use super::{LoopBuilder, ValueId};
use crate::ast::ASTNode;
use crate::mir::utils::is_current_block_terminated;
use crate::mir::ConstValue;

impl<'a> LoopBuilder<'a> {
    pub(super) fn build_statement(&mut self, stmt: ASTNode) -> Result<ValueId, String> {
        // Preserve the originating span for loop-local control instructions (break/continue/phi).
        self.parent_builder.current_span = stmt.span();
        match stmt {
            // Ensure nested bare blocks inside loops are lowered with loop-aware semantics
            ASTNode::Program { statements, .. } => {
                let mut last = None;
                for s in statements.into_iter() {
                    last = Some(self.build_statement(s)?);
                    // フェーズS修正：統一終端検出ユーティリティ使用
                    if is_current_block_terminated(self.parent_builder)? {
                        break;
                    }
                }
                Ok(last.unwrap_or_else(|| {
                    let void_id = self.new_value();
                    // Emit a void const to keep SSA consistent when block is empty
                    let _ = self.emit_const(void_id, ConstValue::Void);
                    void_id
                }))
            }
            ASTNode::If {
                condition,
                then_body,
                else_body,
                ..
            } => self.lower_if_in_loop(*condition, then_body, else_body),
            ASTNode::Break { .. } => self.do_break(),
            ASTNode::Continue { .. } => self.do_continue(),
            other => self.parent_builder.build_expression(other),
        }
    }
}