first commit

.gitignore

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+/target

Cargo.toml

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+[package]
+name = "todoapp_cli"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+serde_json = "1.0.60"

README.md

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+# This is Todo App with Rust lang.
+
+CLI's Todo App.
+
+## Usage
+
+### For Example
+
+Input command
+
+```
+$ cargo run -- add "todo test1"
+```
+
+confirmation
+
+```
+$ cat ./data/db.json
+```

data/db.json

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+{
+  "second test": true,
+  "code test": true,
+  "first test": false
+}

src/main.rs

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+use std::collections::HashMap;
+
+struct Todo {
+    map: HashMap<String, bool>,
+}
+
+impl Todo {
+    fn insert(&mut self, key: String) {
+        // insert a new item into our map.
+        // we pass true as value
+        self.map.insert(key, true);
+    }
+
+    fn save(self) -> Result<(), Box<dyn std::error::Error>> {
+        let content = std::fs::OpenOptions::new()
+            .write(true)
+            .create(true)
+            .truncate(true)
+            .open("./data/db.json")?;
+        serde_json::to_writer_pretty(content, &self.map)?;
+        Ok(())
+    }
+
+    fn new() -> Result<Todo, std::io::Error> {
+        let list = std::fs::OpenOptions::new()
+            .write(true)
+            .create(true)
+            .read(true)
+            .open("./data/db.json")?;
+
+        match serde_json::from_reader(list) {
+            Ok(map) => Ok(Todo {map}),
+            Err(e) if e.is_eof() => Ok(Todo {
+                map: HashMap::new(),
+            }),
+            Err(e) => panic!("An error occurred: {}", e),
+        }
+    }
+
+    fn complete(&mut self, key: &String) -> Option<()> {
+        match self.map.get_mut(key) {
+            Some(v) => Some(*v = false),
+            None => None,
+        }
+    }
+
+
+}
+
+fn main() {
+    let action = std::env::args().nth(1).expect("Please specify an action");
+    let item = std::env::args().nth(2).expect("Please specify an item");
+
+    let mut todo = Todo::new().expect("Initialisation of db failed");
+
+    if action == "add" {
+        todo.insert(item);
+        match todo.save() {
+            Ok(_) => println!("todo saved"),
+            Err(why) => println!("An error occurred: {}", why),
+        }
+    } else if action == "complete" {
+        match todo.complete(&item) {
+            None => println!("'{}' is not present in the list", item),
+            Some(_) => match todo.save() {
+                Ok(_) => println!("todo saved"),
+                Err(why) => println!("An error occurred: {}", why),
+            },
+        }
+    }
+}