//pub mod async_file_ext;
use async_std::fs::{File, OpenOptions};
use async_std::io::{ErrorKind as IOErrorKind, BufReader};
use async_std::io::prelude::*;
use async_std::task::spawn_blocking;
use async_trait::async_trait;
use crate::database::{ErrorKind, Result, Storage, StorageError};
use fd_lock::RwLock;
use log::debug;
use std::path::{Path, PathBuf};

impl From<std::io::Error> for StorageError {
    fn from(source: std::io::Error) -> Self {
        Self::with_source(
            match source.kind() {
                IOErrorKind::NotFound => ErrorKind::NotFound,
                _ => ErrorKind::Backend,
            },
            "file I/O error",
            Box::new(source),
        )
    }
}

async fn get_lockable_file(file: File) -> RwLock<File> {
    debug!("Trying to create a file lock");
    spawn_blocking(move || RwLock::new(file)).await
}

fn url_to_path(root: &Path, url: &str) -> PathBuf {
    let url = http_types::Url::parse(url).expect("Couldn't parse a URL");
    let mut path: PathBuf = root.to_owned();
    path.push(url.origin().ascii_serialization() + &url.path().to_string() + ".json");

    path
}

#[derive(Clone)]
pub struct FileStorage {
    root_dir: PathBuf,
}

impl FileStorage {
    pub async fn new(root_dir: PathBuf) -> Result<Self> {
        // TODO check if the dir is writable
        Ok(Self { root_dir })
    }
}

#[async_trait]
impl Storage for FileStorage {
    async fn post_exists(&self, url: &str) -> Result<bool> {
        let path = url_to_path(&self.root_dir, url);
        debug!("Checking if {:?} exists...", path);
        Ok(spawn_blocking(move || path.is_file()).await)
    }

    async fn get_post(&self, url: &str) -> Result<Option<serde_json::Value>> {
        let path = url_to_path(&self.root_dir, url);
        debug!("Opening {:?}", path);
        // We have to special-case in here because the function should return Ok(None) on 404
        match File::open(path).await {
            Ok(f) => {
                let lock = get_lockable_file(f).await;
                let guard = lock.read()?;

                // HOW DOES THIS TYPECHECK?!!!!!!!!
                // Read::read(&mut self) requires a mutable reference
                // yet Read is implemented for &File
                // We can't get a &mut File from &File, can we?
                // And we need a &mut File to use Read::read_to_string()
                // Yet if we pass it to a BufReader it works?!!
                //
                // I hate magic
                //
                // TODO find a way to get rid of BufReader here
                let mut content = String::new();
                let mut reader = BufReader::new(&*guard);
                reader.read_to_string(&mut content).await?;
                drop(reader);
                drop(guard);
                Ok(Some(serde_json::from_str(&content)?))
            }
            Err(err) => {
                if err.kind() == IOErrorKind::NotFound {
                    Ok(None)
                } else {
                    Err(err.into())
                }
            }
        }
    }

    async fn put_post<'a>(&self, post: &'a serde_json::Value, user: &'a str) -> Result<()> {
        let key = post["properties"]["uid"][0]
        .as_str()
        .expect("Tried to save a post without UID");
        let path = url_to_path(&self.root_dir, key);

        debug!("Creating {:?}", path);

        let parent = path.parent().unwrap().to_owned();
        if !spawn_blocking(move || parent.is_dir()).await {
            async_std::fs::create_dir_all(path.parent().unwrap()).await?;
        }

        let f = OpenOptions::new()
            .write(true)
            .create_new(true)
            .open(&path)
            .await?;
        
        let mut lock = get_lockable_file(f).await;
        let mut guard = lock.write()?;

        (*guard).write(post.to_string().as_bytes()).await?;
        drop(guard);

        if post["properties"]["url"].is_array() {
            for url in post["properties"]["url"]
                .as_array()
                .unwrap()
                .iter()
                .map(|i| i.as_str().unwrap())
            {
                // TODO consider using the symlink crate
                // to promote cross-platform compat on Windows
                // do we even need to support Windows?...
                if url != key && url.starts_with(user) {
                    let link = url_to_path(&self.root_dir, url);
                    debug!("Creating a symlink at {:?}", link);
                    let orig = path.clone();
                    spawn_blocking(move || { std::os::unix::fs::symlink(orig, link) }).await?;
                }
            }
        }

        Ok(())
    }

    async fn update_post<'a>(&self, url: &'a str, update: serde_json::Value) -> Result<()> {
        todo!()
    }

    async fn get_channels(
        &self,
        user: &crate::indieauth::User,
    ) -> Result<Vec<super::MicropubChannel>> {
        todo!()
    }

    async fn read_feed_with_limit<'a>(
        &self,
        url: &'a str,
        after: &'a Option<String>,
        limit: usize,
        user: &'a Option<String>,
    ) -> Result<Option<serde_json::Value>> {
        todo!()
    }

    async fn delete_post<'a>(&self, url: &'a str) -> Result<()> {
        todo!()
    }

    async fn get_setting<'a>(&self, setting: &'a str, user: &'a str) -> Result<String> {
        todo!()
    }

    async fn set_setting<'a>(&self, setting: &'a str, user: &'a str, value: &'a str) -> Result<()> {
        todo!()
    }
}