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import antlr4 from 'antlr4';
import TinyPLListener from './TinyPLListener.js'

class MyVisitor extends TinyPLListener {
constructor(output) {
super();
this.output = output;
this.scopes = [{}];
this.level = 0;
}

enterStatements(ctx) {
this.scopes.push({});
}

exitStatements(ctx) {
this.scopes.pop();
}


enterVariableDeclaration(ctx) {
if (this.level > 0) return;

this.scopes[this.scopes.length - 1][ctx.Identifier().getText()] = null;
}


enterAssignment(ctx) {
if (this.level > 0) return;

var value = null;
if (ctx.Number() == null) {
var variableName = ctx.Identifier(1).getText();

// get the current value of the variable by searching from inner to outer scope
for (let i = this.scopes.length - 1; i >= 0; i--) {
if (variableName in this.scopes[i]) {
value = this.scopes[i][variableName];
break;
}
}

} else {
value = ctx.Number().getText();
}

// update the value of the variable by searching from inner to outer scope
var variableName = ctx.Identifier(0).getText();
for (let i = this.scopes.length - 1; i >= 0; i--) {
if (variableName in this.scopes[i]) {
this.scopes[i][variableName] = value;
break;
}
}
}


enterFunctionDeclaration(ctx) {
this.level += 1;
this.scopes[this.scopes.length - 1][ctx.Identifier(0).getText()] = ctx.statements();
}

exitFunctionDeclaration(ctx) {
this.level -= 1;
}


enterCall(ctx) {
if (this.level > 0) return;

if (ctx.PrintKeyword() != null) {
// print function is called
var variableName = ctx.Identifier(0).getText();

// search for the variables in the scopes, starting with the most recent one (inner)
this.output.push(this.findSomethingInStack(variableName));
console.log(this.output);
} else {
// any other function call
var functionName = ctx.Identifier(0).getText();
var statements = this.findSomethingInStack(functionName);
// use the antlr4 parser to walk the statements
antlr4.tree.ParseTreeWalker.DEFAULT.walk(this, statements);
}
}

findSomethingInStack(identifier) {
for (let i = this.scopes.length - 1; i >= 0; i--) {
if (identifier in this.scopes[i]) {
return this.scopes[i][identifier];
}
}
}
}

export default class Milestone1 {
constructor(tree) {
this.tree = tree;
}

run() {
var output = [];
var treeVisitor = new MyVisitor(output);
antlr4.tree.ParseTreeWalker.DEFAULT.walk(treeVisitor, this.tree);
return output;
}
}