Add new 'deps add' command

This makes it easier to add new dependencies, without having to
  manually edit the `aiken.toml` file.

  The command is accessible via two different paths:

  - aiken deps add

  or simply

  - aiken add

  for this is quite common to find at the top-level of the command-line,
  and, we still want to keep commands for managing dependencies grouped
  under a command sub-group and not all at the top-level. So we're
  merely promoting that one for visibility.

crates/aiken-project/src/config.rs

@@ -2,17 +2,13 @@ use crate::{package_name::PackageName, Error};
 use aiken_lang::ast::Span;
 use miette::NamedSource;
 use serde::{Deserialize, Serialize};
-use std::{
-    fmt::Display,
-    fs, io,
-    path::{Path, PathBuf},
-};
+use std::{fmt::Display, fs, io, path::Path};
 
 #[derive(Deserialize, Serialize)]
 pub struct Config {
     pub name: PackageName,
     pub version: String,
-    pub license: String,
+    pub license: Option<String>,
     #[serde(default)]
     pub description: String,
     pub repository: Option<Repository>,
@@ -57,7 +53,7 @@ impl Config {
         Config {
             name: name.clone(),
             version: "0.0.0".to_string(),
-            license: "Apache-2.0".to_string(),
+            license: Some("Apache-2.0".to_string()),
             description: format!("Aiken contracts for project '{name}'"),
             repository: Some(Repository {
                 user: name.owner.clone(),
@@ -81,10 +77,11 @@ impl Config {
         fs::write(aiken_toml_path, aiken_toml)
     }
 
-    pub fn load(dir: PathBuf) -> Result<Config, Error> {
+    pub fn load(dir: &Path) -> Result<Config, Error> {
         let config_path = dir.join("aiken.toml");
-        let raw_config = fs::read_to_string(&config_path)
-            .map_err(|_| Error::MissingManifest { path: dir.clone() })?;
+        let raw_config = fs::read_to_string(&config_path).map_err(|_| Error::MissingManifest {
+            path: dir.to_path_buf(),
+        })?;
 
         let result: Self = toml::from_str(&raw_config).map_err(|e| Error::TomlLoading {
             path: config_path.clone(),
@@ -100,4 +97,19 @@ impl Config {
 
         Ok(result)
     }
+
+    pub fn insert(mut self, dependency: &Dependency, and_replace: bool) -> Option<Self> {
+        for mut existing in self.dependencies.iter_mut() {
+            if existing.name == dependency.name {
+                return if and_replace {
+                    existing.version = dependency.version.clone();
+                    Some(self)
+                } else {
+                    None
+                };
+            }
+        }
+        self.dependencies.push(dependency.clone());
+        Some(self)
+    }
 }

crates/aiken-project/src/error.rs

@@ -1,4 +1,4 @@
-use crate::{deps::manifest::Package, pretty, script::EvalHint};
+use crate::{deps::manifest::Package, package_name::PackageName, pretty, script::EvalHint};
 use aiken_lang::{
     ast::{BinOp, Span},
     parser::error::ParseError,
@@ -418,6 +418,8 @@ pub enum Warning {
         #[source]
         warning: tipo::error::Warning,
     },
+    #[error("{name} is already a dependency.")]
+    DependencyAlreadyExists { name: PackageName },
 }
 
 impl Diagnostic for Warning {
@@ -429,6 +431,7 @@ impl Diagnostic for Warning {
         match self {
             Warning::Type { named, .. } => Some(named),
             Warning::NoValidators => None,
+            Warning::DependencyAlreadyExists { .. } => None,
         }
     }
 
@@ -436,6 +439,7 @@ impl Diagnostic for Warning {
         match self {
             Warning::Type { warning, .. } => warning.labels(),
             Warning::NoValidators => None,
+            Warning::DependencyAlreadyExists { .. } => None,
         }
     }
 
@@ -443,6 +447,19 @@ impl Diagnostic for Warning {
         match self {
             Warning::Type { .. } => Some(Box::new("aiken::check")),
             Warning::NoValidators => Some(Box::new("aiken::check")),
+            Warning::DependencyAlreadyExists { .. } => {
+                Some(Box::new("aiken::deps::already_exists"))
+            }
+        }
+    }
+
+    fn help<'a>(&'a self) -> Option<Box<dyn Display + 'a>> {
+        match self {
+            Warning::Type { .. } => None,
+            Warning::NoValidators => None,
+            Warning::DependencyAlreadyExists { .. } => Some(Box::new(
+                "If you need to change the version, try 'aiken packages upgrade' instead.",
+            )),
         }
     }
 }

crates/aiken-project/src/lib.rs

@@ -86,7 +86,7 @@ where
         module_types.insert("aiken".to_string(), builtins::prelude(&id_gen));
         module_types.insert("aiken/builtin".to_string(), builtins::plutus(&id_gen));
 
-        let config = Config::load(root.clone())?;
+        let config = Config::load(&root)?;
 
         Ok(Project {
             config,

crates/aiken-project/src/package_name.rs

@@ -13,22 +13,24 @@ pub struct PackageName {
 }
 
 impl PackageName {
-    fn validate(&self) -> Result<(), Error> {
-        let name = format!("{}/{}", self.owner, self.repo);
-
+    pub fn restrict(&self) -> Result<(), Error> {
         if self.owner.starts_with("aiken") {
             return Err(Error::InvalidProjectName {
                 reason: InvalidProjectNameReason::Reserved,
-                name,
+                name: self.to_string(),
             });
         }
 
+        Ok(())
+    }
+
+    fn validate(&self) -> Result<(), Error> {
         let r = regex::Regex::new("^[a-z0-9_-]+$").expect("regex could not be compiled");
 
         if !(r.is_match(&self.owner) && r.is_match(&self.repo)) {
             return Err(Error::InvalidProjectName {
                 reason: InvalidProjectNameReason::Format,
-                name,
+                name: self.to_string(),
             });
         }