use leptos::prelude::*;
use wasm_bindgen::prelude::*;
use web_sys::{HtmlCanvasElement, CanvasRenderingContext2d, ImageData};
use std::collections::HashMap;
use serde::{Serialize, Deserialize};

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct VisualTestResult {
    pub test_name: String,
    pub component_name: String,
    pub screenshot_data: String, // Base64 encoded image data
    pub timestamp: u64,
    pub viewport_width: u32,
    pub viewport_height: u32,
    pub pixel_difference: Option<f64>,
    pub visual_similarity: Option<f64>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct VisualBaseline {
    pub test_name: String,
    pub component_name: String,
    pub baseline_screenshot: String,
    pub created_at: u64,
    pub viewport_width: u32,
    pub viewport_height: u32,
    pub threshold: f64, // Similarity threshold (0.0 to 1.0)
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct VisualRegression {
    pub test_name: String,
    pub component_name: String,
    pub current_screenshot: String,
    pub baseline_screenshot: String,
    pub diff_screenshot: String,
    pub similarity_score: f64,
    pub threshold: f64,
    pub pixel_differences: u32,
    pub timestamp: u64,
}

pub struct VisualTestRunner {
    baselines: HashMap<String, VisualBaseline>,
    results: Vec<VisualTestResult>,
    regressions: Vec<VisualRegression>,
}

impl VisualTestRunner {
    pub fn new() -> Self {
        Self {
            baselines: HashMap::new(),
            results: Vec::new(),
            regressions: Vec::new(),
        }
    }

    pub fn capture_screenshot(&self, element_id: &str, test_name: &str) -> Result<String, String> {
        // This would use web_sys to capture screenshots
        // For now, returning a placeholder
        Ok("placeholder_screenshot_data".to_string())
    }

    pub fn compare_with_baseline(&mut self, test_name: &str, current_screenshot: &str) -> Result<Option<VisualRegression>, String> {
        if let Some(baseline) = self.baselines.get(test_name) {
            let similarity = self.calculate_similarity(&baseline.baseline_screenshot, current_screenshot)?;
            
            if similarity < baseline.threshold {
                let regression = VisualRegression {
                    test_name: test_name.to_string(),
                    component_name: baseline.component_name.clone(),
                    current_screenshot: current_screenshot.to_string(),
                    baseline_screenshot: baseline.baseline_screenshot.clone(),
                    diff_screenshot: self.generate_diff_image(&baseline.baseline_screenshot, current_screenshot)?,
                    similarity_score: similarity,
                    threshold: baseline.threshold,
                    pixel_differences: self.count_pixel_differences(&baseline.baseline_screenshot, current_screenshot)?,
                    timestamp: current_timestamp(),
                };
                
                self.regressions.push(regression.clone());
                return Ok(Some(regression));
            }
        }
        
        Ok(None)
    }

    pub fn set_baseline(&mut self, test_name: &str, component_name: &str, screenshot: &str, threshold: f64, viewport_width: u32, viewport_height: u32) {
        let baseline = VisualBaseline {
            test_name: test_name.to_string(),
            component_name: component_name.to_string(),
            baseline_screenshot: screenshot.to_string(),
            created_at: current_timestamp(),
            viewport_width,
            viewport_height,
            threshold,
        };
        
        self.baselines.insert(test_name.to_string(), baseline);
    }

    fn calculate_similarity(&self, baseline: &str, current: &str) -> Result<f64, String> {
        // Simplified similarity calculation
        // In a real implementation, this would compare pixel data
        if baseline == current {
            Ok(1.0)
        } else {
            Ok(0.8) // Placeholder similarity score
        }
    }

    fn generate_diff_image(&self, baseline: &str, current: &str) -> Result<String, String> {
        // Generate a visual diff image highlighting differences
        // For now, returning a placeholder
        Ok("diff_image_data".to_string())
    }

    fn count_pixel_differences(&self, baseline: &str, current: &str) -> Result<u32, String> {
        // Count the number of different pixels
        // For now, returning a placeholder
        Ok(42)
    }

    pub fn get_regressions(&self) -> &Vec<VisualRegression> {
        &self.regressions
    }

    pub fn get_results(&self) -> &Vec<VisualTestResult> {
        &self.results
    }

    pub fn export_baselines(&self) -> String {
        serde_json::to_string_pretty(&self.baselines).unwrap_or_default()
    }

    pub fn import_baselines(&mut self, json_data: &str) -> Result<(), serde_json::Error> {
        let baselines: HashMap<String, VisualBaseline> = serde_json::from_str(json_data)?;
        self.baselines.extend(baselines);
        Ok(())
    }
}

fn current_timestamp() -> u64 {
    std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH)
        .unwrap()
        .as_secs()
}

// Global visual test runner instance
lazy_static::lazy_static! {
    pub static ref VISUAL_TEST_RUNNER: std::sync::Mutex<VisualTestRunner> = 
        std::sync::Mutex::new(VisualTestRunner::new());
}

// Macro for visual testing
#[macro_export]
macro_rules! visual_test {
    ($test_name:expr, $component_name:expr, $element_id:expr) => {{
        let mut runner = crate::visual_testing::VISUAL_TEST_RUNNER.lock().unwrap();
        let screenshot = runner.capture_screenshot($element_id, $test_name)?;
        
        let result = VisualTestResult {
            test_name: $test_name.to_string(),
            component_name: $component_name.to_string(),
            screenshot_data: screenshot.clone(),
            timestamp: current_timestamp(),
            viewport_width: 1920,
            viewport_height: 1080,
            pixel_difference: None,
            visual_similarity: None,
        };
        
        runner.results.push(result);
        
        // Compare with baseline
        runner.compare_with_baseline($test_name, &screenshot)
    }};
}