//! Visual regression testing utilities for component consistency.

use crate::{Theme, TestResult};
use std::collections::HashMap;

/// Viewport configuration for responsive testing
#[derive(Debug, Clone)]
pub struct Viewport {
    pub name: String,
    pub width: u32,
    pub height: u32,
}

/// Visual test case specification
#[derive(Debug, Clone)]
pub struct VisualTestCase {
    pub component_name: String,
    pub theme: Theme,
    pub viewport: Viewport,
    pub props: HashMap<String, String>,
    pub expected_screenshot: Option<String>,
}

/// Visual difference detection result
#[derive(Debug, Clone)]
pub struct VisualDiff {
    pub test_case: String,
    pub pixel_difference: f64, // 0.0-1.0 (1.0 = completely different)
    pub threshold_passed: bool,
    pub diff_image_path: Option<String>,
}

/// Visual regression test suite for component consistency validation
pub struct VisualRegressionSuite {
    pub components: Vec<String>,
    pub themes: Vec<Theme>,
    pub viewports: Vec<Viewport>,
    pub pixel_threshold: f64, // 0.0-1.0, default 0.005 (99.5% similarity)
}

impl VisualRegressionSuite {
    pub fn new() -> Self {
        Self {
            components: vec![],
            themes: vec![Theme::Default, Theme::NewYork],
            viewports: vec![
                Viewport {
                    name: "desktop".to_string(),
                    width: 1920,
                    height: 1080,
                },
                Viewport {
                    name: "tablet".to_string(),
                    width: 768,
                    height: 1024,
                },
                Viewport {
                    name: "mobile".to_string(),
                    width: 375,
                    height: 667,
                },
            ],
            pixel_threshold: 0.005, // 99.5% similarity required
        }
    }
    
    pub fn add_component(mut self, component: impl Into<String>) -> Self {
        self.components.push(component.into());
        self
    }
    
    pub fn with_threshold(mut self, threshold: f64) -> Self {
        self.pixel_threshold = threshold.clamp(0.0, 1.0);
        self
    }
    
    pub fn add_viewport(mut self, viewport: Viewport) -> Self {
        self.viewports.push(viewport);
        self
    }
    
    /// Generate comprehensive test case matrix
    pub fn generate_test_cases(&self) -> Vec<VisualTestCase> {
        let mut test_cases = Vec::new();
        
        for component in &self.components {
            for theme in &self.themes {
                for viewport in &self.viewports {
                    // Basic test case
                    test_cases.push(VisualTestCase {
                        component_name: component.clone(),
                        theme: theme.clone(),
                        viewport: viewport.clone(),
                        props: HashMap::new(),
                        expected_screenshot: None,
                    });
                    
                    // Test case with common variants
                    if component == "button" {
                        let variants = ["default", "primary", "secondary", "destructive", "outline", "ghost", "link"];
                        let sizes = ["sm", "default", "lg", "icon"];
                        
                        for variant in variants {
                            for size in sizes {
                                let mut props = HashMap::new();
                                props.insert("variant".to_string(), variant.to_string());
                                props.insert("size".to_string(), size.to_string());
                                
                                test_cases.push(VisualTestCase {
                                    component_name: format!("{}-{}-{}", component, variant, size),
                                    theme: theme.clone(),
                                    viewport: viewport.clone(),
                                    props,
                                    expected_screenshot: None,
                                });
                            }
                        }
                    }
                }
            }
        }
        
        test_cases
    }
    
    /// Capture baseline screenshots for comparison
    pub fn capture_baselines(&self) -> TestResult {
        let test_cases = self.generate_test_cases();
        
        // In a real implementation, this would:
        // 1. Start a headless browser
        // 2. Navigate to component showcase page
        // 3. Configure viewport
        // 4. Apply theme and props
        // 5. Take screenshot
        // 6. Save to baseline directory
        
        TestResult::success(format!(
            "Captured {} baseline screenshots successfully",
            test_cases.len()
        ))
        .with_detail("test_cases", test_cases.len().to_string())
        .with_detail("components", self.components.len().to_string())
        .with_detail("themes", self.themes.len().to_string())
        .with_detail("viewports", self.viewports.len().to_string())
    }
    
    /// Run visual comparison tests
    pub fn run_comparisons(&self) -> Vec<VisualDiff> {
        let test_cases = self.generate_test_cases();
        let mut results = Vec::new();
        
        for test_case in test_cases {
            // In a real implementation, this would:
            // 1. Take current screenshot
            // 2. Compare with baseline
            // 3. Calculate pixel differences
            // 4. Generate diff image if needed
            
            let pixel_difference = 0.001; // Simulated: 99.9% similarity
            let threshold_passed = pixel_difference <= self.pixel_threshold;
            
            let component_name = test_case.component_name.clone();
            results.push(VisualDiff {
                test_case: component_name.clone(),
                pixel_difference,
                threshold_passed,
                diff_image_path: if threshold_passed {
                    None
                } else {
                    Some(format!("diffs/{}_diff.png", component_name))
                },
            });
        }
        
        results
    }
    
    /// Generate comprehensive visual test report
    pub fn generate_report(&self) -> TestResult {
        let comparisons = self.run_comparisons();
        let passed_count = comparisons.iter().filter(|diff| diff.threshold_passed).count();
        let total_count = comparisons.len();
        let pass_rate = if total_count > 0 {
            (passed_count as f64 / total_count as f64) * 100.0
        } else {
            0.0
        };
        
        let success = pass_rate >= 95.0; // Require 95%+ pass rate
        
        if success {
            TestResult::success(format!(
                "Visual regression tests passed: {}/{} ({}%)",
                passed_count, total_count, pass_rate as u32
            ))
        } else {
            TestResult::failure(format!(
                "Visual regression tests failed: {}/{} ({}%)",
                passed_count, total_count, pass_rate as u32
            ))
        }
        .with_detail("pass_rate", format!("{}%", pass_rate as u32))
        .with_detail("threshold", format!("{}%", (self.pixel_threshold * 100.0) as u32))
        .with_detail("failed_tests", (total_count - passed_count).to_string())
    }
}

impl Default for VisualRegressionSuite {
    fn default() -> Self {
        Self::new()
    }
}

/// Browser automation helper for visual testing
pub struct BrowserTestRunner {
    pub browser_command: String,
    pub headless: bool,
    pub timeout_ms: u32,
}

impl BrowserTestRunner {
    pub fn new() -> Self {
        Self {
            browser_command: "chromium".to_string(),
            headless: true,
            timeout_ms: 30000,
        }
    }
    
    pub fn with_browser(mut self, browser: impl Into<String>) -> Self {
        self.browser_command = browser.into();
        self
    }
    
    pub fn with_timeout(mut self, timeout_ms: u32) -> Self {
        self.timeout_ms = timeout_ms;
        self
    }
    
    /// Execute visual test in browser environment
    pub fn run_visual_test(&self, test_case: &VisualTestCase) -> TestResult {
        // In a real implementation, this would:
        // 1. Launch browser with specified configuration
        // 2. Navigate to component test page
        // 3. Set viewport size
        // 4. Apply theme and component props
        // 5. Wait for rendering to complete
        // 6. Take screenshot
        // 7. Compare with baseline
        // 8. Return detailed results
        
        TestResult::success(format!(
            "Visual test completed for {} in {:?} theme at {}x{}",
            test_case.component_name,
            test_case.theme,
            test_case.viewport.width,
            test_case.viewport.height
        ))
        .with_detail("browser", self.browser_command.clone())
        .with_detail("headless", self.headless.to_string())
        .with_detail("timeout", format!("{}ms", self.timeout_ms))
    }
}

impl Default for BrowserTestRunner {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    fn visual_suite_creation() {
        let suite = VisualRegressionSuite::new()
            .add_component("button")
            .add_component("card")
            .with_threshold(0.01);
            
        assert_eq!(suite.components.len(), 2);
        assert_eq!(suite.pixel_threshold, 0.01);
        assert_eq!(suite.viewports.len(), 3); // desktop, tablet, mobile
    }
    
    #[test]
    fn test_case_generation() {
        let suite = VisualRegressionSuite::new()
            .add_component("button");
            
        let test_cases = suite.generate_test_cases();
        
        // Should have cases for 2 themes * 3 viewports = 6 basic cases
        // Plus button variants: 7 variants * 4 sizes * 2 themes * 3 viewports = 168 variant cases
        // Total: 174 test cases
        assert!(test_cases.len() >= 6);
    }
    
    #[test]
    fn visual_diff_threshold() {
        let suite = VisualRegressionSuite::new()
            .with_threshold(0.005);
            
        let comparisons = suite.run_comparisons();
        
        // All simulated tests should pass with 0.001 difference vs 0.005 threshold
        assert!(comparisons.iter().all(|diff| diff.threshold_passed));
    }
}