mod comment;
pub use comment::*;

mod database;
pub use database::*;

mod error;
pub use error::*;

use actix_cors::Cors;
use actix_web::{get, post, web, App, HttpRequest, HttpResponse, HttpServer};
use clap::Parser;
use sanitize_html::{rules::predefined::DEFAULT, sanitize_str};
use scraper::{Html, Selector};
use serde::Deserialize;
use std::fs::File;
use std::sync::Mutex;
use std::{collections::HashMap, sync::MutexGuard};
use validator::Validate;
use webhook::client::WebhookClient;

struct AppState {
    databases: HashMap<String, Mutex<Database>>,
}

impl AppState {
    fn get_db<'a>(&'a self, origin: &str) -> Result<MutexGuard<'a, Database>, Error> {
        match self.databases.get(origin) {
            Some(database) => Ok(database.lock()?),
            None => return Err(Error::InvalidOrigin),
        }
    }
}

fn trim_protocol(url: &str) -> String {
    url.replace("http://", "").replace("https://", "")
}

fn get_request_origin(request: &HttpRequest) -> Result<String, Error> {
    match request.head().headers().get("Origin") {
        Some(origin) => match origin.to_str() {
            Ok(origin) => Ok(trim_protocol(origin)),
            Err(_) => Err(Error::InvalidOrigin),
        },
        None => Err(Error::InvalidOrigin),
    }
}

#[derive(Default, Parser)]
#[clap(author, version, about)]
struct Arguments {
    #[clap(default_value = "soudan.yaml", help = "Set configuration file")]
    config: String,
    #[clap(
        short,
        long,
        default_value = "8080",
        help = "Set port where HTTP requests will be received"
    )]
    port: u16,
    #[clap(
        short,
        long,
        help = "Run in testing mode, with in-memory database(s) and permissive CORS policy"
    )]
    testing: bool,
}

async fn _get_comments(
    data: web::Data<AppState>,
    request: HttpRequest,
    content_id: web::Path<String>,
) -> Result<Vec<Comment>, Error> {
    let origin = get_request_origin(&request)?;
    web::block(move || Ok(data.get_db(&origin)?.get_comments(&content_id)?)).await?
}

#[get("/{content_id}")]
async fn get_comments(
    data: web::Data<AppState>,
    request: HttpRequest,
    content_id: web::Path<String>,
) -> HttpResponse {
    match _get_comments(data, request, content_id).await {
        Ok(comments) => HttpResponse::Ok().json(comments),
        Err(err) => err.to_http_response(),
    }
}

#[derive(Deserialize)]
struct PostCommentsRequest {
    url: String,
    comment: Comment,
}

async fn _post_comment(
    data: web::Data<AppState>,
    request: HttpRequest,
    bytes: web::Bytes,
) -> Result<(), Error> {
    let PostCommentsRequest { url, comment } = {
        let mut req =
            serde_json::from_str::<PostCommentsRequest>(&String::from_utf8(bytes.to_vec())?)?;
        req.comment.text = sanitize_str(&DEFAULT, &req.comment.text)?.replace("&gt;", ">"); // required for markdown quotes
        if let Some(ref mut author) = req.comment.author {
            *author = sanitize_str(&DEFAULT, &author)?;
        }
        req
    };
    comment.validate()?;
    let origin = get_request_origin(&request)?;
    // Check to see if provided URL is in scope.
    // This is to prevent malicious requests that try to get server to fetch external websites.
    // (requires loop because "labels on blocks are unstable")
    // https://github.com/rust-lang/rust/issues/48594
    'outer: loop {
        for site_root in data.databases.keys() {
            if site_root.eq(&origin) && trim_protocol(&url).starts_with(site_root) {
                break 'outer;
            }
        }
        return Err(Error::InvalidUrl);
    }
    let page_data = match get_page_data(&url).await? {
        Some(page_data) => {
            if page_data.content_id != comment.content_id {
                return Err(Error::InvalidContentId);
            }
            page_data
        }
        None => return Err(Error::InvalidUrl), // e.g. 404
    };
    // TODO: Use web::block
    // Create comment in database
    let database = data.get_db(&origin)?;
    if comment.author.is_none() && database.settings.name_required {
        return Err(Error::NameRequired);
    }
    if comment.email.is_none() && database.settings.email_required {
        return Err(Error::EmailRequired);
    }
    if let Some(parent) = comment.parent {
        'outer2: loop {
            let comments = database.get_comments(&comment.content_id)?;
            for other_comment in comments.iter() {
                if other_comment.id.unwrap() == parent {
                    if other_comment.parent.is_none() {
                        break 'outer2;
                    }
                    break;
                }
            }
            return Err(Error::InvalidParent);
        }
    }
    database.create_comment(&comment)?;
    // Send notification webhook
    if let Some(webhook) = &database.settings.webhook {
        let client = WebhookClient::new(&webhook);
        client.send(|message| {
            let author = match &comment.author {
                Some(author) => &author,
                None => "Annonymous",
            };
            message
                .username(&author)
                .avatar_url(&format!(
                    "https://www.gravatar.com/avatar/{}?d=mp",
                    get_gravatar(&comment.email)
                ))
                .embed(|embed| embed
                    .title(&format!("New comment on {}", page_data.content_id))
                    .description(&comment.text)
                    .field("Link", &format!("{}#{}",
                        &url // Remove any trailing hash from URL
                            .split("#")
                            .next()
                            .unwrap(),
                        &database // Get ID of just created comment
                            .get_comments(&page_data.content_id)
                            .unwrap()
                            .first() // returned in reverse chronological order
                            .unwrap()
                            .id
                            .unwrap()
                        ), true)
                    .field("Content ID", &page_data.content_id, true)
                    .field("Email", match &comment.email {
                        Some(email) => email,
                        None => "None",
                    }, false)
                )
            }
        ).await.unwrap();
    }

    Ok(())
}

#[post("/")]
async fn post_comment(
    data: web::Data<AppState>,
    request: HttpRequest,
    bytes: web::Bytes,
) -> HttpResponse {
    match _post_comment(data, request, bytes).await {
        Ok(_) => HttpResponse::Ok().finish(),
        Err(err) => err.to_http_response(),
    }
}

// Contains all page details stored in meta tags.
// Currently, only content_id, but this is wrapped in this struct
// to make adding other meta tags, such as locked comments, in the future
struct PageData {
    content_id: String,
}

async fn get_page_data(url: &str) -> Result<Option<PageData>, reqwest::Error> {
    let response = reqwest::get(url).await?;
    if !response.status().is_success() {
        return Ok(None);
    }
    let content = response.text_with_charset("utf-8").await?;
    let document = Html::parse_document(&content);
    let get_meta = |name: &str| -> Option<String> {
        let selector = Selector::parse(&format!("meta[name=\"{}\"]", name)).unwrap();
        match document.select(&selector).next() {
            Some(element) => match element.value().attr("content") {
                Some(value) => Some(value.to_owned()),
                None => return None,
            },
            None => return None,
        }
    };
    return Ok(Some(PageData {
        content_id: match get_meta("soudan-content-id") {
            Some(id) => id,
            None => return Ok(None),
        },
    }));
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    let arguments = Arguments::parse();
    let database_settings: HashMap<String, DatabaseSettings> =
        match serde_yaml::from_reader(File::open(arguments.config)?) {
            Ok(settings) => settings,
            Err(_) => {
                return Err(std::io::Error::new(
                    std::io::ErrorKind::Other,
                    "invalid config file",
                ))
            }
        };
    let mut databases = HashMap::new();
    for (site, settings) in database_settings.iter() {
        databases.insert(
            site.to_owned(),
            Mutex::new(Database::new(arguments.testing, site, settings.clone()).unwrap()),
        );
    }
    let port = arguments.port;
    let state = web::Data::new(AppState { databases });
    HttpServer::new(move || {
        App::new()
            .service(get_comments)
            .service(post_comment)
            .app_data(state.clone())
            // Issue with CORS on POST requests,
            // keeping permissive for now
            .wrap(
                Cors::permissive(), /* if arguments.testing {
                                        Cors::permissive()
                                    } else {
                                        let mut cors = Cors::default()
                                           .allowed_methods(vec!["GET", "POST"]);
                                        for domain in arguments.sites.iter() {
                                            cors = cors.allowed_origin(domain);
                                        }
                                        cors
                                    } */
            )
    })
    .bind(("127.0.0.1", port))?
    .run()
    .await
}