// HookBuiltin uses the builtin package that provides neccessary
// builtin functions for IR generation
func (p *Pkg) HookBuiltin(pkg *link8.Pkg) error {
	var err error
	se := func(e error) {
		if err != nil {
			err = e
		}
	}

	o := func(f string) *FuncSym {
		sym := pkg.SymbolByName(f)
		if sym == nil {
			se(fmt.Errorf("%s missing in builtin", f))
		} else if sym.Type != link8.SymFunc {
			se(fmt.Errorf("%s is not a function", f))
		}

		return &FuncSym{pkg: pkg.Path(), name: f}
	}

	p.g.memCopy = o("MemCopy")
	p.g.memClear = o("MemClear")

	return err
}

func (p *strPool) declare(lib *link8.Pkg) {
	if lib.Path() != p.pkg {
		panic("package name mismatch")
	}

	ndigit := countDigit(len(p.strs))
	nfmt := fmt.Sprintf(":str_%%0%dd", ndigit)

	for i, s := range p.strs {
		s.name = fmt.Sprintf(nfmt, i)
		s.pkg = p.pkg
		v := link8.NewVar(0)
		v.Write([]byte(s.str))

		lib.DeclareVar(s.name)
		lib.DefineVar(s.name, v)
	}
}

func (p *datPool) declare(lib *link8.Pkg) {
	if lib.Path() != p.pkg {
		panic("package name mismatch")
	}

	if len(p.dat) == 0 {
		return
	}

	ndigit := countDigit(len(p.dat))
	nfmt := fmt.Sprintf(":dat_%%0%dd", ndigit)
	for i, d := range p.dat {
		d.name = fmt.Sprintf(nfmt, i)
		align := uint32(0)
		if d.regSizeAlign {
			align = regSize
		}
		v := link8.NewVar(align)
		v.Write(d.bs)

		lib.DeclareVar(d.name)
		lib.DefineVar(d.name, v)
	}
}

func declareBuiltin(b *builder, builtin *link8.Pkg) {
	path := builtin.Path()
	e := b.p.HookBuiltin(builtin)
	if e != nil {
		b.Errorf(nil, e.Error())
		return
	}

	o := func(name, as string, t *types.Func) ir.Ref {
		sym := builtin.SymbolByName(name)
		if sym == nil {
			b.Errorf(nil, "builtin symbol %s missing", name)
			return nil
		} else if sym.Type != link8.SymFunc {
			b.Errorf(nil, "builtin symbol %s is not a function", name)
			return nil
		}

		ref := ir.NewFuncSym(path, name, makeFuncSig(t))
		obj := &objFunc{name: as, ref: newRef(t, ref)}
		s := sym8.Make(b.path, as, tast.SymFunc, obj, t, nil)
		pre := b.scope.Declare(s)
		if pre != nil {
			b.Errorf(nil, "builtin symbol %s declare failed", name)
			return nil
		}
		return ref
	}

	// TODO: export these as generic function pointer symbols, and convert
	// them into G functions in g files, rather than inside here in the
	// compiler.
	o("PrintInt32", "printInt", types.NewVoidFunc(types.Int))
	o("PrintUint32", "printUint", types.NewVoidFunc(types.Uint))
	o("PrintChar", "printChar", types.NewVoidFunc(types.Int8))
	b.panicFunc = o("Panic", "panic", types.VoidFunc)

	bi := func(name string) {
		t := types.NewBuiltInFunc(name)
		obj := &objFunc{name: name, ref: newRef(t, nil)}
		s := sym8.Make(b.path, name, tast.SymFunc, obj, t, nil)
		pre := b.scope.Declare(s)
		if pre != nil {
			b.Errorf(nil, "builtin symbol %s declare failed", name)
		}
	}

	bi("len")
	bi("make")

	c := func(name string, r *ref) {
		// TODO: declare these as typed consts
		obj := &objConst{name, r}
		s := sym8.Make(b.path, name, tast.SymConst, obj, r.Type(), nil)
		pre := b.scope.Declare(s)
		if pre != nil {
			b.Errorf(nil, "builtin symbol %s declare failed", name)
		}
	}

	c("true", refTrue)
	c("false", refFalse)
	c("nil", refNil)

	t := func(name string, t types.T) {
		s := sym8.Make(b.path, name, tast.SymType, nil, &types.Type{t}, nil)
		pre := b.scope.Declare(s)
		if pre != nil {
			b.Errorf(nil, "builtin symbol %s declare failed", name)
		}
	}

	t("int", types.Int)
	t("uint", types.Uint)
	t("int32", types.Int)
	t("uint32", types.Uint)
	t("int8", types.Int8)
	t("uint8", types.Uint8)
	t("char", types.Int8)
	t("byte", types.Uint8)
	t("bool", types.Bool)
	t("float", types.Float32)
	t("string", types.String)
	// t("ptr", &types.Pointer{types.Uint8})
	// t("float32", types.Float32)
	// t("string", types.String)
}