Add get_video_information endpoint

Signed-off-by: trivernis <trivernis@protonmail.com>

.gitignore

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+/target
+Cargo.lock
+.idea

Cargo.toml

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+[package]
+name = "youtube-metadata"
+version = "0.1.0"
+authors = ["trivernis <trivernis@protonmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+reqwest = "0.11.3"
+scraper = "0.12.0"
+thiserror = "1.0.24"
+lazy_static = "1.4.0"
+
+[dev-dependencies]
+tokio = {version = "1.5.0", features = ["macros", "rt-multi-thread"]}

src/endpoints.rs

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+use crate::error::YoutubeResult;
+use crate::parsing::video_information::parse_video_information;
+use crate::types::VideoInformation;
+
+/// Returns information about a video
+pub async fn get_video_information(url: &str) -> YoutubeResult<VideoInformation> {
+    let response = reqwest::get(url).await?;
+    let response_text = response.text().await?;
+
+    parse_video_information(&response_text)
+}

src/error.rs

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+use thiserror::Error;
+
+pub type YoutubeResult<T> = Result<T, YoutubeError>;
+
+#[derive(Debug, Error)]
+pub enum YoutubeError {
+    #[error(transparent)]
+    Reqwest(#[from] reqwest::Error),
+
+    #[error("Parse Error: {0}")]
+    ParseError(String),
+}
+
+impl From<&str> for YoutubeError {
+    fn from(s: &str) -> Self {
+        Self::ParseError(s.to_string())
+    }
+}

src/lib.rs

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+pub(crate) mod endpoints;
+pub mod error;
+pub(crate) mod parsing;
+pub(crate) mod types;
+
+pub use endpoints::get_video_information;
+
+#[cfg(test)]
+mod tests;

src/parsing/mod.rs

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+use crate::error::{YoutubeError, YoutubeResult};
+use scraper::{ElementRef, Html, Selector};
+
+pub mod video_information;
+
+/// Tries selecting one element or fails if the element can't be found
+fn try_select_one<'a>(document: &'a Html, selector: &Selector) -> YoutubeResult<ElementRef<'a>> {
+    document
+        .select(selector)
+        .next()
+        .ok_or(YoutubeError::ParseError(format!(
+            "Missing Element: {:?}",
+            selector
+        )))
+}
+
+/// Tries to select a given attribute
+fn try_select_attribute<'a>(
+    document: &'a Html,
+    selector: &Selector,
+    attribute: &str,
+) -> YoutubeResult<&'a str> {
+    let element = try_select_one(document, selector)?;
+    element
+        .value()
+        .attr(attribute)
+        .ok_or(YoutubeError::ParseError(format!(
+            "Missing attribute '{}'",
+            attribute
+        )))
+}

src/parsing/video_information.rs

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+use crate::error::YoutubeResult;
+use crate::parsing::try_select_attribute;
+use crate::types::VideoInformation;
+use scraper::{Html, Selector};
+
+lazy_static::lazy_static! {
+    static ref TITLE_SELECTOR: Selector = Selector::parse(r#"meta[property="og:title"]"#).unwrap();
+    static ref THUMBNAIL_SELECTOR: Selector = Selector::parse(r#"meta[property="og:image"]"#).unwrap();
+    static ref URL_SELECTOR: Selector = Selector::parse(r#"link[rel="canonical"]"#).unwrap();
+}
+
+/// Parses information about a video from the html
+pub fn parse_video_information(html: &str) -> YoutubeResult<VideoInformation> {
+    let document = Html::parse_document(html);
+    let url = try_select_attribute(&document, &URL_SELECTOR, "href")?;
+    let title = try_select_attribute(&document, &TITLE_SELECTOR, "content")?;
+    let thumbnail = try_select_attribute(&document, &THUMBNAIL_SELECTOR, "content").ok();
+
+    Ok(VideoInformation {
+        url: url.to_string(),
+        title: title.to_string(),
+        thumbnail: thumbnail.map(|s| s.to_string()),
+    })
+}

src/tests/endpoints_test.rs

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+use crate::endpoints::get_video_information;
+
+#[tokio::test]
+async fn test_get_video_information() {
+    let information = get_video_information("https://www.youtube.com/watch?v=dQw4w9WgXcQ")
+        .await
+        .unwrap();
+    assert_eq!(
+        information.url,
+        "https://www.youtube.com/watch?v=dQw4w9WgXcQ".to_string()
+    );
+    assert_eq!(
+        information.title,
+        "Rick Astley - Never Gonna Give You Up (Video)".to_string()
+    );
+    assert_eq!(
+        information.thumbnail,
+        Some("https://i.ytimg.com/vi/dQw4w9WgXcQ/maxresdefault.jpg".to_string())
+    );
+
+    assert!(
+        get_video_information("https://www.youtube.com/watch?v=FFFFFFFFFFF")
+            .await
+            .is_err()
+    );
+}

src/tests/mod.rs

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+#[cfg(test)]
+mod endpoints_test;

src/types.rs

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+#[derive(Clone, Debug)]
+pub struct VideoInformation {
+    pub url: String,
+    pub title: String,
+    pub thumbnail: Option<String>,
+}