package template

import (
	"fmt"
	"reflect"

	"golang.org/x/exp/slices"
)

type Schema map[string]FieldInfo

type FieldType string

const (
	FieldTypeString  = FieldType("string")
	FieldTypeInt     = FieldType("integer")
	FieldTypeFloat   = FieldType("float")
	FieldTypeBoolean = FieldType("boolean")
)

type FieldInfo struct {
	Type        FieldType `json:"type"`
	Description string    `json:"description"`
	Validation  string    `json:"validate"`
}

// function to check whether a float value represents an integer
func isIntegerValue(v float64) bool {
	return v == float64(int(v))
}

// cast value to integer for config values that are floats but are supposed to be
// integeres according to the schema
//
// Needed because the default json unmarshaller for maps converts all numbers to floats
func (schema Schema) CastFloatToInt(config map[string]any) error {
	for k, v := range config {
		// error because all config keys should be defined in schema too
		if _, ok := schema[k]; !ok {
			return fmt.Errorf("%s is not defined as an input parameter for the template", k)
		}

		// skip non integer fields
		fieldInfo := schema[k]
		if fieldInfo.Type != FieldTypeInt {
			continue
		}

		// convert floating point type values to integer
		valueType := reflect.TypeOf(v)
		switch valueType.Kind() {
		case reflect.Float32:
			floatVal := v.(float32)
			if !isIntegerValue(float64(floatVal)) {
				return fmt.Errorf("expected %s to have integer value but it is %v", k, v)
			}
			config[k] = int(floatVal)
		case reflect.Float64:
			floatVal := v.(float64)
			if !isIntegerValue(floatVal) {
				return fmt.Errorf("expected %s to have integer value but it is %v", k, v)
			}
			config[k] = int(floatVal)
		}
	}
	return nil
}

func validateType(v any, fieldType FieldType) error {
	switch fieldType {
	case FieldTypeString:
		if _, ok := v.(string); !ok {
			return fmt.Errorf("expected type string, but value is %#v", v)
		}
	case FieldTypeInt:
		if !slices.Contains([]reflect.Kind{reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64},
			reflect.TypeOf(v).Kind()) {
			return fmt.Errorf("expected type integer, but value is %#v", v)
		}
	case FieldTypeFloat:
		if !slices.Contains([]reflect.Kind{reflect.Float32, reflect.Float64},
			reflect.TypeOf(v).Kind()) {
			return fmt.Errorf("expected type float, but value is %#v", v)
		}
	case FieldTypeBoolean:
		if _, ok := v.(bool); !ok {
			return fmt.Errorf("expected type boolean, but value is %#v", v)
		}
	}
	return nil
}

// TODO: add validation check for regex for string types
func (schema Schema) ValidateConfig(config map[string]any) error {
	for k, v := range config {
		fieldMetadata, ok := schema[k]
		if !ok {
			return fmt.Errorf("%s is not defined as an input parameter for the template", k)
		}
		err := validateType(v, fieldMetadata.Type)
		if err != nil {
			return fmt.Errorf("incorrect type for %s. %w", k, err)
		}
	}
	return nil
}