package main

import (
	"fmt"
)

type (
	// ------------------
	// Interfaces
	// ------------------
	DatabaseLayerLargeInterface interface { /* Most likely defined in a separate package */
		Find(map[string]interface{}) []interface{}
		Create()
		Update()
		Delete()
	}

	TemplateStorage interface {
		Find(map[string]interface{}) []interface{} /* matches DatabaseLayerLargeInterface.Find signature */
	}

	TemplateFinder interface {
		Find(namespace, language string) string
	}

	// ---------------
	// Implementations
	// ---------------

	Database        struct{} /* Most likely defined in a separate package */
	TemplateFinder1 struct{ storage DatabaseLayerLargeInterface }
	TemplateFinder2 struct{ storage TemplateStorage }
)

func (db Database) Find(criteria map[string]interface{}) []interface{} { return []interface{}{} }
func (db Database) Create()                                            {}
func (db Database) Update()                                            {}
func (db Database) Delete()                                            {}

func NewTemplateFinder1(storage DatabaseLayerLargeInterface) TemplateFinder {
	return TemplateFinder1{storage}
}
func NewTemplateFinder2(storage TemplateStorage) TemplateFinder {
	return TemplateFinder2{storage}
}

func (f TemplateFinder1) Find(namespace, language string) string {
	return "TemplateFinder1 will delegate the actual 'finding' to its (bloated) DatabaseLayerLargeInterface storage... this is not the actual template!"
}
func (f TemplateFinder2) Find(namespace, language string) string {
	return "TemplateFinder2 will delegate the actual 'finding' to its (slim) TemplateStorage storage... this is not the actual template!"
}

func main() {
	db := Database{}

	tf1 := NewTemplateFinder1(db)
	tf2 := NewTemplateFinder2(db)

	namespace := "push.fact.loan"
	language := "br"

	fmt.Println(tf1.Find(namespace, language))
	fmt.Println(tf2.Find(namespace, language))

	// Questions
	//
	// When testing TemplateFinder1 ...
	// - how many methods do we need to mock in TemplateFinder1.storage?
	// - what if our DatabaseLayerLargeInterface expands?
	//
	// When testing TemplateFinder2 ...
	// - how many methods do we need to mock in TemplateFinder2.storage?
	// - what if our DatabaseLayerLargeInterface expands?
}