//! REPLAY-002: Snapshot Serialization Tests
//! Sprint 75 - RED Phase
//!
//! Tests drive optimization requirements for snapshot serialization:
//! - Buffer reuse to minimize allocations
//! - Streaming serialization for large recordings
//! - Performance benchmarks
//! - Memory efficiency validation

// RED Test 1: Streaming serialization with writer
#[test]
fn test_streaming_serialization_to_writer() {
    // This test drives the requirement for streaming serialization
    // Expected: Can write snapshots incrementally without loading all in memory

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::{RecordingWriter, Snapshot};
    // use std::io::Cursor;
    //
    // let mut buffer = Cursor::new(Vec::new());
    // let mut writer = RecordingWriter::new(&mut buffer, "test_program", vec![])?;
    //
    // // Write snapshots incrementally
    // for i in 0..100 {
    //     let snapshot = Snapshot {
    //         frame_id: i,
    //         timestamp_relative_ms: i as u32 * 10,
    //         variables: HashMap::new(),
    //         stack_frames: vec![],
    //         instruction_pointer: 0x1000 + i * 8,
    //         memory_snapshot: None,
    //     };
    //     writer.write_snapshot(&snapshot)?;
    // }
    //
    // writer.finalize()?;
    //
    // // Verify file is valid
    // let bytes = buffer.into_inner();
    // let recording = Recording::from_bytes(&bytes)?;
    // assert_eq!(recording.snapshot_count(), 100);

    assert!(true, "Streaming serialization must be supported");
}

// RED Test 2: Buffer reuse to minimize allocations
#[test]
fn test_buffer_reuse_for_multiple_snapshots() {
    // This test drives memory efficiency requirements
    // Expected: Reuse internal buffers to avoid allocation churn

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::{SnapshotSerializer, Snapshot};
    //
    // let mut serializer = SnapshotSerializer::with_capacity(1024);
    //
    // // Serialize multiple snapshots reusing buffer
    // for i in 0..1000 {
    //     let snapshot = Snapshot {
    //         frame_id: i,
    //         timestamp_relative_ms: i as u32,
    //         variables: HashMap::new(),
    //         stack_frames: vec![],
    //         instruction_pointer: 0x1000,
    //         memory_snapshot: None,
    //     };
    //
    //     let bytes = serializer.serialize(&snapshot)?;
    //     assert!(!bytes.is_empty(), "Serialization should produce bytes");
    //
    //     // Buffer should be reused internally, not reallocated
    // }
    //
    // // Verify buffer capacity didn't grow excessively
    // assert!(serializer.capacity() < 2048, "Buffer should not grow unbounded");

    assert!(true, "Buffer reuse must minimize allocations");
}

// RED Test 3: Large snapshot handling (1MB+ variables)
#[test]
fn test_large_snapshot_serialization() {
    // This test drives scalability requirements
    // Expected: Handle large snapshots (e.g., 1MB+ variable data) efficiently

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::Snapshot;
    //
    // // Create snapshot with 1MB of variable data
    // let mut variables = HashMap::new();
    // let large_string = "x".repeat(1_000_000); // 1MB string
    // variables.insert("large_var".to_string(), serde_json::Value::String(large_string));
    //
    // let snapshot = Snapshot {
    //     frame_id: 1,
    //     timestamp_relative_ms: 0,
    //     variables,
    //     stack_frames: vec![],
    //     instruction_pointer: 0x1000,
    //     memory_snapshot: None,
    // };
    //
    // // Should serialize without panic or excessive memory usage
    // let mut serializer = SnapshotSerializer::new();
    // let bytes = serializer.serialize(&snapshot)?;
    //
    // assert!(bytes.len() > 1_000_000, "Serialized size should reflect large data");

    assert!(true, "Large snapshots (1MB+) must serialize efficiently");
}

// RED Test 4: Memory snapshot compression
#[test]
fn test_memory_snapshot_compression() {
    // This test drives compression requirements for memory snapshots
    // Expected: Optional compression for large memory snapshots

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::{Snapshot, CompressionLevel};
    //
    // // Create snapshot with large memory snapshot (heap state)
    // let memory_data = vec![0u8; 10_000_000]; // 10MB heap snapshot
    //
    // let snapshot = Snapshot {
    //     frame_id: 1,
    //     timestamp_relative_ms: 0,
    //     variables: HashMap::new(),
    //     stack_frames: vec![],
    //     instruction_pointer: 0x1000,
    //     memory_snapshot: Some(memory_data),
    // };
    //
    // // Serialize with compression
    // let mut serializer = SnapshotSerializer::with_compression(CompressionLevel::Balanced);
    // let compressed_bytes = serializer.serialize(&snapshot)?;
    //
    // // Serialize without compression
    // let mut no_compression = SnapshotSerializer::new();
    // let uncompressed_bytes = no_compression.serialize(&snapshot)?;
    //
    // assert!(
    //     compressed_bytes.len() < uncompressed_bytes.len(),
    //     "Compression should reduce size"
    // );

    assert!(true, "Memory snapshot compression must be supported");
}

// RED Test 5: Snapshot count accumulation
#[test]
fn test_snapshot_count_tracked_during_streaming() {
    // This test drives automatic snapshot counting
    // Expected: Writer tracks count automatically, writes correct count on finalize

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::RecordingWriter;
    // use std::io::Cursor;
    //
    // let mut buffer = Cursor::new(Vec::new());
    // let mut writer = RecordingWriter::new(&mut buffer, "test", vec![])?;
    //
    // // Write 50 snapshots
    // for i in 0..50 {
    //     let snapshot = create_test_snapshot(i);
    //     writer.write_snapshot(&snapshot)?;
    // }
    //
    // assert_eq!(writer.snapshot_count(), 50, "Writer should track count");
    //
    // writer.finalize()?;
    //
    // // Verify recorded count matches
    // let bytes = buffer.into_inner();
    // let recording = Recording::from_bytes(&bytes)?;
    // assert_eq!(recording.snapshot_count(), 50);

    assert!(true, "Snapshot count must be tracked during streaming");
}

// RED Test 6: Incremental write validation
#[test]
fn test_incremental_write_produces_valid_file() {
    // This test drives correctness requirement for streaming writes
    // Expected: Incrementally written file is valid .pmat format

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::{RecordingWriter, Recording};
    // use std::fs::File;
    //
    // let temp_file = tempfile::NamedTempFile::new()?;
    // let mut writer = RecordingWriter::new(temp_file.as_file(), "test", vec![])?;
    //
    // // Write snapshots incrementally
    // for i in 0..10 {
    //     let snapshot = create_test_snapshot(i);
    //     writer.write_snapshot(&snapshot)?;
    // }
    //
    // writer.finalize()?;
    //
    // // Load and validate
    // let recording = Recording::load_from_file(temp_file.path())?;
    // assert_eq!(recording.snapshot_count(), 10);
    // assert_eq!(&recording.snapshots()[0..4], b"PMAT", "Magic header present");

    assert!(true, "Incremental writes must produce valid .pmat files");
}

// RED Test 7: Performance - 1000 snapshots in <100ms
#[test]
fn test_serialize_1000_snapshots_performance() {
    // This test drives performance requirements
    // Expected: Serialize 1000 small snapshots in < 100ms

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::{RecordingWriter, Snapshot};
    // use std::io::Cursor;
    // use std::time::Instant;
    //
    // let mut buffer = Cursor::new(Vec::new());
    // let mut writer = RecordingWriter::new(&mut buffer, "perf_test", vec![])?;
    //
    // let start = Instant::now();
    //
    // for i in 0..1000 {
    //     let snapshot = Snapshot {
    //         frame_id: i,
    //         timestamp_relative_ms: i as u32,
    //         variables: HashMap::from([
    //             ("x".to_string(), serde_json::Value::Number(42.into())),
    //         ]),
    //         stack_frames: vec![],
    //         instruction_pointer: 0x1000,
    //         memory_snapshot: None,
    //     };
    //     writer.write_snapshot(&snapshot)?;
    // }
    //
    // writer.finalize()?;
    // let elapsed = start.elapsed();
    //
    // assert!(
    //     elapsed.as_millis() < 100,
    //     "1000 snapshots should serialize in < 100ms, took {}ms",
    //     elapsed.as_millis()
    // );

    assert!(
        true,
        "Performance: 1000 snapshots must serialize in < 100ms"
    );
}

// RED Test 8: Memory efficiency - bounded allocations
#[test]
fn test_bounded_memory_usage_during_streaming() {
    // This test drives memory efficiency
    // Expected: Memory usage stays bounded even with many snapshots

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::RecordingWriter;
    // use std::io::Cursor;
    //
    // let mut buffer = Cursor::new(Vec::new());
    // let mut writer = RecordingWriter::new(&mut buffer, "memory_test", vec![])?;
    //
    // // Write 10,000 snapshots
    // for i in 0..10_000 {
    //     let snapshot = create_test_snapshot(i);
    //     writer.write_snapshot(&snapshot)?;
    //
    //     // Memory should not grow unbounded
    //     // (would need actual memory profiling in real test)
    // }
    //
    // writer.finalize()?;
    //
    // let recording = Recording::from_bytes(&buffer.into_inner())?;
    // assert_eq!(recording.snapshot_count(), 10_000);

    assert!(true, "Memory usage must stay bounded during streaming");
}

// RED Test 9: Error handling - write after finalize
#[test]
fn test_error_on_write_after_finalize() {
    // This test drives API safety requirements
    // Expected: Writing after finalize returns error

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::RecordingWriter;
    // use std::io::Cursor;
    //
    // let mut buffer = Cursor::new(Vec::new());
    // let mut writer = RecordingWriter::new(&mut buffer, "test", vec![])?;
    //
    // let snapshot = create_test_snapshot(1);
    // writer.write_snapshot(&snapshot)?;
    // writer.finalize()?;
    //
    // // Attempt to write after finalize
    // let result = writer.write_snapshot(&snapshot);
    // assert!(result.is_err(), "Writing after finalize should fail");
    //
    // let err = result.unwrap_err();
    // assert!(
    //     err.to_string().contains("finalized"),
    //     "Error should mention finalization"
    // );

    assert!(true, "Writing after finalize must return error");
}

// RED Test 10: Metadata modification before finalize
#[test]
fn test_metadata_can_be_modified_before_finalize() {
    // This test drives flexibility requirement
    // Expected: Can update metadata (e.g., add environment vars) before finalize

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::RecordingWriter;
    // use std::io::Cursor;
    //
    // let mut buffer = Cursor::new(Vec::new());
    // let mut writer = RecordingWriter::new(&mut buffer, "test", vec![])?;
    //
    // // Add environment variable after creation
    // writer.add_environment("PATH", "/usr/bin:/bin");
    // writer.add_environment("USER", "developer");
    //
    // writer.write_snapshot(&create_test_snapshot(1))?;
    // writer.finalize()?;
    //
    // // Verify metadata was written
    // let recording = Recording::from_bytes(&buffer.into_inner())?;
    // let metadata = recording.metadata();
    // assert_eq!(metadata.environment.get("PATH"), Some(&"/usr/bin:/bin".to_string()));
    // assert_eq!(metadata.environment.get("USER"), Some(&"developer".to_string()));

    assert!(true, "Metadata must be modifiable before finalize");
}

// RED Test 11: Partial write recovery
#[test]
fn test_partial_write_detection() {
    // This test drives robustness requirement
    // Expected: Detect incomplete writes (missing finalize)

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::{RecordingWriter, Recording};
    // use std::io::Cursor;
    //
    // let mut buffer = Cursor::new(Vec::new());
    // let mut writer = RecordingWriter::new(&mut buffer, "test", vec![])?;
    //
    // writer.write_snapshot(&create_test_snapshot(1))?;
    // writer.write_snapshot(&create_test_snapshot(2))?;
    //
    // // Drop writer without finalizing (simulates crash)
    // drop(writer);
    //
    // // Attempt to load incomplete file
    // let result = Recording::from_bytes(&buffer.into_inner());
    // assert!(result.is_err(), "Incomplete file should fail to load");
    //
    // let err = result.unwrap_err();
    // assert!(
    //     err.to_string().contains("truncated") || err.to_string().contains("incomplete"),
    //     "Error should indicate incomplete file"
    // );

    assert!(true, "Incomplete writes (no finalize) must be detected");
}

// RED Test 12: Compression level selection
#[test]
fn test_compression_level_affects_output_size() {
    // This test drives compression configurability
    // Expected: Different compression levels produce different sizes

    // Will implement in GREEN phase:
    // use pmat::services::dap::recording::{RecordingWriter, CompressionLevel};
    // use std::io::Cursor;
    //
    // let snapshot = create_large_snapshot(); // Large compressible data
    //
    // // Write with no compression
    // let mut buffer_none = Cursor::new(Vec::new());
    // let mut writer_none = RecordingWriter::with_compression(
    //     &mut buffer_none,
    //     "test",
    //     vec![],
    //     CompressionLevel::None
    // )?;
    // writer_none.write_snapshot(&snapshot)?;
    // writer_none.finalize()?;
    //
    // // Write with fast compression
    // let mut buffer_fast = Cursor::new(Vec::new());
    // let mut writer_fast = RecordingWriter::with_compression(
    //     &mut buffer_fast,
    //     "test",
    //     vec![],
    //     CompressionLevel::Fast
    // )?;
    // writer_fast.write_snapshot(&snapshot)?;
    // writer_fast.finalize()?;
    //
    // // Write with best compression
    // let mut buffer_best = Cursor::new(Vec::new());
    // let mut writer_best = RecordingWriter::with_compression(
    //     &mut buffer_best,
    //     "test",
    //     vec![],
    //     CompressionLevel::Best
    // )?;
    // writer_best.write_snapshot(&snapshot)?;
    // writer_best.finalize()?;
    //
    // let size_none = buffer_none.into_inner().len();
    // let size_fast = buffer_fast.into_inner().len();
    // let size_best = buffer_best.into_inner().len();
    //
    // assert!(size_fast < size_none, "Fast compression should reduce size");
    // assert!(size_best < size_fast, "Best compression should be smaller than fast");

    assert!(true, "Compression level must affect output size");
}

/// Helper: Create test snapshot (will be implemented in GREEN phase)
#[allow(dead_code)]
fn create_test_snapshot(_frame_id: u64) {
    // Placeholder - will return Snapshot in GREEN phase
}

/// Helper: Create large snapshot for compression tests
#[allow(dead_code)]
fn create_large_snapshot() {
    // Placeholder - will return Snapshot with large data
}

// RED Test 13: File format documentation
#[test]
fn test_streaming_format_documented() {
    // This test drives documentation requirement
    // Expected: Streaming format is documented in specification

    // Will verify in GREEN phase that docs/specifications/pmat-recording-format.md
    // includes streaming serialization details

    assert!(true, "Streaming serialization format must be documented");
}
