1 files changed, 180 insertions, 0 deletions
diff --git a/pkg/eax/updatemgr.go b/pkg/eax/updatemgr.go
new file mode 100644
index 0000000..d1a6a59
--- /dev/null
+++ b/pkg/eax/updatemgr.go
@@ -0,0 +1,180 @@
+package eax
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"strconv"
+	"sync"
+	"time"
+)
+
+// UpdateMgr manages EAX client version information.
+type UpdateMgr struct {
+	// HTTP client to use. If not provided, [net/http.DefaultClient] will be
+	// used.
+	Client *http.Client
+
+	// Timeout is the timeout for refreshing tokens. If zero, a reasonable
+	// default is used. If negative, there is no timeout.
+	Timeout time.Duration
+
+	// Interval to update at. If zero, will not auto-update.
+	AutoUpdateInterval time.Duration
+
+	// Auto-update staged roll-out bucket.
+	AutoUpdateBucket int
+
+	// Auto-update backoff, if provided, checks if another auto-update is
+	// allowed after a failure. If it returns false, ErrAutoUpdateBackoff will be
+	// returned from the function triggering the auto-update.
+	AutoUpdateBackoff func(err error, time time.Time, count int) bool
+
+	// AutoUpdateHook is called for every auto-update attempt with the new (or
+	// current if error) version, and any error which occurred.
+	AutoUpdateHook func(v string, err error)
+
+	verInit     sync.Once
+	verPf       bool       // ensures only one auto-update runs at a time
+	verCv       *sync.Cond // allows other goroutines to wait for that update to complete
+	verErr      error      // last auto-update error
+	verErrTime  time.Time  // last auto-update error time
+	verErrCount int        // consecutive auto-update errors
+	ver         string     // current version
+	verTime     time.Time  // last update check time
+}
+
+var ErrAutoUpdateBackoff = errors.New("not updating eax client version due to backoff")
+
+func (u *UpdateMgr) init() {
+	u.verInit.Do(func() {
+		u.verCv = sync.NewCond(new(sync.Mutex))
+	})
+}
+
+// SetVersion sets the current version.
+func (u *UpdateMgr) SetVersion(v string) {
+	u.init()
+	u.verCv.L.Lock()
+	for u.verPf {
+		u.verCv.Wait()
+	}
+	u.ver = v
+	u.verErr = nil
+	u.verTime = time.Now()
+	u.verCv.L.Unlock()
+}
+
+// Update gets the latest version, following u.AutoUpdateInterval if provided,
+// unless the version is not set or force is true. If another update is in
+// progress, it waits for the result of it. True is returned (on success or
+// failure) if this call performed a update. This function may block for up to
+// Timeout.
+func (u *UpdateMgr) Update(force bool) (string, bool, error) {
+	u.init()
+	if u.verCv.L.Lock(); u.verPf {
+		for u.verPf {
+			u.verCv.Wait()
+		}
+		defer u.verCv.L.Unlock()
+		return u.ver, false, u.verErr
+	} else {
+		if force || u.ver == "" || (u.AutoUpdateInterval != 0 && time.Since(u.verTime) > u.AutoUpdateInterval) {
+			u.verPf = true
+			u.verCv.L.Unlock()
+			defer func() {
+				u.verCv.L.Lock()
+				u.verCv.Broadcast()
+				u.verPf = false
+				u.verCv.L.Unlock()
+			}()
+		} else {
+			defer u.verCv.L.Unlock()
+			return u.ver, false, u.verErr
+		}
+	}
+	if u.verErr != nil && u.AutoUpdateBackoff != nil {
+		if !u.AutoUpdateBackoff(u.verErr, u.verErrTime, u.verErrCount) {
+			return u.ver, true, fmt.Errorf("%w (%d attempts, last error: %v)", ErrAutoUpdateBackoff, u.verErrCount, u.verErr)
+		}
+	}
+	u.verErr = func() error {
+		var ctx context.Context
+		var cancel context.CancelFunc
+		if u.Timeout > 0 {
+			ctx, cancel = context.WithTimeout(context.Background(), u.Timeout)
+		} else if u.Timeout == 0 {
+			ctx, cancel = context.WithTimeout(context.Background(), time.Second*15)
+		} else {
+			ctx, cancel = context.WithCancel(context.Background())
+		}
+		defer cancel()
+
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, "https://autopatch.juno.ea.com/autopatch/upgrade/buckets/"+strconv.Itoa(u.AutoUpdateBucket), nil)
+		if err != nil {
+			return err
+		}
+		if u.ver != "" {
+			req.Header.Set("User-Agent", "EADesktop/"+u.ver)
+		} else {
+			req.Header.Set("User-Agent", "")
+		}
+
+		cl := u.Client
+		if cl == nil {
+			cl = http.DefaultClient
+		}
+
+		resp, err := cl.Do(req)
+		if err != nil {
+			return err
+		}
+		defer resp.Body.Close()
+
+		var obj struct {
+			Minimum struct {
+				Version        string `json:"version"`
+				ActivationDate string `json:"activationDate"`
+			} `json:"minimum"`
+			Recommended struct {
+				Version string `json:"version"`
+			} `json:"recommended"`
+		}
+		if resp.StatusCode != http.StatusOK {
+			return fmt.Errorf("response status %d (%s)", resp.StatusCode, resp.Status)
+		}
+		if err := json.NewDecoder(resp.Body).Decode(&obj); err != nil {
+			return fmt.Errorf("parse autopatch response: %w", err)
+		}
+
+		var version string
+		if v := obj.Minimum.Version; v != "" {
+			version = v
+		}
+		if v := obj.Recommended.Version; v != "" {
+			version = v
+		}
+		if version == "" {
+			return fmt.Errorf("parse autopatch response: missing minimum or recommended version")
+		}
+		u.ver = version
+		u.verTime = time.Now()
+		return nil
+	}()
+	if u.verErrCount != 0 {
+		u.verErr = fmt.Errorf("%w (attempt %d)", u.verErr, u.verErrCount)
+	}
+	if u.verErr != nil {
+		u.verErrCount++
+		u.verErrTime = time.Now()
+	} else {
+		u.verErrCount = 0
+		u.verErrTime = time.Time{}
+	}
+	if u.AutoUpdateHook != nil {
+		go u.AutoUpdateHook(u.ver, u.verErr)
+	}
+	return u.ver, true, u.verErr
+}