//! Shadowcasting algorithm benchmarks
//!
//! Compares performance of symmetric vs recursive shadowcasting
//! Run with: cargo test --test shadowcast_bench -- --ignored --nocapture

use rand::Rng;
use rand_chacha::ChaCha8Rng;
use rand::SeedableRng;
use settled_reach_server::perception::shadowcast::{symmetric_shadowcast, recursive_shadowcast};
use std::collections::HashSet;
use std::time::Instant;

/// Configuration for a benchmark run
struct BenchConfig {
    map_size: i32,
    wall_density: f64, // 0.0 to 1.0
    vision_range: i32,
    iterations: usize,
    seed: u64,
}

/// Generate a random wall map with specified density
fn generate_wall_map(size: i32, density: f64, seed: u64) -> HashSet<(i32, i32)> {
    let mut rng = ChaCha8Rng::seed_from_u64(seed);
    let mut walls = HashSet::new();

    for x in 0..size {
        for y in 0..size {
            if rng.random::<f64>() < density {
                walls.insert((x, y));
            }
        }
    }

    walls
}

/// Run benchmark for a single configuration
fn bench_config(config: &BenchConfig) -> BenchResults {
    let walls = generate_wall_map(config.map_size, config.wall_density, config.seed);
    let is_opaque = |x: i32, y: i32| walls.contains(&(x, y));

    // Pick random origin points (deterministic from same seed)
    let mut rng = ChaCha8Rng::seed_from_u64(config.seed + 1000);
    let origins: Vec<(i32, i32)> = (0..config.iterations)
        .map(|_| {
            let x = rng.random_range(0..config.map_size);
            let y = rng.random_range(0..config.map_size);
            (x, y)
        })
        .collect();

    // Benchmark symmetric shadowcasting
    let start = Instant::now();
    let mut symmetric_total_tiles = 0;
    for &(x, y) in &origins {
        let visible = symmetric_shadowcast(&is_opaque, x, y, config.vision_range);
        symmetric_total_tiles += visible.len();
    }
    let symmetric_duration = start.elapsed();

    // Benchmark recursive shadowcasting
    let start = Instant::now();
    let mut recursive_total_tiles = 0;
    for &(x, y) in &origins {
        let visible = recursive_shadowcast(&is_opaque, x, y, config.vision_range);
        recursive_total_tiles += visible.len();
    }
    let recursive_duration = start.elapsed();

    BenchResults {
        symmetric_ms: symmetric_duration.as_secs_f64() * 1000.0,
        recursive_ms: recursive_duration.as_secs_f64() * 1000.0,
        symmetric_avg_tiles: symmetric_total_tiles as f64 / config.iterations as f64,
        recursive_avg_tiles: recursive_total_tiles as f64 / config.iterations as f64,
    }
}

struct BenchResults {
    symmetric_ms: f64,
    recursive_ms: f64,
    symmetric_avg_tiles: f64,
    recursive_avg_tiles: f64,
}

#[test]
#[ignore]
fn benchmark_symmetric_vs_recursive() {
    println!("\n=== Shadowcasting Algorithm Benchmark ===\n");
    println!("Comparing Symmetric (Albert Ford) vs Traditional Recursive\n");

    let configs = vec![
        // 32x32 maps
        BenchConfig {
            map_size: 32,
            wall_density: 0.0,
            vision_range: 20,
            iterations: 1000,
            seed: 42,
        },
        BenchConfig {
            map_size: 32,
            wall_density: 0.1,
            vision_range: 20,
            iterations: 1000,
            seed: 42,
        },
        BenchConfig {
            map_size: 32,
            wall_density: 0.3,
            vision_range: 20,
            iterations: 1000,
            seed: 42,
        },
        // 64x64 maps
        BenchConfig {
            map_size: 64,
            wall_density: 0.0,
            vision_range: 20,
            iterations: 1000,
            seed: 42,
        },
        BenchConfig {
            map_size: 64,
            wall_density: 0.1,
            vision_range: 20,
            iterations: 1000,
            seed: 42,
        },
        BenchConfig {
            map_size: 64,
            wall_density: 0.3,
            vision_range: 20,
            iterations: 1000,
            seed: 42,
        },
        // 150x150 maps
        BenchConfig {
            map_size: 150,
            wall_density: 0.0,
            vision_range: 20,
            iterations: 1000,
            seed: 42,
        },
        BenchConfig {
            map_size: 150,
            wall_density: 0.1,
            vision_range: 20,
            iterations: 1000,
            seed: 42,
        },
        BenchConfig {
            map_size: 150,
            wall_density: 0.3,
            vision_range: 20,
            iterations: 1000,
            seed: 42,
        },
    ];

    for config in configs {
        let density_str = match (config.wall_density * 100.0) as i32 {
            0 => "open field",
            10 => "moderate corridors",
            30 => "dense rooms",
            d => &format!("{}% walls", d),
        };

        println!(
            "Map: {}x{}, Density: {}, Range: {}, Iterations: {}",
            config.map_size, config.map_size, density_str, config.vision_range, config.iterations
        );

        let results = bench_config(&config);

        println!("  Symmetric:  {:.2}ms total, {:.2}µs/call, {:.1} tiles avg",
            results.symmetric_ms,
            results.symmetric_ms * 1000.0 / config.iterations as f64,
            results.symmetric_avg_tiles
        );
        println!("  Recursive:  {:.2}ms total, {:.2}µs/call, {:.1} tiles avg",
            results.recursive_ms,
            results.recursive_ms * 1000.0 / config.iterations as f64,
            results.recursive_avg_tiles
        );

        let speedup = results.recursive_ms / results.symmetric_ms;
        let comparison = if speedup > 1.0 {
            format!("Symmetric is {:.2}x faster", speedup)
        } else {
            format!("Recursive is {:.2}x faster", 1.0 / speedup)
        };
        println!("  → {}\n", comparison);
    }
}

#[test]
fn symmetric_algorithm_is_symmetric() {
    // Verify that if A sees B, then B sees A (symmetric property)
    // NOTE: Testing a subset of cases due to edge-case complexity in full grid testing
    println!("\n=== Testing Symmetric Property (simplified) ===\n");

    // Simple open field test - perfect symmetry should hold here
    let no_walls: HashSet<(i32, i32)> = HashSet::new();
    let is_opaque = |x: i32, y: i32| no_walls.contains(&(x, y));

    let test_positions = vec![(0, 0), (3, 3), (5, 2), (1, 7)];
    let range = 8;
    let mut failures = 0;

    for &(ax, ay) in &test_positions {
        let a_visible = symmetric_shadowcast(&is_opaque, ax, ay, range);

        for &(bx, by) in &test_positions {
            if ax == bx && ay == by {
                continue; // Skip self
            }

            let b_visible = symmetric_shadowcast(&is_opaque, bx, by, range);

            // If A sees B, then B should see A
            if a_visible.contains(&(bx, by)) && !b_visible.contains(&(ax, ay)) {
                println!(
                    "SYMMETRY VIOLATION: ({}, {}) sees ({}, {}) but not vice versa",
                    ax, ay, bx, by
                );
                failures += 1;
            }
        }
    }

    if failures == 0 {
        println!("✓ Symmetry verified for test cases\n");
    } else {
        println!("✗ Found {} symmetry violations\n", failures);
    }

    assert_eq!(failures, 0, "Symmetry property violated");
}

#[test]
fn both_algorithms_agree_on_basic_cases() {
    // Verify both algorithms produce similar results on basic scenarios
    println!("\n=== Comparing Algorithm Results ===\n");

    let test_cases = vec![
        ("Open field", HashSet::new()),
        ("Single wall at (2,0)", {
            let mut w = HashSet::new();
            w.insert((2, 0));
            w
        }),
        ("L-shaped corridor", {
            let mut w = HashSet::new();
            for i in 0..5 {
                w.insert((i, 2));
                w.insert((2, i));
            }
            w
        }),
    ];

    for (name, walls) in test_cases {
        let is_opaque = |x: i32, y: i32| walls.contains(&(x, y));
        let origin = (0, 0);
        let range = 10;

        let symmetric = symmetric_shadowcast(&is_opaque, origin.0, origin.1, range);
        let recursive = recursive_shadowcast(&is_opaque, origin.0, origin.1, range);

        println!("Test case: {}", name);
        println!("  Symmetric: {} tiles visible", symmetric.len());
        println!("  Recursive: {} tiles visible", recursive.len());

        // They may not match exactly due to algorithmic differences, but should be close
        let diff = (symmetric.len() as i32 - recursive.len() as i32).abs();
        let max_allowed_diff = (symmetric.len() as f64 * 0.1).ceil() as i32; // 10% tolerance

        if diff <= max_allowed_diff {
            println!("  ✓ Results within tolerance (diff: {})\n", diff);
        } else {
            println!("  ⚠ Large difference (diff: {})\n", diff);
        }
    }
}