i-can-has-cat/src/lib.rs

extern crate serde;
extern crate serde_json;
#[macro_use] extern crate serde_derive;
extern crate reqwest;
#[macro_use] extern crate derive_error;

use std::collections::HashMap;
use std::io::Read;

use std::fmt;
use std::fmt::{Display, Formatter};

pub struct Dogs {
    url: String
}

impl Dogs {
    pub fn new() -> Dogs {
        Dogs::with_url("https://dog.ceo/api/")
    }

    pub fn with_url(url: &str) -> Dogs {
        let mut api_url = url.to_owned();
        if api_url.ends_with("/") {
            api_url.remove(url.len() - 1);
        }

        Dogs {
            url: api_url
        }
    }

    pub fn random_image(&self) -> Result<Image, Error> {
        Ok(self.make_call("/breeds/image/random")?.message)
    }

    pub fn breeds(&self) -> Result<Breeds, Error> {
        Ok(self.make_call("/breeds/list/all")?.message)
    }

    pub fn subbreeds(&self, breed: &str) -> Result<Subbreeds, Error> {
        Ok(self.make_call(&format!("/breed/{}/list", breed))?.message)
    }

    pub fn images_by_breed(&self, breed: &str) -> Result<Images, Error> {
        Ok(self.make_call(&format!("/breed/{}/images", breed))?.message)
    }

    pub fn random_image_by_breed(&self, breed: &str) -> Result<Image, Error> {
        Ok(self.make_call(&format!("/breed/{}/images/random", breed))?.message)
    }

    pub fn images_by_subbreed(&self, breed: &str, subbreed: &str) -> Result<Images, Error> {
        Ok(self.make_call(&format!("/breed/{}/{}/images", breed, subbreed))?.message)
    }

    pub fn random_image_by_subbreed(&self, breed: &str, subbreed: &str) -> Result<Image, Error> {
        Ok(self.make_call(&format!("/breed/{}/{}/images/random", breed, subbreed))?.message)
    }

    fn make_call<T>(&self, endpoint: &str) -> Result<Response<T>, Error>
        where for <'a> T: serde::Deserialize<'a> {
        let mut response = reqwest::get(&format!(
            "{}{}",
            self.url,
            endpoint
        ))?;

        let mut content = String::new();
        response.read_to_string(&mut content)?;

        let parsed_response: Response<T> = serde_json::from_str(&content)?;
        if parsed_response.is_success() {
            Ok(parsed_response)
        } else {
            Err(Error::API(serde_json::from_str(&content)?))
        }
    }
}

pub type Breed = String;
pub type Image = String;
pub type Images = Vec<Image>;
pub type Subbreeds = Vec<String>;
pub type Breeds = HashMap<Breed, Subbreeds>;

#[derive(Debug, Error)]
pub enum Error {
    /// HTTP request failed
    HTTP(reqwest::Error),
    /// IO error
    IO(std::io::Error),
    /// Failed to parse
    Parse(serde_json::Error),
    /// Error from API
    API(APIError)
}

#[derive(Serialize, Deserialize, Debug)]
pub struct APIError {
    pub status: String,
    pub code: String,
    pub message: Option<String>
}

impl std::error::Error for APIError {
    fn description(&self) -> &str {
        self.message.as_ref().map(|message| message.as_str()).unwrap_or("")
    }
    fn cause(&self) -> Option<&std::error::Error> {
        None
    }
}

impl Display for APIError {
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        match self.message {
            Some(ref message) => write!(f, "{}: {}", self.code, message),
            None => write!(f, "{}", self.code)
        }
    }
}

#[derive(Serialize, Deserialize, Debug)]
struct Response<T> {
    status: String,
    message: T
}

impl<T> Response<T> {
    pub fn is_success(&self) -> bool {
        self.status == "success"
    }
}