use actix_form_data::{Field, Form, Value};
use actix_web::{
    guard,
    http::header::{CacheControl, CacheDirective, LastModified, Range, ACCEPT_RANGES},
    web, App, HttpResponse, HttpResponseBuilder, HttpServer,
};
use awc::Client;
use futures_util::{
    stream::{empty, once},
    Stream, TryStreamExt,
};
use once_cell::sync::Lazy;
use std::{
    collections::BTreeSet,
    future::ready,
    path::PathBuf,
    sync::atomic::{AtomicU64, Ordering},
    time::SystemTime,
};
use tokio::{io::AsyncReadExt, sync::Semaphore};
use tracing::{debug, info, instrument};
use tracing_actix_web::TracingLogger;
use tracing_awc::Tracing;
use tracing_futures::Instrument;

mod concurrent_processor;
mod config;
mod details;
mod either;
mod error;
mod exiftool;
mod ffmpeg;
mod file;
mod init_tracing;
mod magick;
mod middleware;
mod migrate;
mod process;
mod processor;
mod queue;
mod range;
mod repo;
mod serde_str;
mod store;
mod stream;
mod tmp_file;
mod upload_manager;
mod validate;

use self::{
    concurrent_processor::CancelSafeProcessor,
    config::{Configuration, ImageFormat, Operation},
    details::Details,
    either::Either,
    error::{Error, UploadError},
    init_tracing::init_tracing,
    magick::details_hint,
    middleware::{Deadline, Internal},
    migrate::LatestDb,
    repo::{Alias, DeleteToken, Repo},
    serde_str::Serde,
    store::{file_store::FileStore, object_store::ObjectStore, Store},
    stream::StreamLimit,
    upload_manager::{UploadManager, UploadManagerSession},
};

const MEGABYTES: usize = 1024 * 1024;
const MINUTES: u32 = 60;
const HOURS: u32 = 60 * MINUTES;
const DAYS: u32 = 24 * HOURS;

static DO_CONFIG: Lazy<(Configuration, Operation)> =
    Lazy::new(|| config::configure().expect("Failed to configure"));
static CONFIG: Lazy<Configuration> = Lazy::new(|| DO_CONFIG.0.clone());
static OPERATION: Lazy<Operation> = Lazy::new(|| DO_CONFIG.1.clone());
static PROCESS_SEMAPHORE: Lazy<Semaphore> =
    Lazy::new(|| Semaphore::new(num_cpus::get().saturating_sub(1).max(1)));

/// Handle responding to succesful uploads
#[instrument(name = "Uploaded files", skip(value, manager))]
async fn upload<S: Store>(
    value: Value<UploadManagerSession<S>>,
    manager: web::Data<UploadManager>,
    store: web::Data<S>,
) -> Result<HttpResponse, Error> {
    let images = value
        .map()
        .and_then(|mut m| m.remove("images"))
        .and_then(|images| images.array())
        .ok_or(UploadError::NoFiles)?;

    let mut files = Vec::new();
    let images = images
        .into_iter()
        .filter_map(|i| i.file())
        .collect::<Vec<_>>();
    for image in &images {
        if let Some(alias) = image.result.alias() {
            info!("Uploaded {} as {:?}", image.filename, alias);
            let delete_token = image.result.delete_token().await?;

            let identifier = manager.identifier_from_alias::<S>(alias).await?;
            let details = manager.details(&identifier).await?;

            let details = if let Some(details) = details {
                debug!("details exist");
                details
            } else {
                debug!("generating new details from {:?}", identifier);
                let hint = details_hint(alias);
                let new_details =
                    Details::from_store((**store).clone(), identifier.clone(), hint).await?;
                debug!("storing details for {:?}", identifier);
                manager.store_details(&identifier, &new_details).await?;
                debug!("stored");
                new_details
            };

            files.push(serde_json::json!({
                "file": alias.to_string(),
                "delete_token": delete_token.to_string(),
                "details": details,
            }));
        }
    }

    for image in images {
        image.result.succeed();
    }
    Ok(HttpResponse::Created().json(&serde_json::json!({
        "msg": "ok",
        "files": files
    })))
}

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

/// download an image from a URL
#[instrument(name = "Downloading file", skip(client, manager))]
async fn download<S: Store>(
    client: web::Data<Client>,
    manager: web::Data<UploadManager>,
    store: web::Data<S>,
    query: web::Query<UrlQuery>,
) -> Result<HttpResponse, Error> {
    let res = client.get(&query.url).send().await?;

    if !res.status().is_success() {
        return Err(UploadError::Download(res.status()).into());
    }

    let stream = res
        .map_err(Error::from)
        .limit((CONFIG.media.max_file_size * MEGABYTES) as u64);

    futures_util::pin_mut!(stream);

    let permit = PROCESS_SEMAPHORE.acquire().await?;
    let session = manager
        .session((**store).clone())
        .upload(CONFIG.media.enable_silent_video, stream)
        .await?;
    let alias = session.alias().unwrap().to_owned();
    drop(permit);
    let delete_token = session.delete_token().await?;

    let identifier = manager.identifier_from_alias::<S>(&alias).await?;

    let details = manager.details(&identifier).await?;

    let details = if let Some(details) = details {
        details
    } else {
        let hint = details_hint(&alias);
        let new_details = Details::from_store((**store).clone(), identifier.clone(), hint).await?;
        manager.store_details(&identifier, &new_details).await?;
        new_details
    };

    session.succeed();
    Ok(HttpResponse::Created().json(&serde_json::json!({
        "msg": "ok",
        "files": [{
            "file": alias.to_string(),
            "delete_token": delete_token.to_string(),
            "details": details,
        }]
    })))
}

/// Delete aliases and files
#[instrument(name = "Deleting file", skip(manager))]
async fn delete(
    manager: web::Data<UploadManager>,
    path_entries: web::Path<(String, String)>,
) -> Result<HttpResponse, Error> {
    let (token, alias) = path_entries.into_inner();

    let token = DeleteToken::from_existing(&token);
    let alias = Alias::from_existing(&alias);

    manager.delete(alias, token).await?;

    Ok(HttpResponse::NoContent().finish())
}

type ProcessQuery = Vec<(String, String)>;

fn prepare_process(
    query: web::Query<ProcessQuery>,
    ext: &str,
    filters: &BTreeSet<String>,
) -> Result<(ImageFormat, Alias, PathBuf, Vec<String>), Error> {
    let (alias, operations) =
        query
            .into_inner()
            .into_iter()
            .fold((String::new(), Vec::new()), |(s, mut acc), (k, v)| {
                if k == "src" {
                    (v, acc)
                } else {
                    acc.push((k, v));
                    (s, acc)
                }
            });

    if alias.is_empty() {
        return Err(UploadError::MissingAlias.into());
    }

    let alias = Alias::from_existing(&alias);

    let operations = operations
        .into_iter()
        .filter(|(k, _)| filters.contains(&k.to_lowercase()))
        .collect::<Vec<_>>();

    let format = ext
        .parse::<ImageFormat>()
        .map_err(|_| UploadError::UnsupportedFormat)?;

    let ext = format.to_string();

    let (thumbnail_path, thumbnail_args) = self::processor::build_chain(&operations, &ext)?;

    Ok((format, alias, thumbnail_path, thumbnail_args))
}

#[instrument(name = "Fetching derived details", skip(manager, filters))]
async fn process_details<S: Store>(
    query: web::Query<ProcessQuery>,
    ext: web::Path<String>,
    manager: web::Data<UploadManager>,
    filters: web::Data<BTreeSet<String>>,
) -> Result<HttpResponse, Error> {
    let (_, alias, thumbnail_path, _) = prepare_process(query, ext.as_str(), &filters)?;

    let identifier = manager
        .variant_identifier::<S>(&alias, &thumbnail_path)
        .await?
        .ok_or(UploadError::MissingAlias)?;

    let details = manager.details(&identifier).await?;

    let details = details.ok_or(UploadError::NoFiles)?;

    Ok(HttpResponse::Ok().json(&details))
}

/// Process files
#[instrument(name = "Serving processed image", skip(manager, filters))]
async fn process<S: Store + 'static>(
    range: Option<web::Header<Range>>,
    query: web::Query<ProcessQuery>,
    ext: web::Path<String>,
    manager: web::Data<UploadManager>,
    store: web::Data<S>,
    filters: web::Data<BTreeSet<String>>,
) -> Result<HttpResponse, Error> {
    let (format, alias, thumbnail_path, thumbnail_args) =
        prepare_process(query, ext.as_str(), &filters)?;

    let identifier_opt = manager
        .variant_identifier::<S>(&alias, &thumbnail_path)
        .await?;

    if let Some(identifier) = identifier_opt {
        let details_opt = manager.details(&identifier).await?;

        let details = if let Some(details) = details_opt {
            details
        } else {
            let hint = details_hint(&alias);
            let details = Details::from_store((**store).clone(), identifier.clone(), hint).await?;
            manager.store_details(&identifier, &details).await?;
            details
        };

        return ranged_file_resp(&**store, identifier, range, details).await;
    }

    let identifier = manager
        .still_identifier_from_alias((**store).clone(), &alias)
        .await?;

    let thumbnail_path2 = thumbnail_path.clone();
    let identifier2 = identifier.clone();
    let process_fut = async {
        let thumbnail_path = thumbnail_path2;

        let permit = PROCESS_SEMAPHORE.acquire().await?;

        let mut processed_reader = crate::magick::process_image_store_read(
            (**store).clone(),
            identifier2,
            thumbnail_args,
            format,
        )?;

        let mut vec = Vec::new();
        processed_reader.read_to_end(&mut vec).await?;
        let bytes = web::Bytes::from(vec);

        drop(permit);

        let details = Details::from_bytes(bytes.clone(), format.as_hint()).await?;

        let identifier = store.save_bytes(bytes.clone()).await?;
        manager.store_details(&identifier, &details).await?;
        manager
            .store_variant(&alias, &thumbnail_path, &identifier)
            .await?;

        Ok((details, bytes)) as Result<(Details, web::Bytes), Error>
    };

    let (details, bytes) =
        CancelSafeProcessor::new(identifier, thumbnail_path.clone(), process_fut)?.await?;

    let (builder, stream) = if let Some(web::Header(range_header)) = range {
        if let Some(range) = range::single_bytes_range(&range_header) {
            let len = bytes.len() as u64;

            if let Some(content_range) = range::to_content_range(range, len) {
                let mut builder = HttpResponse::PartialContent();
                builder.insert_header(content_range);
                let stream = range::chop_bytes(range, bytes, len)?;

                (builder, Either::left(Either::left(stream)))
            } else {
                (
                    HttpResponse::RangeNotSatisfiable(),
                    Either::left(Either::right(empty())),
                )
            }
        } else {
            return Err(UploadError::Range.into());
        }
    } else {
        (HttpResponse::Ok(), Either::right(once(ready(Ok(bytes)))))
    };

    Ok(srv_response(
        builder,
        stream,
        details.content_type(),
        7 * DAYS,
        details.system_time(),
    ))
}

/// Fetch file details
#[instrument(name = "Fetching details", skip(manager))]
async fn details<S: Store>(
    alias: web::Path<String>,
    manager: web::Data<UploadManager>,
    store: web::Data<S>,
) -> Result<HttpResponse, Error> {
    let alias = alias.into_inner();
    let alias = Alias::from_existing(&alias);

    let identifier = manager.identifier_from_alias::<S>(&alias).await?;

    let details = manager.details(&identifier).await?;

    let details = if let Some(details) = details {
        details
    } else {
        let hint = details_hint(&alias);
        let new_details = Details::from_store((**store).clone(), identifier.clone(), hint).await?;
        manager.store_details(&identifier, &new_details).await?;
        new_details
    };

    Ok(HttpResponse::Ok().json(&details))
}

/// Serve files
#[instrument(name = "Serving file", skip(manager))]
async fn serve<S: Store>(
    range: Option<web::Header<Range>>,
    alias: web::Path<String>,
    manager: web::Data<UploadManager>,
    store: web::Data<S>,
) -> Result<HttpResponse, Error> {
    let alias = alias.into_inner();
    let alias = Alias::from_existing(&alias);
    let identifier = manager.identifier_from_alias::<S>(&alias).await?;

    let details = manager.details(&identifier).await?;

    let details = if let Some(details) = details {
        details
    } else {
        let hint = details_hint(&alias);
        let details = Details::from_store((**store).clone(), identifier.clone(), hint).await?;
        manager.store_details(&identifier, &details).await?;
        details
    };

    ranged_file_resp(&**store, identifier, range, details).await
}

async fn ranged_file_resp<S: Store>(
    store: &S,
    identifier: S::Identifier,
    range: Option<web::Header<Range>>,
    details: Details,
) -> Result<HttpResponse, Error> {
    let (builder, stream) = if let Some(web::Header(range_header)) = range {
        //Range header exists - return as ranged
        if let Some(range) = range::single_bytes_range(&range_header) {
            let len = store.len(&identifier).await?;

            if let Some(content_range) = range::to_content_range(range, len) {
                let mut builder = HttpResponse::PartialContent();
                builder.insert_header(content_range);
                (
                    builder,
                    Either::left(Either::left(
                        range::chop_store(range, store, &identifier, len)
                            .await?
                            .map_err(Error::from),
                    )),
                )
            } else {
                (
                    HttpResponse::RangeNotSatisfiable(),
                    Either::left(Either::right(empty())),
                )
            }
        } else {
            return Err(UploadError::Range.into());
        }
    } else {
        //No Range header in the request - return the entire document
        let stream = store
            .to_stream(&identifier, None, None)
            .await?
            .map_err(Error::from);
        (HttpResponse::Ok(), Either::right(stream))
    };

    Ok(srv_response(
        builder,
        stream,
        details.content_type(),
        7 * DAYS,
        details.system_time(),
    ))
}

// A helper method to produce responses with proper cache headers
fn srv_response<S, E>(
    mut builder: HttpResponseBuilder,
    stream: S,
    ext: mime::Mime,
    expires: u32,
    modified: SystemTime,
) -> HttpResponse
where
    S: Stream<Item = Result<web::Bytes, E>> + 'static,
    E: std::error::Error + 'static,
    actix_web::Error: From<E>,
{
    builder
        .insert_header(LastModified(modified.into()))
        .insert_header(CacheControl(vec![
            CacheDirective::Public,
            CacheDirective::MaxAge(expires),
            CacheDirective::Extension("immutable".to_owned(), None),
        ]))
        .insert_header((ACCEPT_RANGES, "bytes"))
        .content_type(ext.to_string())
        .streaming(stream)
}

#[derive(Debug, serde::Deserialize)]
struct AliasQuery {
    alias: String,
}

#[instrument(name = "Purging file", skip(upload_manager))]
async fn purge(
    query: web::Query<AliasQuery>,
    upload_manager: web::Data<UploadManager>,
) -> Result<HttpResponse, Error> {
    let alias = Alias::from_existing(&query.alias);
    let aliases = upload_manager.aliases_by_alias(&alias).await?;

    for alias in aliases.iter() {
        upload_manager
            .delete_without_token(alias.to_owned())
            .await?;
    }

    Ok(HttpResponse::Ok().json(&serde_json::json!({
        "msg": "ok",
        "aliases": aliases.iter().map(|a| a.to_string()).collect::<Vec<_>>()
    })))
}

#[instrument(name = "Fetching aliases", skip(upload_manager))]
async fn aliases(
    query: web::Query<AliasQuery>,
    upload_manager: web::Data<UploadManager>,
) -> Result<HttpResponse, Error> {
    let alias = Alias::from_existing(&query.alias);
    let aliases = upload_manager.aliases_by_alias(&alias).await?;

    Ok(HttpResponse::Ok().json(&serde_json::json!({
        "msg": "ok",
        "aliases": aliases.iter().map(|a| a.to_string()).collect::<Vec<_>>()
    })))
}

fn transform_error(error: actix_form_data::Error) -> actix_web::Error {
    let error: Error = error.into();
    let error: actix_web::Error = error.into();
    error
}

fn build_client() -> awc::Client {
    Client::builder()
        .wrap(Tracing)
        .add_default_header(("User-Agent", "pict-rs v0.3.0-main"))
        .finish()
}

fn build_reqwest_client() -> reqwest::Result<reqwest::Client> {
    reqwest::Client::builder()
        .user_agent("pict-rs v0.3.0-main")
        .build()
}

fn next_worker_id() -> String {
    static WORKER_ID: AtomicU64 = AtomicU64::new(0);

    let next_id = WORKER_ID.fetch_add(1, Ordering::Relaxed);

    format!("{}-{}", CONFIG.server.worker_id, next_id)
}

async fn launch<S: Store + Clone + 'static>(
    manager: UploadManager,
    store: S,
) -> color_eyre::Result<()> {
    // Create a new Multipart Form validator
    //
    // This form is expecting a single array field, 'images' with at most 10 files in it
    let manager2 = manager.clone();
    let store2 = store.clone();
    let form = Form::new()
        .max_files(10)
        .max_file_size(CONFIG.media.max_file_size * MEGABYTES)
        .transform_error(transform_error)
        .field(
            "images",
            Field::array(Field::file(move |filename, _, stream| {
                let store = store2.clone();
                let manager = manager2.clone();

                let span = tracing::info_span!("file-upload", ?filename);

                async move {
                    let permit = PROCESS_SEMAPHORE.acquire().await?;

                    let res = manager
                        .session(store)
                        .upload(
                            CONFIG.media.enable_silent_video,
                            stream.map_err(Error::from),
                        )
                        .await;

                    drop(permit);
                    res
                }
                .instrument(span)
            })),
        );

    // Create a new Multipart Form validator for internal imports
    //
    // This form is expecting a single array field, 'images' with at most 10 files in it
    let manager2 = manager.clone();
    let store2 = store.clone();
    let import_form = Form::new()
        .max_files(10)
        .max_file_size(CONFIG.media.max_file_size * MEGABYTES)
        .transform_error(transform_error)
        .field(
            "images",
            Field::array(Field::file(move |filename, _, stream| {
                let store = store2.clone();
                let manager = manager2.clone();

                let span = tracing::info_span!("file-import", ?filename);

                async move {
                    let permit = PROCESS_SEMAPHORE.acquire().await?;

                    let res = manager
                        .session(store)
                        .import(
                            filename,
                            !CONFIG.media.skip_validate_imports,
                            CONFIG.media.enable_silent_video,
                            stream.map_err(Error::from),
                        )
                        .await;

                    drop(permit);
                    res
                }
                .instrument(span)
            })),
        );

    HttpServer::new(move || {
        let manager = manager.clone();
        let store = store.clone();

        actix_rt::spawn(queue::process_jobs(
            manager.repo().clone(),
            store.clone(),
            next_worker_id(),
        ));

        App::new()
            .wrap(TracingLogger::default())
            .wrap(Deadline)
            .app_data(web::Data::new(store))
            .app_data(web::Data::new(manager))
            .app_data(web::Data::new(build_client()))
            .app_data(web::Data::new(CONFIG.media.filters.clone()))
            .service(
                web::scope("/image")
                    .service(
                        web::resource("")
                            .guard(guard::Post())
                            .wrap(form.clone())
                            .route(web::post().to(upload::<S>)),
                    )
                    .service(web::resource("/download").route(web::get().to(download::<S>)))
                    .service(
                        web::resource("/delete/{delete_token}/{filename}")
                            .route(web::delete().to(delete))
                            .route(web::get().to(delete)),
                    )
                    .service(web::resource("/original/{filename}").route(web::get().to(serve::<S>)))
                    .service(web::resource("/process.{ext}").route(web::get().to(process::<S>)))
                    .service(
                        web::scope("/details")
                            .service(
                                web::resource("/original/{filename}")
                                    .route(web::get().to(details::<S>)),
                            )
                            .service(
                                web::resource("/process.{ext}")
                                    .route(web::get().to(process_details::<S>)),
                            ),
                    ),
            )
            .service(
                web::scope("/internal")
                    .wrap(Internal(
                        CONFIG.server.api_key.as_ref().map(|s| s.to_owned()),
                    ))
                    .service(
                        web::resource("/import")
                            .wrap(import_form.clone())
                            .route(web::post().to(upload::<S>)),
                    )
                    .service(web::resource("/purge").route(web::post().to(purge)))
                    .service(web::resource("/aliases").route(web::get().to(aliases))),
            )
    })
    .bind(CONFIG.server.address)?
    .run()
    .await?;

    crate::tmp_file::remove_tmp_dir().await?;

    Ok(())
}

async fn migrate_inner<S1>(
    manager: &UploadManager,
    repo: &Repo,
    from: S1,
    to: &config::Store,
) -> color_eyre::Result<()>
where
    S1: Store,
{
    match to {
        config::Store::Filesystem(config::Filesystem { path }) => {
            let to = FileStore::build(path.clone(), repo.clone()).await?;
            manager.migrate_store::<S1, FileStore>(from, to).await?;
        }
        config::Store::ObjectStorage(config::ObjectStorage {
            bucket_name,
            region,
            access_key,
            secret_key,
            security_token,
            session_token,
        }) => {
            let to = ObjectStore::build(
                bucket_name,
                region.as_ref().clone(),
                Some(access_key.clone()),
                Some(secret_key.clone()),
                security_token.clone(),
                session_token.clone(),
                repo.clone(),
                build_reqwest_client()?,
            )
            .await?;

            manager.migrate_store::<S1, ObjectStore>(from, to).await?;
        }
    }

    Ok(())
}

#[actix_rt::main]
async fn main() -> color_eyre::Result<()> {
    init_tracing(&CONFIG.tracing)?;

    let repo = Repo::open(CONFIG.repo.clone())?;

    let db = LatestDb::exists(CONFIG.old_db.path.clone()).migrate()?;
    repo.from_db(db).await?;

    let manager = UploadManager::new(repo.clone(), CONFIG.media.format).await?;

    match (*OPERATION).clone() {
        Operation::Run => (),
        Operation::MigrateStore { from, to } => {
            match from {
                config::Store::Filesystem(config::Filesystem { path }) => {
                    let from = FileStore::build(path.clone(), repo.clone()).await?;
                    migrate_inner(&manager, &repo, from, &to).await?;
                }
                config::Store::ObjectStorage(config::ObjectStorage {
                    bucket_name,
                    region,
                    access_key,
                    secret_key,
                    security_token,
                    session_token,
                }) => {
                    let from = ObjectStore::build(
                        &bucket_name,
                        Serde::into_inner(region),
                        Some(access_key),
                        Some(secret_key),
                        security_token,
                        session_token,
                        repo.clone(),
                        build_reqwest_client()?,
                    )
                    .await?;

                    migrate_inner(&manager, &repo, from, &to).await?;
                }
            }

            return Ok(());
        }
    }

    match CONFIG.store.clone() {
        config::Store::Filesystem(config::Filesystem { path }) => {
            let store = FileStore::build(path, repo).await?;
            launch(manager, store).await
        }
        config::Store::ObjectStorage(config::ObjectStorage {
            bucket_name,
            region,
            access_key,
            secret_key,
            security_token,
            session_token,
        }) => {
            let store = ObjectStore::build(
                &bucket_name,
                Serde::into_inner(region),
                Some(access_key),
                Some(secret_key),
                security_token,
                session_token,
                repo,
                build_reqwest_client()?,
            )
            .await?;

            launch(manager, store).await
        }
    }
}