use serde::{Deserialize, Serialize};

use crate::error::SfAuthError;

const VALIDATION_URL: &str = "https://snazzyfellas.com/api/redirect/validate";

/// Request payload for validation API
#[derive(Debug, Serialize)]
struct ValidationRequest {
    user_id: String,
    key: String,
}

/// Response from validation API
#[derive(Debug, Deserialize)]
struct ValidationResponse {
    valid: bool,
    user_id: String,
}

/// Validates user credentials with the SF authentication server.
///
/// Makes a POST request to the validation endpoint with the user_id and key.
/// Returns `Ok(user_id)` if validation succeeds, or an error otherwise.
///
/// # Arguments
///
/// * `user_id` - The user ID to validate
/// * `key` - The authentication key to validate
///
/// # Errors
///
/// Returns an error if:
/// - The HTTP request fails
/// - The validation response indicates invalid credentials
/// - The returned user_id doesn't match the requested user_id
pub(crate) async fn validate_user(user_id: String, key: String) -> Result<String, SfAuthError> {
    let client = reqwest::Client::new();

    let request_payload = ValidationRequest {
        user_id: user_id.clone(),
        key,
    };

    let response = client
        .post(VALIDATION_URL)
        .json(&request_payload)
        .send()
        .await?;

    let validation_response: ValidationResponse = response.json().await?;

    // Check if validation succeeded
    if !validation_response.valid {
        return Err(SfAuthError::ValidationFailed);
    }

    // Verify that the returned user_id matches what we sent
    if validation_response.user_id != user_id {
        return Err(SfAuthError::UserIdMismatch);
    }

    Ok(validation_response.user_id)
}