vorteil/direktiv

package engine

import (
    "bytes"
    "encoding/json"
    "errors"
    "fmt"
)

const (
    instanceChildInfoVersion1 = "v1"
)

var ErrInvalidInstanceChildInfo = errors.New("invalid instance child info")

// ChildInfo is part of the ChildrenInfo structure. It represents useful information about a single child action.
type ChildInfo struct {
    ID          string `json:"id"`
    Async       bool   `json:"async"`
    Complete    bool   `json:"complete"`
    Type        string `json:"type"`
    Attempts    int    `json:"attempts"`
    ServiceName string `json:"service_name"`
}

// ChildrenInfo keeps some useful information about all direct child actions of this instance.
type InstanceChildrenInfo struct {
    Version  string // to let us identify and correct outdated versions of this struct
    Children []ChildInfo
}

func (info *InstanceChildrenInfo) MarshalJSON() ([]byte, error) {
    if info == nil {
        return json.Marshal(&InstanceChildInfoV1{
            Version: instanceChildInfoVersion1,
        })
    }

    return json.Marshal(&InstanceChildInfoV1{
        Version:  instanceChildInfoVersion1,
        Children: info.Children,
    })
}

type InstanceChildInfoV1 struct {
    Version  string      `json:"version"`
    Children []ChildInfo `json:"children"`
}

func LoadInstanceChildInfo(data []byte) (*InstanceChildrenInfo, error) {
    m := make(map[string]interface{})

    err := json.Unmarshal(data, &m)
    if err != nil {
        return nil, err
    }

    version, defined := m["version"]
    if !defined {
        return nil, fmt.Errorf("failed to load instance child info: %w: missing version", ErrInvalidInstanceChildInfo)
    }

    var info *InstanceChildrenInfo

    dec := json.NewDecoder(bytes.NewReader(data))
    dec.DisallowUnknownFields()

    switch version {
    case instanceChildInfoVersion1:
        var v1 InstanceChildInfoV1
        err = dec.Decode(&v1)
        if err != nil {
            return nil, fmt.Errorf("failed to load instance child info: %w: %w", ErrInvalidInstanceChildInfo, err)
        }

        info = &InstanceChildrenInfo{
            Version:  v1.Version,
            Children: v1.Children,
        }

    default:
        return nil, fmt.Errorf("failed to load instance child info: %w: unknown version", ErrInvalidInstanceChildInfo)
    }

    return info, nil
}