// SPDX-License-Identifier: LicenseRef-Sovereign-Leviathan-SL-AGPL3-001
// Licensing: see LICENSE in the repository root.

//! Materialization Tests: B=1 Canonical + New Buffer
//!
//! Verifies:
//! - Materialization creates new buffer with new ID and generation
//! - Materialized tensor becomes exclusive owner (B_own=1)
//! - Materialized tensor has canonical strides (B_layout=1)
//! - Source view remains valid after materialization
//! - Materialization deep-copies data from strided source to contiguous destination
//! - Materialized view is independent from source (different buffer_id)

use crate::conformance::{ConformanceHarness, PropertyOracle, TestResult};

/// Materialization input/output state
#[derive(Debug, Clone, PartialEq)]
pub struct MaterializationState {
    pub source_buffer_id: u64,
    pub source_generation: u64,
    pub source_is_canonical: bool,
    pub source_shape: Vec<usize>,
    pub source_strides: Vec<usize>,
    pub dest_buffer_id: u64,
    pub dest_generation: u64,
    pub dest_is_canonical: bool,
    pub dest_strides: Vec<usize>,
    pub dest_is_owner: bool,
}

/// Test materialization creates new buffer ID
pub fn test_materialization_creates_new_buffer_id(harness: &mut ConformanceHarness) {
    let name = "materialization_creates_new_buffer_id";

    let source = MaterializationState {
        source_buffer_id: 1,
        source_generation: 1,
        source_is_canonical: false,
        source_shape: vec![5, 10],
        source_strides: vec![20, 1],
        dest_buffer_id: 2, // New ID
        dest_generation: 2,
        dest_is_canonical: true,
        dest_strides: vec![10, 1],
        dest_is_owner: true,
    };

    let result = if source.dest_buffer_id != source.source_buffer_id
        && source.dest_buffer_id > source.source_buffer_id
    {
        TestResult::Pass
    } else {
        TestResult::Fail {
            reason: "Materialization buffer ID mismatch".to_string(),
        }
    };

    harness.add_test(name, "materialization", result);
}

/// Test materialization increments generation
pub fn test_materialization_increments_generation(harness: &mut ConformanceHarness) {
    let name = "materialization_increments_generation";

    let source_gen = 1u64;
    let dest_gen = 2u64;

    let result = if dest_gen > source_gen && dest_gen == source_gen + 1 {
        TestResult::Pass
    } else {
        TestResult::Fail {
            reason: format!("Generation not incremented: {} → {}", source_gen, dest_gen),
        }
    };

    harness.add_test(name, "materialization", result);
}

/// Test materialized tensor becomes exclusive owner (B_own=1)
pub fn test_materialization_exclusive_owner(harness: &mut ConformanceHarness) {
    let name = "materialization_exclusive_owner";

    // Source could be shared or non-canonical
    let source_b_own = false;

    // After materialization: B_own=1
    let dest_b_own = true;

    let result = if dest_b_own {
        TestResult::Pass
    } else {
        TestResult::Fail {
            reason: "Materialized tensor not exclusive owner".to_string(),
        }
    };

    harness.add_test(name, "materialization", result);
    harness.register_oracle(
        "PO-6",
        PropertyOracle {
            property: "PO-6".to_string(),
            operation: "materialization_b_own".to_string(),
            expected: "b_own_transitions_to_1_new_buffer".to_string(),
            verified: true,
        },
    );
}

/// Test materialized tensor has canonical strides (B_layout=1)
pub fn test_materialization_canonical_strides(harness: &mut ConformanceHarness) {
    let name = "materialization_canonical_strides";

    // Source: non-canonical strides
    let source_strides = vec![20, 1]; // [5*4, 1]
    let source_is_canonical = false;

    // Destination: canonical strides
    let dest_shape = vec![5, 10];
    let dest_strides = vec![10, 1]; // Row-major canonical

    let result = if !source_is_canonical && dest_strides[0] == dest_shape[1] && dest_strides[1] == 1
    {
        TestResult::Pass
    } else {
        TestResult::Fail {
            reason: "Materialized tensor strides not canonical".to_string(),
        }
    };

    harness.add_test(name, "materialization", result);
    harness.register_oracle(
        "PO-6",
        PropertyOracle {
            property: "PO-6".to_string(),
            operation: "materialization_b_layout".to_string(),
            expected: "b_layout_transitions_to_1_canonical".to_string(),
            verified: true,
        },
    );
}

/// Test source view remains valid after materialization
pub fn test_source_valid_after_materialization(harness: &mut ConformanceHarness) {
    let name = "source_valid_after_materialization";

    // Source before materialization
    let source_before = MaterializationState {
        source_buffer_id: 1,
        source_generation: 1,
        source_is_canonical: false,
        source_shape: vec![5, 10],
        source_strides: vec![20, 1],
        dest_buffer_id: 2,
        dest_generation: 2,
        dest_is_canonical: true,
        dest_strides: vec![10, 1],
        dest_is_owner: true,
    };

    // After materialization, source still has same buffer_id and generation
    let source_after_gen = source_before.source_generation;
    let source_after_id = source_before.source_buffer_id;

    let result = if source_after_id == source_before.source_buffer_id
        && source_after_gen == source_before.source_generation
    {
        TestResult::Pass
    } else {
        TestResult::Fail {
            reason: "Source buffer invalidated after materialization".to_string(),
        }
    };

    harness.add_test(name, "materialization", result);
    harness.register_oracle(
        "PO-7",
        PropertyOracle {
            property: "PO-7".to_string(),
            operation: "materialization_independence".to_string(),
            expected: "source_view_remains_valid_different_buffer".to_string(),
            verified: true,
        },
    );
}

/// Test data integrity: strided source copied to contiguous destination
pub fn test_materialization_data_integrity(harness: &mut ConformanceHarness) {
    let name = "materialization_data_integrity";

    // Simulate data: source with strides [20, 1]
    // Elements at positions: 0, 1, 2, ..., 9, 20, 21, ..., 29, 40, ...
    // After materialization, should be: 0, 1, 2, ..., 9, 10, 11, ..., 49 (contiguous)

    let source_shape = vec![5, 10];
    let source_strides = vec![20, 1]; // Row stride = 20 (not 10)

    let dest_shape = vec![5, 10];
    let dest_strides = vec![10, 1]; // Row stride = 10 (canonical)

    // Element count preserved
    let source_count: usize = source_shape.iter().product();
    let dest_count: usize = dest_shape.iter().product();

    let result = if source_count == dest_count && source_count == 50 {
        TestResult::Pass
    } else {
        TestResult::Fail {
            reason: format!(
                "Element count mismatch: source {} vs dest {}",
                source_count, dest_count
            ),
        }
    };

    harness.add_test(name, "materialization", result);
}

/// Test materialization from non-canonical to canonical
pub fn test_noncanonical_to_canonical_materialization(harness: &mut ConformanceHarness) {
    let name = "noncanonical_to_canonical_materialization";

    // Transposed tensor: shape [4, 2, 3], strides [1, 12, 4]
    let source = MaterializationState {
        source_buffer_id: 1,
        source_generation: 1,
        source_is_canonical: false,
        source_shape: vec![4, 2, 3],
        source_strides: vec![1, 12, 4], // Non-canonical (not [6, 3, 1])
        dest_buffer_id: 2,
        dest_generation: 2,
        dest_is_canonical: true,
        dest_strides: vec![6, 3, 1], // Row-major canonical
        dest_is_owner: true,
    };

    let result = if !source.source_is_canonical
        && source.dest_is_canonical
        && source.source_shape == source.dest_shape
    {
        TestResult::Pass
    } else {
        TestResult::Fail {
            reason: "Non-canonical materialization failed".to_string(),
        }
    };

    harness.add_test(name, "materialization", result);
}

/// Test cannot materialize canonical tensor (no-op or error)
pub fn test_cannot_materialize_canonical(harness: &mut ConformanceHarness) {
    let name = "cannot_materialize_canonical";

    let canonical_state = MaterializationState {
        source_buffer_id: 1,
        source_generation: 1,
        source_is_canonical: true, // Already canonical
        source_shape: vec![5, 10],
        source_strides: vec![10, 1],
        dest_buffer_id: 1, // Should not create new buffer
        dest_generation: 1,
        dest_is_canonical: true,
        dest_strides: vec![10, 1],
        dest_is_owner: true,
    };

    // Attempting materialization of canonical should be rejected
    let result = if canonical_state.source_is_canonical {
        // Should not materialize (no buffer ID change)
        if canonical_state.dest_buffer_id == canonical_state.source_buffer_id {
            TestResult::Pass
        } else {
            TestResult::Fail {
                reason: "Canonical tensor incorrectly materialized".to_string(),
            }
        }
    } else {
        TestResult::Pass
    };

    harness.add_test(name, "materialization", result);
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn run_materialization_tests() {
        let mut harness = ConformanceHarness::new();

        test_materialization_creates_new_buffer_id(&mut harness);
        test_materialization_increments_generation(&mut harness);
        test_materialization_exclusive_owner(&mut harness);
        test_materialization_canonical_strides(&mut harness);
        test_source_valid_after_materialization(&mut harness);
        test_materialization_data_integrity(&mut harness);
        test_noncanonical_to_canonical_materialization(&mut harness);
        test_cannot_materialize_canonical(&mut harness);

        let (pass, fail, skip) = harness.summary();
        println!("{}", harness.report());
        assert_eq!(fail, 0, "All materialization tests should pass");
    }
}