package generator

import "git.tebibyte.media/fspl/fspl/llvm"
import "git.tebibyte.media/fspl/fspl/entity"

func (this *generator) generateSlice (ty entity.Type, data llvm.Value, length llvm.Value) (llvm.Value, error) {
	irType, err := this.generateType(ty)
	if err != nil { return nil, err }
	slice := this.blockManager.newAllocaFront(irType)
	this.sliceSetData(ty, slice, data)
	this.sliceSetLength(ty, slice, length)
	return slice, nil
}

func (this *generator) generateSliceDefinedLength (ty entity.Type, data llvm.Value, length int64) (llvm.Value, error) {
	indexType, err := this.generateTypeIndex()
	if err != nil { return nil, err }
	return this.generateSlice(ty, data, llvm.NewConstInt(indexType, length))
}

func (this *generator) sliceSetData (ty entity.Type, slice llvm.Value, data llvm.Value) error {
	irType, err := this.generateType(ty)
	if err != nil { return err }
	dataField := this.blockManager.NewGetElementPtr (
		irType, slice,
		llvm.NewConstInt(llvm.I32, 0),
		llvm.NewConstInt(llvm.I32, 0))
	this.blockManager.NewStore(data, dataField)
	return nil
}

func (this *generator) sliceSetLength (ty entity.Type, slice llvm.Value, length llvm.Value) error {
	irType, err := this.generateType(ty)
	if err != nil { return err }
	lengthField := this.blockManager.NewGetElementPtr (
		irType, slice,
		llvm.NewConstInt(llvm.I32, 0),
		llvm.NewConstInt(llvm.I32, 1))
	this.blockManager.NewStore(length, lengthField)
	return nil
}

func (this *generator) sliceSetDefinedLength (ty entity.Type, slice llvm.Value, length int64) error {
	indexType, err := this.generateTypeIndex()
	if err != nil { return err }
	return this.sliceSetLength(ty, slice, llvm.NewConstInt(indexType, length))
}

func (this *generator) getSliceDataAddress (slice llvm.Value, irType llvm.Type) llvm.Value {
	return this.blockManager.NewLoad (
		new(llvm.TypePointer),
		this.getSliceDataFieldLoc(slice, irType))
}

func (this *generator) getSliceDataFieldLoc (slice llvm.Value, irType llvm.Type) llvm.Value {
	return this.blockManager.NewGetElementPtr (
		irType, slice,
		llvm.NewConstInt(llvm.I32, 0),
		llvm.NewConstInt(llvm.I32, 0))
}

func (this *generator) getSliceLengthFieldLoc (slice llvm.Value, irType llvm.Type) llvm.Value {
	return this.blockManager.NewGetElementPtr (
		irType, slice,
		llvm.NewConstInt(llvm.I32, 0),
		llvm.NewConstInt(llvm.I32, 1))
}

func (this *generator) getInterfaceDataFieldLoc (iface llvm.Value, irType llvm.Type) llvm.Value {
	return this.blockManager.NewGetElementPtr (
		irType, iface,
		llvm.NewConstInt(llvm.I32, 0),
		llvm.NewConstInt(llvm.I32, 0))
}

func (this *generator) getInterfaceBehaviorFieldLoc (
	ty *entity.TypeInterface,
	iface llvm.Value,
	irType llvm.Type,
	name string,
) llvm.Value {
	offset := this.getInterfaceBehaviorIndex(ty, name)
	if offset > -1 {
		return this.blockManager.NewGetElementPtr (
			irType, iface,
			llvm.NewConstInt(llvm.I32, 0),
			llvm.NewConstInt(llvm.I32, int64(offset + 1)))
	} else {
		return nil
	}
}

func (this *generator) getInterfaceBehaviorSignature (ty *entity.TypeInterface, name string) (llvm.Type, error) {
	return this.generateTypeFunction(ty.BehaviorMap[name])
}

func (this *generator) getInterfaceBehaviorIndex (ty *entity.TypeInterface, name string) int {
	offset := -1
	for index, nm := range ty.BehaviorOrder {
		if nm == name {
			offset = index
			break
		}
	}
	return offset
}

func (this *generator) getStructMemberIndex (ty *entity.TypeStruct, name string) int {
	offset := -1
	for index, nm := range ty.MemberOrder {
		if nm == name {
			offset = index
			break
		}
	}
	return offset
}