very basic list management

Cargo.toml

@@ -14,7 +14,10 @@ keywords = ["download", "http", "https"]
 [dependencies]
 anyhow = "1.0.75"
 clap = { version = "4.4.6", features = ["env", "derive", "wrap_help", "cargo", "unicode"] }
+directories = "5.0.1"
+fs4 = "0.6.6"
 human-panic = "1.2.1"
+rand = "0.8.5"
 reqwest = { version = "0.11.20", features = ["brotli", "deflate", "gzip"] }
 serde = { version = "1.0.188", features = ["derive"] }
 serde_json = "1.0.107"

src/cli.rs

@@ -1,11 +0,0 @@
-use clap::{Parser, Subcommand};
-
-#[derive(Debug, Parser)]
-#[clap(author, version, about)]
-pub struct CLI {
-    #[clap(subcommand)]
-    command: Command,
-}
-
-#[derive(Debug, Subcommand)]
-pub enum Command {}

src/cli/list.rs

@@ -0,0 +1,33 @@
+use clap::Subcommand;
+
+#[derive(Debug, Subcommand)]
+pub enum ListCommand {
+    /// Create a new download list.
+    #[clap(visible_alias = "new", visible_alias = "c")]
+    Create {
+        /// A unique name, which will be used to refer to the list.
+        name: String,
+        /// A short description of the lists purpose.
+        #[clap(long, short, default_value = "", hide_default_value = true)]
+        description: String,
+    },
+    /// Delete a download list.
+    #[clap(visible_alias = "rm", visible_alias = "d")]
+    Delete {
+        /// The name of the list to remove.
+        name: String,
+    },
+    /// Update an existing list.
+    ///
+    /// Only values specified for this command are changed.
+    #[clap(visible_alias = "u")]
+    Update {
+        /// The name of the list to change.
+        name: String,
+        /// A short description of the lists purpose.
+        ///
+        /// Set this to an empty string (e.g. pass "" as value) to remove the current description.
+        #[clap(long, short)]
+        description: Option<String>,
+    },
+}

src/cli/mod.rs

@@ -0,0 +1,22 @@
+use clap::{Parser, Subcommand};
+
+mod list;
+
+pub use list::*;
+
+#[derive(Debug, Parser)]
+#[clap(author, version, about)]
+pub struct CLI {
+    #[clap(subcommand)]
+    pub command: Command,
+}
+
+#[derive(Debug, Subcommand)]
+pub enum Command {
+    /// Manage entire download lists.
+    #[clap(visible_alias = "l")]
+    List {
+        #[clap(subcommand)]
+        command: ListCommand,
+    },
+}

src/data.rs

@@ -0,0 +1,28 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Deserialize, Serialize)]
+pub struct DownloadList {
+    name: String,
+    description: String,
+}
+
+impl DownloadList {
+    pub fn new(name: String) -> Self {
+        Self {
+            name,
+            description: String::new(),
+        }
+    }
+
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+
+    pub fn description(&self) -> &str {
+        &self.description
+    }
+
+    pub fn set_description(&mut self, description: String) {
+        self.description = description;
+    }
+}

src/main.rs

@@ -1,11 +1,72 @@
+use std::{
+    fs,
+    path::{Path, PathBuf},
+};
+
+use anyhow::{ensure, Context};
 use clap::Parser;
+use directories::ProjectDirs;
+
+use crate::store::DownloadListStore;
 
 mod cli;
+mod data;
+mod store;
 
-#[tokio::main]
+fn main() -> anyhow::Result<()> {
-async fn main() -> anyhow::Result<()> {
     human_panic::setup_panic!();
     let cli = cli::CLI::parse();
+    let (state, data) = prepare_directories()?;
 
-    Ok(())
+    match cli.command {
+        cli::Command::List { command } => match command {
+            cli::ListCommand::Update { name, description } => {
+                let mut list = DownloadListStore::load(&name, &data)?;
+
+                if let Some(description) = description {
+                    list.set_description(description);
+                }
+
+                list.save()
+            }
+            cli::ListCommand::Create { name, description } => {
+                let mut list = DownloadListStore::new(name, &data)?;
+
+                list.set_description(description);
+
+                list.save()
+            }
+            cli::ListCommand::Delete { name } => DownloadListStore::delete(&name, &data),
+        },
+    }
+}
+
+fn prepare_directories() -> anyhow::Result<(PathBuf, PathBuf)> {
+    let dirs = ProjectDirs::from("dev", "TFLD", "listload")
+        .context("failed to discover project directories")?;
+
+    let state = dirs.state_dir().unwrap_or_else(|| dirs.data_local_dir());
+    prepare_directory(state)?;
+
+    let data = dirs.data_dir();
+    prepare_directory(data)?;
+
+    Ok((state.to_path_buf(), data.to_path_buf()))
+}
+
+fn prepare_directory(path: &Path) -> anyhow::Result<()> {
+    if path.is_dir() {
+        return Ok(());
+    }
+
+    ensure!(
+        !path.exists(),
+        "required directory is not a directory: {}",
+        path.display()
+    );
+
+    fs::create_dir_all(path).context(format!(
+        "failed to create required directory: {}",
+        path.display()
+    ))
 }

src/store.rs

@@ -0,0 +1,103 @@
+use std::{
+    fs::{self, File, OpenOptions},
+    io::{BufReader, BufWriter, Seek},
+    ops::{Deref, DerefMut},
+    path::Path,
+};
+
+use anyhow::{ensure, Context};
+use fs4::FileExt;
+
+use crate::data::DownloadList;
+
+#[derive(Debug)]
+pub struct DownloadListStore {
+    list: DownloadList,
+    file: File,
+}
+
+impl DownloadListStore {
+    pub fn new(name: String, directory: &Path) -> anyhow::Result<Self> {
+        let path = Self::path_in_directory(directory, &name);
+
+        let file = OpenOptions::new()
+            .create_new(true)
+            .read(true)
+            .write(true)
+            .open(&path)
+            .context("failed to create list file")?;
+
+        file.lock_exclusive()
+            .context("failed to acquire list file lock")?;
+
+        Ok(Self {
+            list: DownloadList::new(name),
+            file,
+        })
+    }
+
+    pub fn load(name: &str, directory: &Path) -> anyhow::Result<Self> {
+        let path = Self::path_in_directory(directory, name);
+
+        let file = OpenOptions::new()
+            .create(false)
+            .read(true)
+            .write(true)
+            .open(&path)
+            .context("failed to open list file")?;
+
+        file.lock_exclusive()
+            .context("failed to acquire list file lock")?;
+
+        let reader = BufReader::new(&file);
+        let list: DownloadList =
+            serde_json::from_reader(reader).context("failed to deserialize list")?;
+
+        ensure!(
+            name == list.name(),
+            "list name mismatch: found {name} instead of {}",
+            list.name()
+        );
+
+        Ok(Self { list, file })
+    }
+
+    pub fn save(&mut self) -> anyhow::Result<()> {
+        self.file.set_len(0).context("failed to clear list file")?;
+        self.file
+            .seek(std::io::SeekFrom::Start(0))
+            .context("failed to find list file start")?;
+
+        let writer = BufWriter::new(&self.file);
+
+        if cfg!(debug_assertions) {
+            serde_json::to_writer_pretty(writer, &self.list)
+        } else {
+            serde_json::to_writer(writer, &self.list)
+        }
+        .context("failed to write list file")
+    }
+
+    pub fn delete(name: &str, directory: &Path) -> anyhow::Result<()> {
+        fs::remove_file(Self::path_in_directory(directory, name))
+            .context("failed to remove list file")
+    }
+
+    fn path_in_directory(directory: &Path, name: &str) -> std::path::PathBuf {
+        directory.join(name).with_extension("json")
+    }
+}
+
+impl Deref for DownloadListStore {
+    type Target = DownloadList;
+
+    fn deref(&self) -> &Self::Target {
+        &self.list
+    }
+}
+
+impl DerefMut for DownloadListStore {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.list
+    }
+}