// ast.js
// AST visualization tool for Baba Yaga language

import { lexer, parser } from '../../lang.js';

const examples = {
  simple: `x : 42;`,
  
  when: `result : when x is 42 then "correct" _ then "wrong";`,
  
  function: `factorial : n -> 
  when n is
    0 then 1
    _ then n * (factorial (n - 1));`,
  
  table: `person : {name: "Baba Yaga", age: 99, active: true};
numbers : {1, 2, 3, 4, 5};`,
  
  arithmetic: `result : 5 + 3 * 2;
composed : compose @double @increment 5;`,
  
  complex: `classify : x y -> 
  when x y is
    0 0 then "both zero"
    0 _ then "x is zero"
    _ 0 then "y is zero"
    _ _ then "neither zero";`
};

// DOM elements - will be initialized when DOM is ready
let codeInput, generateBtn, examplesSelect, astOutput, tokensOutput, errorOutput, copyAstBtn, copyTokensBtn;

// Initialize when DOM is ready
document.addEventListener('DOMContentLoaded', () => {
  // Initialize DOM elements
  codeInput = document.getElementById('code-input');
  generateBtn = document.getElementById('generate-btn');
  examplesSelect = document.getElementById('examples');
  astOutput = document.getElementById('ast-output');
  tokensOutput = document.getElementById('tokens-output');
  errorOutput = document.getElementById('error-output');
  copyAstBtn = document.getElementById('copy-ast-btn');
  copyTokensBtn = document.getElementById('copy-tokens-btn');

  // Example selector functionality
  examplesSelect.addEventListener('change', () => {
    const selectedExample = examplesSelect.value;
    if (selectedExample && examples[selectedExample]) {
      codeInput.value = examples[selectedExample];
      generateAST();
    }
  });

  // Generate button click handler
  generateBtn.addEventListener('click', generateAST);

  // Copy button click handlers
  copyAstBtn.addEventListener('click', () => copyToClipboard(astOutput, 'AST'));
  copyTokensBtn.addEventListener('click', () => copyToClipboard(tokensOutput, 'Tokens'));

  // Auto-generate on Enter key (but not in textarea)
  document.addEventListener('keydown', (e) => {
    if (e.key === 'Enter' && e.ctrlKey && document.activeElement !== codeInput) {
      generateAST();
    }
  });

  // Initialize with a default example
  codeInput.value = examples.when;
  generateAST();
});

// Generate AST from code
function generateAST() {
  if (!codeInput) return; // DOM not ready yet
  
  const code = codeInput.value.trim();
  
  if (!code) {
    showError('Please enter some code to analyze.');
    return;
  }
  
  try {
    // Generate tokens
    const tokens = lexer(code);
    showTokens(tokens);
    
    // Generate AST
    const ast = parser(tokens);
    showAST(ast);
    
    // Clear any previous errors
    showError('');
    
  } catch (error) {
    showError(`Parsing Error: ${error.message}`);
    showAST(null);
    showTokens(null);
  }
}

// Display AST in formatted JSON
function showAST(ast) {
  if (!astOutput) return; // DOM not ready yet
  
  if (ast) {
    astOutput.value = JSON.stringify(ast, null, 2);
  } else {
    astOutput.value = 'No AST available due to parsing error.';
  }
}

// Display tokens in formatted JSON
function showTokens(tokens) {
  if (!tokensOutput) return; // DOM not ready yet
  
  if (tokens) {
    tokensOutput.value = JSON.stringify(tokens, null, 2);
  } else {
    tokensOutput.value = 'No tokens available due to parsing error.';
  }
}

// Display error message
function showError(message) {
  if (!errorOutput) return; // DOM not ready yet
  
  if (message) {
    errorOutput.textContent = message;
    errorOutput.style.display = 'block';
  } else {
    errorOutput.style.display = 'none';
  }
}

// Copy text to clipboard
async function copyToClipboard(textarea, label) {
  if (!textarea || !textarea.value) {
    showError(`No ${label} content to copy.`);
    return;
  }
  
  try {
    await navigator.clipboard.writeText(textarea.value);
    
    // Show temporary success message
    const originalText = errorOutput.textContent;
    showError(`${label} copied to clipboard!`);
    
    // Clear success message after 2 seconds
    setTimeout(() => {
      if (errorOutput.textContent === `${label} copied to clipboard!`) {
        showError('');
      }
    }, 2000);
    
  } catch (error) {
    showError(`Failed to copy ${label}: ${error.message}`);
  }
}