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use std::collections::HashMap;
use std::fs;
use std::io;
use std::path::Path;
use tera::{Context, Tera};
/// A builder for creating and rendering templates using the Tera template engine.
#[derive(Clone)]
pub struct TemplateBuilder {
template_path: String,
context: Context,
tera: Option<Tera>,
}
impl TemplateBuilder {
/// Creates a new TemplateBuilder with the specified template path.
///
/// # Arguments
///
/// * `template_path` - The path to the template file
///
/// # Returns
///
/// A new TemplateBuilder instance
///
/// # Example
///
/// ```
/// use sal_text::TemplateBuilder;
///
/// let builder = TemplateBuilder::open("templates/example.html");
/// ```
pub fn open<P: AsRef<Path>>(template_path: P) -> io::Result<Self> {
let path_str = template_path.as_ref().to_string_lossy().to_string();
// Verify the template file exists
if !Path::new(&path_str).exists() {
return Err(io::Error::new(
io::ErrorKind::NotFound,
format!("Template file not found: {}", path_str),
));
}
Ok(Self {
template_path: path_str,
context: Context::new(),
tera: None,
})
}
/// Adds a variable to the template context.
///
/// # Arguments
///
/// * `name` - The name of the variable to add
/// * `value` - The value to associate with the variable
///
/// # Returns
///
/// The builder instance for method chaining
///
/// # Example
///
/// ```no_run
/// use sal_text::TemplateBuilder;
///
/// fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let builder = TemplateBuilder::open("templates/example.html")?
/// .add_var("title", "Hello World")
/// .add_var("username", "John Doe");
/// Ok(())
/// }
/// ```
pub fn add_var<S, V>(mut self, name: S, value: V) -> Self
where
S: AsRef<str>,
V: serde::Serialize,
{
self.context.insert(name.as_ref(), &value);
self
}
/// Adds multiple variables to the template context from a HashMap.
///
/// # Arguments
///
/// * `vars` - A HashMap containing variable names and values
///
/// # Returns
///
/// The builder instance for method chaining
///
/// # Example
///
/// ```no_run
/// use sal_text::TemplateBuilder;
/// use std::collections::HashMap;
///
/// fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let mut vars = HashMap::new();
/// vars.insert("title", "Hello World");
/// vars.insert("username", "John Doe");
///
/// let builder = TemplateBuilder::open("templates/example.html")?
/// .add_vars(vars);
/// Ok(())
/// }
/// ```
pub fn add_vars<S, V>(mut self, vars: HashMap<S, V>) -> Self
where
S: AsRef<str>,
V: serde::Serialize,
{
for (name, value) in vars {
self.context.insert(name.as_ref(), &value);
}
self
}
/// Initializes the Tera template engine with the template file.
///
/// This method is called automatically by render() if not called explicitly.
///
/// # Returns
///
/// The builder instance for method chaining
fn initialize_tera(&mut self) -> Result<(), tera::Error> {
if self.tera.is_none() {
// Create a new Tera instance with just this template
let mut tera = Tera::default();
// Read the template content
let template_content = fs::read_to_string(&self.template_path)
.map_err(|e| tera::Error::msg(format!("Failed to read template file: {}", e)))?;
// Add the template to Tera
let template_name = Path::new(&self.template_path)
.file_name()
.and_then(|n| n.to_str())
.unwrap_or("template");
tera.add_raw_template(template_name, &template_content)?;
self.tera = Some(tera);
}
Ok(())
}
/// Renders the template with the current context.
///
/// # Returns
///
/// The rendered template as a string
///
/// # Example
///
/// ```no_run
/// use sal_text::TemplateBuilder;
///
/// fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let result = TemplateBuilder::open("templates/example.html")?
/// .add_var("title", "Hello World")
/// .add_var("username", "John Doe")
/// .render()?;
///
/// println!("Rendered template: {}", result);
/// Ok(())
/// }
/// ```
pub fn render(&mut self) -> Result<String, tera::Error> {
// Initialize Tera if not already done
self.initialize_tera()?;
// Get the template name
let template_name = Path::new(&self.template_path)
.file_name()
.and_then(|n| n.to_str())
.unwrap_or("template");
// Render the template
let tera = self.tera.as_ref().unwrap();
tera.render(template_name, &self.context)
}
/// Renders the template and writes the result to a file.
///
/// # Arguments
///
/// * `output_path` - The path where the rendered template should be written
///
/// # Returns
///
/// Result indicating success or failure
///
/// # Example
///
/// ```no_run
/// use sal_text::TemplateBuilder;
///
/// fn main() -> Result<(), Box<dyn std::error::Error>> {
/// TemplateBuilder::open("templates/example.html")?
/// .add_var("title", "Hello World")
/// .add_var("username", "John Doe")
/// .render_to_file("output.html")?;
/// Ok(())
/// }
/// ```
pub fn render_to_file<P: AsRef<Path>>(&mut self, output_path: P) -> io::Result<()> {
let rendered = self.render().map_err(|e| {
io::Error::new(
io::ErrorKind::Other,
format!("Template rendering error: {}", e),
)
})?;
fs::write(output_path, rendered)
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::io::Write;
use tempfile::NamedTempFile;
#[test]
fn test_template_rendering() -> Result<(), Box<dyn std::error::Error>> {
// Create a temporary template file
let temp_file = NamedTempFile::new()?;
let template_content = "Hello, {{ name }}! Welcome to {{ place }}.\n";
fs::write(temp_file.path(), template_content)?;
// Create a template builder and add variables
let mut builder = TemplateBuilder::open(temp_file.path())?;
builder = builder.add_var("name", "John").add_var("place", "Rust");
// Render the template
let result = builder.render()?;
assert_eq!(result, "Hello, John! Welcome to Rust.\n");
Ok(())
}
#[test]
fn test_template_with_multiple_vars() -> Result<(), Box<dyn std::error::Error>> {
// Create a temporary template file
let temp_file = NamedTempFile::new()?;
let template_content = "{% if show_greeting %}Hello, {{ name }}!{% endif %}\n{% for item in items %}{{ item }}{% if not loop.last %}, {% endif %}{% endfor %}\n";
fs::write(temp_file.path(), template_content)?;
// Create a template builder and add variables
let mut builder = TemplateBuilder::open(temp_file.path())?;
// Add variables including a boolean and a vector
builder = builder
.add_var("name", "Alice")
.add_var("show_greeting", true)
.add_var("items", vec!["apple", "banana", "cherry"]);
// Render the template
let result = builder.render()?;
assert_eq!(result, "Hello, Alice!\napple, banana, cherry\n");
Ok(())
}
#[test]
fn test_template_with_hashmap_vars() -> Result<(), Box<dyn std::error::Error>> {
// Create a temporary template file
let mut temp_file = NamedTempFile::new()?;
writeln!(temp_file, "{{{{ greeting }}}}, {{{{ name }}}}!")?;
temp_file.flush()?;
// Create a HashMap of variables
let mut vars = HashMap::new();
vars.insert("greeting", "Hi");
vars.insert("name", "Bob");
// Create a template builder and add variables from HashMap
let mut builder = TemplateBuilder::open(temp_file.path())?;
builder = builder.add_vars(vars);
// Render the template
let result = builder.render()?;
assert_eq!(result, "Hi, Bob!\n");
Ok(())
}
#[test]
fn test_render_to_file() -> Result<(), Box<dyn std::error::Error>> {
// Create a temporary template file
let temp_file = NamedTempFile::new()?;
let template_content = "{{ message }}\n";
fs::write(temp_file.path(), template_content)?;
// Create an output file
let output_file = NamedTempFile::new()?;
// Create a template builder, add a variable, and render to file
let mut builder = TemplateBuilder::open(temp_file.path())?;
builder = builder.add_var("message", "This is a test");
builder.render_to_file(output_file.path())?;
// Read the output file and verify its contents
let content = fs::read_to_string(output_file.path())?;
assert_eq!(content, "This is a test\n");
Ok(())
}
}