use crate::constants_table::ConstantsTable;
use crate::ir::assemble::{Assemble, InstructionsBuilder};
use crate::ir::ir_operation::IrOperation;
use crate::ir::ir_variable::{IrVariable, IrVariableDescriptor, IrVrVariableDescriptor};
use crate::ir::register_allocation::VrUser;
use crate::ir::util::propagate_spills;
use crate::offset_counter::OffsetCounter;
use dvm_lib::instruction::Instruction;
use std::cell::RefCell;
use std::collections::{HashMap, HashSet};
use std::fmt::{Display, Formatter};
use std::rc::Rc;

pub struct IrAssign {
    destination: Rc<RefCell<IrVariable>>,
    initializer: Box<IrOperation>,
}

impl IrAssign {
    pub fn new(destination: Rc<RefCell<IrVariable>>, initializer: IrOperation) -> Self {
        Self {
            destination,
            initializer: initializer.into(),
        }
    }
}

impl VrUser for IrAssign {
    fn vr_definitions(&self) -> HashSet<IrVrVariableDescriptor> {
        self.destination
            .borrow()
            .descriptor()
            .vr_variable_descriptors()
    }

    fn vr_uses(&self) -> HashSet<IrVrVariableDescriptor> {
        self.initializer.vr_uses()
    }

    fn propagate_spills(&mut self, spills: &HashSet<IrVrVariableDescriptor>) {
        propagate_spills(&mut self.destination, spills);
    }

    fn propagate_register_assignments(
        &mut self,
        assignments: &HashMap<IrVrVariableDescriptor, usize>,
    ) {
        let mut borrowed_destination = self.destination.borrow_mut();
        if let IrVariableDescriptor::VirtualRegister(vr_variable) =
            borrowed_destination.descriptor_mut()
        {
            if assignments.contains_key(vr_variable) {
                vr_variable.set_assigned_register(assignments[vr_variable]);
            }
        }
    }

    fn propagate_stack_offsets(&mut self, counter: &mut OffsetCounter) {
        let mut borrowed_destination = self.destination.borrow_mut();
        if let IrVariableDescriptor::Stack(stack_variable) = borrowed_destination.descriptor_mut() {
            stack_variable.use_next_offset(counter);
        }
    }
}

impl Assemble for IrAssign {
    fn assemble(&self, builder: &mut InstructionsBuilder, constants_table: &mut ConstantsTable) {
        let destination = self.destination.borrow().descriptor().as_location();

        match self.initializer.as_ref() {
            IrOperation::GetFieldRef(ir_get_field_ref) => {
                let self_location = ir_get_field_ref.self_parameter_or_variable().as_location();
                builder.push(Instruction::GetFieldPointer(
                    self_location,
                    ir_get_field_ref.field_index(),
                    destination,
                ));
            }
            IrOperation::GetFieldRefMut(ir_get_field_ref_mut) => {
                let self_location = ir_get_field_ref_mut
                    .self_parameter_or_variable()
                    .as_location();
                builder.push(Instruction::GetFieldPointerMut(
                    self_location,
                    ir_get_field_ref_mut.field_index(),
                    destination,
                ));
            }
            IrOperation::ReadField(ir_read_field) => {
                let field_ref_location = ir_read_field
                    .field_ref_variable()
                    .borrow()
                    .descriptor()
                    .as_location();
                builder.push(Instruction::ReadField(field_ref_location, destination));
            }
            IrOperation::Load(ir_expression) => {
                let move_operand = ir_expression.move_operand(constants_table);
                builder.push(Instruction::Move(move_operand, destination));
            }
            IrOperation::Binary(ir_binary_operation) => {
                ir_binary_operation.assemble_assign(builder, constants_table, destination);
            }
            IrOperation::Call(ir_call) => {
                ir_call.assemble(builder, constants_table);
                builder.push(Instruction::Pop(Some(destination)));
            }
            IrOperation::Allocate(ir_allocate) => builder.push(Instruction::Allocate(
                ir_allocate.class_fqn_owned(),
                destination,
            )),
        }
    }
}

impl Display for IrAssign {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        write!(
            f,
            "{}: {} = {}",
            self.destination.borrow(),
            self.destination.borrow().type_info(),
            self.initializer
        )
    }
}