implement from_url method

src/storage.rs

@@ -1,4 +1,4 @@
-use anyhow::{anyhow, Error, Result};
+use anyhow::{anyhow, bail, Error, Result};
 use std::{
     fs::{create_dir_all, remove_file, rename, File},
     path::{PathBuf, MAIN_SEPARATOR},
@@ -18,6 +18,35 @@ pub struct Item {
 impl Item {
     // Constructors
 
+    /// Build new `Self` from URL (request)
+    /// * e.g. 123 -> /directory/1/2/3
+    pub fn from_url(url: &str, directory: &str) -> Result<Self> {
+        let s = match url.rfind('/') {
+            Some(pos) => match url.get(pos + 1..) {
+                Some(u) => u.parse::<u64>()?,
+                None => bail!("Invalid request"),
+            },
+            None => bail!("ID not found"),
+        }
+        .to_string();
+        let mut p = String::with_capacity(s.len());
+        for (i, d) in s.chars().enumerate() {
+            if i > 0 {
+                p.push(MAIN_SEPARATOR)
+            }
+            p.push(d)
+        }
+        let path = PathBuf::from_str(&format!(
+            "{}{MAIN_SEPARATOR}{p}",
+            directory.trim_end_matches(MAIN_SEPARATOR),
+        ))?;
+        Ok(Self {
+            file: File::open(&path)?,
+            path,
+        })
+    }
+
+    /// Create new `Self` with unique pathname in the root `directory`
     pub fn create(directory: &str) -> Result<Self> {
         loop {
             // generate file id from current unix time
@@ -83,12 +112,14 @@ impl Item {
         }
     }
 
+    /// Delete `Self`, cleanup FS
     pub fn delete(self) -> Result<()> {
         Ok(remove_file(self.path)?)
     }
 
     // Getters
 
+    /// Shared helper to build public URI
     pub fn to_uri(&self, directory: &str) -> String {
         self.path
             .to_str()
@@ -96,7 +127,4 @@ impl Item {
             .replace(directory, "")
             .replace("/", "")
     }
-
-    /* @TODO implement short links handle without slash
-    pub fn alias(&self, relative: &str) -> String {} */
 }