package handler

import (
	"context"
	"net/http"
	"os"
)

// HandlerFunc describes the signature all metric handler functions must have.
type HandlerFunc func(
	ctx context.Context,
	metricParams map[string]string,
	extraParams ...string,
) (any, error)

// Handler hold client and syscall implementation for request functions.
type Handler struct {
	client   *http.Client
	sysCalls systemCalls
}

type systemCalls interface {
	environ() []string
	lookupEnv(key string) (string, bool)
}

type osWrapper struct{}

// New creates a new handler with initialized clients for system and tcp calls.
func New() *Handler {
	return &Handler{
		client:   http.DefaultClient,
		sysCalls: osWrapper{},
	}
}

func (osWrapper) environ() []string {
	return os.Environ()
}

func (osWrapper) lookupEnv(key string) (string, bool) {
	return os.LookupEnv(key)
}