#![warn(missing_docs)]
use crate::indieauth::User;
use async_trait::async_trait;
use serde::{Deserialize, Serialize};

mod redis;
pub use crate::database::redis::RedisStorage;
#[cfg(test)]
pub use redis::tests::{get_redis_instance, RedisInstance};

#[derive(Serialize, Deserialize, PartialEq, Debug)]
pub struct MicropubChannel {
    pub uid: String,
    pub name: String,
}

#[derive(Debug, Clone, Copy)]
pub enum ErrorKind {
    Backend,
    PermissionDenied,
    JsonParsing,
    NotFound,
    BadRequest,
    Other,
}

#[derive(Debug)]
pub struct StorageError {
    msg: String,
    source: Option<Box<dyn std::error::Error>>,
    kind: ErrorKind,
}
unsafe impl Send for StorageError {}
unsafe impl Sync for StorageError {}
impl From<StorageError> for tide::Response {
    fn from(err: StorageError) -> Self {
        tide::Response::builder(match err.kind() {
            ErrorKind::BadRequest => 400,
            ErrorKind::NotFound => 404,
            _ => 500,
        })
        .body(serde_json::json!({
            "error": match err.kind() {
                ErrorKind::BadRequest => "invalid_request",
                ErrorKind::NotFound => "not_found",
                _ => "database_error"
            },
            "error_description": err
        }))
        .build()
    }
}
impl std::error::Error for StorageError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        self.source.as_ref().map(|e| e.as_ref())
    }
}
impl From<serde_json::Error> for StorageError {
    fn from(err: serde_json::Error) -> Self {
        Self {
            msg: format!("{}", err),
            source: Some(Box::new(err)),
            kind: ErrorKind::JsonParsing,
        }
    }
}
impl std::fmt::Display for StorageError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match match self.kind {
            ErrorKind::Backend => write!(f, "backend error: "),
            ErrorKind::JsonParsing => write!(f, "error while parsing JSON: "),
            ErrorKind::PermissionDenied => write!(f, "permission denied: "),
            ErrorKind::NotFound => write!(f, "not found: "),
            ErrorKind::BadRequest => write!(f, "bad request: "),
            ErrorKind::Other => write!(f, "generic storage layer error: "),
        } {
            Ok(_) => write!(f, "{}", self.msg),
            Err(err) => Err(err),
        }
    }
}
impl serde::Serialize for StorageError {
    fn serialize<S: serde::Serializer>(
        &self,
        serializer: S,
    ) -> std::result::Result<S::Ok, S::Error> {
        serializer.serialize_str(&self.to_string())
    }
}
impl StorageError {
    /// Create a new StorageError of an ErrorKind with a message.
    fn new(kind: ErrorKind, msg: &str) -> Self {
        StorageError {
            msg: msg.to_string(),
            source: None,
            kind,
        }
    }
    /// Get the kind of an error.
    pub fn kind(&self) -> ErrorKind {
        self.kind
    }
    pub fn msg(&self) -> &str {
        &self.msg
    }
}

/// A special Result type for the Micropub backing storage.
pub type Result<T> = std::result::Result<T, StorageError>;

/// A storage backend for the Micropub server.
///
/// Implementations should note that all methods listed on this trait MUST be fully atomic
/// or lock the database so that write conflicts or reading half-written data should not occur.
#[async_trait]
pub trait Storage: Clone + Send + Sync {
    /// Check if a post exists in the database.
    async fn post_exists(&self, url: &str) -> Result<bool>;

    /// Load a post from the database in MF2-JSON format, deserialized from JSON.
    async fn get_post(&self, url: &str) -> Result<Option<serde_json::Value>>;

    /// Save a post to the database as an MF2-JSON structure.
    ///
    /// Note that the `post` object MUST have `post["properties"]["uid"][0]` defined.
    async fn put_post<'a>(&self, post: &'a serde_json::Value) -> Result<()>;

    /*/// Save a post and add it to the relevant feeds listed in `post["properties"]["channel"]`.
    ///
    /// Note that the `post` object MUST have `post["properties"]["uid"][0]` defined
    /// and `post["properties"]["channel"]` defined, even if it's empty.
    async fn put_and_index_post<'a>(&mut self, post: &'a serde_json::Value) -> Result<()>;*/

    /// Modify a post using an update object as defined in the Micropub spec.
    ///
    /// Note to implementors: the update operation MUST be atomic OR MUST lock the database
    /// to prevent two clients overwriting each other's changes.
    ///
    /// You can assume concurrent updates will never contradict each other, since that will be dumb.
    /// The last update always wins.
    async fn update_post<'a>(&self, url: &'a str, update: serde_json::Value) -> Result<()>;

    /// Get a list of channels available for the user represented by the `user` object to write.
    async fn get_channels(&self, user: &User) -> Result<Vec<MicropubChannel>>;

    /// Fetch a feed at `url` and return a an h-feed object containing
    /// `limit` posts after a post by url `after`, filtering the content
    /// in context of a user specified by `user` (or an anonymous user).
    ///
    /// Specifically, private posts that don't include the user in the audience
    /// will be elided from the feed, and the posts containing location and not
    /// specifying post["properties"]["location-visibility"][0] == "public"
    /// will have their location data (but not check-in data) stripped.
    ///
    /// This function is used as an optimization so the client, whatever it is,
    /// doesn't have to fetch posts, then realize some of them are private, and
    /// fetch more posts.
    ///
    /// Note for implementors: if you use streams to fetch posts in parallel
    /// from the database, preferably make this method use a connection pool
    /// to reduce overhead of creating a database connection per post for
    /// parallel fetching.
    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>>;

    /// Deletes a post from the database irreversibly. 'nuff said. Must be idempotent.
    async fn delete_post<'a>(&self, url: &'a str) -> Result<()>;

    /// Gets a setting from the setting store and passes the result.
    async fn get_setting<'a>(&self, setting: &'a str, user: &'a str) -> Result<String>;

    /// Commits a setting to the setting store.
    async fn set_setting<'a>(&self, setting: &'a str, user: &'a str, value: &'a str) -> Result<()>;
}

#[cfg(test)]
mod tests {
    use super::redis::tests::get_redis_instance;
    use super::{MicropubChannel, Storage};
    use serde_json::json;

    async fn test_backend_basic_operations<Backend: Storage>(backend: Backend) {
        let post: serde_json::Value = json!({
            "type": ["h-entry"],
            "properties": {
                "content": ["Test content"],
                "author": ["https://fireburn.ru/"],
                "uid": ["https://fireburn.ru/posts/hello"],
                "url": ["https://fireburn.ru/posts/hello", "https://fireburn.ru/posts/test"]
            }
        });
        let key = post["properties"]["uid"][0].as_str().unwrap().to_string();
        let alt_url = post["properties"]["url"][1].as_str().unwrap().to_string();

        // Reading and writing
        backend.put_post(&post).await.unwrap();
        if let Ok(Some(returned_post)) = backend.get_post(&key).await {
            assert!(returned_post.is_object());
            assert_eq!(
                returned_post["type"].as_array().unwrap().len(),
                post["type"].as_array().unwrap().len()
            );
            assert_eq!(
                returned_post["type"].as_array().unwrap(),
                post["type"].as_array().unwrap()
            );
            let props: &serde_json::Map<String, serde_json::Value> =
                post["properties"].as_object().unwrap();
            for key in props.keys() {
                assert_eq!(
                    returned_post["properties"][key].as_array().unwrap(),
                    post["properties"][key].as_array().unwrap()
                )
            }
        } else {
            panic!("For some reason the backend did not return the post.")
        }
        // Check the alternative URL - it should return the same post
        if let Ok(Some(returned_post)) = backend.get_post(&alt_url).await {
            assert!(returned_post.is_object());
            assert_eq!(
                returned_post["type"].as_array().unwrap().len(),
                post["type"].as_array().unwrap().len()
            );
            assert_eq!(
                returned_post["type"].as_array().unwrap(),
                post["type"].as_array().unwrap()
            );
            let props: &serde_json::Map<String, serde_json::Value> =
                post["properties"].as_object().unwrap();
            for key in props.keys() {
                assert_eq!(
                    returned_post["properties"][key].as_array().unwrap(),
                    post["properties"][key].as_array().unwrap()
                )
            }
        } else {
            panic!("For some reason the backend did not return the post.")
        }
    }

    async fn test_backend_get_channel_list<Backend: Storage>(backend: Backend) {
        let feed = json!({
            "type": ["h-feed"],
            "properties": {
                "name": ["Main Page"],
                "author": ["https://fireburn.ru/"],
                "uid": ["https://fireburn.ru/feeds/main"]
            },
            "children": []
        });
        backend.put_post(&feed).await.unwrap();
        let chans = backend
            .get_channels(&crate::indieauth::User::new(
                "https://fireburn.ru/",
                "https://quill.p3k.io/",
                "create update media",
            ))
            .await
            .unwrap();
        assert_eq!(chans.len(), 1);
        assert_eq!(
            chans[0],
            MicropubChannel {
                uid: "https://fireburn.ru/feeds/main".to_string(),
                name: "Main Page".to_string()
            }
        );
    }

    async fn test_backend_settings<Backend: Storage>(backend: Backend) {
        backend
            .set_setting("site_name", "https://fireburn.ru/", "Vika's Hideout")
            .await
            .unwrap();
        assert_eq!(
            backend
                .get_setting("site_name", "https://fireburn.ru/")
                .await
                .unwrap(),
            "Vika's Hideout"
        );
    }

    #[async_std::test]
    async fn test_redis_storage_basic_operations() {
        let redis_instance = get_redis_instance().await;
        let backend = super::RedisStorage::new(redis_instance.uri().to_string())
            .await
            .unwrap();
        test_backend_basic_operations(backend).await;
    }
    #[async_std::test]
    async fn test_redis_storage_channel_list() {
        let redis_instance = get_redis_instance().await;
        let backend = super::RedisStorage::new(redis_instance.uri().to_string())
            .await
            .unwrap();
        test_backend_get_channel_list(backend).await;
    }

    #[async_std::test]
    async fn test_redis_settings() {
        let redis_instance = get_redis_instance().await;
        let backend = super::RedisStorage::new(redis_instance.uri().to_string())
            .await
            .unwrap();
        test_backend_settings(backend).await;
    }
}