# rapr.rs - source
Source of the Rust file `src/rapr.rs`.
Keywords: rust, rustlang, rust-lang

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    extern crate json;
    extern crate reqwest;
    extern crate tokio;
    use std::fmt;

    /// Error enum
    #[derive(Debug, Error)]
    pub enum Error {
        UnexpectedJson,
        NoneError,
        JsonParseError(json::Error),
        RequestError(reqwest::Error),
    }

    /// Items related to the post
    #[derive(Debug, Clone)]
    pub struct RaPostItems {
        pub upvotes: u32,
        pub downvotes: u32,
        pub permalink: String,
        pub url: Option<String>,
    }

    impl RaPostItems {
        /// Create a new struct of items for a post
        /// You probably don't need this fucntion.
        pub fn new(upvotes: u32, downvotes: u32, permalink: &str, url: Option<String>) -> Self {
            Self {
                upvotes,
                downvotes,
                permalink: permalink.to_string(),
                url,
            }
        }
    }

    /// Reddit post object
    /// (more like repost object).
    /// Keeps track of post information.
    #[derive(Clone)]
    pub struct RaPost {
        pub id: String,
        pub title: String,
        pub text: Option<String>,
        pub items: RaPostItems,
        pub json: json::JsonValue,
    }

    impl fmt::Debug for RaPost {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            f.debug_struct("RaPost")
                .field("id", &self.id)
                .field("title", &self.title)
                .field("text", &self.text)
                .field("permalink", &self.items.permalink)
                .field("url", &self.items.url)
                .finish()
        }
    }

    impl RaPost {
        /// Generate new post object (you probably don't need this).
        pub fn new(
            id: &str,
            title: &str,
            text: Option<&str>,
            items: RaPostItems,
            json: &json::JsonValue,
        ) -> Self {
            Self {
                id: id.to_string(),
                title: title.to_string(),
                text: text.map(String::from),
                items,
                json: json.clone(),
            }
        }

        /// Parse json from `json['data']['children']` array elements.
        /// Note: In case of url mission reddit make url the permalink
        pub fn parse(post: &json::JsonValue) -> Result<RaPost, Error> {
            let id = post["name"].as_str().ok_or(Error::UnexpectedJson)?;
            let title = post["title"].as_str().ok_or(Error::UnexpectedJson)?;
            let upvotes = post["ups"].as_u32().ok_or(Error::UnexpectedJson)?;
            let downvotes = post["downs"].as_u32().ok_or(Error::UnexpectedJson)?;
            let permalink = post["permalink"].as_str().ok_or(Error::UnexpectedJson)?;
            let url = post["url"].as_str().map(String::from);

            let mut selftext = post["selftext"].as_str();
            if selftext.ok_or(Error::NoneError)?.is_empty() {
                selftext = post["selftext_html"].as_str();
            }
            let items = RaPostItems::new(upvotes, downvotes, permalink, url);

            Ok(RaPost::new(id, title, selftext, items, post))
        }
    }

    ///# RaSub
    ///Subreddit object
    ///Keeps track of posts
    #[derive(Debug, Clone)]
    pub struct RaSub {
        pub name: String,
        pub posts: Vec<RaPost>,
        after: Option<String>,
    }

    impl From<&str> for RaSub {
        fn from(name: &str) -> Self {
            Self {
                name: String::from(name),
                posts: Vec::new(),
                after: None,
            }
        }
    }
    impl From<String> for RaSub {
        fn from(name: String) -> Self {
            Self::from(name.as_ref())
        }
    }
    impl RaSub {
        /// Generate subreddit object
        pub fn new(name: &str) -> Self {
            Self::from(name)
        }
    }

    /// Reddit api client.
    /// Uses a [reqwest::Client](https://docs.rs/reqwest/0.11.2/reqwest/struct.Client.html) internally.
    /// Currently no authentication
    #[derive(Debug)]
    pub struct RaprClient {
        oauth: Option<String>,
        rwclient: reqwest::Client,
    }

    impl Default for RaprClient {
        /// Return the default RaprClient
        fn default() -> Self {
            Self::new()
        }
    }

    impl RaprClient {
        /// Make a RaprClient
        pub fn new() -> Self {
            Self {
                oauth: None,
                rwclient: reqwest::Client::new(),
            }
        }
        /// Make a RaprClient with a custom user_agent (since reddit ratelimits same user agent being
        /// used a ton of times)
        pub fn with_user_agent(user_agent: &str) -> Result<Self, Error> {
            Ok(Self {
                oauth: None,
                rwclient: reqwest::Client::builder().user_agent(user_agent).build()?,
            })
        }
        pub fn default() -> Self {
            Self::new()
        }

        /// Fetch posts from subreddit and store them in the subreddit object.
        /// Note: First fetch always seems to pull two pinned posts which are not marked pinned in the json
        pub async fn fetch(&self, count: u32, sub: &mut RaSub) -> Result<Vec<RaPost>, Error> {
            let url = match self.oauth {
                None => format!("https://reddit.com/r/{}.json", sub.name),
                Some(_) => format!("https://oauth.reddit.com/r/{}.json", sub.name),
            };

            let res = match &sub.after {
                None => {
                    self.rwclient
                        .get(url)
                        .query(&[("limit", count), ("raw_json", 1)])
                        .send()
                        .await?
                }
                Some(after) => {
                    self.rwclient
                        .get(url)
                        .query(&[
                            ("limit", count.to_string().as_str()),
                            ("after", after.as_str()),
                            ("raw_json", "1"),
                        ])
                        .send()
                        .await?
                }
            };

            let mut parsed = json::parse(res.text().await?.as_str())?;

            let raw_posts: Vec<json::JsonValue> = match parsed["data"]["children"].take() {
                json::JsonValue::Array(arr) => arr,
                _ => return Err(Error::UnexpectedJson),
            };

            let mut parsed_posts: Vec<RaPost> = Vec::new();

            for post in raw_posts {
                if post["kind"].as_str().ok_or(Error::NoneError)? == "t3" {
                    // 't3' is the 'post' type in reddit api
                    parsed_posts.push(RaPost::parse(&post["data"])?);
                }
            }
            if parsed["data"]["after"].is_string() {
                sub.after = Some(parsed["data"]["after"].to_string());
            }
            sub.posts.append(&mut parsed_posts);
            Ok(parsed_posts)
        }
    }