use crate::{obj::prelude::*, vm::inst::Inst};
use std::{collections::BTreeMap, sync::Arc};
use std::fmt::{self, Formatter, Debug};

pub type FrameBindings = BTreeMap<usize, ObjRef>;

#[derive(Debug)]
pub enum Frame {
    User(UserFrame),
    Native(NativeFrame),
}

impl Frame {
    pub fn user_frame(&self) -> Option<&UserFrame> {
        if let Frame::User(frame) = self {
            Some(frame)
        } else {
            None
        }
    }

    pub fn user_frame_mut(&mut self) -> Option<&mut UserFrame> {
        if let Frame::User(frame) = self {
            Some(frame)
        } else {
            None
        }
    }

    pub fn native_frame(&self) -> Option<&NativeFrame> {
        if let Frame::Native(frame) = self {
            Some(frame)
        } else {
            None
        }
    }

    pub fn native_frame_mut(&mut self) -> Option<&mut NativeFrame> {
        if let Frame::Native(frame) = self {
            Some(frame)
        } else {
            None
        }
    }
}

#[derive(Debug, Clone)]
pub struct UserFrame {
    callee: ObjRef,
    bindings: FrameBindings,
    last_pc: usize,
    code: Arc<Vec<Inst>>,
}

impl UserFrame {
    pub fn new(callee: ObjRef, bindings: FrameBindings, last_pc: usize, code: Arc<Vec<Inst>>) -> Self {
        Self { callee, bindings, last_pc, code, }
    }

    pub fn bindings(&self) -> &FrameBindings {
        &self.bindings
    }

    pub fn bindings_mut(&mut self) -> &mut FrameBindings {
        &mut self.bindings
    }

    pub fn last_pc(&self) -> usize {
        self.last_pc
    }

    pub fn code(&self) -> &Arc<Vec<Inst>> {
        &self.code
    }

    pub fn callee(&self) -> &ObjRef {
        &self.callee
    }
}

pub struct NativeFrame {
    callee: ObjRef,
    fun_ptr: NativeFunPtr,
    args: Vec<ObjRef>,
}

impl NativeFrame {
    pub fn new(callee: ObjRef, fun_ptr: NativeFunPtr, args: Vec<ObjRef>) -> Self {
        Self { callee, fun_ptr, args }
    }

    pub fn fun_ptr(&self) -> &NativeFunPtr {
        &self.fun_ptr
    }

    pub fn args(&self) -> &Vec<ObjRef> {
        &self.args
    }

    pub fn callee(&self) -> &ObjRef {
        &self.callee
    }
}

impl Debug for NativeFrame {
    fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
        fmt.debug_struct("NativeFrame")
            .field("fun_ptr", &format!("{:#x}", &self.fun_ptr as *const _ as usize))
            .finish()
    }
}