use crate::ast::environment::Environment;
use std::fs;
use std::time::{Duration, Instant};
use regex::Regex;

pub struct TestResult {
    pub name: String,
    pub success: bool,
    pub message: String,
}

pub struct BenchmarkResult {
    pub name: String,
    pub median: Duration,
    pub baseline: Option<Duration>,
    pub diff_pct: Option<f64>,
    pub status: String,
}

pub fn run_functional_tests() -> Vec<TestResult> {
    let mut results = Vec::new();
    let entries = fs::read_dir("examples").unwrap();
    let env = Environment::new();

    for entry in entries.filter_map(|e| e.ok()) {
        let path = entry.path();
        if path.extension().map_or(false, |ext| ext == "myc") {
            let content = fs::read_to_string(&path).unwrap();
            let name = path.file_name().unwrap().to_string_lossy().to_string();
            
            let expected_output = Regex::new(r";; Output: (.*)").unwrap()
                .captures(&content)
                .map(|m| m.get(1).unwrap().as_str().trim().to_string());

            if let Some(expected) = expected_output {
                match env.run_script(&content) {
                    Ok(val) => {
                        let val_str = format!("{}", val);
                        if val_str == expected {
                            results.push(TestResult { name, success: true, message: format!("OK: {}", val_str) });
                        } else {
                            results.push(TestResult { name, success: false, message: format!("Expected {}, got {}", expected, val_str) });
                        }
                    }
                    Err(e) => results.push(TestResult { name, success: false, message: format!("Error: {}", e) }),
                }
            }
        }
    }
    results
}

pub fn run_benchmarks(update: bool) -> Vec<BenchmarkResult> {
    let mut results = Vec::new();
    let entries = fs::read_dir("examples").unwrap();
    let env = Environment::new();
    let is_release = !cfg!(debug_assertions);

    for entry in entries.filter_map(|e| e.ok()) {
        let path = entry.path();
        if path.extension().map_or(false, |ext| ext == "myc") {
            let content = fs::read_to_string(&path).unwrap();
            let name = path.file_name().unwrap().to_string_lossy().to_string();
            
            let baseline_pattern = Regex::new(r";; Benchmark: ([\d\.]+\w+)").unwrap();
            let baseline_match = baseline_pattern.captures(&content);
            
            // Measure
            let mut runs = Vec::new();
            for _ in 0..100 {
                let start = Instant::now();
                let _ = env.run_script(&content);
                runs.push(start.elapsed());
            }
            runs.sort();
            let median = runs[runs.len() / 2];

            if update {
                let new_val = format_duration(median);
                let updated_content = if let Some(m) = baseline_match {
                    content.replace(m.get(0).unwrap().as_str(), &format!(";; Benchmark: {}", new_val))
                } else {
                    format!(";; Benchmark: {}
{}", new_val, content)
                };
                fs::write(&path, updated_content).unwrap();
                results.push(BenchmarkResult { name, median, baseline: None, diff_pct: None, status: format!("UPDATED: {}", new_val) });
            } else {
                if let Some(m) = baseline_match {
                    let baseline_str = m.get(1).unwrap().as_str();
                    let baseline = parse_duration(baseline_str).unwrap();
                    let diff = (median.as_nanos() as f64 / baseline.as_nanos() as f64) - 1.0;
                    
                    let threshold = if is_release { 0.10 } else { 0.25 };
                    let status = if median > baseline && diff > threshold { "FAILED" } else { "OK" };
                    
                    results.push(BenchmarkResult { name, median, baseline: Some(baseline), diff_pct: Some(diff * 100.0), status: status.to_string() });
                } else {
                    results.push(BenchmarkResult { name, median, baseline: None, diff_pct: None, status: "MISSING BASELINE".to_string() });
                }
            }
        }
    }
    results
}

fn format_duration(d: Duration) -> String {
    if d.as_nanos() < 1000 { format!("{}ns", d.as_nanos()) }
    else if d.as_micros() < 1000 { format!("{:.1}us", d.as_nanos() as f64 / 1000.0) }
    else if d.as_millis() < 1000 { format!("{:.1}ms", d.as_micros() as f64 / 1000.0) }
    else { format!("{:.1}s", d.as_millis() as f64 / 1000.0) }
}

fn parse_duration(s: &str) -> Option<Duration> {
    let re = Regex::new(r"([\d\.]+)(\w+)").unwrap();
    let caps = re.captures(s)?;
    let val: f64 = caps[1].parse().ok()?;
    let unit = &caps[2];
    match unit {
        "ns" => Some(Duration::from_nanos(val as u64)),
        "us" => Some(Duration::from_nanos((val * 1000.0) as u64)),
        "ms" => Some(Duration::from_nanos((val * 1_000_000.0) as u64)),
        "s" => Some(Duration::from_nanos((val * 1_000_000_000.0) as u64)),
        _ => None,
    }
}