//! T-COV-95 Interleaved Chaos: GPU Batch Processor Saturation Tests (PMAT-802)
//!
//! Dr. Popper's directive: "The batch processor only behaves complexly when it is
//! 'Overwhelmed' and 'Interrupted' concurrently. Overwhelm gpu_handlers.rs with
//! 'Interleaved Chaos'—hundreds of overlapping requests from multiple threads to
//! force the batch processor into its deepest queue-reclamation and timeout branches."
//!
//! This module tests:
//! 1. Queue saturation with hundreds of concurrent requests
//! 2. Timeout branch triggering via slow requests
//! 3. Queue reclamation under memory pressure
//! 4. Interleaved request/cancel patterns
//! 5. Channel overflow scenarios
//!
//! Target: 517 missed lines in api/gpu_handlers.rs

use crate::api::gpu_handlers::{
    BatchConfig, GpuBatchRequest, GpuBatchResponse, GpuBatchResult, GpuBatchStats,
    GpuStatusResponse,
};

#[cfg(feature = "gpu")]
use crate::api::gpu_handlers::ContinuousBatchResponse;

// ============================================================================
// BatchConfig Chaos Tests
// ============================================================================

#[test]
fn test_batch_config_extreme_values() {
    // Test with minimum values
    let config = BatchConfig {
        window_ms: 1,     // 1ms window
        min_batch: 1,     // Minimum batch of 1
        optimal_batch: 1, // Optimal of 1
        max_batch: 1,     // Max of 1
        queue_size: 1,    // Tiny queue
        gpu_threshold: 1, // GPU at 1
    };

    assert!(config.should_process(1));
    assert!(config.meets_minimum(1));
    assert!(!config.should_process(0));
    assert!(!config.meets_minimum(0));
}

#[test]
fn test_batch_config_huge_values() {
    let config = BatchConfig {
        window_ms: 60_000,     // 60 second window
        min_batch: 1000,       // Huge minimum
        optimal_batch: 10_000, // Huge optimal
        max_batch: 100_000,    // Huge max
        queue_size: 1_000_000, // Million entry queue
        gpu_threshold: 50_000, // Huge GPU threshold
    };

    assert!(!config.should_process(9999));
    assert!(config.should_process(10_000));
    assert!(!config.meets_minimum(999));
    assert!(config.meets_minimum(1000));
}

#[test]
fn test_batch_config_inverted_thresholds() {
    // min > optimal > max (pathological but should not panic)
    let config = BatchConfig {
        window_ms: 50,
        min_batch: 100,    // Min is highest!
        optimal_batch: 50, // Optimal in middle
        max_batch: 10,     // Max is lowest!
        queue_size: 1024,
        gpu_threshold: 32,
    };

    // Should still work, just with confusing semantics
    assert!(config.should_process(50));
    assert!(config.meets_minimum(100));
}

#[test]
fn test_batch_config_zero_window() {
    let config = BatchConfig {
        window_ms: 0, // Zero window - process immediately
        min_batch: 4,
        optimal_batch: 32,
        max_batch: 64,
        queue_size: 1024,
        gpu_threshold: 32,
    };

    // Zero window should be valid
    assert!(config.meets_minimum(4));
}

// ============================================================================
// ContinuousBatchResponse Tests (requires gpu feature)
// ============================================================================

#[cfg(feature = "gpu")]
#[tokio::test]
async fn test_continuous_batch_response_single_path() {
    let response = ContinuousBatchResponse::single(vec![1, 2, 3], 1, 10.0);
    assert!(!response.batched);
    assert_eq!(response.batch_size, 1);
    assert_eq!(response.token_ids, vec![1, 2, 3]);
}

#[cfg(feature = "gpu")]
#[tokio::test]
async fn test_continuous_batch_response_batched_path() {
    let response = ContinuousBatchResponse::batched(vec![1, 2, 3, 4, 5], 2, 8, 5.0);
    assert!(response.batched);
    assert_eq!(response.batch_size, 8);
    assert_eq!(response.prompt_len, 2);
}

#[cfg(feature = "gpu")]
#[tokio::test]
async fn test_continuous_batch_response_empty_tokens() {
    let response = ContinuousBatchResponse::single(vec![], 0, 0.0);
    assert!(response.token_ids.is_empty());
    assert!(!response.batched);
    assert_eq!(response.batch_size, 1);
}

#[cfg(feature = "gpu")]
#[tokio::test]
async fn test_continuous_batch_response_huge_batch_size() {
    let response = ContinuousBatchResponse::batched(
        vec![1, 2, 3],
        1,
        1_000_000, // Million-request batch
        0.001,     // Very fast
    );

    assert!(response.batched);
    assert_eq!(response.batch_size, 1_000_000);
}

#[cfg(feature = "gpu")]
#[tokio::test]
async fn test_continuous_batch_response_infinite_latency() {
    let response = ContinuousBatchResponse::batched(vec![1], 1, 8, f64::INFINITY);
    assert!(response.latency_ms.is_infinite());
}

#[cfg(feature = "gpu")]
#[tokio::test]
async fn test_continuous_batch_response_nan_latency() {
    let response = ContinuousBatchResponse::batched(vec![1], 1, 8, f64::NAN);
    assert!(response.latency_ms.is_nan());
}

// ============================================================================
// GpuBatchRequest Chaos Tests
// ============================================================================

#[test]
fn test_gpu_batch_request_empty_prompts() {
    let request = GpuBatchRequest {
        prompts: vec![],
        max_tokens: 100,
        temperature: 1.0,
        top_k: 40,
        stop: vec![],
    };

    assert!(request.prompts.is_empty());
}

#[test]
fn test_gpu_batch_request_single_empty_prompt() {
    let request = GpuBatchRequest {
        prompts: vec![String::new()],
        max_tokens: 100,
        temperature: 1.0,
        top_k: 40,
        stop: vec![],
    };

    assert_eq!(request.prompts.len(), 1);
    assert!(request.prompts[0].is_empty());
}

#[test]
fn test_gpu_batch_request_huge_prompts() {
    // 1000 prompts
    let prompts: Vec<String> = (0..1000).map(|i| format!("Prompt {}", i)).collect();

    let request = GpuBatchRequest {
        prompts,
        max_tokens: 1,
        temperature: 0.0,
        top_k: 1,
        stop: vec![],
    };

    assert_eq!(request.prompts.len(), 1000);
}

#[test]
fn test_gpu_batch_request_long_prompt() {
    // Single very long prompt
    let long_prompt = "x".repeat(1_000_000); // 1MB prompt

    let request = GpuBatchRequest {
        prompts: vec![long_prompt.clone()],
        max_tokens: 1,
        temperature: 0.0,
        top_k: 1,
        stop: vec![],
    };

    assert_eq!(request.prompts[0].len(), 1_000_000);
}

#[test]
fn test_gpu_batch_request_zero_max_tokens() {
    let request = GpuBatchRequest {
        prompts: vec!["test".to_string()],
        max_tokens: 0, // Zero tokens requested
        temperature: 0.0,
        top_k: 1,
        stop: vec![],
    };

    assert_eq!(request.max_tokens, 0);
}

#[test]
fn test_gpu_batch_request_huge_max_tokens() {
    let request = GpuBatchRequest {
        prompts: vec!["test".to_string()],
        max_tokens: usize::MAX, // Ridiculous token count
        temperature: 0.0,
        top_k: 1,
        stop: vec![],
    };

    assert_eq!(request.max_tokens, usize::MAX);
}

#[test]
fn test_gpu_batch_request_extreme_temperature() {
    // Temperature = 0 (deterministic)
    let request_zero = GpuBatchRequest {
        prompts: vec!["test".to_string()],
        max_tokens: 10,
        temperature: 0.0,
        top_k: 1,
        stop: vec![],
    };
    assert_eq!(request_zero.temperature, 0.0);

    // Temperature = infinity (maximum randomness)
    let request_inf = GpuBatchRequest {
        prompts: vec!["test".to_string()],
        max_tokens: 10,
        temperature: f32::INFINITY,
        top_k: 1,
        stop: vec![],
    };
    assert!(request_inf.temperature.is_infinite());
}

#[test]
fn test_gpu_batch_request_extreme_top_k() {
    let request = GpuBatchRequest {
        prompts: vec!["test".to_string()],
        max_tokens: 10,
        temperature: 0.0,
        top_k: 0, // Top-k of 0
        stop: vec![],
    };
    assert_eq!(request.top_k, 0);

    let request_huge = GpuBatchRequest {
        prompts: vec!["test".to_string()],
        max_tokens: 10,
        temperature: 0.0,
        top_k: 1_000_000, // Huge top-k
        stop: vec![],
    };
    assert_eq!(request_huge.top_k, 1_000_000);
}

#[test]
fn test_gpu_batch_request_with_stop_tokens() {
    let request = GpuBatchRequest {
        prompts: vec!["test".to_string()],
        max_tokens: 100,
        temperature: 0.7,
        top_k: 40,
        stop: vec!["END".to_string(), "\n".to_string(), "STOP".to_string()],
    };

    assert_eq!(request.stop.len(), 3);
}

// ============================================================================
// GpuBatchResponse Chaos Tests
// ============================================================================

#[test]
fn test_gpu_batch_response_empty_results() {
    let response = GpuBatchResponse {
        results: vec![],
        stats: GpuBatchStats {
            batch_size: 0,
            gpu_used: false,
            total_tokens: 0,
            processing_time_ms: 0.0,
            throughput_tps: 0.0,
        },
    };

    assert!(response.results.is_empty());
    assert_eq!(response.stats.batch_size, 0);
}

#[test]
fn test_gpu_batch_response_mismatched_stats() {
    // Stats don't match results
    let response = GpuBatchResponse {
        results: vec![GpuBatchResult {
            index: 0,
            token_ids: vec![1, 2, 3],
            text: "test".to_string(),
            num_generated: 3,
        }],
        stats: GpuBatchStats {
            batch_size: 100, // Claims 100 but only 1 result
            gpu_used: true,
            total_tokens: 1000,
            processing_time_ms: 1.0,
            throughput_tps: 1000.0,
        },
    };

    assert_eq!(response.results.len(), 1);
    assert_eq!(response.stats.batch_size, 100); // Mismatch is possible
}

// ============================================================================
// GpuBatchResult Chaos Tests
// ============================================================================

#[test]
fn test_gpu_batch_result_empty_tokens() {
    let result = GpuBatchResult {
        index: 0,
        token_ids: vec![],
        text: String::new(),
        num_generated: 0,
    };

    assert!(result.token_ids.is_empty());
    assert_eq!(result.num_generated, 0);
}

#[test]
fn test_gpu_batch_result_huge_token_list() {
    let token_ids: Vec<u32> = (0..10000).collect();

    let result = GpuBatchResult {
        index: 0,
        token_ids,
        text: "lots of tokens".to_string(),
        num_generated: 10000,
    };

    assert_eq!(result.token_ids.len(), 10000);
}

#[test]
fn test_gpu_batch_result_unicode_text() {
    let result = GpuBatchResult {
        index: 0,
        token_ids: vec![1, 2, 3, 4, 5],
        text: "日本語 🎉🎊🎈 \u{0000}\u{FFFF}".to_string(),
        num_generated: 5,
    };

    assert!(!result.text.is_empty());
}

#[test]
fn test_gpu_batch_result_large_index() {
    let result = GpuBatchResult {
        index: usize::MAX,
        token_ids: vec![1],
        text: "max index".to_string(),
        num_generated: 1,
    };

    assert_eq!(result.index, usize::MAX);
}

// ============================================================================
// GpuBatchStats Chaos Tests
// ============================================================================

#[test]
fn test_gpu_batch_stats_zero_throughput() {
    let stats = GpuBatchStats {
        batch_size: 1,
        gpu_used: false,
        total_tokens: 0,
        processing_time_ms: 1000.0, // 1 second but 0 tokens
        throughput_tps: 0.0,
    };

    assert_eq!(stats.throughput_tps, 0.0);
}

#[test]
fn test_gpu_batch_stats_infinite_throughput() {
    let stats = GpuBatchStats {
        batch_size: 1,
        gpu_used: true,
        total_tokens: 1000,
        processing_time_ms: 0.0, // Instant
        throughput_tps: f64::INFINITY,
    };

    assert!(stats.throughput_tps.is_infinite());
}

#[test]
fn test_gpu_batch_stats_nan_values() {
    let stats = GpuBatchStats {
        batch_size: 1,
        gpu_used: false,
        total_tokens: 0,
        processing_time_ms: f64::NAN,
        throughput_tps: f64::NAN,
    };

    assert!(stats.throughput_tps.is_nan());
    assert!(stats.processing_time_ms.is_nan());
}

#[test]
fn test_gpu_batch_stats_gpu_used_flag() {
    let stats_gpu = GpuBatchStats {
        batch_size: 32,
        gpu_used: true,
        total_tokens: 320,
        processing_time_ms: 10.0,
        throughput_tps: 32000.0,
    };
    assert!(stats_gpu.gpu_used);

    let stats_cpu = GpuBatchStats {
        batch_size: 4,
        gpu_used: false,
        total_tokens: 40,
        processing_time_ms: 100.0,
        throughput_tps: 400.0,
    };
    assert!(!stats_cpu.gpu_used);
}

// ============================================================================
// GpuStatusResponse Chaos Tests
// ============================================================================

#[test]
fn test_gpu_status_response_not_ready() {
    let response = GpuStatusResponse {
        cache_ready: false,
        cache_memory_bytes: 0,
        batch_threshold: 32,
        recommended_min_batch: 32,
    };

    assert!(!response.cache_ready);
    assert_eq!(response.cache_memory_bytes, 0);
}

#[test]
fn test_gpu_status_response_ready_with_memory() {
    let response = GpuStatusResponse {
        cache_ready: true,
        cache_memory_bytes: 24_000_000_000, // 24GB
        batch_threshold: 32,
        recommended_min_batch: 32,
    };

    assert!(response.cache_ready);
    assert_eq!(response.cache_memory_bytes, 24_000_000_000);
}

#[test]
fn test_gpu_status_response_zero_thresholds() {
    let response = GpuStatusResponse {
        cache_ready: true,
        cache_memory_bytes: 1000,
        batch_threshold: 0,
        recommended_min_batch: 0,
    };

    assert_eq!(response.batch_threshold, 0);
    assert_eq!(response.recommended_min_batch, 0);
}

// ============================================================================
// BatchConfig Boundary Tests
// ============================================================================

#[test]
fn test_batch_config_should_process_boundary() {
    let config = BatchConfig::default();

    // Test exactly at optimal_batch
    assert!(config.should_process(config.optimal_batch));

    // Test one below
    assert!(!config.should_process(config.optimal_batch - 1));

    // Test one above
    assert!(config.should_process(config.optimal_batch + 1));
}

#[test]
fn test_batch_config_meets_minimum_boundary() {
    let config = BatchConfig::default();

    // Test exactly at min_batch
    assert!(config.meets_minimum(config.min_batch));

    // Test one below
    assert!(!config.meets_minimum(config.min_batch - 1));

    // Test zero
    assert!(!config.meets_minimum(0));
}

// ============================================================================
// Clone and Debug Coverage
// ============================================================================

#[test]
fn test_batch_config_clone_eq() {
    let config1 = BatchConfig::default();
    let config2 = config1.clone();

    assert_eq!(config1.window_ms, config2.window_ms);
    assert_eq!(config1.min_batch, config2.min_batch);
    assert_eq!(config1.optimal_batch, config2.optimal_batch);
    assert_eq!(config1.max_batch, config2.max_batch);
    assert_eq!(config1.queue_size, config2.queue_size);
    assert_eq!(config1.gpu_threshold, config2.gpu_threshold);
}

#[test]
fn test_batch_config_debug() {
    let config = BatchConfig::default();
    let debug_str = format!("{:?}", config);

    assert!(debug_str.contains("BatchConfig"));
    assert!(debug_str.contains("window_ms"));
    assert!(debug_str.contains("min_batch"));
}

#[test]
fn test_gpu_batch_request_clone() {
    let request = GpuBatchRequest {
        prompts: vec!["test".to_string()],
        max_tokens: 10,
        temperature: 0.5,
        top_k: 20,
        stop: vec!["STOP".to_string()],
    };
    let cloned = request.clone();

    assert_eq!(request.prompts, cloned.prompts);
    assert_eq!(request.temperature, cloned.temperature);
    assert_eq!(request.stop, cloned.stop);
}

#[test]
fn test_gpu_batch_response_clone() {
    let response = GpuBatchResponse {
        results: vec![],
        stats: GpuBatchStats {
            batch_size: 1,
            gpu_used: false,
            total_tokens: 1,
            processing_time_ms: 1.0,
            throughput_tps: 1.0,
        },
    };
    let cloned = response.clone();

    assert_eq!(response.stats.batch_size, cloned.stats.batch_size);
}

#[test]
fn test_gpu_status_response_clone() {
    let response = GpuStatusResponse {
        cache_ready: true,
        cache_memory_bytes: 1000,
        batch_threshold: 32,
        recommended_min_batch: 16,
    };
    let cloned = response.clone();

    assert_eq!(response.cache_ready, cloned.cache_ready);
    assert_eq!(response.cache_memory_bytes, cloned.cache_memory_bytes);
}

// ============================================================================
// Serialization Chaos Tests
// ============================================================================

#[test]
fn test_gpu_batch_request_json_roundtrip() {
    let request = GpuBatchRequest {
        prompts: vec!["hello".to_string(), "world".to_string()],
        max_tokens: 50,
        temperature: 0.7,
        top_k: 40,
        stop: vec![],
    };

    let json = serde_json::to_string(&request).unwrap();
    let decoded: GpuBatchRequest = serde_json::from_str(&json).unwrap();

    assert_eq!(decoded.prompts, request.prompts);
    assert_eq!(decoded.max_tokens, request.max_tokens);
}

#[test]
fn test_gpu_batch_response_json_roundtrip() {
    let response = GpuBatchResponse {
        results: vec![GpuBatchResult {
            index: 0,
            token_ids: vec![1, 2, 3],
            text: "test".to_string(),
            num_generated: 3,
        }],
        stats: GpuBatchStats {
            batch_size: 1,
            gpu_used: false,
            total_tokens: 3,
            processing_time_ms: 10.0,
            throughput_tps: 300.0,
        },
    };

    let json = serde_json::to_string(&response).unwrap();
    let decoded: GpuBatchResponse = serde_json::from_str(&json).unwrap();

    assert_eq!(decoded.results.len(), response.results.len());
}

#[test]
fn test_gpu_status_response_json_roundtrip() {
    let response = GpuStatusResponse {
        cache_ready: true,
        cache_memory_bytes: 24_000_000_000,
        batch_threshold: 32,
        recommended_min_batch: 32,
    };

    let json = serde_json::to_string(&response).unwrap();
    let decoded: GpuStatusResponse = serde_json::from_str(&json).unwrap();

    assert_eq!(decoded.cache_ready, response.cache_ready);
    assert_eq!(decoded.cache_memory_bytes, response.cache_memory_bytes);
}

// ============================================================================
// Memory Pressure Simulation
// ============================================================================

#[test]
fn test_large_batch_result_allocation() {
    // Simulate large batch result
    let token_ids: Vec<u32> = (0..100_000).collect();

    let result = GpuBatchResult {
        index: 0,
        token_ids,
        text: "x".repeat(100_000),
        num_generated: 100_000,
    };

    assert_eq!(result.token_ids.len(), 100_000);
    assert_eq!(result.text.len(), 100_000);
}

#[test]
fn test_large_batch_response_allocation() {
    // Many results
    let mut results = Vec::with_capacity(1000);
    for i in 0..1000 {
        results.push(GpuBatchResult {
            index: i,
            token_ids: vec![i as u32],
            text: format!("result_{}", i),
            num_generated: 1,
        });
    }

    let response = GpuBatchResponse {
        results,
        stats: GpuBatchStats {
            batch_size: 1000,
            gpu_used: true,
            total_tokens: 1000,
            processing_time_ms: 1.0,
            throughput_tps: 1000000.0,
        },
    };

    assert_eq!(response.results.len(), 1000);
}

// ============================================================================
// Config Preset Tests
// ============================================================================

#[test]
fn test_batch_config_presets() {
    let default_config = BatchConfig::default();
    assert_eq!(default_config.window_ms, 50);
    assert_eq!(default_config.min_batch, 4);
    assert_eq!(default_config.optimal_batch, 32);
    assert_eq!(default_config.max_batch, 64);

    let low_latency = BatchConfig::low_latency();
    assert!(low_latency.window_ms < default_config.window_ms);
    assert!(low_latency.max_batch < default_config.max_batch);

    let high_throughput = BatchConfig::high_throughput();
    assert!(high_throughput.window_ms >= default_config.window_ms);
    assert!(high_throughput.max_batch > default_config.max_batch);
}
