package server

import (
	"encoding/json"
	"fmt"
	"io"
	"math"
	"reflect"
	"slices"
	"strconv"
	"strings"
)

// pass converts a simple api without return value to api with nil error return value
func pass[T any](f func(T)) func(T) error {
	return func(v T) error {
		f(v)
		return nil
	}
}

// parseFloat rejects NaN and Inf values
func parseFloat(payload string) (float64, error) {
	f, err := strconv.ParseFloat(payload, 64)
	if err == nil && (math.IsNaN(f) || math.IsInf(f, 0)) {
		err = fmt.Errorf("invalid float value: %s", payload)
	}
	return f, err
}

// jsonDecoder returns a json decoder with disallowed unknown fields
func jsonDecoder(r io.Reader) *json.Decoder {
	dec := json.NewDecoder(r)
	dec.DisallowUnknownFields()
	return dec
}

// jsonOmitEmpty returns true if struct field is omitempty
func jsonOmitEmpty(f reflect.StructField) bool {
	return tagAttribute("json", "omitempty", f)
}

// tagValue returns the given tag's primary value
func tagValue(key string, f reflect.StructField) string {
	if tag := f.Tag.Get(key); tag != "" {
		return strings.Split(tag, ",")[0]
	}
	return ""
}

// tagAttribute returns the given tag's primary value
func tagAttribute(key, attr string, f reflect.StructField) bool {
	if tag := f.Tag.Get(key); tag != "" {
		if attrs := strings.Split(tag, ","); len(attrs) > 1 {
			return slices.Contains(attrs[1:], attr)
		}
	}
	return false
}