Oneshot mode and general improved error handling

Cargo.lock

@@ -17,6 +17,12 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e999941b234f3131b00bc13c22d06e8c5ff726d1b6318ac7eb276997bbb4fef0"
 
+[[package]]
+name = "anyhow"
+version = "1.0.71"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c7d0618f0e0b7e8ff11427422b64564d5fb0be1940354bfe2e0529b18a9d9b8"
+
 [[package]]
 name = "autocfg"
 version = "1.1.0"
@@ -1133,6 +1139,7 @@ checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 name = "screencap-bot"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
  "dotenvy",
  "eggbug",
  "env_logger",

Cargo.toml

@@ -6,6 +6,7 @@ authors = ["xenofem <xenofem@xeno.science>"]
 license = "MIT"
 
 [dependencies]
+anyhow = "1.0.71"
 dotenvy = "0.15.7"
 eggbug = { git = "https://github.com/iliana/eggbug-rs.git", branch = "main" }
 env_logger = "0.10"

README.md

@@ -19,7 +19,8 @@ directory:
 
 - `SCREENCAP_BOT_SHOWS_FILE`: path of a YAML file specifying what shows to take screencaps from (default: `./shows.yaml`)
 - `SCREENCAP_BOT_GLOBAL_TAGS`: tags to put on every post the bot makes, as a comma-separated list (eg `bot account,automated post,The Cohost Bot Feed`) (default: none)
-- `SCREENCAP_BOT_POST_INTERVAL`: the interval between posts, in seconds (default: 6 hours)
+- `SCREENCAP_BOT_POST_INTERVAL`: the interval between posts, in
+  seconds (default: 0, post a single screencap and then exit)
 - `SCREENCAP_BOT_COHOST_EMAIL`: the email address the bot should use to log into cohost
 - `SCREENCAP_BOT_COHOST_PASSWORD`: the password the bot should use to log into cohost
 - `SCREENCAP_BOT_COHOST_PAGE`: the cohost page the bot should post from

src/config.rs

@@ -38,7 +38,7 @@ pub fn load() -> Config {
         global_tags: get_var("GLOBAL_TAGS")
             .map(|s| s.split(',').map(String::from).collect())
             .unwrap_or_default(),
-        post_interval: Duration::from_secs(parse_var("POST_INTERVAL").unwrap_or(6 * 3600)),
+        post_interval: Duration::from_secs(parse_var("POST_INTERVAL").unwrap_or_default()),
         cohost_email: expect_var("COHOST_EMAIL"),
         cohost_password: expect_var("COHOST_PASSWORD"),
         cohost_page: expect_var("COHOST_PAGE"),

src/main.rs

@@ -1,8 +1,11 @@
 use std::time::Duration;
 
+use anyhow::{anyhow, Context};
+use config::Config;
 use lazy_static::lazy_static;
 use log::{debug, error, info};
 use rand::{distributions::Standard, seq::IteratorRandom, Rng};
+use shows::Shows;
 
 mod config;
 mod shows;
@@ -15,7 +18,7 @@ lazy_static! {
 }
 
 #[tokio::main]
-async fn main() {
+async fn main() -> anyhow::Result<()> {
     dotenvy::dotenv().ok();
     env_logger::init();
     ffmpeg_next::init().unwrap();
@@ -25,24 +28,56 @@ async fn main() {
     let conf = config::load();
 
     info!("Loading shows from {}", conf.shows_file.display());
-    let shows = shows::load(conf.shows_file);
+    let shows = shows::load(&conf.shows_file).with_context(|| {
+        format!(
+            "Failed to load shows from file {}",
+            conf.shows_file.display()
+        )
+    })?;
+    if shows.is_empty() {
+        return Err(anyhow!("Shows file is empty!"));
+    }
 
     info!("Logging into cohost as {}", conf.cohost_email);
     let session = eggbug::Session::login(&conf.cohost_email, &conf.cohost_password)
         .await
-        .expect("Failed to login to cohost");
+        .context("Failed to login to cohost")?;
 
     loop {
-        let (title, show) = shows.iter().choose(&mut rng).expect("No shows found!");
-        let episodes = match show.episodes() {
-            Ok(eps) => eps,
+        let result = post_random_screencap(&conf, &shows, &session, &mut rng)
+            .await
+            .context("Failed to post a random screencap");
+
+        if conf.post_interval == Duration::ZERO {
+            return result;
+        }
+
+        let delay = match result {
+            Ok(()) => conf.post_interval,
             Err(e) => {
-                error!("Failed to get episodes for {}: {}", title, e);
-                tokio::time::sleep(*RETRY_INTERVAL).await;
-                continue;
+                error!("{}", e);
+                *RETRY_INTERVAL
             }
         };
-        let (num, file) = episodes.iter().choose(&mut rng).unwrap();
+        tokio::time::sleep(delay).await;
+    }
+}
+
+async fn post_random_screencap<R: Rng>(
+    conf: &Config,
+    shows: &Shows,
+    session: &eggbug::Session,
+    rng: &mut R,
+) -> anyhow::Result<()> {
+    let (title, show) = shows.iter().choose(rng).unwrap();
+    let episodes = show.episodes().with_context(|| {
+        format!(
+            "Failed to get episode list for show {} with path {}",
+            title,
+            show.path.display()
+        )
+    })?;
+    let (num, file) = episodes.iter().choose(rng).unwrap();
 
     let descriptor = format!(
         "{}{}",
@@ -50,14 +85,18 @@ async fn main() {
         match num {
             EpisodeNumber::Standalone => String::new(),
             EpisodeNumber::SingleSeason(n) => format!(" episode {}", n),
-                EpisodeNumber::MultiSeason(season, ep) =>
-                    format!(" season {} episode {}", season, ep),
+            EpisodeNumber::MultiSeason(season, ep) => format!(" season {} episode {}", season, ep),
         }
     );
 
     info!("Selected: {} - {}", descriptor, file.display());
 
-        let video_info = video::get_video_info(file, Some("eng")).unwrap();
+    let video_info = video::get_video_info(file, Some("eng")).with_context(|| {
+        format!(
+            "Failed to get duration and subtitle stream index for video file {}",
+            file.display()
+        )
+    })?;
     debug!(
         "Video duration: {}",
         format_timestamp(video_info.duration_secs, None)
@@ -71,24 +110,12 @@ async fn main() {
     let formatted_timestamp = format_timestamp(timestamp, Some(video_info.duration_secs));
     info!("Taking screencap at {}", formatted_timestamp);
 
-        let img_data =
-            match video::take_screencap(file, timestamp, video_info.subtitle_stream_index).await {
-                Ok(data) => data,
-                Err(e) => {
-                    error!("Failed to take screencap: {}", e);
-                    tokio::time::sleep(*RETRY_INTERVAL).await;
-                    continue;
-                }
-            };
+    let img_data = video::take_screencap(file, timestamp, video_info.subtitle_stream_index)
+        .await
+        .context("Failed to take screencap")?;
 
-        let img_size = match imagesize::blob_size(&img_data) {
-            Ok(size) => size,
-            Err(e) => {
-                error!("Failed to get image size: {}", e);
-                tokio::time::sleep(*RETRY_INTERVAL).await;
-                continue;
-            }
-        };
+    let img_size = imagesize::blob_size(&img_data)
+        .context("Failed to get image size for screencap image data")?;
 
     let attachment = eggbug::Attachment::new(
         img_data,
@@ -105,7 +132,7 @@ async fn main() {
     let mut tags = show.tags.clone();
     tags.extend_from_slice(&conf.global_tags);
 
-        match session
+    let chost_id = session
         .create_post(
             &conf.cohost_page,
             &mut eggbug::Post {
@@ -120,17 +147,10 @@ async fn main() {
             },
         )
         .await
-        {
-            Ok(id) => info!("Created post {}", id),
-            Err(e) => {
-                error!("Failed to create post: {}", e);
-                tokio::time::sleep(*RETRY_INTERVAL).await;
-                continue;
-            }
-        }
+        .context("Failed to create chost")?;
+    info!("Created post {}", chost_id);
 
-        tokio::time::sleep(conf.post_interval).await;
-    }
+    Ok(())
 }
 
 fn format_timestamp(timestamp: f64, total_duration: Option<f64>) -> String {

src/shows/mod.rs

@@ -1,5 +1,10 @@
-use std::{collections::HashMap, fs, io::ErrorKind, path::PathBuf};
+use std::{
+    collections::HashMap,
+    fs,
+    path::{Path, PathBuf},
+};
 
+use anyhow::{anyhow, Context};
 use log::{debug, error};
 use serde::Deserialize;
 
@@ -12,6 +17,8 @@ pub struct Show {
     pub tags: Vec<String>,
 }
 
+pub type Shows = HashMap<String, Show>;
+
 #[derive(Debug, Eq, Hash, PartialEq)]
 pub enum EpisodeNumber {
     Standalone,
@@ -21,15 +28,16 @@ pub enum EpisodeNumber {
 
 type Episodes = HashMap<EpisodeNumber, PathBuf>;
 
-pub fn load(shows_file: PathBuf) -> HashMap<String, Show> {
-    serde_yaml::from_reader(fs::File::open(shows_file).expect("Failed to open shows file"))
-        .expect("Failed to parse YAML from shows file")
+pub fn load<P: AsRef<Path>>(shows_file: P) -> anyhow::Result<Shows> {
+    serde_yaml::from_reader(fs::File::open(shows_file).context("Failed to open shows file")?)
+        .context("Failed to parse YAML from shows file")
 }
 
 impl Show {
-    pub fn episodes(&self) -> std::io::Result<Episodes> {
+    pub fn episodes(&self) -> anyhow::Result<Episodes> {
         let path = &self.path;
-        let metadata = fs::metadata(path)?;
+        let metadata =
+            fs::metadata(path).context("Failed to stat the show's path to determine file type")?;
         if metadata.is_file() {
             debug!("{} is a file, standalone", path.display());
             Ok(HashMap::from([(
@@ -38,10 +46,21 @@ impl Show {
             )]))
         } else if metadata.is_dir() {
             debug!("{} is a directory, enumerating episodes", path.display());
-            let files: Vec<PathBuf> = fs::read_dir(path)?
+            let files: Vec<PathBuf> = fs::read_dir(path)
+                .context("Failed to get a directory listing for the show's path")?
                 .map(|entry| {
-                    let entry = entry?;
-                    if !entry.file_type()?.is_file() {
+                    let entry =
+                        entry.context("Failed to read a directory entry under the show's path")?;
+                    if !entry
+                        .file_type()
+                        .with_context(|| {
+                            format!(
+                                "Failed to get file type for directory entry {}",
+                                entry.path().display()
+                            )
+                        })?
+                        .is_file()
+                    {
                         debug!("Skipping {}, not a file", entry.path().display());
                         return Ok(None);
                     }
@@ -55,16 +74,11 @@ impl Show {
                     Ok(Some(entry.path()))
                 })
                 .filter_map(|r| r.transpose())
-                .collect::<std::io::Result<Vec<PathBuf>>>()?;
-            enumeration::enumerate_episodes(files).ok_or(std::io::Error::new(
-                ErrorKind::InvalidData,
-                "No valid prefixes found",
-            ))
+                .collect::<anyhow::Result<Vec<PathBuf>>>()?;
+            enumeration::enumerate_episodes(files)
+                .ok_or(anyhow!("Could not detect any episode numbering scheme"))
         } else {
-            Err(std::io::Error::new(
-                ErrorKind::InvalidInput,
-                format!("Invalid file type for {}", path.display()),
-            ))
+            Err(anyhow!("The show's path is not a file or a directory"))
         }
     }
 }

src/video.rs

@@ -1,3 +1,4 @@
+use anyhow::{anyhow, Context};
 use ffmpeg_next::{
     format::{input, stream::Disposition},
     media::Type,
@@ -7,7 +8,7 @@ use regex::Regex;
 use tempfile::tempdir;
 use tokio::{fs, process::Command};
 
-use std::{io::ErrorKind, path::Path};
+use std::path::Path;
 
 lazy_static! {
     static ref SUBTITLE_FORBID_REGEX: Regex = Regex::new("(?i)sign|song").unwrap();
@@ -22,8 +23,8 @@ pub struct VideoInfo {
 pub fn get_video_info<P: AsRef<Path>>(
     source: &P,
     subtitle_lang: Option<&str>,
-) -> Result<VideoInfo, ffmpeg_next::Error> {
-    let ctx = input(source)?;
+) -> anyhow::Result<VideoInfo> {
+    let ctx = input(source).context("Failed to load video file")?;
 
     let duration_secs = ctx.duration() as f64 / f64::from(ffmpeg_next::ffi::AV_TIME_BASE);
 
@@ -63,18 +64,21 @@ pub async fn take_screencap<P: AsRef<Path>>(
     source: &P,
     timestamp_secs: f64,
     subtitle_stream_index: Option<usize>,
-) -> std::io::Result<Vec<u8>> {
+) -> anyhow::Result<Vec<u8>> {
     let ext = source.as_ref().extension().and_then(|s| s.to_str());
     if ext != Some("mkv") && ext != Some("mp4") {
-        return Err(std::io::Error::new(
-            ErrorKind::Other,
-            "unexpected file extension",
+        return Err(anyhow!(
+            "Video file {} had unexpected file extension",
+            source.as_ref().display()
         ));
     }
 
-    let tmp_dir = tempdir()?;
+    let tmp_dir = tempdir()
+        .context("Failed to create temporary directory for ffmpeg input and output files")?;
     let link_path = tmp_dir.path().join(format!("in.{}", ext.unwrap()));
-    fs::symlink(source, &link_path).await?;
+    fs::symlink(source, &link_path)
+        .await
+        .context("Failed to create symlink for video file")?;
     let dest_path = tmp_dir.path().join("out.png");
 
     let mut cmd = Command::new("ffmpeg");
@@ -98,12 +102,18 @@ pub async fn take_screencap<P: AsRef<Path>>(
         .arg("-y")
         .arg(&dest_path);
 
-    if !cmd.status().await?.success() {
-        return Err(std::io::Error::new(
-            ErrorKind::Other,
-            "ffmpeg command failed",
-        ));
+    let status = cmd
+        .status()
+        .await
+        .with_context(|| format!("Error running ffmpeg child process {:?}", cmd))?;
+    if !status.success() {
+        match status.code() {
+            Some(code) => return Err(anyhow!("ffmpeg exited with status code {code}")),
+            None => return Err(anyhow!("ffmpeg terminated by signal")),
+        }
     }
 
-    fs::read(&dest_path).await
+    fs::read(&dest_path)
+        .await
+        .with_context(|| format!("Failed to read ffmpeg output file {}", dest_path.display()))
 }