package options

import (
	"os"
	"path"
	"reflect"
	"strings"
	"time"

	"github.com/spf13/cast"
)

func fill(opt interface{}) {
	v := reflect.ValueOf(opt)
	if v.Kind() != reflect.Ptr {
		panic("expecting a pointer, not a value")
	}

	if v.IsNil() {
		panic("nil pointer passed")
	}

	v = v.Elem()

	length := v.NumField()
	for i := 0; i < length; i++ {
		f := v.Field(i)
		t := v.Type().Field(i)
		if tag := t.Tag.Get("env"); tag != "" {
			if !f.CanSet() {
				panic("unexpected pointer for field " + t.Name)
			}

			if f.Type() == reflect.TypeOf(time.Duration(1)) {
				v.FieldByName(t.Name).SetInt(int64(EnvDuration(tag, time.Duration(f.Int()))))
				continue
			}

			if f.Kind() == reflect.String {
				v.FieldByName(t.Name).SetString(EnvString(tag, f.String()))
				continue
			}

			if f.Kind() == reflect.Bool {
				v.FieldByName(t.Name).SetBool(EnvBool(tag, f.Bool()))
				continue
			}

			if f.Kind() == reflect.Int {
				v.FieldByName(t.Name).SetInt(int64(EnvInt(tag, int(f.Int()))))
				continue
			}

			if f.Kind() == reflect.Float32 {
				v.FieldByName(t.Name).SetFloat(float64(EnvFloat32(tag, float32(f.Float()))))
				continue
			}

			panic("unsupported type/kind for field " + t.Name)
		}
	}
}

func guessHostname() string {
	// All env keys we'll check, first that has any value set, will be used as hostname
	candidates := []string{
		os.Getenv("DOMAIN"),
		os.Getenv("LETSENCRYPT_HOST"),
		os.Getenv("VIRTUAL_HOST"),
		os.Getenv("HOSTNAME"),
		os.Getenv("HOST"),
	}

	for _, host := range candidates {
		if len(host) > 0 {
			return host
		}
	}

	return "local.cortezaproject.org"
}

// returns path prefix
func pathPrefix(pp ...string) string {
	return CleanBase(append([]string{EnvString("HTTP_BASE_URL", "")}, pp...)...)
}

// will return base URL with domain and prefix path
func fullURL(pp ...string) string {
	var (
		full string
		host = guessHostname()
	)

	if strings.Contains(host, "local.") || strings.Contains(host, "localhost") || !isSecure() {
		full = "http://" + host
	} else {
		full = "https://" + host
	}

	if pfix := pathPrefix(pp...); pfix != "" {
		return full + pfix
	}

	return full
}

// Checks value of HTTP_SSL_TERMINATED and fallbacks to checking existence of LETSENCRYPT_HOST
// to determinate we are behind a SSL termination infrastructure
func isSecure() bool {
	var _, is = os.LookupEnv("LETSENCRYPT_HOST")

	// We're accessing to HTTP_SSL_TERMINATED directly here and not via HttpServerOpt.SslTerminated
	// because we need to get to this value early and directly
	return EnvBool("HTTP_SSL_TERMINATED", is)
}

// Path joins all parts with / and prefixes result (if not empty) with /
func CleanBase(pp ...string) string {
	//if p := strings.Trim(path.Join(pp...), "/"); p != "" {
	//	// prefix base with slash
	//	return "/" + p
	//}

	return "/" + strings.Trim(path.Join(pp...), "/")
}

func EnvString(key string, def string) string {
	if val, has := os.LookupEnv(key); has {
		return val
	}
	return def
}

func EnvBool(key string, def bool) bool {
	if val, has := os.LookupEnv(key); has {
		if b, err := cast.ToBoolE(val); err == nil {
			return b
		}
	}
	return def
}

func EnvInt(key string, def int) int {
	if val, has := os.LookupEnv(key); has {
		if i, err := cast.ToIntE(val); err == nil {
			return i
		}
	}
	return def
}

func EnvFloat32(key string, def float32) float32 {
	if val, has := os.LookupEnv(key); has {
		if i, err := cast.ToFloat32E(val); err == nil {
			return i
		}
	}
	return def
}

func EnvDuration(key string, def time.Duration) time.Duration {
	if val, has := os.LookupEnv(key); has {
		if d, err := cast.ToDurationE(val); err == nil {
			return d
		}
	}
	return def
}