use crate::generator::Generator;
use crate::parser::node_type::*;

pub struct JsGenerator;

impl Generator for JsGenerator {
    fn generate(prog: Program) -> String {
        let mut code = prog
            .func
            .into_iter()
            .map(|f| generate_function(f))
            .collect();

        // Until we have a stdlib, it should suffice to print the result of main to stdout
        code += "console.log(main())";

        return code;
    }
}

fn generate_function(func: Function) -> String {
    let arguments: String = func
        .arguments
        .into_iter()
        .map(|var| var.name)
        .collect::<Vec<String>>()
        .join(", ");
    let mut raw = format!("function {N}({A})", N = func.name, A = arguments);

    raw += " {\n";

    for statement in func.statements {
        raw += &generate_statement(statement);
    }

    raw += "}\n";

    raw
}

fn generate_statement(statement: Statement) -> String {
    match statement {
        Statement::Return(ret) => generate_return(ret),
        Statement::Declare(_, _) => todo!(),
        Statement::Exp(val) => generate_expression(val),
        Statement::Compound(_) => todo!(),
        Statement::If(_, _, _) => todo!(),
        Statement::While(_, _) => todo!(),
    }
}

fn generate_expression(expr: Expression) -> String {
    match expr {
        Expression::Int(val) => val.to_string(),
        Expression::Variable(val) | Expression::Str(val) => val,
        Expression::Char(_) => todo!(),
        Expression::FunctionCall(name, e) => generate_function_call(name, e),
        Expression::Assign(_, _) => todo!(),
    }
}

fn generate_function_call(func: String, args: Vec<Expression>) -> String {
    let formatted_args = args
        .into_iter()
        .map(|arg| match arg {
            Expression::Char(c) => c.to_string(),
            Expression::Int(i) => i.to_string(),
            Expression::FunctionCall(n, a) => generate_function_call(n, a),
            Expression::Str(s) | Expression::Variable(s) => s,
            Expression::Assign(_, _) => todo!(),
        })
        .collect::<Vec<String>>()
        .join(",");
    format!("{N}({A})\n", N = func, A = formatted_args)
}

fn generate_return(ret: Option<Expression>) -> String {
    match ret {
        Some(expr) => format!("return {}\n", generate_expression(expr)),
        None => "return;\n".to_string(),
    }
}