feat: add comments in header with metadata

Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+chrono = "0.4.44"
 clap = { version = "4", features = ["derive"] }
 dotenvy = "0.15"
 regex = "1"

src/schema/mod.rs

@@ -106,6 +106,25 @@ impl TryFrom<RawEntryKind> for EntryKind {
 pub fn generate_env(schema: &Schema, existing_env: &HashMap<String, String>) -> String {
     let mut output = String::new();
 
+    // Add header comments and metadata
+    let version = option_env!("CENV_VERSION").unwrap_or("unknown");
+    output.push_str("# This file is auto-generated by cenv. Do not edit directly.\n");
+    output.push_str("# To update this file, edit the schema and run `cenv fix`.\n");
+    output.push_str(format!("#schema-version={}\n", version).as_str());
+    output.push_str(format!("#generated-at={}\n\n", chrono::Utc::now().to_rfc3339()).as_str());
+
+    // Add the key=value pairs for each entry in the schema,
+    // using existing env values or defaults as needed.
+    let env_content = generate_env_vars(schema, existing_env);
+    output.push_str(&env_content);
+
+    output
+}
+
+// Generates the key=value lines for the .env file based on the schema and existing env values.
+fn generate_env_vars(schema: &Schema, existing_env: &HashMap<String, String>) -> String {
+    let mut output = String::new();
+
     for entry in &schema.entries {
         // Determine the value to use:
         // 1. Use existing value from .env if present and non-empty

src/schema/tests.rs

@@ -31,7 +31,7 @@ fn default_options() -> Entry {
     default_entry()
 }
 
-// ==================== generate_env Tests ====================
+// ==================== generate_env_vars Tests ====================
 
 mod generate_env_tests {
     use super::*;
@@ -40,15 +40,15 @@ mod generate_env_tests {
     fn empty_schema_produces_empty_output() {
         let schema = create_schema(vec![]);
         let existing = HashMap::new();
-        let output = generate_env(&schema, &existing);
+        let output = generate_env_vars(&schema, &existing);
         assert_eq!(output, "");
     }
 
     #[test]
     fn single_entry_no_existing_no_default() {
         let schema = create_schema(vec![create_entry("FOO", default_options())]);
         let existing = HashMap::new();
-        let output = generate_env(&schema, &existing);
+        let output = generate_env_vars(&schema, &existing);
         assert_eq!(output, "FOO=\n");
     }
 
@@ -58,7 +58,7 @@ mod generate_env_tests {
         opts.default = Some("bar".to_string());
         let schema = create_schema(vec![create_entry("FOO", opts)]);
         let existing = HashMap::new();
-        let output = generate_env(&schema, &existing);
+        let output = generate_env_vars(&schema, &existing);
         assert_eq!(output, "FOO=bar\n");
     }
 
@@ -69,7 +69,7 @@ mod generate_env_tests {
         let schema = create_schema(vec![create_entry("FOO", opts)]);
         let mut existing = HashMap::new();
         existing.insert("FOO".to_string(), "existing_value".to_string());
-        let output = generate_env(&schema, &existing);
+        let output = generate_env_vars(&schema, &existing);
         assert_eq!(output, "FOO=existing_value\n");
     }
 
@@ -80,7 +80,7 @@ mod generate_env_tests {
         let schema = create_schema(vec![create_entry("FOO", opts)]);
         let mut existing = HashMap::new();
         existing.insert("FOO".to_string(), "".to_string());
-        let output = generate_env(&schema, &existing);
+        let output = generate_env_vars(&schema, &existing);
         assert_eq!(output, "FOO=default_value\n");
     }
 
@@ -89,7 +89,7 @@ mod generate_env_tests {
         let schema = create_schema(vec![create_entry("FOO", default_options())]);
         let mut existing = HashMap::new();
         existing.insert("FOO".to_string(), "".to_string());
-        let output = generate_env(&schema, &existing);
+        let output = generate_env_vars(&schema, &existing);
         assert_eq!(output, "FOO=\n");
     }
 
@@ -101,7 +101,7 @@ mod generate_env_tests {
             create_entry("CCC", default_options()),
         ]);
         let existing = HashMap::new();
-        let output = generate_env(&schema, &existing);
+        let output = generate_env_vars(&schema, &existing);
         assert_eq!(output, "AAA=\nBBB=\nCCC=\n");
     }
 
@@ -118,7 +118,7 @@ mod generate_env_tests {
         let mut existing = HashMap::new();
         existing.insert("AAA".to_string(), "value_a".to_string());
         existing.insert("CCC".to_string(), "value_c".to_string());
-        let output = generate_env(&schema, &existing);
+        let output = generate_env_vars(&schema, &existing);
         assert_eq!(output, "AAA=value_a\nBBB=default_b\nCCC=value_c\n");
     }
 
@@ -129,7 +129,7 @@ mod generate_env_tests {
         existing.insert("FOO".to_string(), "foo_value".to_string());
         existing.insert("BAR".to_string(), "bar_value".to_string());
         existing.insert("BAZ".to_string(), "baz_value".to_string());
-        let output = generate_env(&schema, &existing);
+        let output = generate_env_vars(&schema, &existing);
         assert_eq!(output, "FOO=foo_value\n");
     }
 
@@ -141,7 +141,7 @@ mod generate_env_tests {
             "FOO".to_string(),
             "value with spaces & special=chars!".to_string(),
         );
-        let output = generate_env(&schema, &existing);
+        let output = generate_env_vars(&schema, &existing);
         assert_eq!(output, "FOO=value with spaces & special=chars!\n");
     }
 }