### Install mixi2 Go SDK

Source: https://developer.mixi.social/docs/guides/sdk

Command to install the official mixi2 application SDK for Go using the go get tool.

```bash
go get github.com/mixigroup/mixi2-application-sdk-go
```

--------------------------------

### InitiatePostMediaUpload

Source: https://developer.mixi.social/docs/reference/api-document

Starts the media upload process and returns a URL for uploading data.

```APIDOC
## RPC InitiatePostMediaUpload

### Description
Initiates media upload for posts or messages and issues an upload URL.

### Method
RPC (gRPC)

### Endpoint
InitiatePostMediaUpload

### Request Body
- **content_type** (string) - Required - Content-Type of the data.
- **data_size** (uint64) - Required - Size of the data in bytes.
- **media_type** (Type) - Required - Type of media.

### Response
#### Success Response (200)
- **media_id** (string) - ID for tracking and attachment.
- **upload_url** (string) - URL to upload the media data.

### Response Example
{
  "media_id": "media_001",
  "upload_url": "https://upload.example.com/v1/media/001"
}
```

--------------------------------

### Initiate Media Upload for Posts/DMs using mixi2 API

Source: https://developer.mixi.social/docs/guides/api-usage

Explains the first step in uploading media (images/videos) for posts or DMs: initiating the upload to get a `media_id` and `upload_url`.

```Go
description := "画像の説明（任意）"
resp, err := client.InitiatePostMediaUpload(ctx, &application_apiv1.InitiatePostMediaUploadRequest{
    MediaType:   application_apiv1.InitiatePostMediaUploadRequest_TYPE_IMAGE,
    ContentType: "image/jpeg",
    DataSize:    uint64(len(imageData)),
    Description: &description,
})

mediaId := resp.MediaId
uploadUrl := resp.UploadUrl
```

--------------------------------

### Run Sample Application

Source: https://developer.mixi.social/docs/guides/sdk

Commands to clone, configure, and run the sample Go application in either gRPC stream or Webhook mode.

```bash
# リポジトリをクローン
git clone https://github.com/mixigroup/mixi2-application-sample-go.git
cd mixi2-application-sample-go

# 環境変数を設定
cp .env.example .env
# .env を編集して環境変数を設定
source .env
go mod tidy

# gRPC ストリームモード（ローカル開発向け）
go run cmd/stream/main.go

# HTTP Webhook モード（デプロイ向け）
go run cmd/webhook/main.go
```

--------------------------------

### Implement OAuth2 Authentication

Source: https://developer.mixi.social/docs/guides/sdk

Demonstrates how to initialize the Authenticator and obtain an authorized context for gRPC requests using environment variables.

```go
package main

import (
    "context"
    "log"
    "os"

    "github.com/mixigroup/mixi2-application-sdk-go/auth"
)

func main() {
    authenticator, err := auth.NewAuthenticator(
        os.Getenv("CLIENT_ID"),
        os.Getenv("CLIENT_SECRET"),
        os.Getenv("TOKEN_URL"),
    )
    if err != nil {
        log.Fatal(err)
    }

    // gRPC リクエスト用のコンテキストを取得
    ctx, err := authenticator.AuthorizedContext(context.Background())
    if err != nil {
        log.Fatal(err)
    }

    // ctx を使って gRPC リクエストを送信
    _ = ctx
}
```

--------------------------------

### Get User Information using Go

Source: https://developer.mixi.social/docs/guides/api-usage

Retrieves user information using the `GetUsers` RPC. This function takes a list of user IDs and returns details such as display name and icon URL. It is limited to fetching information for users that the application has access to.

```Go
resp, err := client.GetUsers(ctx, &application_apiv1.GetUsersRequest{
    UserIdList: []string{event.Post.CreatorId},
})

for _, user := range resp.Users {
    fmt.Printf("ユーザー名: %s\n", user.DisplayName)
}
```

--------------------------------

### Generate Code without SDK

Source: https://developer.mixi.social/docs/guides/sdk

Commands to generate Protocol Buffers code directly from the API definition repository using buf.

```bash
# API Proto リポジトリをクローン
git clone https://github.com/mixigroup/mixi2-api.git

# buf を使用してコード生成
cd mixi2-api
buf generate
```

--------------------------------

### Get Post Information using Go

Source: https://developer.mixi.social/docs/guides/api-usage

Retrieves post information using the `GetPosts` RPC. This function allows fetching details of specific posts, including their text, media, and stamps, by providing a list of post IDs. It is limited to retrieving posts that the application has access to.

```Go
resp, err := client.GetPosts(ctx, &application_apiv1.GetPostsRequest{
    PostIdList: []string{event.Post.GetInReplyToPostId()},
})

for _, post := range resp.Posts {
    fmt.Printf("ポスト本文: %s\n", post.Text)
}
```

--------------------------------

### Create a Basic Post using mixi2 API

Source: https://developer.mixi.social/docs/guides/api-usage

Demonstrates how to create a simple text post using the `CreatePost` RPC. This is the most basic form of posting content.

```Go
resp, err := client.CreatePost(ctx, &application_apiv1.CreatePostRequest{
    Text: "こんにちは！",
})
```

--------------------------------

### Reply to a Post using mixi2 API

Source: https://developer.mixi.social/docs/guides/api-usage

Shows how to reply to an existing post by specifying the `in_reply_to_post_id`. This allows for conversational threads within the platform.

```Go
inReplyToPostId := event.Post.PostId
resp, err := client.CreatePost(ctx, &application_apiv1.CreatePostRequest{
    Text:            "返信ありがとうございます！",
    InReplyToPostId: &inReplyToPostId,
})
```

--------------------------------

### GET /healthz

Source: https://developer.mixi.social/docs/guides/webhook

A health check endpoint used to verify the availability of the webhook server.

```APIDOC
## GET /healthz

### Description
Provides a simple health check mechanism for the webhook server.

### Method
GET

### Endpoint
/healthz

### Response
#### Success Response (200)
- **status** (string) - Returns "OK" or similar status indicating the server is healthy.
```

--------------------------------

### Define Event Handler Interface

Source: https://developer.mixi.social/docs/guides/sdk

Defines the EventHandler interface required for processing events in both Webhook and gRPC stream modes.

```go
import modelv1 "github.com/mixigroup/mixi2-application-sdk-go/gen/go/social/mixi/application/model/v1"

type EventHandler interface {
    Handle(ctx context.Context, event *modelv1.Event) error
}
```

--------------------------------

### Quote a Post using mixi2 API

Source: https://developer.mixi.social/docs/guides/api-usage

Illustrates how to quote another post by using the `quoted_post_id` parameter. Note that `in_reply_to_post_id` and `quoted_post_id` cannot be used simultaneously.

```Go
quotedPostId := originalPostId
resp, err := client.CreatePost(ctx, &application_apiv1.CreatePostRequest{
    Text:         "これは面白い投稿ですね！",
    QuotedPostId: &quotedPostId,
})
```

--------------------------------

### Upload Media Data to Provided URL

Source: https://developer.mixi.social/docs/guides/api-usage

Details the second step of media upload: sending the actual media data to the `upload_url` obtained from `InitiatePostMediaUpload` using an HTTP POST request.

```Go
req, err := http.NewRequest(http.MethodPost, uploadUrl, bytes.NewReader(imageData))
req.Header.Set("Content-Type", "image/jpeg")
httpClient.Do(req)
```

--------------------------------

### Control Post Publishing Type using mixi2 API

Source: https://developer.mixi.social/docs/guides/api-usage

Demonstrates how to control the visibility of a post using the `PublishingType` field. This allows posts to be visible only on the profile or to followers.

```Go
publishingType := constv1.PostPublishingType_POST_PUBLISHING_TYPE_NOT_PUBLISHING
resp, err := client.CreatePost(ctx, &application_apiv1.CreatePostRequest{
    Text:           "このポストはプロフィールにのみ表示されます",
    PublishingType: &publishingType,
})
```

--------------------------------

### Create a Masked Post (Spoiler/Sensitive) using mixi2 API

Source: https://developer.mixi.social/docs/guides/api-usage

Explains how to create posts with masks for sensitive content or spoilers using the `PostMask` field. This is useful for content warnings.

```Go
caption := "映画のネタバレ注意"
resp, err := client.CreatePost(ctx, &application_apiv1.CreatePostRequest{
    Text: "ネタバレを含む内容です...",
    PostMask: &modelv1.PostMask{
        MaskType: constv1.PostMaskType_POST_MASK_TYPE_SPOILER,
        Caption:  &caption,
    },
})
```

--------------------------------

### Attach Uploaded Media to a Post using mixi2 API

Source: https://developer.mixi.social/docs/guides/api-usage

The final step in media integration: attaching the processed media to a post by including the `media_id` in the `CreatePost` request.

```Go
resp, err := client.CreatePost(ctx, &application_apiv1.CreatePostRequest{
    Text:        "画像を添付しました！",
    MediaIdList: []string{mediaId},
})
```

--------------------------------

### Send a Direct Message using mixi2 API

Source: https://developer.mixi.social/docs/guides/api-usage

Shows how to send a direct message (DM) using the `SendChatMessage` RPC. Note that direct messages can only be sent in reply to a user's message.

```Go
text := "メッセージを受け取りました！"
resp, err := client.SendChatMessage(ctx, &application_apiv1.SendChatMessageRequest{
    RoomId: event.Message.RoomId,
    Text:   &text,
})
```

--------------------------------

### Add Stamp to Post using Go

Source: https://developer.mixi.social/docs/guides/api-usage

Adds a stamp to a post using the `AddStampToPost` RPC. It first retrieves available stamps using `GetStamps` and then applies the selected stamp to the specified post. Limitations include only official stamps can be used and a post cannot be stamped multiple times by the same application.

```Go
// 利用可能なスタンプ一覧を取得
language := constv1.LanguageCode_LANGUAGE_CODE_JP
stampsResp, err := client.GetStamps(ctx, &application_apiv1.GetStampsRequest{
    OfficialStampLanguage: &language,
})

// スタンプを付与
_, err = client.AddStampToPost(ctx, &application_apiv1.AddStampToPostRequest{
    PostId:  postId,
    StampId: stampsResp.OfficialStampSets[0].Stamps[0].StampId,
})
```

--------------------------------

### Check Media Upload Status using mixi2 API

Source: https://developer.mixi.social/docs/guides/api-usage

Describes the third step in media upload: polling the `GetPostMediaStatus` RPC to check the processing status of the uploaded media until it's `STATUS_COMPLETED` or `STATUS_FAILED`.

```Go
for {
    statusResp, err := client.GetPostMediaStatus(ctx, &application_apiv1.GetPostMediaStatusRequest{
        MediaId: mediaId,
    })
    if statusResp.Status == application_apiv1.GetPostMediaStatusResponse_STATUS_COMPLETED {
        break
    }
    if statusResp.Status == application_apiv1.GetPostMediaStatusResponse_STATUS_FAILED {
        // エラー処理: アップロードをやり直す必要があります
        return errors.New("media processing failed")
    }
    time.Sleep(1 * time.Second)
}
```

--------------------------------

### Go SDK を使用した Webhook イベント受信サーバーの実装

Source: https://developer.mixi.social/docs/guides/webhook

Go SDK を使用して Webhook イベントを受信するサーバーを実装する方法を示します。このコードは、指定されたポートでリッスンし、受信したイベントをログに記録します。署名検証は SDK によって自動的に処理されます。

```go
package main

import (
    "context"
    "crypto/ed25519"
    "encoding/base64"
    "log"
    "os"

    "github.com/mixigroup/mixi2-application-sdk-go/event/webhook"
    modelv1 "github.com/mixigroup/mixi2-application-sdk-go/gen/go/social/mixi/application/model/v1"
)

type MyHandler struct{}

func (h *MyHandler) Handle(ctx context.Context, ev *modelv1.Event) error {
    log.Printf("Received event: %v", ev)
    return nil
}

func main() {
    publicKeyBase64 := os.Getenv("SIGNATURE_PUBLIC_KEY")
    publicKey, err := base64.StdEncoding.DecodeString(publicKeyBase64)
    if err != nil {
        log.Fatal(err)
    }

    server := webhook.NewServer(
        ":8080",
        ed25519.PublicKey(publicKey),
        &MyHandler{},
    )

    if err := server.Start(); err != nil {
        log.Fatal(err)
    }
}
```

--------------------------------

### gRPCストリームによるイベント受信の実装 (Go)

Source: https://developer.mixi.social/docs/guides/grpc-stream

mixi2 SDK for Goを使用してgRPCストリームを確立し、イベントを処理する実装例です。認証情報の初期化、gRPCコネクションの作成、およびStreamWatcherによるイベント監視の開始手順を示しています。

```go
package main

import (
    "context"
    "crypto/tls"
    "log"
    "os"

    "google.golang.org/grpc"
    "google.golang.org/grpc/credentials"

    "github.com/mixigroup/mixi2-application-sdk-go/auth"
    "github.com/mixigroup/mixi2-application-sdk-go/event/stream"
    application_streamv1 "github.com/mixigroup/mixi2-application-sdk-go/gen/go/social/mixi/application/service/application_stream/v1"
    modelv1 "github.com/mixigroup/mixi2-application-sdk-go/gen/go/social/mixi/application/model/v1"
)

type MyHandler struct{}

func (h *MyHandler) Handle(ctx context.Context, ev *modelv1.Event) error {
    log.Printf("Received event: %v", ev)
    return nil
}

func main() {
    authenticator, err := auth.NewAuthenticator(
        os.Getenv("CLIENT_ID"),
        os.Getenv("CLIENT_SECRET"),
        os.Getenv("TOKEN_URL"),
    )
    if err != nil {
        log.Fatal(err)
    }

    conn, err := grpc.NewClient(
        os.Getenv("STREAM_ADDRESS"),
        grpc.WithTransportCredentials(credentials.NewTLS(&tls.Config{})),
    )
    if err != nil {
        log.Fatal(err)
    }
    defer conn.Close()

    client := application_streamv1.NewApplicationServiceClient(conn)
    watcher := stream.NewStreamWatcher(client, authenticator)

    if err := watcher.Watch(context.Background(), &MyHandler{}); err != nil {
        log.Fatal(err)
    }
}
```

--------------------------------

### CreatePost

Source: https://developer.mixi.social/docs/reference/api-document

Creates a new post on the platform, supporting replies, quotes, and media attachments.

```APIDOC
## RPC CreatePost

### Description
Creates a post. Note: in_reply_to_post_id and quoted_post_id cannot be specified simultaneously.

### Method
RPC (gRPC)

### Endpoint
CreatePost

### Request Body
- **text** (string) - Required - The body of the post.
- **in_reply_to_post_id** (optional string) - Optional - ID of the post to reply to.
- **quoted_post_id** (optional string) - Optional - ID of the post to quote.
- **media_id_list** (repeated string) - Optional - List of media IDs to attach (max 4).
- **publishing_type** (optional PostPublishingType) - Optional - Publishing settings.

### Response
#### Success Response (200)
- **post** (Post) - The created post object.

### Response Example
{
  "post": { "id": "post789", "text": "Hello World" }
}
```

--------------------------------

### POST /events

Source: https://developer.mixi.social/docs/guides/webhook

The event reception endpoint used by the mixi2 platform to push events to your application server.

```APIDOC
## POST /events

### Description
This endpoint receives event payloads from the mixi2 platform. It must be implemented as an HTTPS endpoint and requires mandatory Ed25519 signature verification.

### Method
POST

### Endpoint
/events

### Parameters
#### Request Headers
- **x-mixi2-application-event-signature** (string) - Required - Base64 encoded Ed25519 signature.
- **x-mixi2-application-event-timestamp** (integer) - Required - Unix timestamp in seconds.

### Request Example
{
  "event_type": "example_event",
  "data": { ... }
}

### Response
#### Success Response (200)
- **status** (string) - Indicates successful receipt and processing of the event.

#### Error Response (401)
- **error** (string) - Returned when signature verification fails or timestamp is invalid.
```

--------------------------------

### GetUsers

Source: https://developer.mixi.social/docs/reference/api-document

Retrieves user information for a specified list of user IDs.

```APIDOC
## RPC GetUsers

### Description
Retrieves user information for a specified list of user IDs.

### Method
RPC (gRPC)

### Endpoint
GetUsers

### Request Body
- **user_id_list** (repeated string) - Required - List of user IDs to retrieve.

### Response
#### Success Response (200)
- **users** (repeated User) - List of user information.

### Response Example
{
  "users": [
    { "id": "user123", "name": "Example User" }
  ]
}
```

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