package validator

import (
	"log"
	"reflect"
	"regexp"
	"strconv"
)

var bakedInValidators = map[string]ValidationFunc{
	"required": required,
	"length":   length,
	"min":      min,
	"max":      max,
	"regex":    regex,
}

func required(field interface{}, param string) bool {

	return field != nil && field != reflect.Zero(reflect.TypeOf(field)).Interface()
}

// length tests whether a variable's length is equal to a given
// value. For strings it tests the number of characters whereas
// for maps and slices it tests the number of items.
func length(field interface{}, param string) bool {

	st := reflect.ValueOf(field)

	switch st.Kind() {

	case reflect.String:
		p := asInt(param)

		return int64(len(st.String())) == p

	case reflect.Slice, reflect.Map, reflect.Array:
		p := asInt(param)

		return int64(st.Len()) == p

	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		p := asInt(param)

		return st.Int() == p

	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		p := asUint(param)

		return st.Uint() == p

	case reflect.Float32, reflect.Float64:
		p := asFloat(param)

		return st.Float() == p

	default:
		log.Fatalf("Bad field type for Input Param %s for %s\n", param, field)
		return false
	}
}

// min tests whether a variable value is larger or equal to a given
// number. For number types, it's a simple lesser-than test; for
// strings it tests the number of characters whereas for maps
// and slices it tests the number of items.
func min(field interface{}, param string) bool {

	st := reflect.ValueOf(field)

	switch st.Kind() {

	case reflect.String:
		p := asInt(param)

		return int64(len(st.String())) >= p

	case reflect.Slice, reflect.Map, reflect.Array:
		p := asInt(param)

		return int64(st.Len()) >= p

	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		p := asInt(param)

		return st.Int() >= p

	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		p := asUint(param)

		return st.Uint() >= p

	case reflect.Float32, reflect.Float64:
		p := asFloat(param)

		return st.Float() >= p

	default:
		log.Fatalf("Bad field type for Input Param %s for %s\n", param, field)
		return false
	}
}

// max tests whether a variable value is lesser than a given
// value. For numbers, it's a simple lesser-than test; for
// strings it tests the number of characters whereas for maps
// and slices it tests the number of items.
func max(field interface{}, param string) bool {

	st := reflect.ValueOf(field)

	switch st.Kind() {

	case reflect.String:
		p := asInt(param)

		return int64(len(st.String())) <= p

	case reflect.Slice, reflect.Map, reflect.Array:
		p := asInt(param)

		return int64(st.Len()) <= p

	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		p := asInt(param)

		return st.Int() <= p

	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		p := asUint(param)

		return st.Uint() <= p

	case reflect.Float32, reflect.Float64:
		p := asFloat(param)

		return st.Float() <= p

	default:
		log.Fatalf("Bad field type for Input Param %s for %s\n", param, field)
		return false
	}
}

// regex is the builtin validation function that checks
// whether the string variable matches a regular expression
func regex(field interface{}, param string) bool {

	s, ok := field.(string)
	if !ok {
		log.Fatalf("Bad field type %s\n", field)
	}

	re, err := regexp.Compile(param)
	if err != nil {
		log.Fatalf("Bad regex param %s\n", param)
	}

	if !re.MatchString(s) {
		return false
	}

	return true
}

// asInt retuns the parameter as a int64
// or panics if it can't convert
func asInt(param string) int64 {

	i, err := strconv.ParseInt(param, 0, 64)

	if err != nil {
		log.Fatalf("Bad Input Param %s\n", param)
	}

	return i
}

// asUint returns the parameter as a uint64
// or panics if it can't convert
func asUint(param string) uint64 {

	i, err := strconv.ParseUint(param, 0, 64)

	if err != nil {
		log.Fatalf("Bad Input Param %s\n", param)
	}

	return i
}

// asFloat returns the parameter as a float64
// or panics if it can't convert
func asFloat(param string) float64 {

	i, err := strconv.ParseFloat(param, 64)

	if err != nil {
		log.Fatalf("Bad Input Param %s\n", param)
	}

	return i
}