Match ex vers

src/providers/elixir.rs

@@ -40,6 +40,66 @@ impl Provider for ElixirProvider {
 
     fn start(&self, _app: &App, _env: &Environment) -> Result<Option<StartPhase>> {
         let start_phase = StartPhase::new("mix run --no-halt".to_string());
-        Ok(Some(start_phase))
+        plan.set_start_phase(start_phase);
+
+        Ok(Some(plan))
+    }
+}
+
+impl ElixirProvider {
+    fn get_nix_elixir_package(app: &App, env: &Environment) -> Result<Pkg> {
+        fn as_default(v: Option<Match>) -> &str {
+            match v {
+                Some(m) => m.as_str(),
+                None => "_",
+            }
+        }
+
+        let mix_exs_content = app.read_file("mix.exs")?;
+        let custom_version = env.get_config_variable("ELIXIR_VERSION");
+
+        let mix_elixir_version_regex = Regex::new(r#"(elixir:[\s].*[> ])([0-9|\.]*)"#)?;
+
+        // If not from env variable, get it from the .elixir-version file then try to parse from mix.exs
+        let custom_version = if custom_version.is_some() {
+            custom_version
+        } else if custom_version.is_none() && app.includes_file(".elixir-version") {
+            Some(app.read_file(".elixir-version")?)
+        } else {
+            mix_elixir_version_regex
+                .captures(&mix_exs_content)
+                .map(|c| c.get(2).unwrap().as_str().to_owned())
+        };
+
+        // If it's still none, return default
+        if custom_version.is_none() {
+            return Ok(Pkg::new(DEFAULT_ELIXIR_PKG_NAME));
+        }
+        let custom_version = custom_version.unwrap();
+
+        // Regex for reading Elixir versions (e.g. 1.8 or 1.12)
+        let elixir_version_regex =
+            Regex::new(r#"^(?:[\sa-zA-Z-"']*)(\d*)(?:\.*)(\d*)(?:\.*\d*)(?:["']?)$"#)?;
+
+        // Capture matches
+        let matches = elixir_version_regex.captures(custom_version.as_str().trim());
+
+        // If no matches, just use default
+        if matches.is_none() {
+            return Ok(Pkg::new(DEFAULT_ELIXIR_PKG_NAME));
+        }
+        let matches = matches.unwrap();
+        let parsed_version = (as_default(matches.get(1)), as_default(matches.get(2)));
+
+        // Match major and minor versions
+        match parsed_version {
+            ("1", "9") => Ok(Pkg::new("elixir_1_9")),
+            ("1", "10") => Ok(Pkg::new("elixir_1_10")),
+            ("1", "11") => Ok(Pkg::new("elixir_1_11")),
+            ("1", "12") => Ok(Pkg::new("elixir_1_12")),
+            ("1", "13") => Ok(Pkg::new("elixir_1_13")),
+            ("1", "14") => Ok(Pkg::new("elixir_1_14")),
+            _ => Ok(Pkg::new(DEFAULT_ELIXIR_PKG_NAME)),
+        }
     }
 }