package generator

import "fmt"
import "errors"
import "strings"
import "git.tebibyte.media/sashakoshka/fspl/llvm"
import "git.tebibyte.media/sashakoshka/fspl/entity"

func (this *generator) generateTypeNamed (ty *entity.TypeNamed) (llvm.Type, error) {
	return this.typedef(ty.Name)
}

func (this *generator) generateTypePointer (ty *entity.TypePointer) (llvm.Type, error) {
	return llvm.Pointer, nil
}

func (this *generator) generateTypeSlice (ty *entity.TypeSlice) (llvm.Type, error) {
	indexType, err := this.typedef("Index")
	if err != nil { return nil, err }
	return &llvm.TypeStruct {
		Fields: []llvm.Type {
			/* data */ llvm.Pointer,
			/* len  */ indexType,
		},
	}, nil
}

func (this *generator) generateTypeArray (ty *entity.TypeArray) (llvm.Type, error) {
	element, err := this.generateType(ty.Element)
	if err != nil { return nil, err }
	return &llvm.TypeArray {
		Length:  uint64(ty.Length),
		Element: element,
	}, nil
}

func (this *generator) generateTypeStruct (ty *entity.TypeStruct) (llvm.Type, error) {
	irStruct := &llvm.TypeStruct {
		Fields: make([]llvm.Type, len(ty.Members)),
	}
	for index, member := range ty.Members {
		field, err := this.generateType(member.Type())
		if err != nil { return nil, err }
		irStruct.Fields[index] = field
	}
	return irStruct, nil
}

func (this *generator) generateTypeInerface (ty *entity.TypeInterface) (llvm.Type, error) {
	irStruct := &llvm.TypeStruct {
		Fields: make([]llvm.Type, len(ty.Behaviors) + 1),
	}
	// object pointer
	irStruct.Fields[0] = llvm.Pointer
	// behaviors
	for index := range ty.Behaviors {
		irStruct.Fields[index + 1] = llvm.Pointer
	}
	return irStruct, nil
}

func (this *generator) generateTypeInt (ty *entity.TypeInt) (llvm.Type, error) {
	return &llvm.TypeInt { BitSize: uint64(ty.Width) }, nil
}

func (this *generator) generateTypeFloat (ty *entity.TypeFloat) (llvm.Type, error) {
	var kind llvm.FloatKind; switch ty.Width {
	case 16: kind = llvm.FloatKindHalf
	case 32: kind = llvm.FloatKindFloat
	case 64: kind = llvm.FloatKindDouble
	case 80:
		if strings.HasPrefix(this.target.Arch, "x86") {
			kind = llvm.FloatKindX86_FP80
		} else {
			return nil, errors.New(fmt.Sprintln (
				ty, "not available on",
				this.target.Arch))
		}
	case 128:
		if strings.HasPrefix(this.target.Arch, "ppc") {
			kind = llvm.FloatKindPPC_FP128
		} else {
			kind = llvm.FloatKindFP128
		}
	default:
		return nil, errors.New(fmt.Sprintln (ty, "has invalid width"))
	}
	return &llvm.TypeFloat { Kind: kind }, nil
}

func (this *generator) generateTypeWord (ty *entity.TypeWord) (llvm.Type, error) {
	return &llvm.TypeInt { BitSize: this.target.WordSize }, nil
}

func (this *generator) generateTypeFunction (
	signature *entity.Signature,
) (
	llvm.Type,
	error,
) {
	irFunc := &llvm.TypeFunction {
		Parameters: make([]llvm.Type, len(signature.Arguments)),
	}
	ret, err := this.generateType(signature.Return)
	if err != nil { return nil, err }
	irFunc.Return = ret
	for index, argument := range signature.Arguments {
		param, err := this.generateType(argument.Type())
		if err != nil { return nil, err }
		irFunc.Parameters[index] = param
	}
	return irFunc, nil
}

func getInterface (ty entity.Type) *entity.TypeInterface {
	switch ty.(type) {
	case *entity.TypeNamed:
		return getInterface(ty.(*entity.TypeNamed).Type)
	case *entity.TypeInterface:
		return ty.(*entity.TypeInterface)
	default:
		return nil
	}
}