go-garth/garth/utils/utils.go

package utils

import (
	"crypto/hmac"
	"crypto/rand"
	"crypto/sha1"
	"encoding/base64"
	"encoding/json"
	"net/http"
	"net/url"
	"sort"
	"strconv"
	"strings"
	"time"

	"garmin-connect/garth/types"
)

var oauthConsumer *types.OAuthConsumer

// LoadOAuthConsumer loads OAuth consumer credentials
func LoadOAuthConsumer() (*types.OAuthConsumer, error) {
	if oauthConsumer != nil {
		return oauthConsumer, nil
	}

	// First try to get from S3 (like the Python library)
	resp, err := http.Get("https://thegarth.s3.amazonaws.com/oauth_consumer.json")
	if err == nil {
		defer resp.Body.Close()
		if resp.StatusCode == 200 {
			var consumer types.OAuthConsumer
			if err := json.NewDecoder(resp.Body).Decode(&consumer); err == nil {
				oauthConsumer = &consumer
				return oauthConsumer, nil
			}
		}
	}

	// Fallback to hardcoded values
	oauthConsumer = &types.OAuthConsumer{
		ConsumerKey:    "fc320c35-fbdc-4308-b5c6-8e41a8b2e0c8",
		ConsumerSecret: "8b344b8c-5bd5-4b7b-9c98-ad76a6bbf0e7",
	}
	return oauthConsumer, nil
}

// GenerateNonce generates a random nonce for OAuth
func GenerateNonce() string {
	b := make([]byte, 32)
	rand.Read(b)
	return base64.StdEncoding.EncodeToString(b)
}

// GenerateTimestamp generates a timestamp for OAuth
func GenerateTimestamp() string {
	return strconv.FormatInt(time.Now().Unix(), 10)
}

// PercentEncode URL encodes a string
func PercentEncode(s string) string {
	return url.QueryEscape(s)
}

// CreateSignatureBaseString creates the base string for OAuth signing
func CreateSignatureBaseString(method, baseURL string, params map[string]string) string {
	var keys []string
	for k := range params {
		keys = append(keys, k)
	}
	sort.Strings(keys)

	var paramStrs []string
	for _, key := range keys {
		paramStrs = append(paramStrs, PercentEncode(key)+"="+PercentEncode(params[key]))
	}
	paramString := strings.Join(paramStrs, "&")

	return method + "&" + PercentEncode(baseURL) + "&" + PercentEncode(paramString)
}

// CreateSigningKey creates the signing key for OAuth
func CreateSigningKey(consumerSecret, tokenSecret string) string {
	return PercentEncode(consumerSecret) + "&" + PercentEncode(tokenSecret)
}

// SignRequest signs an OAuth request
func SignRequest(consumerSecret, tokenSecret, baseString string) string {
	signingKey := CreateSigningKey(consumerSecret, tokenSecret)
	mac := hmac.New(sha1.New, []byte(signingKey))
	mac.Write([]byte(baseString))
	return base64.StdEncoding.EncodeToString(mac.Sum(nil))
}

// CreateOAuth1AuthorizationHeader creates the OAuth1 authorization header
func CreateOAuth1AuthorizationHeader(method, requestURL string, params map[string]string, consumerKey, consumerSecret, token, tokenSecret string) string {
	oauthParams := map[string]string{
		"oauth_consumer_key":     consumerKey,
		"oauth_nonce":            GenerateNonce(),
		"oauth_signature_method": "HMAC-SHA1",
		"oauth_timestamp":        GenerateTimestamp(),
		"oauth_version":          "1.0",
	}

	if token != "" {
		oauthParams["oauth_token"] = token
	}

	// Combine OAuth params with request params
	allParams := make(map[string]string)
	for k, v := range oauthParams {
		allParams[k] = v
	}
	for k, v := range params {
		allParams[k] = v
	}

	// Parse URL to get base URL without query params
	parsedURL, _ := url.Parse(requestURL)
	baseURL := parsedURL.Scheme + "://" + parsedURL.Host + parsedURL.Path

	// Create signature base string
	baseString := CreateSignatureBaseString(method, baseURL, allParams)

	// Sign the request
	signature := SignRequest(consumerSecret, tokenSecret, baseString)
	oauthParams["oauth_signature"] = signature

	// Build authorization header
	var headerParts []string
	for key, value := range oauthParams {
		headerParts = append(headerParts, PercentEncode(key)+"=\""+PercentEncode(value)+"\"")
	}
	sort.Strings(headerParts)

	return "OAuth " + strings.Join(headerParts, ", ")
}

// Min returns the smaller of two integers
func Min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

// DateRange generates a date range from end date backwards for n days
func DateRange(end time.Time, days int) []time.Time {
	dates := make([]time.Time, days)
	for i := 0; i < days; i++ {
		dates[i] = end.AddDate(0, 0, -i)
	}
	return dates
}