/**
 * Comments generator
 * POST /comment - submits a comment
 * 
 * GET /form - generate html comment form
 * GET /comment - gets html fragment with comments
 * both accept a query parameter ?page=<url>
 */ 
 
use askama::Template;
use axum::{
    extract::{Query, Form, State},
    response::{Redirect,Html},
    http::StatusCode,
    routing::get,
    Router,
};
use lettre::{
    AsyncSmtpTransport, AsyncTransport, Message, Tokio1Executor,
    transport::smtp::authentication::Credentials
};
use serde::Deserialize;
use sqlx::{
    postgres::{PgPool, PgPoolOptions},
    types::{
        time::OffsetDateTime,
        uuid::Uuid,
    },
};
use std::{net::SocketAddr, time::Duration};


// Useful global thingies
#[derive(Clone)]
struct Ctx {
    pool: PgPool,
    base_path: String,
    mail_opts: Option<MailCtx>,
}

#[derive(Clone)]
struct MailCtx {
    notification_address: String,
    smtp_server: String,
    smtp_credentials: Credentials,
}

#[tokio::main]
async fn main() {
    let base_path = std::env::var("BASE_PATH")
        .unwrap_or_else(|_| "/api".to_string());
        
    let db_connection_str = std::env::var("DATABASE_URL")
        .unwrap_or_else(|_| "postgres://postgres:password@localhost".to_string());

    let notification_address = std::env::var("NOTIFICATION_ADDRESS").ok();
    let mail_opts = notification_address.map(|na| {
        let smtp_server = std::env::var("SMTP_SERVER").expect("SMTP_SERVER  not supplied!");
        let smtp_username = std::env::var("SMTP_USERNAME").expect("SMTP_USERNAME not supplied!");
        let smtp_password = std::env::var("SMTP_PASSWORD").expect("SMTP_PASSWORD not supplied!");
        MailCtx{
            smtp_server: smtp_server,
            smtp_credentials: Credentials::new(smtp_username, smtp_password),
            notification_address: na,
        }
    });

    let pool = PgPoolOptions::new()
        .max_connections(5)
        .connect_timeout(Duration::from_secs(3))
        .connect(&db_connection_str)
        .await
        .expect("can't connect to database");
    sqlx::migrate!()
        .run(&pool)
        .await
        .expect("failed to run migrations");
    
    let ctx = Ctx {pool, base_path: base_path.clone(), mail_opts};

    let app = Router::new()
        .nest(&base_path, Router::new()
            .route(
                "/form",
                get(get_form),
            )
            .route(
                "/comment",
                get(get_comments).post(post_comments),
            )
            .with_state(ctx));

    let addr = SocketAddr::from(([127, 0, 0, 1], 5678));
    axum::Server::bind(&addr)
        .serve(app.into_make_service())
        .await
        .unwrap();
}

#[derive(Deserialize)]
struct UrlQuery {
    url: String
}

#[derive(Template)]
#[template(path = "form.html")]
struct CommentForm {
    url: String,
    capcha_question: String,
    capcha_id: Uuid,
    base_path: String,
}

async fn get_form(
    State(ctx): State<Ctx>,
    Query(uq): Query<UrlQuery>
) -> Result<Html<String>, (StatusCode, String)> {
    let capcha = sqlx::query!("select id, question from capchas order by random() limit 1")
        .fetch_one(&ctx.pool)
        .await
        .map_err(internal_error)?;
    let c = CommentForm{url: uq.url, capcha_question: capcha.question, capcha_id: capcha.id, base_path: ctx.base_path};
    let res = c.render().map_err(internal_error)?;
    Ok(Html(res))
}

#[derive(Template)]
#[template(path = "comments.html")]
struct Comments {
    comments: Vec<Comment>,
}
struct Comment {
    author: String,
    comment: String,
    ts: OffsetDateTime,
}

async fn get_comments(
    State(ctx): State<Ctx>,
    Query(uq): Query<UrlQuery>) -> Result<Html<String>, (StatusCode,String)> {
    let comments = sqlx::query!("select author,comment,ts from comments where url = $1 order by ts", uq.url)
        .fetch_all(&ctx.pool)
        .await
        .map_err(internal_error)?;
    let render_comments: Vec<Comment> = comments.into_iter().map(|comment| {
        Comment {
            author: comment.author,
            comment: comment.comment,
            ts: comment.ts,
        }
    }).collect();
    let c = Comments{comments: render_comments};
    let res = c.render().map_err(internal_error)?;
    Ok(Html(res))
}

#[derive(Deserialize)]
struct PostComment {
    url: String,
    author: String,
    comment: String,
    capcha_id: String,
    capcha_answer: String,
}

struct CapchaAnswer {
    answer:String
}

#[derive(Template)]
#[template(path = "notification.txt")]
struct Notification<'a> {
    url: &'a str,
    comment: &'a str,
    author: &'a str,
}

async fn post_comments(
    State(ctx): State<Ctx>,
    Form(post_comment): Form<PostComment>) -> Result<Redirect,(StatusCode,String)> {
    let capcha_id: Uuid = post_comment.capcha_id.parse()
        .map_err(|_| {(StatusCode::BAD_REQUEST, "Invalid capcha_id".to_string())})?;
    let ans: CapchaAnswer = sqlx::query_as!(CapchaAnswer, "select answer from capchas where id = $1", capcha_id)
        .fetch_one(&ctx.pool)
        .await
        .map_err(internal_error)?;
    if post_comment.capcha_answer != ans.answer {
        return Err((StatusCode::BAD_REQUEST, "Capcha was wrong!".to_string()));
    }
    sqlx::query!("insert into comments(url,author,comment) values($1, $2, $3)", post_comment.url, post_comment.author, post_comment.comment)
        .execute(&ctx.pool)
        .await
        .map_err(internal_error)?;

    if let Some(mail_opts) = ctx.mail_opts {
        let mail_body = Notification{
            url: &post_comment.url,
            author: &post_comment.author,
            comment: &post_comment.comment
        }.render().unwrap();
        let email = Message::builder()
            // TODO should be a config value
            .from("Comments Service <comments@mfashby.net>".parse().unwrap())
            .to(mail_opts.notification_address.parse().unwrap())
            .subject(format!("New comment on {}", post_comment.url))
            .body(mail_body)
            .unwrap();
        let mailer: AsyncSmtpTransport<Tokio1Executor> =
            AsyncSmtpTransport::<Tokio1Executor>::relay(&mail_opts.smtp_server)
                .unwrap()
                .credentials(mail_opts.smtp_credentials)
                .build();
        match mailer.send(email).await {
            Ok(_) => (),
            Err(e) => eprintln!("Could not send email: {:?}", e),
        }
    };
    
    Ok(Redirect::temporary(&post_comment.url))
}

fn internal_error<E>(err: E) -> (StatusCode, String)
where
    E: std::error::Error,
{
    (StatusCode::INTERNAL_SERVER_ERROR, err.to_string())
}