//! Retrieve data about a peer.
//!
//! Implements the following methods:
//!
//! - [`Sbot::get_about_info`]
//! - [`Sbot::get_about_message_stream`]
//! - [`Sbot::get_description`]
//! - [`Sbot::get_latest_about_message`]
//! - [`Sbot::get_name`]
//! - [`Sbot::get_name_and_image`]
//! - [`Sbot::get_profile_info`]

use std::collections::HashMap;

use async_std::stream::{Stream, StreamExt};

use crate::{
    api::get_subset::{SubsetQuery, SubsetQueryOptions},
    error::GolgiError,
    messages::{SsbMessageContentType, SsbMessageValue},
    sbot::Sbot,
};

impl Sbot {
    /// Get all the `about` type messages for a peer in order of recency
    /// (ie. most recent messages first).
    ///
    /// # Example
    ///
    /// ```rust
    /// use async_std::stream::{Stream, StreamExt};
    /// use golgi::{Sbot, GolgiError, sbot::Keystore};
    ///
    /// async fn about_message_stream() -> Result<(), GolgiError> {
    ///     let mut sbot_client = Sbot::init(Keystore::Patchwork, None, None).await?;
    ///
    ///     let ssb_id = "@zqshk7o2Rpd/OaZ/MxH6xXONgonP1jH+edK9+GZb/NY=.ed25519";
    ///
    ///     let about_message_stream = sbot_client.get_about_message_stream(ssb_id).await?;
    ///
    ///     // Make the stream into an iterator.
    ///     futures::pin_mut!(about_message_stream);
    ///
    ///     about_message_stream.for_each(|msg| {
    ///         match msg {
    ///             Ok(val) => println!("msg value: {:?}", val),
    ///             Err(e) => eprintln!("error: {}", e),
    ///         }
    ///     }).await;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn get_about_message_stream(
        &mut self,
        ssb_id: &str,
    ) -> Result<impl Stream<Item = Result<SsbMessageValue, GolgiError>>, GolgiError> {
        let query = SubsetQuery::Author {
            op: "author".to_string(),
            feed: ssb_id.to_string(),
        };

        // specify that most recent messages should be returned first
        let query_options = SubsetQueryOptions {
            descending: Some(true),
            keys: None,
            page_limit: None,
        };

        let get_subset_stream = self.get_subset_stream(query, Some(query_options)).await?;

        // TODO: after fixing sbot regression,
        // change this subset query to filter by type about in addition to author
        // and remove this filter section
        // filter down to about messages
        let about_message_stream = get_subset_stream.filter(|msg| match msg {
            Ok(val) => val.is_message_type(SsbMessageContentType::About),
            Err(_err) => false,
        });

        // return about message stream
        Ok(about_message_stream)
    }

    /// Get the value of the latest `about` type message, containing the given
    /// `key`, for a peer.
    ///
    /// # Example
    ///
    /// ```rust
    /// use golgi::{Sbot, GolgiError, sbot::Keystore};
    ///
    /// async fn name_info() -> Result<(), GolgiError> {
    ///     let mut sbot_client = Sbot::init(Keystore::Patchwork, None, None).await?;
    ///
    ///     let ssb_id = "@zqshk7o2Rpd/OaZ/MxH6xXONgonP1jH+edK9+GZb/NY=.ed25519";
    ///     let key = "name";
    ///
    ///     let name_info = sbot_client.get_latest_about_message(ssb_id, key).await?;
    ///
    ///     match name_info {
    ///         Some(name) => println!("peer {} is named {}", ssb_id, name),
    ///         None => println!("no name found for peer {}", ssb_id)
    ///     }
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn get_latest_about_message(
        &mut self,
        ssb_id: &str,
        key: &str,
    ) -> Result<Option<String>, GolgiError> {
        // get about_message_stream
        let about_message_stream = self.get_about_message_stream(ssb_id).await?;

        // now we have a stream of about messages with most recent at the front
        // of the vector
        futures::pin_mut!(about_message_stream);

        // iterate through the vector looking for most recent about message with
        // the given key
        let latest_about_message_res: Option<Result<SsbMessageValue, GolgiError>> =
            about_message_stream
                // find the first msg that contains the field `key`
                .find(|res| match res {
                    Ok(msg) => msg.content.get(key).is_some(),
                    Err(_) => false,
                })
                .await;

        // Option<Result<SsbMessageValue, GolgiError>> -> Option<SsbMessageValue>
        let latest_about_message = latest_about_message_res.and_then(|msg| msg.ok());

        // Option<SsbMessageValue> -> Option<String>
        let latest_about_value = latest_about_message.and_then(|msg| {
            msg
                // SsbMessageValue -> Option<&Value>
                .content
                .get(key)
                // Option<&Value> -> <Option<&str>
                .and_then(|value| value.as_str())
                // Option<&str> -> Option<String>
                .map(|value| value.to_string())
        });

        // return value is either `Ok(Some(String))` or `Ok(None)`
        Ok(latest_about_value)
    }

    /// Get the latest `name`, `description` and `image` values for a peer,
    /// as defined in their `about` type messages.
    ///
    /// # Example
    ///
    /// ```rust
    /// use golgi::{Sbot, GolgiError, sbot::Keystore};
    ///
    /// async fn profile_info() -> Result<(), GolgiError> {
    ///     let mut sbot_client = Sbot::init(Keystore::Patchwork, None, None).await?;
    ///
    ///     let ssb_id = "@zqshk7o2Rpd/OaZ/MxH6xXONgonP1jH+edK9+GZb/NY=.ed25519";
    ///
    ///     let profile_info = sbot_client.get_profile_info(ssb_id).await?;
    ///
    ///     let name = profile_info.get("name");
    ///     let description = profile_info.get("description");
    ///     let image = profile_info.get("image");
    ///
    ///     match (name, description, image) {
    ///         (Some(name), Some(desc), Some(image)) => {
    ///             println!(
    ///                 "peer {} is named {}. their profile image blob reference is {} and they describe themself as follows: {}",
    ///                 ssb_id, name, image, desc,
    ///             )
    ///         },
    ///         (_, _, _) => {
    ///             eprintln!("failed to retrieve all profile info values")
    ///         }
    ///     }
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn get_profile_info(
        &mut self,
        ssb_id: &str,
    ) -> Result<HashMap<String, String>, GolgiError> {
        let keys_to_search_for = vec!["name", "description", "image"];
        self.get_about_info(ssb_id, keys_to_search_for).await
    }

    /// Get the latest `name` and `image` values for a peer. This method can
    /// be used to display profile images of a list of users.
    ///
    /// # Example
    ///
    /// ```rust
    /// use golgi::{Sbot, GolgiError, sbot::Keystore};
    ///
    /// async fn name_and_image_info() -> Result<(), GolgiError> {
    ///     let mut sbot_client = Sbot::init(Keystore::Patchwork, None, None).await?;
    ///
    ///     let ssb_id = "@zqshk7o2Rpd/OaZ/MxH6xXONgonP1jH+edK9+GZb/NY=.ed25519";
    ///
    ///     let profile_info = sbot_client.get_name_and_image(ssb_id).await?;
    ///
    ///     let name = profile_info.get("name");
    ///     let image = profile_info.get("image");
    ///
    ///     match (name, image) {
    ///         (Some(name), Some(image)) => {
    ///             println!(
    ///                 "peer {} is named {}. their profile image blob reference is {}.",
    ///                 ssb_id, name, image,
    ///             )
    ///         },
    ///         (Some(name), None) => {
    ///             println!(
    ///                 "peer {} is named {}. no image blob reference was found for them.",
    ///                 ssb_id, name,
    ///             )
    ///         },
    ///         (_, _) => {
    ///             eprintln!("failed to retrieve all profile info values")
    ///         }
    ///     }
    ///
    ///     Ok(())
    /// }
    pub async fn get_name_and_image(
        &mut self,
        ssb_id: &str,
    ) -> Result<HashMap<String, String>, GolgiError> {
        let keys_to_search_for = vec!["name", "image"];
        self.get_about_info(ssb_id, keys_to_search_for).await
    }

    /// Get the latest values for the provided keys from the `about` type
    /// messages of a peer. The method will return once a value has been
    /// found for each key, or once all messages have been checked.
    ///
    /// # Example
    ///
    /// ```rust
    /// use golgi::{Sbot, GolgiError, sbot::Keystore};
    ///
    /// async fn about_info() -> Result<(), GolgiError> {
    ///     let mut sbot_client = Sbot::init(Keystore::Patchwork, None, None).await?;
    ///
    ///     let ssb_id = "@zqshk7o2Rpd/OaZ/MxH6xXONgonP1jH+edK9+GZb/NY=.ed25519";
    ///     let keys_to_search_for = vec!["name", "description"];
    ///
    ///     let about_info = sbot_client.get_about_info(ssb_id, keys_to_search_for).await?;
    ///
    ///     let name = about_info.get("name");
    ///     let description = about_info.get("description");
    ///
    ///     match (name, description) {
    ///         (Some(name), Some(desc)) => {
    ///             println!(
    ///                 "peer {} is named {}. they describe themself as: {}",
    ///                 ssb_id, name, desc,
    ///             )
    ///         },
    ///         (Some(name), None) => {
    ///             println!(
    ///                 "peer {} is named {}. no description was found for them.",
    ///                 ssb_id, name,
    ///             )
    ///         },
    ///         (_, _) => {
    ///             eprintln!("failed to retrieve all profile info values")
    ///         }
    ///     }
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn get_about_info(
        &mut self,
        ssb_id: &str,
        mut keys_to_search_for: Vec<&str>,
    ) -> Result<HashMap<String, String>, GolgiError> {
        // get about_message_stream
        let about_message_stream = self.get_about_message_stream(ssb_id).await?;

        // now we have a stream of about messages with most recent at the front
        // of the vector

        // `pin_mut!` is needed for iteration
        futures::pin_mut!(about_message_stream);

        let mut profile_info: HashMap<String, String> = HashMap::new();

        // iterate through the stream while it still has more values and
        // we still have keys we are looking for
        while let Some(res) = about_message_stream.next().await {
            // if there are no more keys we are looking for, then we are done
            if keys_to_search_for.is_empty() {
                break;
            }
            // if there are still keys we are looking for, then continue searching
            match res {
                Ok(msg) => {
                    // for each key we are searching for, check if this about
                    // message contains a value for that key
                    for key in &keys_to_search_for.clone() {
                        let about_val = msg.content.get("about").and_then(|val| val.as_str());
                        let option_val = msg
                            .content
                            .get(key)
                            .and_then(|val| val.as_str())
                            .map(|val| val.to_string());
                        match option_val {
                            // only return val if this msg is about the given ssb_id
                            Some(val) if about_val == Some(ssb_id) => {
                                // if a value is found, then insert it
                                profile_info.insert(key.to_string(), val);
                                // remove this key from keys_to_search_for,
                                // since we are no longer searching for it
                                keys_to_search_for.retain(|val| val != key)
                            }
                            _ => continue,
                        }
                    }
                }
                Err(_err) => {
                    // skip errors
                    continue;
                }
            }
        }

        Ok(profile_info)
    }

    /// Get the latest `name` value for a peer.
    ///
    /// # Example
    ///
    /// ```rust
    /// use golgi::{Sbot, GolgiError, sbot::Keystore};
    ///
    /// async fn name_info() -> Result<(), GolgiError> {
    ///     let mut sbot_client = Sbot::init(Keystore::Patchwork, None, None).await?;
    ///
    ///     let ssb_id = "@zqshk7o2Rpd/OaZ/MxH6xXONgonP1jH+edK9+GZb/NY=.ed25519";
    ///
    ///     if let Some(name) = sbot_client.get_name(ssb_id).await? {
    ///         println!("peer {} is named {}", ssb_id, name)
    ///     } else {
    ///         eprintln!("no name found for peer {}", ssb_id)
    ///     }
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn get_name(&mut self, ssb_id: &str) -> Result<Option<String>, GolgiError> {
        self.get_latest_about_message(ssb_id, "name").await
    }

    /// Get the latest `description` value for a peer.
    ///
    /// # Example
    ///
    /// ```rust
    /// use golgi::{Sbot, GolgiError, sbot::Keystore};
    ///
    /// async fn description_info() -> Result<(), GolgiError> {
    ///     let mut sbot_client = Sbot::init(Keystore::Patchwork, None, None).await?;
    ///
    ///     let ssb_id = "@zqshk7o2Rpd/OaZ/MxH6xXONgonP1jH+edK9+GZb/NY=.ed25519";
    ///
    ///     if let Some(desc) = sbot_client.get_description(ssb_id).await? {
    ///         println!("peer {} describes themself as follows: {}", ssb_id, desc)
    ///     } else {
    ///         eprintln!("no description found for peer {}", ssb_id)
    ///     }
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn get_description(&mut self, ssb_id: &str) -> Result<Option<String>, GolgiError> {
        self.get_latest_about_message(ssb_id, "description").await
    }
}