worker-rsからSlackに投稿する

use worker::*;
use reqwest;
use std::collections::HashMap;

async fn post_slack(channel: &str, token: &str, message: &str) -> Result<Response> {
    let url = "https://slack.com/api/chat.postMessage";

    let mut payload = HashMap::new();
    payload.insert("channel", channel);
    payload.insert("text", message);
    let payload_json = serde_json::to_string(&payload).unwrap();

    let client = reqwest::Client::new();
    let response =  client
        .post(url)
        .header("Content-Type", "application/json; charset=UTF-8")
        .header("Authorization", &format!("Bearer {}", token))
        .body(payload_json)
        .send()
        .await
        .map_err(|e| Error::from(format!("Request failed: {:?}", e)))?;

    let body = response.text().await
        .map_err(|e| Error::from(format!("Failed to read response body: {:?}", e)))?;

    Ok(Response::ok(body)?)
}

#[event(fetch)]
async fn main(req: Request, env: Env, ctx: Context) -> Result<Response> {
    let channel = env.var("SLACK_CHANNEL")?.to_string();
    let oauth_token = env.var("SLACK_OAUTH_TOKEN")?.to_string();  

    post_slack(&channel, &oauth_token, "Hello from Cloudflare Workers .").await?; 

    Ok(Response::ok("hello")?) 
}