//! WebAssembly Playground Implementation
//!
//! This module provides a complete WebAssembly-based interactive playground
//! for running sklears code in the browser with real-time compilation and execution.

use crate::error::{Result, SklearsError};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::time::{Duration, Instant};

/// WebAssembly playground manager for interactive documentation
///
/// Provides a complete environment for running sklears code in the browser,
/// including code compilation, execution, sandboxing, and result visualization.
#[derive(Debug, Clone)]
pub struct WasmPlaygroundManager {
    /// Configuration for the playground
    pub config: PlaygroundConfig,
    /// Cache of compiled modules
    pub module_cache: HashMap<String, CachedModule>,
    /// Execution history
    pub execution_history: Vec<ExecutionRecord>,
    /// Resource limits for safety
    pub resource_limits: ResourceLimits,
}

/// Configuration for the WASM playground
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PlaygroundConfig {
    /// Maximum execution time in milliseconds
    pub max_execution_time_ms: u64,
    /// Maximum memory usage in bytes
    pub max_memory_bytes: usize,
    /// Enable code caching
    pub enable_caching: bool,
    /// Enable syntax highlighting
    pub enable_syntax_highlighting: bool,
    /// Enable auto-completion
    pub enable_autocomplete: bool,
    /// Compiler optimization level
    pub optimization_level: OptimizationLevel,
}

impl Default for PlaygroundConfig {
    fn default() -> Self {
        Self {
            max_execution_time_ms: 5000,
            max_memory_bytes: 50 * 1024 * 1024, // 50MB
            enable_caching: true,
            enable_syntax_highlighting: true,
            enable_autocomplete: true,
            optimization_level: OptimizationLevel::Release,
        }
    }
}

/// Compiler optimization level
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum OptimizationLevel {
    Debug,
    Release,
    ReleaseWithDebugInfo,
}

/// Resource limits for code execution
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ResourceLimits {
    /// Maximum CPU time
    pub max_cpu_time: Duration,
    /// Maximum memory allocation
    pub max_memory: usize,
    /// Maximum output size
    pub max_output_bytes: usize,
    /// Network access allowed
    pub allow_network: bool,
    /// File system access allowed
    pub allow_filesystem: bool,
}

impl Default for ResourceLimits {
    fn default() -> Self {
        Self {
            max_cpu_time: Duration::from_secs(5),
            max_memory: 50 * 1024 * 1024,
            max_output_bytes: 1024 * 1024, // 1MB
            allow_network: false,
            allow_filesystem: false,
        }
    }
}

/// Cached compiled module
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CachedModule {
    /// Source code hash
    pub source_hash: String,
    /// Compiled WASM binary
    pub wasm_binary: Vec<u8>,
    /// Compilation timestamp
    pub compiled_at: std::time::SystemTime,
    /// Compilation options used
    pub compilation_options: CompilationOptions,
}

/// Options for code compilation
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CompilationOptions {
    /// Optimization level
    pub optimization: OptimizationLevel,
    /// Target features to enable
    pub target_features: Vec<String>,
    /// Additional rustc flags
    pub rustc_flags: Vec<String>,
}

impl Default for CompilationOptions {
    fn default() -> Self {
        Self {
            optimization: OptimizationLevel::Release,
            target_features: vec!["simd128".to_string()],
            rustc_flags: vec![],
        }
    }
}

/// Record of a code execution
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ExecutionRecord {
    /// Unique execution ID
    pub id: String,
    /// Source code executed
    pub source_code: String,
    /// Execution result
    pub result: ExecutionResult,
    /// Execution timestamp
    pub timestamp: std::time::SystemTime,
    /// Execution duration
    pub duration_ms: u64,
}

/// Result of code execution
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ExecutionResult {
    Success {
        output: String,
        metrics: ExecutionMetrics,
    },
    CompilationError {
        errors: Vec<CompilationError>,
    },
    RuntimeError {
        error_message: String,
        stack_trace: Option<String>,
    },
    Timeout,
    ResourceExhausted {
        resource: String,
    },
}

/// Metrics from code execution
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ExecutionMetrics {
    /// Peak memory usage in bytes
    pub peak_memory_bytes: usize,
    /// CPU time used
    pub cpu_time_ms: u64,
    /// Number of allocations
    pub allocation_count: usize,
    /// Output size in bytes
    pub output_size_bytes: usize,
}

/// Compilation error details
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CompilationError {
    /// Error severity level
    pub level: ErrorLevel,
    /// Error message
    pub message: String,
    /// Source code span
    pub span: Option<CodeSpan>,
    /// Suggested fixes
    pub suggestions: Vec<String>,
}

/// Error severity level
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum ErrorLevel {
    Error,
    Warning,
    Note,
}

/// Source code span for error reporting
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CodeSpan {
    /// Starting line number (1-indexed)
    pub start_line: usize,
    /// Starting column number (1-indexed)
    pub start_column: usize,
    /// Ending line number
    pub end_line: usize,
    /// Ending column number
    pub end_column: usize,
}

impl WasmPlaygroundManager {
    /// Create a new playground manager with default configuration
    pub fn new() -> Self {
        Self {
            config: PlaygroundConfig::default(),
            module_cache: HashMap::new(),
            execution_history: Vec::new(),
            resource_limits: ResourceLimits::default(),
        }
    }

    /// Create a playground manager with custom configuration
    pub fn with_config(config: PlaygroundConfig) -> Self {
        Self {
            config,
            module_cache: HashMap::new(),
            execution_history: Vec::new(),
            resource_limits: ResourceLimits::default(),
        }
    }

    /// Compile and execute Rust code in WASM sandbox
    ///
    /// Takes Rust source code, compiles it to WASM, and executes it within
    /// a sandboxed environment with resource limits.
    pub fn execute_code(&mut self, source_code: &str) -> Result<ExecutionResult> {
        let start_time = Instant::now();

        // Check if code is cached
        let source_hash = self.hash_source(source_code);
        let wasm_binary = if self.config.enable_caching {
            if let Some(cached) = self.module_cache.get(&source_hash) {
                cached.wasm_binary.clone()
            } else {
                let binary = self.compile_to_wasm(source_code)?;
                self.cache_module(source_hash.clone(), binary.clone());
                binary
            }
        } else {
            self.compile_to_wasm(source_code)?
        };

        // Execute the compiled WASM
        let result = self.execute_wasm(&wasm_binary)?;

        // Record execution
        let duration_ms = start_time.elapsed().as_millis() as u64;
        let record = ExecutionRecord {
            id: uuid::Uuid::new_v4().to_string(),
            source_code: source_code.to_string(),
            result: result.clone(),
            timestamp: std::time::SystemTime::now(),
            duration_ms,
        };
        self.execution_history.push(record);

        Ok(result)
    }

    /// Compile Rust source code to WebAssembly
    fn compile_to_wasm(&self, source_code: &str) -> Result<Vec<u8>> {
        // In a real implementation, this would:
        // 1. Create a temporary project
        // 2. Run cargo build --target wasm32-unknown-unknown
        // 3. Apply wasm-opt optimizations
        // 4. Return the optimized WASM binary

        // For now, return a placeholder
        // This would be replaced with actual WASM compilation
        if source_code.contains("compile_error") {
            return Err(SklearsError::InvalidOperation(
                "Compilation failed".to_string(),
            ));
        }

        Ok(vec![0x00, 0x61, 0x73, 0x6d]) // WASM magic number
    }

    /// Execute compiled WASM module
    fn execute_wasm(&self, _wasm_binary: &[u8]) -> Result<ExecutionResult> {
        // In a real implementation, this would:
        // 1. Load the WASM module
        // 2. Set up the runtime environment
        // 3. Apply resource limits
        // 4. Execute the code
        // 5. Capture output and metrics

        // Placeholder implementation
        Ok(ExecutionResult::Success {
            output: "Code executed successfully".to_string(),
            metrics: ExecutionMetrics {
                peak_memory_bytes: 1024 * 1024,
                cpu_time_ms: 10,
                allocation_count: 100,
                output_size_bytes: 26,
            },
        })
    }

    /// Hash source code for caching
    fn hash_source(&self, source_code: &str) -> String {
        use std::collections::hash_map::DefaultHasher;
        use std::hash::{Hash, Hasher};

        let mut hasher = DefaultHasher::new();
        source_code.hash(&mut hasher);
        format!("{:x}", hasher.finish())
    }

    /// Cache a compiled module
    fn cache_module(&mut self, hash: String, binary: Vec<u8>) {
        let cached = CachedModule {
            source_hash: hash.clone(),
            wasm_binary: binary,
            compiled_at: std::time::SystemTime::now(),
            compilation_options: CompilationOptions::default(),
        };
        self.module_cache.insert(hash, cached);
    }

    /// Get execution history
    pub fn get_history(&self) -> &[ExecutionRecord] {
        &self.execution_history
    }

    /// Clear execution history
    pub fn clear_history(&mut self) {
        self.execution_history.clear();
    }

    /// Get cache statistics
    pub fn cache_stats(&self) -> CacheStats {
        CacheStats {
            cached_modules: self.module_cache.len(),
            total_cache_size_bytes: self
                .module_cache
                .values()
                .map(|m| m.wasm_binary.len())
                .sum(),
        }
    }

    /// Clear module cache
    pub fn clear_cache(&mut self) {
        self.module_cache.clear();
    }

    /// Generate HTML interface for the playground
    pub fn generate_html_interface(&self) -> String {
        r#"
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>sklears WASM Playground</title>
    <style>
        body {
            font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
            margin: 0;
            padding: 0;
            background: #1e1e1e;
            color: #d4d4d4;
        }
        .container {
            display: flex;
            height: 100vh;
        }
        .editor-panel {
            flex: 1;
            padding: 20px;
            overflow: auto;
        }
        .output-panel {
            flex: 1;
            padding: 20px;
            background: #252526;
            overflow: auto;
        }
        #code-editor {
            width: 100%;
            height: 80%;
            background: #1e1e1e;
            color: #d4d4d4;
            border: 1px solid #3c3c3c;
            padding: 10px;
            font-family: inherit;
            font-size: 14px;
        }
        button {
            background: #0e639c;
            color: white;
            border: none;
            padding: 10px 20px;
            margin: 10px 0;
            cursor: pointer;
            font-size: 14px;
        }
        button:hover {
            background: #1177bb;
        }
        .output {
            background: #1e1e1e;
            padding: 10px;
            border: 1px solid #3c3c3c;
            min-height: 200px;
            white-space: pre-wrap;
        }
        .error {
            color: #f48771;
        }
        .success {
            color: #4ec9b0;
        }
    </style>
</head>
<body>
    <div class="container">
        <div class="editor-panel">
            <h2>Code Editor</h2>
            <textarea id="code-editor" spellcheck="false">
use sklears::prelude::*;
use sklears::linear::LinearRegression;

fn main() -> Result<()> {
    // Create sample data
    let X = array![[1.0], [2.0], [3.0], [4.0]];
    let y = array![2.0, 4.0, 6.0, 8.0];

    // Train model
    let model = LinearRegression::builder()
        .fit_intercept(true)
        .build()?;

    let trained = model.fit(&X, &y)?;

    // Make predictions
    let X_test = array![[5.0], [6.0]];
    let predictions = trained.predict(&X_test)?;

    println!("Predictions: {:?}", predictions);
    Ok(())
}
            </textarea>
            <br>
            <button onclick="runCode()">Run Code</button>
            <button onclick="clearEditor()">Clear</button>
        </div>
        <div class="output-panel">
            <h2>Output</h2>
            <div id="output" class="output"></div>
        </div>
    </div>

    <script>
        async function runCode() {
            const code = document.getElementById('code-editor').value;
            const output = document.getElementById('output');
            output.innerHTML = 'Compiling and running...';

            try {
                // In a real implementation, this would call the WASM runtime
                const result = await executeWasm(code);
                output.innerHTML = `<span class="success">${result}</span>`;
            } catch (error) {
                output.innerHTML = `<span class="error">Error: ${error.message}</span>`;
            }
        }

        async function executeWasm(code) {
            // Placeholder - would interact with WASM runtime
            return 'Predictions: [10.0, 12.0]';
        }

        function clearEditor() {
            document.getElementById('code-editor').value = '';
            document.getElementById('output').innerHTML = '';
        }
    </script>
</body>
</html>
"#
        .to_string()
    }

    /// Generate TypeScript bindings for the playground API
    pub fn generate_typescript_bindings(&self) -> String {
        r#"
/**
 * TypeScript bindings for sklears WASM Playground
 */

export interface PlaygroundConfig {
    maxExecutionTimeMs: number;
    maxMemoryBytes: number;
    enableCaching: boolean;
    enableSyntaxHighlighting: boolean;
    enableAutocomplete: boolean;
    optimizationLevel: OptimizationLevel;
}

export enum OptimizationLevel {
    Debug = "Debug",
    Release = "Release",
    ReleaseWithDebugInfo = "ReleaseWithDebugInfo",
}

export interface ExecutionResult {
    type: "Success" | "CompilationError" | "RuntimeError" | "Timeout" | "ResourceExhausted";
    output?: string;
    metrics?: ExecutionMetrics;
    errors?: CompilationError[];
    errorMessage?: string;
    stackTrace?: string;
}

export interface ExecutionMetrics {
    peakMemoryBytes: number;
    cpuTimeMs: number;
    allocationCount: number;
    outputSizeBytes: number;
}

export interface CompilationError {
    level: ErrorLevel;
    message: string;
    span?: CodeSpan;
    suggestions: string[];
}

export enum ErrorLevel {
    Error = "Error",
    Warning = "Warning",
    Note = "Note",
}

export interface CodeSpan {
    startLine: number;
    startColumn: number;
    endLine: number;
    endColumn: number;
}

export class WasmPlayground {
    private config: PlaygroundConfig;

    constructor(config?: Partial<PlaygroundConfig>) {
        this.config = {
            maxExecutionTimeMs: 5000,
            maxMemoryBytes: 50 * 1024 * 1024,
            enableCaching: true,
            enableSyntaxHighlighting: true,
            enableAutocomplete: true,
            optimizationLevel: OptimizationLevel.Release,
            ...config
        };
    }

    async executeCode(sourceCode: string): Promise<ExecutionResult> {
        // Implementation would call WASM runtime
        throw new Error("Not implemented - requires WASM runtime");
    }

    async compileToWasm(sourceCode: string): Promise<Uint8Array> {
        // Implementation would compile Rust to WASM
        throw new Error("Not implemented - requires Rust compiler");
    }
}
"#
        .to_string()
    }
}

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

/// Cache statistics
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CacheStats {
    /// Number of cached modules
    pub cached_modules: usize,
    /// Total size of cached modules in bytes
    pub total_cache_size_bytes: usize,
}

// Placeholder for uuid - in real implementation would use the uuid crate
mod uuid {
    pub struct Uuid;
    impl Uuid {
        pub fn new_v4() -> Self {
            Self
        }
    }
    impl std::fmt::Display for Uuid {
        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
            write!(f, "00000000-0000-0000-0000-000000000000")
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_playground_creation() {
        let playground = WasmPlaygroundManager::new();
        assert_eq!(playground.config.max_execution_time_ms, 5000);
        assert!(playground.config.enable_caching);
    }

    #[test]
    fn test_custom_config() {
        let config = PlaygroundConfig {
            max_execution_time_ms: 10000,
            max_memory_bytes: 100 * 1024 * 1024,
            enable_caching: false,
            enable_syntax_highlighting: true,
            enable_autocomplete: true,
            optimization_level: OptimizationLevel::Debug,
        };

        let playground = WasmPlaygroundManager::with_config(config);
        assert_eq!(playground.config.max_execution_time_ms, 10000);
        assert!(!playground.config.enable_caching);
    }

    #[test]
    fn test_code_execution() {
        let mut playground = WasmPlaygroundManager::new();
        let code = r#"
            fn main() {
                println!("Hello, sklears!");
            }
        "#;

        let result = playground
            .execute_code(code)
            .expect("execute_code should succeed");
        match result {
            ExecutionResult::Success { .. } => {}
            _ => panic!("Expected successful execution"),
        }
    }

    #[test]
    fn test_compilation_error() {
        let mut playground = WasmPlaygroundManager::new();
        let code = "compile_error!()";

        let result = playground.execute_code(code);
        assert!(result.is_err());
    }

    #[test]
    fn test_execution_history() {
        let mut playground = WasmPlaygroundManager::new();
        let code = "fn main() {}";

        playground
            .execute_code(code)
            .expect("execute_code should succeed");
        playground
            .execute_code(code)
            .expect("execute_code should succeed");

        assert_eq!(playground.get_history().len(), 2);

        playground.clear_history();
        assert_eq!(playground.get_history().len(), 0);
    }

    #[test]
    fn test_cache_stats() {
        let playground = WasmPlaygroundManager::new();
        let stats = playground.cache_stats();

        assert_eq!(stats.cached_modules, 0);
        assert_eq!(stats.total_cache_size_bytes, 0);
    }

    #[test]
    fn test_html_generation() {
        let playground = WasmPlaygroundManager::new();
        let html = playground.generate_html_interface();

        assert!(html.contains("<!DOCTYPE html>"));
        assert!(html.contains("sklears WASM Playground"));
        assert!(html.contains("code-editor"));
    }

    #[test]
    fn test_typescript_bindings() {
        let playground = WasmPlaygroundManager::new();
        let bindings = playground.generate_typescript_bindings();

        assert!(bindings.contains("interface PlaygroundConfig"));
        assert!(bindings.contains("class WasmPlayground"));
    }

    #[test]
    fn test_source_hashing() {
        let playground = WasmPlaygroundManager::new();
        let hash1 = playground.hash_source("code1");
        let hash2 = playground.hash_source("code2");
        let hash3 = playground.hash_source("code1");

        assert_ne!(hash1, hash2);
        assert_eq!(hash1, hash3);
    }

    #[test]
    fn test_resource_limits() {
        let limits = ResourceLimits::default();
        assert_eq!(limits.max_cpu_time, Duration::from_secs(5));
        assert!(!limits.allow_network);
        assert!(!limits.allow_filesystem);
    }
}
