/*!
 * Minimal MIR Interpreter
 *
 * Executes a subset of MIR instructions for fast iteration without LLVM/JIT.
 * Supported: Const, BinOp(Add/Sub/Mul/Div/Mod), Compare, Load/Store, Branch, Jump, Return,
 * Print/Debug (best-effort), Barrier/Safepoint (no-op).
 */

use std::collections::HashMap;

use crate::box_trait::NyashBox;

pub(super) use crate::backend::abi_util::{eq_vm, to_bool_vm};
pub(super) use crate::backend::vm::{VMError, VMValue};
pub(super) use crate::mir::{
    BasicBlockId, BinaryOp, Callee, CompareOp, ConstValue, MirFunction, MirInstruction, MirModule,
    ValueId,
};

mod exec;
mod handlers;
mod helpers;

pub struct MirInterpreter {
    pub(super) regs: HashMap<ValueId, VMValue>,
    pub(super) mem: HashMap<ValueId, VMValue>,
    pub(super) obj_fields: HashMap<ValueId, HashMap<String, VMValue>>,
    pub(super) functions: HashMap<String, MirFunction>,
    pub(super) cur_fn: Option<String>,
}

impl MirInterpreter {
    pub fn new() -> Self {
        Self {
            regs: HashMap::new(),
            mem: HashMap::new(),
            obj_fields: HashMap::new(),
            functions: HashMap::new(),
            cur_fn: None,
        }
    }

    /// Execute module entry (main) and return boxed result
    pub fn execute_module(&mut self, module: &MirModule) -> Result<Box<dyn NyashBox>, VMError> {
        // Snapshot functions for call resolution
        self.functions = module.functions.clone();
        let func = module
            .functions
            .get("main")
            .ok_or_else(|| VMError::InvalidInstruction("missing main".into()))?;
        let ret = self.execute_function(func)?;
        Ok(ret.to_nyash_box())
    }

    fn execute_function(&mut self, func: &MirFunction) -> Result<VMValue, VMError> {
        self.exec_function_inner(func, None)
    }
}