SupabaseのGoogle OAuthの設定とNext.jsでサインインボタンの作成

## GCPとSupabaseでのGoogle OAuthの設定手順

1. (gcp) Google Cloudでプロジェクトを作成
2. (gcp) OAuth同意画面でアプリ登録
    1. (gcp) APIとサービス > OAuth同意画面 > User Type > 外部 で作成ボタンを押す
    2. (gcp) アプリ名、ユーザーサポートメール、デベロッパーの連絡先情報 を入力し保存（1~4の項目すべて保存でOK）
3. (gcp) 認証情報の作成
    1. (gcp) APIとサービス > 認証情報、認証情報を作成 > OAuthクライエントID、アプリケーションの種類と名前を入力
    2. (supabase) Authentication > Providers > Google の`Callback URL (for OAuth)`をコピー
    3. コピーしたURLを承認済みのリダイレクトURIに追加。一番下で作成
4. (supabase) OAuthクライエント情報をSupabaseプロジェクトに設定
    1. (gcp) クライアント IDとクライアント シークレットをコピーする
    2. (supabase) Authentication > Providers > Google の`Client ID (for OAuth)`と`Client Secret (for OAuth)`にペーストする
    3. Saveする

## Next.jsでGoogle OAuthでサインインする用のボタンを作成

- https://supabase.com/docs/guides/auth/server-side/creating-a-client?queryGroups=environment&environment=server
- https://supabase.com/docs/guides/auth/social-login/auth-google?queryGroups=environment&environment=client
- https://developers.google.com/identity/branding-guidelines?hl=ja
  - tailwind形式に書き換えてます

上記のサイトの通りにコードを実装する

![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/611668/52fd2cb2-e099-37a0-361c-0075b3bdc8d8.png)

```utils/supabase/server.tsx
import { cookies } from "next/headers";
import { createServerClient } from "@supabase/ssr";

export const createClient = () => {
  const cookieStore = cookies();

  return createServerClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!,
    {
      cookies: {
        getAll() {
          return cookieStore.getAll();
        },
        setAll(cookiesToSet) {
          try {
            cookiesToSet.forEach(({ name, value, options }) =>
              cookieStore.set(name, value, options),
            );
          } catch {
            // The `setAll` method was called from a Server Component.
            // This can be ignored if you have middleware refreshing
            // user sessions.
          }
        },
      },
    },
  );
};
```


```app/auth/callback/route.ts
import { NextResponse } from 'next/server'
// The client you created from the Server-Side Auth instructions
import { createClient } from '@/utils/supabase/server'

export async function GET(request: Request) {
  const { searchParams, origin } = new URL(request.url)
  const code = searchParams.get('code')
  // if "next" is in param, use it as the redirect URL
  const next = searchParams.get('next') ?? '/'

  if (code) {
    const supabase = createClient()
    const { error } = await supabase.auth.exchangeCodeForSession(code)
    if (!error) {
      const forwardedHost = request.headers.get('x-forwarded-host') // original origin before load balancer
      const isLocalEnv = process.env.NODE_ENV === 'development'
      if (isLocalEnv) {
        // we can be sure that there is no load balancer in between, so no need to watch for X-Forwarded-Host
        return NextResponse.redirect(`${origin}${next}`)
      } else if (forwardedHost) {
        return NextResponse.redirect(`https://${forwardedHost}${next}`)
      } else {
        return NextResponse.redirect(`${origin}${next}`)
      }
    }
  }

  // return the user to an error page with instructions
  return NextResponse.redirect(`${origin}/auth/auth-code-error`)
}
```


```app/signin/page.tsx
"use client";

import { useState } from "react";
import { useSearchParams } from "next/navigation";
import { createClient } from "@/utils/supabase/client";

export default function SignInPage() {
  const [isGoogleLoading, setIsGoogleLoading] = useState<boolean>(false);
  const supabase = createClient();

  const searchParams = useSearchParams();

  const next = searchParams.get("next");

  async function signInWithGoogle() {
    setIsGoogleLoading(true);
    try {
      const { error } = await supabase.auth.signInWithOAuth({
        provider: "google",
        options: {
          redirectTo: `${window.location.origin}/auth/callback${
            next ? `?next=${encodeURIComponent(next)}` : ""
          }`,
        },
      });

      if (error) {
        throw error;
      }
    } catch {
      alert("Please try again.");
      setIsGoogleLoading(false);
    }
  }

  return (
    <button
      className="mt-4 relative flex items-center justify-between w-auto min-w-min max-w-lg py-0 px-3.5 h-10 text-[14px] font-medium text-[#1f1f1f] bg-white border border-gray-200 rounded-md cursor-pointer transition duration-200 hover:border-gray-700 hover:shadow-md focus:shadow-outline active:bg-gray-800 disabled:bg-white/60 disabled:border-[#1f1f1f1f] disabled:cursor-default disabled:opacity-38"
      onClick={signInWithGoogle}
      disabled={isGoogleLoading}
    >
      <div className="absolute inset-0 opacity-0 transition duration-200"></div>
      <div className="flex items-center h-full w-full">
        <div className="w-5 h-5 mr-3">
          <svg
            version="1.1"
            xmlns="http://www.w3.org/2000/svg"
            viewBox="0 0 48 48"
            xmlnsXlink="http://www.w3.org/1999/xlink"
            className="block"
          >
            <path
              fill="#EA4335"
              d="M24 9.5c3.54 0 6.71 1.22 9.21 3.6l6.85-6.85C35.9 2.38 30.47 0 24 0 14.62 0 6.51 5.38 2.56 13.22l7.98 6.19C12.43 13.72 17.74 9.5 24 9.5z"
            ></path>
            <path
              fill="#4285F4"
              d="M46.98 24.55c0-1.57-.15-3.09-.38-4.55H24v9.02h12.94c-.58 2.96-2.26 5.48-4.78 7.18l7.73 6c4.51-4.18 7.09-10.36 7.09-17.65z"
            ></path>
            <path
              fill="#FBBC05"
              d="M10.53 28.59c-.48-1.45-.76-2.99-.76-4.59s.27-3.14.76-4.59l-7.98-6.19C.92 16.46 0 20.12 0 24c0 3.88.92 7.54 2.56 10.78l7.97-6.19z"
            ></path>
            <path
              fill="#34A853"
              d="M24 48c6.48 0 11.93-2.13 15.89-5.81l-7.73-6c-2.15 1.45-4.92 2.3-8.16 2.3-6.26 0-11.57-4.22-13.47-9.91l-7.98 6.19C6.51 42.62 14.62 48 24 48z"
            ></path>
            <path fill="none" d="M0 0h48v48H0z"></path>
          </svg>
        </div>
        <span className="flex-grow overflow-hidden text-ellipsis m-0 text-[14px] leading-[16px] tracking-[-0.1px] text-inherit font-bold">
          Sign in with Google
        </span>
      </div>
    </button>
  );
}
```