use anyhow::{Context, Result};
use serde::Deserialize;

use super::{OAuthConfig, OAuthUserInfo};

#[derive(Deserialize)]
struct TokenResponse {
    access_token: String,
    #[allow(dead_code)]
    token_type: String,
    #[allow(dead_code)]
    id_token: Option<String>,
}

#[derive(Deserialize)]
struct UserInfo {
    sub: String,
    email: Option<String>,
    name: Option<String>,
    picture: Option<String>,
}

/// Exchange authorization code for tokens and fetch user profile.
pub async fn exchange_code(
    client: &reqwest::Client,
    config: &OAuthConfig,
    code: &str,
) -> Result<OAuthUserInfo> {
    let token_resp: TokenResponse = client
        .post("https://oauth2.googleapis.com/token")
        .form(&[
            ("code", code),
            ("client_id", &config.client_id),
            ("client_secret", &config.client_secret),
            ("redirect_uri", &config.redirect_uri),
            ("grant_type", "authorization_code"),
        ])
        .send()
        .await
        .context("failed to exchange Google code")?
        .error_for_status()
        .context("Google token endpoint error")?
        .json()
        .await
        .context("failed to parse Google token response")?;

    let user: UserInfo = client
        .get("https://openidconnect.googleapis.com/v1/userinfo")
        .bearer_auth(&token_resp.access_token)
        .send()
        .await
        .context("failed to fetch Google userinfo")?
        .error_for_status()
        .context("Google userinfo endpoint error")?
        .json()
        .await
        .context("failed to parse Google userinfo")?;

    Ok(OAuthUserInfo {
        provider: "google".to_string(),
        provider_id: user.sub,
        email: user.email,
        name: user.name,
        avatar_url: user.picture,
    })
}