chore: refactor plugin structure (#18335)

plugin/calc.go

@@ -0,0 +1,169 @@
+package plugin
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"math"
+
+	"github.com/evcc-io/evcc/util"
+)
+
+type calcPlugin struct {
+	add, mul, div []func() (float64, error)
+	abs, sign     func() (float64, error)
+}
+
+func init() {
+	registry.AddCtx("calc", NewCalcFromConfig)
+}
+
+// NewCalcFromConfig creates calc provider
+func NewCalcFromConfig(ctx context.Context, other map[string]interface{}) (Plugin, error) {
+	var cc struct {
+		Add  []Config
+		Mul  []Config
+		Div  []Config
+		Abs  *Config
+		Sign *Config
+	}
+
+	if err := util.DecodeOther(other, &cc); err != nil {
+		return nil, err
+	}
+
+	cnt := min(len(cc.Add), 1) + min(len(cc.Mul), 1) + min(len(cc.Div), 1)
+	if cc.Abs != nil {
+		cnt++
+	}
+	if cc.Sign != nil {
+		cnt++
+	}
+	if cnt != 1 {
+		return nil, errors.New("can only have either add, mul, div, abs or sign")
+	}
+
+	o := new(calcPlugin)
+
+	for idx, cc := range cc.Add {
+		f, err := cc.FloatGetter(ctx)
+		if err != nil {
+			return nil, fmt.Errorf("add[%d]: %w", idx, err)
+		}
+		o.add = append(o.add, f)
+	}
+
+	for idx, cc := range cc.Mul {
+		f, err := cc.FloatGetter(ctx)
+		if err != nil {
+			return nil, fmt.Errorf("mul[%d]: %w", idx, err)
+		}
+		o.mul = append(o.mul, f)
+	}
+
+	for idx, cc := range cc.Div {
+		f, err := cc.FloatGetter(ctx)
+		if err != nil {
+			return nil, fmt.Errorf("div[%d]: %w", idx, err)
+		}
+		o.div = append(o.div, f)
+	}
+
+	var err error
+
+	o.abs, err = cc.Abs.FloatGetter(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("abs: %w", err)
+	}
+
+	o.sign, err = cc.Sign.FloatGetter(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("sign: %w", err)
+	}
+
+	return o, nil
+}
+
+var _ IntGetter = (*calcPlugin)(nil)
+
+func (o *calcPlugin) IntGetter() (func() (int64, error), error) {
+	return func() (int64, error) {
+		f, err := o.floatGetter()
+		return int64(f), err
+	}, nil
+}
+
+var _ StringGetter = (*calcPlugin)(nil)
+
+func (o *calcPlugin) StringGetter() (func() (string, error), error) {
+	return func() (string, error) {
+		f, err := o.floatGetter()
+		return fmt.Sprintf("%c", int(f)), err
+	}, nil
+}
+
+var _ FloatGetter = (*calcPlugin)(nil)
+
+func (o *calcPlugin) FloatGetter() (func() (float64, error), error) {
+	return o.floatGetter, nil
+}
+
+func (o *calcPlugin) floatGetter() (float64, error) {
+	var res float64
+
+	switch {
+	case len(o.mul) > 0:
+		res = 1
+		for idx, p := range o.mul {
+			v, err := p()
+			if err != nil {
+				return 0, fmt.Errorf("mul[%d]: %w", idx, err)
+			}
+			res *= v
+		}
+
+	case len(o.add) > 0:
+		for idx, p := range o.add {
+			v, err := p()
+			if err != nil {
+				return 0, fmt.Errorf("add[%d]: %w", idx, err)
+			}
+			res += v
+		}
+
+	case len(o.div) > 0:
+		for idx, p := range o.div {
+			v, err := p()
+			if err != nil {
+				return 0, fmt.Errorf("div[%d]: %w", idx, err)
+			}
+			if idx == 0 {
+				if v == 0 {
+					break
+				}
+				res = v
+			} else if v != 0 {
+				res /= v
+			} else if v == 0 {
+				res = 0
+				break
+			}
+		}
+
+	case o.abs != nil:
+		v, err := o.abs()
+		if err != nil {
+			return 0, fmt.Errorf("abs: %w", err)
+		}
+		res = math.Abs(v)
+
+	default:
+		v, err := o.sign()
+		if err != nil {
+			return 0, fmt.Errorf("sign: %w", err)
+		}
+		res = math.Copysign(1, v)
+	}
+
+	return res, nil
+}