use oxide_bytecode::opcode::OpCode;
use oxide_types::object::JsObject;
use oxide_types::value::JsValue;

use crate::coercion;
use crate::vm::Vm;

impl Vm {
    pub(crate) fn dispatch_member_op(&mut self, op: OpCode, rd: usize, a: usize, b: usize) -> Result<(), String> {
        match op {
            OpCode::MEMBER_INC => self.dispatch_member_inc(rd, a, b),
            OpCode::MEMBER_DEC => self.dispatch_member_dec(rd, a, b),
            OpCode::DYN_MEMBER_INC => self.dispatch_dyn_member_inc(rd, a, b),
            OpCode::DYN_MEMBER_DEC => self.dispatch_dyn_member_dec(rd, a, b),
            OpCode::COMPOUND_MEMBER_ADD => self.dispatch_compound_member_add(rd, a, b),
            OpCode::COMPOUND_MEMBER_SUB => {
                self.dispatch_compound_member_numeric(rd, a, b, "COMPOUND_MEMBER_SUB on non-object", |l, r| l - r)
            }
            OpCode::COMPOUND_MEMBER_MUL => {
                self.dispatch_compound_member_numeric(rd, a, b, "COMPOUND_MEMBER_MUL on non-object", |l, r| l * r)
            }
            OpCode::COMPOUND_MEMBER_DIV => {
                self.dispatch_compound_member_numeric(rd, a, b, "COMPOUND_MEMBER_DIV on non-object", |l, r| l / r)
            }
            OpCode::COMPOUND_MEMBER_MOD => {
                self.dispatch_compound_member_numeric(rd, a, b, "COMPOUND_MEMBER_MOD on non-object", |l, r| l % r)
            }
            OpCode::COMPOUND_MEMBER_EXP => {
                self.dispatch_compound_member_numeric(rd, a, b, "COMPOUND_MEMBER_EXP on non-object", |l, r| l.powf(r))
            }
            _ => unreachable!("non-member opcode passed to dispatch_member_op"),
        }
    }

    fn member_target(&mut self, rd: usize, b: usize, error_msg: &str) -> Result<(*mut JsObject, u32), String> {
        let Some(obj_ptr) = self.checked_object_ptr(self.regs[rd], error_msg)? else {
            return Err(String::new());
        };
        let prop_name_si = self.property_key_si(self.regs[b]);
        Ok((obj_ptr, prop_name_si))
    }

    fn dispatch_member_inc(&mut self, rd: usize, a: usize, b: usize) -> Result<(), String> {
        let Ok((obj_ptr, prop_name_si)) = self.member_target(rd, b, "MEMBER_INC on non-object") else {
            return Ok(());
        };
        let receiver = self.regs[rd];
        let obj = unsafe { &mut *obj_ptr };
        let prop_val = self.read_member_prop(obj, prop_name_si, receiver)?;
        let n = self.coerce_number_bounded(prop_val)?;
        let new_val = JsValue::float(n + 1.0);
        self.set_member_prop(obj, prop_name_si, new_val, receiver)?;
        self.regs[a] = new_val;
        Ok(())
    }

    fn dispatch_member_dec(&mut self, rd: usize, a: usize, b: usize) -> Result<(), String> {
        let Ok((obj_ptr, prop_name_si)) = self.member_target(rd, b, "MEMBER_DEC on non-object") else {
            return Ok(());
        };
        let receiver = self.regs[rd];
        let obj = unsafe { &mut *obj_ptr };
        let prop_val = self.read_member_prop(obj, prop_name_si, receiver)?;
        let n = self.coerce_number_bounded(prop_val)?;
        let new_val = JsValue::float(n - 1.0);
        self.set_member_prop(obj, prop_name_si, new_val, receiver)?;
        self.regs[a] = new_val;
        Ok(())
    }

    fn dispatch_dyn_member_inc(&mut self, rd: usize, a: usize, b: usize) -> Result<(), String> {
        let Some(obj_ptr) = self.checked_object_ptr(self.regs[rd], "DYN_MEMBER_INC on non-object")? else {
            return Ok(());
        };
        let receiver = self.regs[rd];
        let obj = unsafe { &mut *obj_ptr };
        let prop_name_si = self.property_key_si(self.regs[a]);
        let prop_val = self.ordinary_get(obj, prop_name_si, receiver)?;
        let n = self.coerce_number_bounded(prop_val)?;
        let new_val = JsValue::float(n + 1.0);
        self.ordinary_set(obj, prop_name_si, new_val, receiver)?;
        self.regs[b] = new_val;
        Ok(())
    }

    fn dispatch_dyn_member_dec(&mut self, rd: usize, a: usize, b: usize) -> Result<(), String> {
        let Some(obj_ptr) = self.checked_object_ptr(self.regs[rd], "DYN_MEMBER_DEC on non-object")? else {
            return Ok(());
        };
        let receiver = self.regs[rd];
        let obj = unsafe { &mut *obj_ptr };
        let prop_name_si = self.property_key_si(self.regs[a]);
        let prop_val = self.ordinary_get(obj, prop_name_si, receiver)?;
        let n = self.coerce_number_bounded(prop_val)?;
        let new_val = JsValue::float(n - 1.0);
        self.ordinary_set(obj, prop_name_si, new_val, receiver)?;
        self.regs[b] = new_val;
        Ok(())
    }

    fn dispatch_compound_member_add(&mut self, rd: usize, a: usize, b: usize) -> Result<(), String> {
        let Ok((obj_ptr, prop_name_si)) = self.member_target(rd, b, "COMPOUND_MEMBER_ADD on non-object") else {
            return Ok(());
        };
        let receiver = self.regs[rd];
        let prop_raw = {
            let obj = unsafe { &mut *obj_ptr };
            self.read_member_prop(obj, prop_name_si, receiver)?
        };
        let prop_val = self.coerce_primitive_bounded(prop_raw, false)?;
        let rhs = self.coerce_primitive_bounded(self.regs[a], false)?;
        let new_val = if prop_val.is_string() || rhs.is_string() {
            let ls = coercion::to_string(self.kernel_core.string_forge().as_ref(), prop_val);
            let rs = coercion::to_string(self.kernel_core.string_forge().as_ref(), rhs);
            self.intern(&format!("{ls}{rs}"))
        } else {
            let ln = coercion::to_number(prop_val, self.kernel_core.string_forge().as_ref());
            let rn = coercion::to_number(rhs, self.kernel_core.string_forge().as_ref());
            JsValue::float(ln + rn)
        };
        let obj = unsafe { &mut *obj_ptr };
        self.set_member_prop(obj, prop_name_si, new_val, receiver)?;
        self.regs[a] = new_val;
        Ok(())
    }

    fn dispatch_compound_member_numeric<F>(
        &mut self, rd: usize, a: usize, b: usize, error_msg: &str, op: F,
    ) -> Result<(), String>
    where
        F: FnOnce(f64, f64) -> f64,
    {
        let Ok((obj_ptr, prop_name_si)) = self.member_target(rd, b, error_msg) else {
            return Ok(());
        };
        let receiver = self.regs[rd];
        let ln = {
            let obj = unsafe { &mut *obj_ptr };
            let prop_val = self.read_member_prop(obj, prop_name_si, receiver)?;
            self.coerce_number_bounded(prop_val)?
        };
        let rn = self.coerce_number_bounded(self.regs[a])?;
        let new_val = JsValue::float(op(ln, rn));
        self.regs[a] = new_val;
        let obj = unsafe { &mut *obj_ptr };
        self.set_member_prop(obj, prop_name_si, new_val, receiver)?;
        Ok(())
    }
}