Update

Cargo.lock

@@ -1169,6 +1169,7 @@ dependencies = [
  "reqwest",
  "spin_on",
  "tokio",
+ "url",
  "urlparse",
  "utf16string",
  "winapi",

Cargo.toml

@@ -27,6 +27,7 @@ reqwest = { version = "0.11", features = ["brotli", "deflate", "gzip", "rustls-t
 RustyXML = "0.3"
 spin_on = "0.1.1"
 tokio = { version = "1.18", features = ["rt", "macros", "rt-multi-thread", "time"] }
+url = "2.2"
 urlparse = "0.7"
 utf16string = { version= "0.2", optional = true }
 

src/download.rs

@@ -7,7 +7,7 @@ use crate::data::json::JSONDataFile;
 #[cfg(feature = "ugoira")]
 use crate::data::video::get_video_metadata;
 use crate::downloader::pd_file::enums::PdFileResult;
-use crate::downloader::pd_file::file::PdFile;
+use crate::downloader::pd_file::PdFile;
 use crate::gettext;
 use crate::opthelper::OptHelper;
 use crate::pixiv_link::PixivID;

src/downloader/downloader.rs

@@ -0,0 +1,75 @@
+use super::pd_file::PdFile;
+use super::pd_file::PdFileResult;
+use super::error::DownloaderError;
+use crate::webclient::WebClient;
+use crate::webclient::ToHeaders;
+use reqwest::IntoUrl;
+use std::collections::HashMap;
+use std::fs::File;
+use std::path::Path;
+use std::sync::Arc;
+use std::sync::RwLock;
+use url::Url;
+
+/// A file downloader
+pub struct Downloader {
+    /// The webclient
+    client: Arc<WebClient>,
+    /// The download status
+    status: Arc<PdFile>,
+    /// The url of the file
+    url: Arc<Url>,
+    /// The HTTP headers map
+    headers: Arc<HashMap<String, String>>,
+    /// The target file
+    file: RwLock<Option<File>>,
+}
+
+impl Downloader {
+    /// Create a new [Downloader] instance
+    /// * `url` - The url of the file
+    /// * `header` - HTTP headers
+    /// * `path` - The path to store downloaded file.
+    /// * `overwrite` - Whether to overwrite file
+    pub fn new<U: IntoUrl, H: ToHeaders, P: AsRef<Path> + ?Sized>(url: U, headers: H, path: Option<&P>, overwrite: Option<bool>) -> Result<Self, DownloaderError> {
+        let h = match headers.to_headers() {
+            Some(h) => { h }
+            None => { HashMap::new() }
+        };
+        let mut already_exists = false;
+        let pd_file = match path {
+            Some(p) => {
+                let p = p.as_ref();
+                match PdFile::open(p)? {
+                    PdFileResult::TargetExisted => {
+                        // #TODO
+                        PdFile::new()
+                    }
+                    PdFileResult::Ok(p) => { p }
+                    PdFileResult::ExistedOk(p) => {
+                        already_exists = true;
+                        p
+                    }
+                }
+            }
+            None => { PdFile::new() }
+        };
+        let file = match path {
+            Some(p) => {
+                if already_exists {
+                    Some(File::open(p)?)
+                } else {
+                    Some(File::create(p)?)
+                }
+            }
+            None => { None }
+        };
+        Ok(Self {
+            client: Arc::new(WebClient::new()),
+            status: Arc::new(pd_file),
+            url: Arc::new(url.into_url()?),
+            headers: Arc::new(h),
+            file: RwLock::new(file),
+        })
+    }
+}

src/downloader/error.rs

@@ -0,0 +1,8 @@
+use crate::downloader::pd_file::PdFileError;
+
+#[derive(Debug, derive_more::From)]
+pub enum DownloaderError {
+    ReqwestError(reqwest::Error),
+    PdFileError(PdFileError),
+    IoError(std::io::Error),
+}

src/downloader/mod.rs

@@ -1 +1,7 @@
+/// A file downloader
+pub mod downloader;
+/// File downloader's error
+pub mod error;
+/// The pd file
 pub mod pd_file;
+pub use downloader::Downloader;

src/downloader/pd_file/mod.rs

@@ -9,3 +9,6 @@ pub mod file;
 pub mod part_status;
 /// Version of the pd file
 pub mod version;
+pub use enums::PdFileResult;
+pub use error::PdFileError;
+pub use file::PdFile;

src/main.rs

@@ -19,6 +19,7 @@ extern crate proc_macros;
 extern crate tokio;
 extern crate regex;
 extern crate reqwest;
+extern crate url;
 extern crate urlparse;
 #[cfg(feature = "utf16string")]
 extern crate utf16string;

src/pixiv_web.rs

@@ -1,4 +1,4 @@
-use crate::downloader::pd_file::file::PdFile;
+use crate::downloader::pd_file::PdFile;
 use crate::ext::rw_lock::GetRwLock;
 use crate::gettext;
 use crate::opthelper::OptHelper;