package saltyim

import (
	"bytes"
	"compress/gzip"
	"crypto/rand"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"github.com/andybalholm/brotli"
	"github.com/oklog/ulid/v2"
	log "github.com/sirupsen/logrus"
)

const (
	defaultRequestTimeout = time.Second * 30
)

// GenerateULID generates a new unique identifer
func GenerateULID() (string, error) {
	entropy := rand.Reader
	id, err := ulid.New(ulid.Timestamp(time.Now()), entropy)
	if err != nil {
		return "", fmt.Errorf("error generating ulid: %w", err)
	}

	return id.String(), nil
}

// MustGenerateULID generates a new unique identifer or fails
func MustGenerateULID() string {
	ulid, err := GenerateULID()
	if err != nil {
		log.WithError(err).Fatal("error generating ulid")
	}
	return ulid
}

// Request is a generic request handling function for making artbitrary HTPT
// requests to Salty endpoints for looking up Salty Addresses, Configs and
// publishing encrypted messages.
func Request(method, uri string, headers http.Header, body io.Reader) (*http.Response, error) {
	if headers == nil {
		headers = make(http.Header)
	}

	if body != nil {
		switch headers.Get("Content-Encoding") {
		case "br":
			buf := &bytes.Buffer{}
			br := brotli.NewWriter(buf)
			io.Copy(br, body)
			br.Close()
			body = buf
		case "gzip":
			buf := &bytes.Buffer{}
			gz := gzip.NewWriter(buf)
			io.Copy(gz, body)
			gz.Close()
			body = buf
		}
	}

	req, err := http.NewRequest(method, uri, body)
	if err != nil {
		return nil, fmt.Errorf("%s: http.NewRequest fail: %s", uri, err)
	}

	// Set a default User-Agent (if none set)
	if headers.Get("User-Agent") == "" {
		headers.Set("User-Agent", fmt.Sprintf("saltyim/%s", FullVersion()))
	}

	req.Header = headers

	client := http.Client{
		Timeout: defaultRequestTimeout,
	}

	res, err := client.Do(req)
	if err != nil {
		return nil, fmt.Errorf("%s: client.Do fail: %s", uri, err)
	}

	if res.StatusCode/100 != 2 {
		return nil, fmt.Errorf("non-2xx response received: %s", res.Status)
	}

	return res, nil
}

// SplitInbox splits and endpoint into it's components (inbox, uri)
// where inbox is a topic queue on the Salty broker uri
func SplitInbox(endpoint string) (string, string) {
	idx := strings.LastIndex(endpoint, "/")
	if idx == -1 {
		return "", ""
	}
	return endpoint[:idx], endpoint[idx+1:]
}