use crate::database::{Storage, StorageError};
use axum::{
    extract::{Host, Path, Query},
    http::{StatusCode, Uri},
    response::IntoResponse,
    Extension,
};
use futures_util::FutureExt;
use serde::Deserialize;
use std::convert::TryInto;
use tracing::{debug, error};
//pub mod login;
pub mod onboarding;

use kittybox_templates::{Entry, ErrorPage, Feed, MainPage, Template, VCard, POSTS_PER_PAGE};

#[derive(Debug, Deserialize)]
pub struct QueryParams {
    after: Option<String>,
}

#[derive(Debug)]
struct FrontendError {
    msg: String,
    source: Option<Box<dyn std::error::Error + Send + Sync + 'static>>,
    code: StatusCode,
}

impl FrontendError {
    pub fn with_code<C>(code: C, msg: &str) -> Self
    where
        C: TryInto<StatusCode>,
    {
        Self {
            msg: msg.to_string(),
            source: None,
            code: code.try_into().unwrap_or(StatusCode::INTERNAL_SERVER_ERROR),
        }
    }
    pub fn msg(&self) -> &str {
        &self.msg
    }
    pub fn code(&self) -> StatusCode {
        self.code
    }
}

impl From<StorageError> for FrontendError {
    fn from(err: StorageError) -> Self {
        Self {
            msg: "Database error".to_string(),
            source: Some(Box::new(err)),
            code: StatusCode::INTERNAL_SERVER_ERROR,
        }
    }
}

impl std::error::Error for FrontendError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        self.source
            .as_ref()
            .map(|e| e.as_ref() as &(dyn std::error::Error + 'static))
    }
}

impl std::fmt::Display for FrontendError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.msg)
    }
}

async fn get_post_from_database<S: Storage>(
    db: &S,
    url: &str,
    after: Option<String>,
    user: &Option<String>,
) -> std::result::Result<serde_json::Value, FrontendError> {
    match db
        .read_feed_with_limit(url, &after, POSTS_PER_PAGE, user)
        .await
    {
        Ok(result) => match result {
            Some(post) => Ok(post),
            None => Err(FrontendError::with_code(
                StatusCode::NOT_FOUND,
                "Post not found in the database",
            )),
        },
        Err(err) => match err.kind() {
            crate::database::ErrorKind::PermissionDenied => {
                // TODO: Authentication
                if user.is_some() {
                    Err(FrontendError::with_code(
                        StatusCode::FORBIDDEN,
                        "User authenticated AND forbidden to access this resource",
                    ))
                } else {
                    Err(FrontendError::with_code(
                        StatusCode::UNAUTHORIZED,
                        "User needs to authenticate themselves",
                    ))
                }
            }
            _ => Err(err.into()),
        },
    }
}

#[tracing::instrument(skip(db))]
pub async fn homepage<D: Storage>(
    Host(host): Host,
    Query(query): Query<QueryParams>,
    Extension(db): Extension<D>,
) -> impl IntoResponse {
    let user = None; // TODO authentication
    let path = format!("https://{}/", host);
    let feed_path = format!("https://{}/feeds/main", host);

    match tokio::try_join!(
        get_post_from_database(&db, &path, None, &user),
        get_post_from_database(&db, &feed_path, query.after, &user)
    ) {
        Ok((hcard, hfeed)) => {
            // Here, we know those operations can't really fail
            // (or it'll be a transient failure that will show up on
            // other requests anyway if it's serious...)
            //
            // btw is it more efficient to fetch these in parallel?
            let (blogname, channels) = tokio::join!(
                db.get_setting(crate::database::Settings::SiteName, &path)
                    .map(|i| i.unwrap_or_else(|_| "Kittybox".to_owned())),
                db.get_channels(&path).map(|i| i.unwrap_or_default())
            );
            // Render the homepage
            (
                StatusCode::OK,
                [(
                    axum::http::header::CONTENT_TYPE,
                    r#"text/html; charset="utf-8""#,
                )],
                Template {
                    title: &blogname,
                    blog_name: &blogname,
                    feeds: channels,
                    user,
                    content: MainPage {
                        feed: &hfeed,
                        card: &hcard,
                    }
                    .to_string(),
                }
                .to_string(),
            )
        }
        Err(err) => {
            if err.code == StatusCode::NOT_FOUND {
                debug!("Transferring to onboarding...");
                // Transfer to onboarding
                (
                    StatusCode::FOUND,
                    [(axum::http::header::LOCATION, "/.kittybox/onboarding")],
                    String::default(),
                )
            } else {
                error!("Error while fetching h-card and/or h-feed: {}", err);
                // Return the error
                let (blogname, channels) = tokio::join!(
                    db.get_setting(crate::database::Settings::SiteName, &path)
                        .map(|i| i.unwrap_or_else(|_| "Kittybox".to_owned())),
                    db.get_channels(&path).map(|i| i.unwrap_or_default())
                );

                (
                    err.code(),
                    [(
                        axum::http::header::CONTENT_TYPE,
                        r#"text/html; charset="utf-8""#,
                    )],
                    Template {
                        title: &blogname,
                        blog_name: &blogname,
                        feeds: channels,
                        user,
                        content: ErrorPage {
                            code: err.code(),
                            msg: Some(err.msg().to_string()),
                        }
                        .to_string(),
                    }
                    .to_string(),
                )
            }
        }
    }
}

#[tracing::instrument(skip(db))]
pub async fn catchall<D: Storage>(
    Extension(db): Extension<D>,
    Host(host): Host,
    Query(query): Query<QueryParams>,
    uri: Uri,
) -> impl IntoResponse {
    let user = None; // TODO authentication
    let path = url::Url::parse(&format!("https://{}/", host))
        .unwrap()
        .join(uri.path())
        .unwrap();

    match get_post_from_database(&db, path.as_str(), query.after, &user).await {
        Ok(post) => {
            let (blogname, channels) = tokio::join!(
                db.get_setting(crate::database::Settings::SiteName, &host)
                    .map(|i| i.unwrap_or_else(|_| "Kittybox".to_owned())),
                db.get_channels(&host).map(|i| i.unwrap_or_default())
            );
            // Render the homepage
            (
                StatusCode::OK,
                [(
                    axum::http::header::CONTENT_TYPE,
                    r#"text/html; charset="utf-8""#,
                )],
                Template {
                    title: &blogname,
                    blog_name: &blogname,
                    feeds: channels,
                    user,
                    content: match post.pointer("/type/0").and_then(|i| i.as_str()) {
                        Some("h-entry") => Entry { post: &post }.to_string(),
                        Some("h-feed") => Feed { feed: &post }.to_string(),
                        Some("h-card") => VCard { card: &post }.to_string(),
                        unknown => {
                            unimplemented!("Template for MF2-JSON type {:?}", unknown)
                        }
                    },
                }
                .to_string(),
            )
        }
        Err(err) => {
            let (blogname, channels) = tokio::join!(
                db.get_setting(crate::database::Settings::SiteName, &host)
                    .map(|i| i.unwrap_or_else(|_| "Kittybox".to_owned())),
                db.get_channels(&host).map(|i| i.unwrap_or_default())
            );
            (
                err.code(),
                [(
                    axum::http::header::CONTENT_TYPE,
                    r#"text/html; charset="utf-8""#,
                )],
                Template {
                    title: &blogname,
                    blog_name: &blogname,
                    feeds: channels,
                    user,
                    content: ErrorPage {
                        code: err.code(),
                        msg: Some(err.msg().to_owned()),
                    }
                    .to_string(),
                }
                .to_string(),
            )
        }
    }
}

const STYLE_CSS: &[u8] = include_bytes!("./style.css");
// XXX const path handling is ugly, and concat!() doesn't take
// constants, only literals... how annoying!
//
// This might break compiling on inferior operating systems that use
// backslashes as their path separator
const ONBOARDING_JS: &[u8] = include_bytes!(concat!(
    env!("OUT_DIR"), "/", "kittybox_js", "/", "onboarding.js"
));
const ONBOARDING_CSS: &[u8] = include_bytes!("./onboarding.css");
const INDIEAUTH_JS: &[u8] = include_bytes!(concat!(
    env!("OUT_DIR"), "/", "kittybox_js", "/", "indieauth.js"
));

const MIME_JS: &str = "application/javascript";
const MIME_CSS: &str = "text/css";
const MIME_PLAIN: &str = "text/plain";

pub async fn statics(Path(name): Path<String>) -> impl IntoResponse {
    use axum::http::header::CONTENT_TYPE;

    match name.as_str() {
        "style.css" => (StatusCode::OK, [(CONTENT_TYPE, MIME_CSS)], STYLE_CSS),
        "onboarding.js" => (StatusCode::OK, [(CONTENT_TYPE, MIME_JS)], ONBOARDING_JS),
        "onboarding.css" => (StatusCode::OK, [(CONTENT_TYPE, MIME_CSS)], ONBOARDING_CSS),
        "indieauth.js" => (StatusCode::OK, [(CONTENT_TYPE, MIME_JS)], INDIEAUTH_JS),
        _ => (
            StatusCode::NOT_FOUND,
            [(CONTENT_TYPE, MIME_PLAIN)],
            "not found".as_bytes(),
        ),
    }
}