use crate::Result;
use axum::extract::State;
use axum::routing::post;
use axum::Form;
use axum::Router;
use axum::{
    http::StatusCode,
    response::{IntoResponse, Response},
};
use chrono::Utc;
use serde::Deserialize;
use sqlx::PgPool;
use unicode_segmentation::UnicodeSegmentation;
use uuid::Uuid;

#[derive(Debug, Deserialize)]
struct FormData {
    email: String,
    name: String,
}

/// Returns `true` if the input satisfies all our validation constraints
/// on subscriber names, `false` otherwise.
pub fn is_valid_name(s: &str) -> bool {
    // `.trim()` returns a view over the input `s` without trailing
    // whitespace-like characters.
    // `.is_empty` checks if the view contains any character.
    let is_empty_or_whitespace = s.trim().is_empty();

    // A grapheme is defined by the Unicode standard as a "user-perceived"
    // character: `å` is a single grapheme, but it is composed of two characters
    // (`a` and `̊`).
    //
    // `graphemes` returns an iterator over the graphemes in the input `s`.
    // `true` specifies that we want to use the extended grapheme definition set,
    // the recommended one.
    let is_too_long = s.graphemes(true).count() > 256;

    // Iterate over all characters in the input `s` to check if any of them matches
    // one of the characters in the forbidden array.
    let forbidden_characters = ['/', '(', ')', '"', '<', '>', '\\', '{', '}'];
    let contains_forbidden_characters = s.chars().any(|g| forbidden_characters.contains(&g));

    // Return `false` if any of our conditions have been violated
    !(is_empty_or_whitespace || is_too_long || contains_forbidden_characters)
}

#[tracing::instrument(
    name = "Adding a new subscriber",
    skip(form, pool),
    fields(
        request_id = %Uuid::new_v4(),
        subscriber_email = %form.email,
        subscriber_name = %form.name
    )
)]
pub async fn subscribe(State(pool): State<PgPool>, Form(form): Form<FormData>) -> Response {
    if !is_valid_name(&form.name) {
        tracing::error!("Failed to add subscriber to the database");
        return (StatusCode::BAD_REQUEST, "Invalid name").into_response();
    }
    match insert_subscriber(&pool, &form).await {
        Ok(_) => {
            tracing::info!("Subscriber added to the database");
            return (StatusCode::OK,).into_response();
        }
        Err(_) => {
            tracing::error!("Failed to add subscriber to the database");
            return (StatusCode::INTERNAL_SERVER_ERROR, "Something went wrong").into_response();
        }
    }
}

#[tracing::instrument(
    name = "Saving new subscriber details in the database",
    skip(form, pool)
)]
pub async fn insert_subscriber(pool: &PgPool, form: &FormData) -> Result<()> {
    let _ = sqlx::query!(
        r#"
            INSERT INTO subscriptions (id, email, name, subscribed_at)
            VALUES ($1, $2, $3, $4)
            "#,
        Uuid::new_v4(),
        form.email,
        form.name,
        Utc::now()
    )
    // We use `get_ref` to get an immutable reference to the `PgConnection`
    // wrapped by `web::Data`.
    .execute(pool)
    .await
    .map_err(|e| {
        tracing::error!("Failed to execute query: {:?}", e);
        e
    });
    Ok(())
}

pub fn routes_subscriptions(pool: PgPool) -> Router {
    Router::new()
        .route("/subscriptions", post(subscribe))
        .with_state(pool)
}