package ram

import (
	"errors"
	"fmt"

	"git.elyanpoujol.fr/elyan/central-arch/pkg/events"
	"git.elyanpoujol.fr/elyan/central-arch/pkg/simcontext"
	"git.elyanpoujol.fr/elyan/central-arch/pkg/simstate"
	"git.elyanpoujol.fr/elyan/central-arch/pkg/simstep"
)

type RAM struct {
	state       simstate.RamState
	stepper     simstep.SimStepper
	eventLogger events.EventLogger
}

const alignment = 4

func New(context simcontext.SimContext, bytes uint) (*RAM, error) {
	if bytes < alignment {
		return nil, errors.New("memory size should be at least 4 bytes")
	}

	return &RAM{
		state:       simstate.RamState{Data: make([]uint32, bytes/alignment)},
		stepper:     context.Stepper,
		eventLogger: context.EventLogger,
	}, nil
}

func (r *RAM) Read(addr uint32) (uint32, error) {
	if addr%alignment != 0 {
		return 0, fmt.Errorf("unaligned memory address: %08x", addr)
	}

	return r.state.Data[addr/alignment], nil
}

func (r *RAM) Write(addr uint32, value uint32) error {
	if addr%alignment != 0 {
		return fmt.Errorf("unaligned memory address: %08x", addr)
	}

	r.state.Data[addr/alignment] = value
	return nil
}

func (m *RAM) Fetch(addr uint32) (uint32, error) {
	return m.Read(addr)
}