Refactor: distinct task errors with type enum.

3 files changed, 148 insertions, 45 deletions

diff --git a/bilibili/errors/errors.go b/bilibili/errors/errors.go
deleted file mode 100644
index 2b810ed..0000000
--- a/bilibili/errors/errors.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package errors
-
-import (
-	"fmt"
-)
-
-/*
-Task errors.
-*/
-
-type RecoverableTaskError struct {
-	err     error
-	message string
-}
-
-func (e *RecoverableTaskError) Error() string {
-	return fmt.Sprintf("%v: %v", e.message, e.err)
-}
-
-func (e *RecoverableTaskError) Unwrap() error {
-	return e.err
-}
-
-func NewRecoverableTaskError(message string, err error) error {
-	return &RecoverableTaskError{message: message, err: err}
-}
-
-type UnrecoverableTaskError struct {
-	err     error
-	message string
-}
-
-func (e *UnrecoverableTaskError) Error() string {
-	return fmt.Sprintf("%v: %v", e.message, e.err)
-}
-
-func (e *UnrecoverableTaskError) Unwrap() error {
-	return e.err
-}
-
-func NewUnrecoverableTaskError(message string, err error) error {
-	return &UnrecoverableTaskError{message: message, err: err}
-}
diff --git a/bilibili/errors/taskerror.go b/bilibili/errors/taskerror.go
new file mode 100644
index 0000000..644a794
--- /dev/null
+++ b/bilibili/errors/taskerror.go
@@ -0,0 +1,146 @@
+package errors
+
+import (
+	"fmt"
+	"github.com/samber/lo"
+	"strings"
+)
+
+type Type int
+
+const (
+	// GetRoomInfo means failed to read live room information
+	GetRoomInfo Type = iota
+	// GetLiveInfo means failed to get live information
+	GetLiveInfo
+	// StreamCopy means an error occurred while reading stream video data
+	StreamCopy
+	// LiveEnded means the live is ended
+	LiveEnded
+	// DanmakuServerConnection means failed to connect to danmaku server, which provides danmaku and other control data
+	DanmakuServerConnection
+	// Heartbeat means an error occurred while sending heartbeat message, which may indicate a broken network connection
+	Heartbeat
+	// InitialLiveStatus means failed to get the live status for the first time, which happens in the early stage
+	InitialLiveStatus
+	// DanmakuExchangeRead means an error occurred while reading danmaku datagram from the server,
+	// which may indicate a broken network connection
+	DanmakuExchangeRead
+	// GetDanmakuServerInfo means failed to get danmaku server info
+	GetDanmakuServerInfo
+	// RecoverLiveStatusChecker means failed to restart live status checker
+	RecoverLiveStatusChecker
+
+	// FileCreation means failed to create a file
+	FileCreation
+	// InvalidLiveInfo means the live info is insufficient for recording
+	InvalidLiveInfo
+	// LiveStatusWatch means the live status watcher encountered an unrecoverable error
+	LiveStatusWatch
+	// Unknown means the error type is unexpected and is not suitable to retry for safety
+	Unknown
+	// InvalidAuthProtocol means authentication failed because the protocol is invalid,
+	// which may indicate the protocol implementation is outdated
+	InvalidAuthProtocol
+	// MessageDecompression means the message cannot be decompressed, and we cannot understand its content
+	MessageDecompression
+	// JsonDecode means we cannot decode a datum which is expected to be a JSON object string
+	JsonDecode
+)
+
+var recoverableErrors = []Type{
+	GetRoomInfo,
+	GetLiveInfo,
+	StreamCopy,
+	LiveEnded,
+	DanmakuServerConnection,
+	Heartbeat,
+	InitialLiveStatus,
+	DanmakuExchangeRead,
+	GetDanmakuServerInfo,
+	RecoverLiveStatusChecker,
+}
+
+var errorStrings = map[Type]string{
+	GetRoomInfo:              "failed to get living room information",
+	GetLiveInfo:              "failed to get live info",
+	StreamCopy:               "stream copy was unexpectedly interrupted",
+	LiveEnded:                "live is ended",
+	DanmakuServerConnection:  "failed to connect to danmaku server",
+	Heartbeat:                "heartbeat failed",
+	InitialLiveStatus:        "check initial live status failed",
+	DanmakuExchangeRead:      "failed to read exchange from server",
+	GetDanmakuServerInfo:     "cannot get notification server info",
+	RecoverLiveStatusChecker: "when recovering from a previous error, another error occurred",
+	FileCreation:             "failed to create file",
+	InvalidLiveInfo:          "invalid live info",
+	LiveStatusWatch:          "failed to watch live status",
+	Unknown:                  "unexpected error type",
+	InvalidAuthProtocol:      "authentication failed, invalid protocol",
+	MessageDecompression:     "failed to decompress server message",
+	JsonDecode:               "invalid JSON response from server",
+}
+
+func (t Type) String() string {
+	if s, ok := errorStrings[t]; ok {
+		return s
+	}
+	return fmt.Sprintf("<Type %v>", int(t))
+}
+
+type taskError struct {
+	typ Type
+	err []error
+}
+
+func (e *taskError) Message() string {
+	//TODO implement me
+	panic("implement me")
+}
+
+func (e *taskError) IsRecoverable() bool {
+	return lo.Contains(recoverableErrors, e.typ)
+}
+
+func (e *taskError) Unwrap() []error {
+	return e.err
+}
+
+func (e taskError) Error() string {
+	sb := strings.Builder{}
+	if e.IsRecoverable() {
+		sb.WriteString("recoverable task error")
+	} else {
+		sb.WriteString("unrecoverable task error")
+	}
+	sb.WriteString(": ")
+	sb.WriteString(fmt.Sprintf("%v", e.typ))
+	if len(e.err) > 0 {
+		sb.WriteString(", ")
+		for i := range e.err {
+			sb.WriteString(fmt.Sprintf("%v", e.err[i]))
+			if i != len(e.err)-1 {
+				sb.WriteString(", ")
+			}
+		}
+	}
+	return sb.String()
+}
+
+type TaskError interface {
+	// IsRecoverable reports if this task error is safe to retry.
+	IsRecoverable() bool
+	// Unwrap returns the underneath errors which cause the task error.
+	Unwrap() []error
+	// Message returns the detailed task-specific error message.
+	Message() string
+	// Error returns this error as string
+	Error() string
+}
+
+func NewError(typ Type, err ...error) TaskError {
+	return &taskError{
+		typ: typ,
+		err: err,
+	}
+}
diff --git a/bilibili/streaming.go b/bilibili/streaming.go
index d081a8f..b985bbb 100644
--- a/bilibili/streaming.go
+++ b/bilibili/streaming.go
@@ -4,7 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	errors2 "github.com/keuin/slbr/bilibili/errors"
+	errs "github.com/keuin/slbr/bilibili/errors"
 	"github.com/keuin/slbr/common"
 	"io"
 	"net/http"
@@ -71,7 +71,7 @@ func (b Bilibili) CopyLiveStream(
 	out, err = fileCreator()
 	if err != nil {
 		b.logger.Error("Cannot open file for writing: %v", err)
-		err = errors2.NewUnrecoverableTaskError("failed to create file", err)
+		err = errs.NewError(errs.FileCreation, err)
 		return
 	}
 	_, err = out.Write(initBytes)