use crate::compiler::{CompileCtx, Compiler, Label};
use oxide_parser::Statement;

impl Compiler {
    pub(crate) fn emit_while_statement(&self, stmt: &Statement, ctx: &mut CompileCtx) -> Result<Option<u8>, String> {
        let Statement::WhileStatement(wh) = stmt else {
            return Ok(None);
        };
        let id = ctx.next_label_id();
        let start_label = Label::WhileStart(id);
        let end_label = Label::WhileEnd(id);
        ctx.labels.label_map.insert(start_label, ctx.bytecode.len());
        ctx.push_loop(end_label, start_label);
        let n_labeled = ctx.take_pending_loop_labels(end_label, start_label);
        let test_reg = self.emit_expression(&wh.test, ctx)?;
        ctx.emit_jmp_if_false_labeled(test_reg, end_label);
        self.emit_statement(&wh.body, ctx)?;
        ctx.emit_jmp_labeled(start_label);
        ctx.labels.label_map.insert(end_label, ctx.bytecode.len());
        ctx.pop_label_scopes(n_labeled);
        ctx.pop_loop();
        Ok(None)
    }
}