// Invariant for property
#[derive(Debug, Clone)]
pub struct Invariant {
    /// Invariant identifier
    pub id: String,
    /// Invariant expression
    pub expression: String,
    /// Invariant scope
    pub scope: InvariantScope,
}

/// Test case generator for property-based testing
#[derive(Debug)]
pub struct TestCaseGenerator {
    /// Generator identifier
    pub id: String,
    /// Generation strategy
    pub strategy: GenerationStrategy,
    /// Size bounds
    pub size_bounds: (usize, usize),
    /// Generation parameters
    pub parameters: HashMap<String, f64>,
}

/// Shrinking strategy for failed test cases
#[derive(Debug)]
pub struct ShrinkingStrategy {
    /// Strategy identifier
    pub id: String,
    /// Shrinking algorithm
    pub algorithm: ShrinkingAlgorithm,
    /// Maximum shrinking attempts
    pub max_attempts: usize,
    /// Shrinking parameters
    pub parameters: HashMap<String, f64>,
}

/// Shrinking algorithms
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ShrinkingAlgorithm {
    /// Linear shrinking
    Linear,
    /// Binary search shrinking
    BinarySearch,
    /// Delta debugging
    DeltaDebugging,
    /// Custom shrinking
    Custom(String),
}

/// Property test execution statistics
#[derive(Debug, Default)]
pub struct PropertyTestStats {
    /// Total test cases generated
    pub cases_generated: usize,
    /// Test cases that passed
    pub cases_passed: usize,
    /// Test cases that failed
    pub cases_failed: usize,
    /// Shrinking attempts made
    pub shrinking_attempts: usize,
    /// Total execution time
    pub execution_time: Duration,
}

impl PropertyBasedTester {
    #[must_use]
    pub fn new() -> Self {
        Self {
            properties: Self::create_default_properties(),
            generators: Self::create_default_generators(),
            shrinking_strategies: Self::create_default_shrinking_strategies(),
            execution_stats: PropertyTestStats::default(),
        }
    }

    /// Create default property definitions
    fn create_default_properties() -> Vec<PropertyDefinition> {
        vec![
            PropertyDefinition {
                id: "solution_feasibility".to_string(),
                description: "All solutions must be feasible".to_string(),
                property_type: PropertyType::Correctness,
                preconditions: vec![Precondition {
                    id: "valid_problem".to_string(),
                    expression: "problem.is_valid()".to_string(),
                    parameters: HashMap::new(),
                }],
                postconditions: vec![Postcondition {
                    id: "solution_valid".to_string(),
                    expression: "solution.is_feasible()".to_string(),
                    expected_result: PropertyValue::Boolean(true),
                    tolerance: 0.0,
                }],
                invariants: vec![Invariant {
                    id: "energy_conservation".to_string(),
                    expression: "energy_is_conserved".to_string(),
                    scope: InvariantScope::Global,
                }],
            },
            PropertyDefinition {
                id: "optimization_monotonicity".to_string(),
                description: "Optimization should improve or maintain solution quality".to_string(),
                property_type: PropertyType::Performance,
                preconditions: vec![Precondition {
                    id: "initial_solution".to_string(),
                    expression: "has_initial_solution".to_string(),
                    parameters: HashMap::new(),
                }],
                postconditions: vec![Postcondition {
                    id: "quality_improvement".to_string(),
                    expression: "final_quality >= initial_quality".to_string(),
                    expected_result: PropertyValue::Boolean(true),
                    tolerance: 0.001,
                }],
                invariants: vec![Invariant {
                    id: "quality_monotonic".to_string(),
                    expression: "quality_non_decreasing".to_string(),
                    scope: InvariantScope::Temporal,
                }],
            },
            PropertyDefinition {
                id: "deterministic_behavior".to_string(),
                description: "Same input should produce same output with fixed seed".to_string(),
                property_type: PropertyType::Consistency,
                preconditions: vec![Precondition {
                    id: "fixed_seed".to_string(),
                    expression: "seed.is_fixed()".to_string(),
                    parameters: HashMap::new(),
                }],
                postconditions: vec![Postcondition {
                    id: "reproducible_result".to_string(),
                    expression: "result1 == result2".to_string(),
                    expected_result: PropertyValue::Boolean(true),
                    tolerance: 0.0,
                }],
                invariants: Vec::new(),
            },
            PropertyDefinition {
                id: "resource_bounds".to_string(),
                description: "Resource usage should remain within bounds".to_string(),
                property_type: PropertyType::Safety,
                preconditions: Vec::new(),
                postconditions: vec![
                    Postcondition {
                        id: "memory_bounded".to_string(),
                        expression: "memory_usage <= max_memory".to_string(),
                        expected_result: PropertyValue::Boolean(true),
                        tolerance: 0.0,
                    },
                    Postcondition {
                        id: "time_bounded".to_string(),
                        expression: "execution_time <= max_time".to_string(),
                        expected_result: PropertyValue::Boolean(true),
                        tolerance: 0.0,
                    },
                ],
                invariants: vec![Invariant {
                    id: "resource_limits".to_string(),
                    expression: "within_resource_limits".to_string(),
                    scope: InvariantScope::Global,
                }],
            },
        ]
    }

    /// Create default test case generators
    fn create_default_generators() -> Vec<TestCaseGenerator> {
        vec![
            TestCaseGenerator {
                id: "random_ising_generator".to_string(),
                strategy: GenerationStrategy::Random,
                size_bounds: (5, 100),
                parameters: {
                    let mut params = HashMap::new();
                    params.insert("density".to_string(), 0.3);
                    params.insert("bias_range".to_string(), 2.0);
                    params.insert("coupling_range".to_string(), 1.0);
                    params
                },
            },
            TestCaseGenerator {
                id: "boundary_value_generator".to_string(),
                strategy: GenerationStrategy::BoundaryValue,
                size_bounds: (1, 1000),
                parameters: {
                    let mut params = HashMap::new();
                    params.insert("boundary_offset".to_string(), 1.0);
                    params
                },
            },
            TestCaseGenerator {
                id: "equivalence_class_generator".to_string(),
                strategy: GenerationStrategy::EquivalenceClass,
                size_bounds: (10, 50),
                parameters: {
                    let mut params = HashMap::new();
                    params.insert("num_classes".to_string(), 5.0);
                    params
                },
            },
        ]
    }

    /// Create default shrinking strategies
    fn create_default_shrinking_strategies() -> Vec<ShrinkingStrategy> {
        vec![
            ShrinkingStrategy {
                id: "linear_shrinking".to_string(),
                algorithm: ShrinkingAlgorithm::Linear,
                max_attempts: 100,
                parameters: {
                    let mut params = HashMap::new();
                    params.insert("shrink_factor".to_string(), 0.5);
                    params
                },
            },
            ShrinkingStrategy {
                id: "binary_search_shrinking".to_string(),
                algorithm: ShrinkingAlgorithm::BinarySearch,
                max_attempts: 50,
                parameters: HashMap::new(),
            },
            ShrinkingStrategy {
                id: "delta_debugging".to_string(),
                algorithm: ShrinkingAlgorithm::DeltaDebugging,
                max_attempts: 200,
                parameters: {
                    let mut params = HashMap::new();
                    params.insert("granularity".to_string(), 2.0);
                    params
                },
            },
        ]
    }

    /// Run property-based tests
    pub fn run_property_tests(
        &mut self,
        property_id: &str,
        num_cases: usize,
    ) -> ApplicationResult<PropertyTestResult> {
        let property = self
            .properties
            .iter()
            .find(|p| p.id == property_id)
            .ok_or_else(|| {
                ApplicationError::ConfigurationError(format!("Property not found: {property_id}"))
            })?
            .clone();

        println!("Running property-based tests for: {}", property.id);
        let start_time = Instant::now();

        let mut cases_tested = 0;
        let mut cases_passed = 0;
        let mut counterexamples = Vec::new();

        // Generate and test cases
        for _ in 0..num_cases {
            let test_case = self.generate_test_case(&property)?;
            cases_tested += 1;

            let result = self.test_property(&property, &test_case)?;

            if result.passed {
                cases_passed += 1;
            } else {
                // Try to shrink the counterexample
                let shrunk_case = {
                    self.execution_stats.shrinking_attempts += 1;
                    self.shrink_counterexample_internal(&property, &test_case)?
                };
                counterexamples.push(format!("Case {cases_tested}: {shrunk_case:?}"));

                // For demonstration, stop after finding a few counterexamples
                if counterexamples.len() >= 3 {
                    break;
                }
            }
        }

        let execution_time = start_time.elapsed();
        let confidence = if cases_tested > 0 {
            cases_passed as f64 / cases_tested as f64
        } else {
            0.0
        };

        // Update statistics
        self.execution_stats.cases_generated += cases_tested;
        self.execution_stats.cases_passed += cases_passed;
        self.execution_stats.cases_failed += cases_tested - cases_passed;
        self.execution_stats.execution_time += execution_time;

        println!("Property test completed: {cases_passed}/{cases_tested} passed");

        Ok(PropertyTestResult {
            property_id: property.id.clone(),
            cases_tested,
            cases_passed,
            counterexamples,
            confidence,
            execution_time,
        })
    }

    /// Generate test case for property
    fn generate_test_case(
        &self,
        property: &PropertyDefinition,
    ) -> ApplicationResult<PropertyTestCase> {
        // Find appropriate generator
        let generator = self
            .generators
            .iter()
            .find(|g| self.is_generator_suitable(g, property))
            .ok_or_else(|| {
                ApplicationError::ConfigurationError(
                    "No suitable generator found for property".to_string(),
                )
            })?;

        self.generate_with_strategy(generator, property)
    }

    /// Check if generator is suitable for property
    const fn is_generator_suitable(
        &self,
        _generator: &TestCaseGenerator,
        _property: &PropertyDefinition,
    ) -> bool {
        // Simplified: assume all generators are suitable
        true
    }

    /// Generate test case with specific strategy
    fn generate_with_strategy(
        &self,
        generator: &TestCaseGenerator,
        _property: &PropertyDefinition,
    ) -> ApplicationResult<PropertyTestCase> {
        match generator.strategy {
            GenerationStrategy::Random => self.generate_random_case(generator),
            GenerationStrategy::BoundaryValue => self.generate_boundary_case(generator),
            GenerationStrategy::EquivalenceClass => self.generate_equivalence_case(generator),
            _ => self.generate_random_case(generator), // Fallback
        }
    }

    /// Generate random test case
    fn generate_random_case(
        &self,
        generator: &TestCaseGenerator,
    ) -> ApplicationResult<PropertyTestCase> {
        let mut rng = thread_rng();
        let size = rng.random_range(generator.size_bounds.0..=generator.size_bounds.1);

        let density = generator.parameters.get("density").unwrap_or(&0.3);
        let bias_range = generator.parameters.get("bias_range").unwrap_or(&1.0);

        Ok(PropertyTestCase {
            id: format!("random_case_{}", thread_rng().random::<u32>()),
            problem_spec: ProblemSpecification {
                problem_type: ProblemType::RandomIsing,
                size_range: (size, size),
                density: DensitySpec {
                    edge_density: (*density, *density),
                    constraint_density: None,
                    bias_sparsity: None,
                },
                constraints: ConstraintSpec {
                    num_constraints: None,
                    constraint_types: Vec::new(),
                    strength_range: (0.1, *bias_range),
                },
                seed: Some(rng.random()),
            },
            input_parameters: {
                let mut params = HashMap::new();
                params.insert("size".to_string(), PropertyValue::Numeric(size as f64));
                params.insert("density".to_string(), PropertyValue::Numeric(*density));
                params
            },
            expected_properties: Vec::new(),
        })
    }

    /// Generate boundary value test case
    fn generate_boundary_case(
        &self,
        generator: &TestCaseGenerator,
    ) -> ApplicationResult<PropertyTestCase> {
        // Use boundary values: minimum, maximum, and near-boundary values
        let boundary_sizes = vec![
            generator.size_bounds.0,
            generator.size_bounds.0 + 1,
            generator.size_bounds.1 - 1,
            generator.size_bounds.1,
        ];

        let mut rng = thread_rng();
        let size = boundary_sizes[rng.random_range(0..boundary_sizes.len())];

        Ok(PropertyTestCase {
            id: format!("boundary_case_{size}"),
            problem_spec: ProblemSpecification {
                problem_type: ProblemType::RandomIsing,
                size_range: (size, size),
                density: DensitySpec {
                    edge_density: (0.1, 0.1),
                    constraint_density: None,
                    bias_sparsity: None,
                },
                constraints: ConstraintSpec {
                    num_constraints: None,
                    constraint_types: Vec::new(),
                    strength_range: (0.1, 1.0),
                },
                seed: Some(42),
            },
            input_parameters: {
                let mut params = HashMap::new();
                params.insert("size".to_string(), PropertyValue::Numeric(size as f64));
                params.insert(
                    "boundary_type".to_string(),
                    PropertyValue::String("size_boundary".to_string()),
                );
                params
            },
            expected_properties: Vec::new(),
        })
    }

    /// Generate equivalence class test case
    fn generate_equivalence_case(
        &self,
        generator: &TestCaseGenerator,
    ) -> ApplicationResult<PropertyTestCase> {
        let num_classes = *generator.parameters.get("num_classes").unwrap_or(&5.0) as usize;
        let mut rng = thread_rng();
        let class_id = rng.random_range(0..num_classes);

        // Define equivalence classes based on problem characteristics
        let (problem_type, density) = match class_id {
            0 => (ProblemType::RandomIsing, 0.1), // Sparse problems
            1 => (ProblemType::RandomIsing, 0.5), // Dense problems
            2 => (ProblemType::MaxCut, 0.3),      // MaxCut problems
            3 => (ProblemType::VertexCover, 0.2), // VertexCover problems
            _ => (ProblemType::RandomIsing, 0.3), // Default class
        };

        let mut rng = thread_rng();
        let size = rng.random_range(generator.size_bounds.0..=generator.size_bounds.1);

        Ok(PropertyTestCase {
            id: format!("equiv_case_{class_id}_{size}"),
            problem_spec: ProblemSpecification {
                problem_type,
                size_range: (size, size),
                density: DensitySpec {
                    edge_density: (density, density),
                    constraint_density: None,
                    bias_sparsity: None,
                },
                constraints: ConstraintSpec {
                    num_constraints: None,
                    constraint_types: Vec::new(),
                    strength_range: (0.1, 1.0),
                },
                seed: Some(42 + class_id as u64),
            },
            input_parameters: {
                let mut params = HashMap::new();
                params.insert(
                    "equivalence_class".to_string(),
                    PropertyValue::Numeric(class_id as f64),
                );
                params.insert("size".to_string(), PropertyValue::Numeric(size as f64));
                params
            },
            expected_properties: Vec::new(),
        })
    }

    /// Test property against test case
    fn test_property(
        &self,
        property: &PropertyDefinition,
        test_case: &PropertyTestCase,
    ) -> ApplicationResult<PropertyTestCaseResult> {
        // Check preconditions
        for precondition in &property.preconditions {
            if !self.evaluate_precondition(precondition, test_case)? {
                return Ok(PropertyTestCaseResult {
                    test_case_id: test_case.id.clone(),
                    passed: false,
                    failure_reason: Some(format!("Precondition failed: {}", precondition.id)),
                    execution_time: Duration::from_millis(1),
                    property_values: HashMap::new(),
                });
            }
        }

        // Execute the test (simplified simulation)
        let start_time = Instant::now();
        let execution_result = self.simulate_test_execution(test_case)?;
        let execution_time = start_time.elapsed();

        // Check postconditions
        let mut all_passed = true;
        let mut failure_reason = None;
        let mut property_values = HashMap::new();

        for postcondition in &property.postconditions {
            let result = self.evaluate_postcondition(postcondition, &execution_result)?;
            property_values.insert(postcondition.id.clone(), result.actual_value.clone());

            if !result.passed {
                all_passed = false;
                failure_reason = Some(format!(
                    "Postcondition failed: {} (expected: {:?}, actual: {:?})",
                    postcondition.id, postcondition.expected_result, result.actual_value
                ));
                break;
            }
        }

        // Check invariants
        if all_passed {
            for invariant in &property.invariants {
                if !self.evaluate_invariant(invariant, &execution_result)? {
                    all_passed = false;
                    failure_reason = Some(format!("Invariant violated: {}", invariant.id));
                    break;
                }
            }
        }

        Ok(PropertyTestCaseResult {
            test_case_id: test_case.id.clone(),
            passed: all_passed,
            failure_reason,
            execution_time,
            property_values,
        })
    }

    /// Evaluate precondition
    const fn evaluate_precondition(
        &self,
        _precondition: &Precondition,
        _test_case: &PropertyTestCase,
    ) -> ApplicationResult<bool> {
        // Simplified: assume all preconditions pass
        Ok(true)
    }

    /// Simulate test execution
    fn simulate_test_execution(
        &self,
        test_case: &PropertyTestCase,
    ) -> ApplicationResult<TestExecutionResult> {
        let size = match test_case.input_parameters.get("size") {
            Some(PropertyValue::Numeric(s)) => *s as usize,
            _ => 10,
        };

        // Simulate execution with some variability
        let quality = thread_rng().random::<f64>().mul_add(0.2, 0.8);
        let execution_time = Duration::from_millis((size as u64 * 10).min(1000));

        Ok(TestExecutionResult {
            solution_quality: quality,
            execution_time,
            final_energy: -quality * size as f64,
            best_solution: vec![1; size],
            convergence_achieved: quality > 0.9,
            memory_used: size * 8,
        })
    }

    /// Evaluate postcondition
    fn evaluate_postcondition(
        &self,
        postcondition: &Postcondition,
        execution_result: &TestExecutionResult,
    ) -> ApplicationResult<PostconditionResult> {
        let actual_value = match postcondition.id.as_str() {
            "solution_valid" => PropertyValue::Boolean(execution_result.convergence_achieved),
            "quality_improvement" => PropertyValue::Numeric(execution_result.solution_quality),
            "reproducible_result" => PropertyValue::Boolean(true), // Simplified
            "memory_bounded" => PropertyValue::Boolean(execution_result.memory_used < 1_000_000),
            "time_bounded" => {
                PropertyValue::Boolean(execution_result.execution_time < Duration::from_secs(60))
            }
            _ => PropertyValue::Boolean(true),
        };

        let passed = match (&postcondition.expected_result, &actual_value) {
            (PropertyValue::Boolean(expected), PropertyValue::Boolean(actual)) => {
                expected == actual
            }
            (PropertyValue::Numeric(expected), PropertyValue::Numeric(actual)) => {
                (expected - actual).abs() <= postcondition.tolerance
            }
            _ => false,
        };

        Ok(PostconditionResult {
            postcondition_id: postcondition.id.clone(),
            passed,
            expected_value: postcondition.expected_result.clone(),
            actual_value,
            deviation: 0.0, // Simplified
        })
    }

    /// Evaluate invariant
    const fn evaluate_invariant(
        &self,
        _invariant: &Invariant,
        _execution_result: &TestExecutionResult,
    ) -> ApplicationResult<bool> {
        // Simplified: assume all invariants hold
        Ok(true)
    }

    /// Shrink counterexample to minimal failing case (internal, doesn't update stats)
    fn shrink_counterexample_internal(
        &self,
        _property: &PropertyDefinition,
        test_case: &PropertyTestCase,
    ) -> ApplicationResult<PropertyTestCase> {
        // Simplified shrinking: just reduce problem size
        let current_size = match test_case.input_parameters.get("size") {
            Some(PropertyValue::Numeric(s)) => (*s as usize).max(1),
            _ => 1,
        };

        let shrunk_size = (current_size / 2).max(1);

        let mut shrunk_case = test_case.clone();
        shrunk_case.id = format!("{}_shrunk", test_case.id);
        shrunk_case.problem_spec.size_range = (shrunk_size, shrunk_size);
        shrunk_case.input_parameters.insert(
            "size".to_string(),
            PropertyValue::Numeric(shrunk_size as f64),
        );

        Ok(shrunk_case)
    }

    /// Add property definition
    pub fn add_property(&mut self, property: PropertyDefinition) {
        self.properties.push(property);
    }

    /// Get property by ID
    #[must_use]
    pub fn get_property(&self, property_id: &str) -> Option<&PropertyDefinition> {
        self.properties.iter().find(|p| p.id == property_id)
    }

    /// Add test case generator
    pub fn add_generator(&mut self, generator: TestCaseGenerator) {
        self.generators.push(generator);
    }

    /// Get execution statistics
    #[must_use]
    pub const fn get_stats(&self) -> &PropertyTestStats {
        &self.execution_stats
    }
}

/// Test case for property-based testing
#[derive(Debug, Clone)]
pub struct PropertyTestCase {
    /// Test case identifier
    pub id: String,
    /// Problem specification
    pub problem_spec: ProblemSpecification,
    /// Input parameters
    pub input_parameters: HashMap<String, PropertyValue>,
    /// Expected properties to hold
    pub expected_properties: Vec<String>,
}

/// Result from property test case execution
#[derive(Debug)]
pub struct PropertyTestCaseResult {
    /// Test case identifier
    pub test_case_id: String,
    /// Whether the test passed
    pub passed: bool,
    /// Failure reason (if failed)
    pub failure_reason: Option<String>,
    /// Execution time
    pub execution_time: Duration,
    /// Property values observed
    pub property_values: HashMap<String, PropertyValue>,
}

/// Result from postcondition evaluation
#[derive(Debug)]
pub struct PostconditionResult {
    /// Postcondition identifier
    pub postcondition_id: String,
    /// Whether postcondition passed
    pub passed: bool,
    /// Expected value
    pub expected_value: PropertyValue,
    /// Actual value observed
    pub actual_value: PropertyValue,
    /// Deviation from expected
    pub deviation: f64,
}