tron/

builder.rs

//! Builder patterns for fluent template construction.
//!
//! This module provides builder patterns for [`TronTemplate`] and [`TronRef`]
//! that allow for more ergonomic and fluent template creation with method chaining.
//!
//! # Examples
//!
//! Using the template builder:
//!
//! ```
//! use tron::TronTemplateBuilder;
//! use std::collections::HashMap;
//!
//! let mut values = HashMap::new();
//! values.insert("name", "greet");
//! values.insert("body", "println!(\"Hello, World!\");");
//!
//! let template = TronTemplateBuilder::new()
//!     .content("fn @[name]@() {\n    @[body]@\n}")
//!     .set("name", "greet")
//!     .set("body", "println!(\"Hello, World!\");")
//!     .build()
//!     .unwrap();
//!
//! let result = template.render().unwrap();
//! ```
//!
//! Using the template reference builder:
//!
//! ```
//! use tron::{TronTemplateBuilder, TronRefBuilder};
//!
//! let template_ref = TronRefBuilder::new()
//!     .content("fn main() {\n    @[body]@\n}")
//!     .dependency("serde = \"1.0\"")
//!     .dependency("tokio = \"1.0\"")
//!     .set("body", "println!(\"Hello from builder!\");")
//!     .build()
//!     .unwrap();
//! ```

use std::collections::HashMap;
use std::path::Path;
use crate::error::{Result, TronError};
use crate::template::TronTemplate;
use crate::template_ref::TronRef;

/// Builder for creating [`TronTemplate`] instances with a fluent API.
///
/// This builder allows you to construct templates step by step, setting
/// content, placeholder values, and other configuration options.
///
/// # Examples
///
/// Basic template building:
///
/// ```
/// use tron::TronTemplateBuilder;
///
/// let template = TronTemplateBuilder::new()
///     .content("Hello @[name]@!")
///     .set("name", "World")
///     .build()
///     .unwrap();
///
/// assert_eq!(template.render().unwrap(), "Hello World!");
/// ```
///
/// Building from file:
///
/// ```no_run
/// use tron::TronTemplateBuilder;
///
/// let template = TronTemplateBuilder::new()
///     .from_file("template.tpl")
///     .set("name", "World")
///     .build()
///     .unwrap();
/// ```
#[derive(Debug, Default)]
pub struct TronTemplateBuilder {
    content: Option<String>,
    file_path: Option<String>,
    placeholder_values: HashMap<String, String>,
}

impl TronTemplateBuilder {
    /// Create a new template builder.
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronTemplateBuilder;
    ///
    /// let builder = TronTemplateBuilder::new();
    /// ```
    pub fn new() -> Self {
        Self::default()
    }

    /// Set the template content directly.
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronTemplateBuilder;
    ///
    /// let template = TronTemplateBuilder::new()
    ///     .content("Hello @[name]@!")
    ///     .build()
    ///     .unwrap();
    /// ```
    pub fn content<S: Into<String>>(mut self, content: S) -> Self {
        self.content = Some(content.into());
        self
    }

    /// Load template content from a file.
    ///
    /// This will override any previously set content.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use tron::TronTemplateBuilder;
    ///
    /// let template = TronTemplateBuilder::new()
    ///     .from_file("templates/function.tpl")
    ///     .build()
    ///     .unwrap();
    /// ```
    pub fn from_file<P: AsRef<Path>>(mut self, path: P) -> Self {
        self.file_path = Some(path.as_ref().to_string_lossy().to_string());
        self
    }

    /// Set a placeholder value.
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronTemplateBuilder;
    ///
    /// let template = TronTemplateBuilder::new()
    ///     .content("Hello @[name]@!")
    ///     .set("name", "World")
    ///     .build()
    ///     .unwrap();
    /// ```
    pub fn set<K, V>(mut self, placeholder: K, value: V) -> Self
    where
        K: Into<String>,
        V: Into<String>,
    {
        self.placeholder_values.insert(placeholder.into(), value.into());
        self
    }

    /// Set multiple placeholder values at once.
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronTemplateBuilder;
    /// use std::collections::HashMap;
    ///
    /// let mut values = HashMap::new();
    /// values.insert("greeting", "Hello");
    /// values.insert("name", "World");
    ///
    /// let template = TronTemplateBuilder::new()
    ///     .content("@[greeting]@ @[name]@!")
    ///     .set_many(values)
    ///     .build()
    ///     .unwrap();
    /// ```
    pub fn set_many<K, V, I>(mut self, values: I) -> Self
    where
        K: Into<String>,
        V: Into<String>,
        I: IntoIterator<Item = (K, V)>,
    {
        for (key, value) in values {
            self.placeholder_values.insert(key.into(), value.into());
        }
        self
    }

    /// Build the final [`TronTemplate`].
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronTemplateBuilder;
    ///
    /// let template = TronTemplateBuilder::new()
    ///     .content("Hello @[name]@!")
    ///     .set("name", "World")
    ///     .build()
    ///     .unwrap();
    /// ```
    ///
    /// # Errors
    ///
    /// Returns an error if:
    /// - Neither content nor file path was provided
    /// - The file path is invalid or the file cannot be read
    /// - The template syntax is invalid
    /// - Any placeholder values reference non-existent placeholders
    pub fn build(self) -> Result<TronTemplate> {
        let mut template = match (self.content, self.file_path) {
            (Some(content), None) => TronTemplate::new(&content)?,
            (None, Some(file_path)) => TronTemplate::from_file(&file_path)?,
            (Some(content), Some(_)) => {
                // Content takes precedence over file path
                TronTemplate::new(&content)?
            },
            (None, None) => {
                return Err(TronError::InvalidSyntax(
                    "Must provide either content or file path".to_string()
                ));
            }
        };

        // Set all placeholder values
        for (key, value) in self.placeholder_values {
            template.set(&key, &value)?;
        }

        Ok(template)
    }
}

/// Builder for creating [`TronRef`] instances with a fluent API.
///
/// This builder allows you to construct template references step by step,
/// setting content, dependencies, placeholder values, and other configuration options.
///
/// # Examples
///
/// Basic template reference building:
///
/// ```
/// use tron::TronRefBuilder;
///
/// let template_ref = TronRefBuilder::new()
///     .content("fn @[name]@() { @[body]@ }")
///     .dependency("serde = \"1.0\"")
///     .set("name", "example")
///     .set("body", "println!(\"Hello!\");")
///     .build()
///     .unwrap();
/// ```
#[derive(Debug, Default)]
pub struct TronRefBuilder {
    template_builder: TronTemplateBuilder,
    dependencies: Vec<String>,
}

impl TronRefBuilder {
    /// Create a new template reference builder.
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronRefBuilder;
    ///
    /// let builder = TronRefBuilder::new();
    /// ```
    pub fn new() -> Self {
        Self::default()
    }

    /// Set the template content directly.
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronRefBuilder;
    ///
    /// let template_ref = TronRefBuilder::new()
    ///     .content("Hello @[name]@!")
    ///     .build()
    ///     .unwrap();
    /// ```
    pub fn content<S: Into<String>>(mut self, content: S) -> Self {
        self.template_builder = self.template_builder.content(content);
        self
    }

    /// Load template content from a file.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use tron::TronRefBuilder;
    ///
    /// let template_ref = TronRefBuilder::new()
    ///     .from_file("templates/function.tpl")
    ///     .build()
    ///     .unwrap();
    /// ```
    pub fn from_file<P: AsRef<Path>>(mut self, path: P) -> Self {
        self.template_builder = self.template_builder.from_file(path);
        self
    }

    /// Set a placeholder value.
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronRefBuilder;
    ///
    /// let template_ref = TronRefBuilder::new()
    ///     .content("Hello @[name]@!")
    ///     .set("name", "World")
    ///     .build()
    ///     .unwrap();
    /// ```
    pub fn set<K, V>(mut self, placeholder: K, value: V) -> Self
    where
        K: Into<String>,
        V: Into<String>,
    {
        self.template_builder = self.template_builder.set(placeholder, value);
        self
    }

    /// Set multiple placeholder values at once.
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronRefBuilder;
    /// use std::collections::HashMap;
    ///
    /// let mut values = HashMap::new();
    /// values.insert("greeting", "Hello");
    /// values.insert("name", "World");
    ///
    /// let template_ref = TronRefBuilder::new()
    ///     .content("@[greeting]@ @[name]@!")
    ///     .set_many(values)
    ///     .build()
    ///     .unwrap();
    /// ```
    pub fn set_many<K, V, I>(mut self, values: I) -> Self
    where
        K: Into<String>,
        V: Into<String>,
        I: IntoIterator<Item = (K, V)>,
    {
        self.template_builder = self.template_builder.set_many(values);
        self
    }

    /// Add a dependency that will be included in rust-script execution.
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronRefBuilder;
    ///
    /// let template_ref = TronRefBuilder::new()
    ///     .content("fn main() {}")
    ///     .dependency("serde = \"1.0\"")
    ///     .dependency("tokio = \"1.0\"")
    ///     .build()
    ///     .unwrap();
    /// ```
    pub fn dependency<S: Into<String>>(mut self, dependency: S) -> Self {
        self.dependencies.push(dependency.into());
        self
    }

    /// Add multiple dependencies at once.
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronRefBuilder;
    ///
    /// let template_ref = TronRefBuilder::new()
    ///     .content("fn main() {}")
    ///     .dependencies(&["serde = \"1.0\"", "tokio = \"1.0\""])
    ///     .build()
    ///     .unwrap();
    /// ```
    pub fn dependencies<I, S>(mut self, dependencies: I) -> Self
    where
        I: IntoIterator<Item = S>,
        S: AsRef<str>,
    {
        for dep in dependencies {
            self.dependencies.push(dep.as_ref().to_string());
        }
        self
    }

    /// Build the final [`TronRef`].
    ///
    /// # Examples
    ///
    /// ```
    /// use tron::TronRefBuilder;
    ///
    /// let template_ref = TronRefBuilder::new()
    ///     .content("Hello @[name]@!")
    ///     .dependency("serde = \"1.0\"")
    ///     .set("name", "World")
    ///     .build()
    ///     .unwrap();
    /// ```
    ///
    /// # Errors
    ///
    /// Returns an error if the underlying template cannot be built.
    pub fn build(self) -> Result<TronRef> {
        let template = self.template_builder.build()?;
        let mut template_ref = TronRef::new(template);
        
        for dependency in self.dependencies {
            template_ref.add_dependency(&dependency);
        }

        Ok(template_ref)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_template_builder_basic() -> Result<()> {
        let template = TronTemplateBuilder::new()
            .content("Hello @[name]@!")
            .set("name", "World")
            .build()?;

        assert_eq!(template.render()?, "Hello World!");
        Ok(())
    }

    #[test]
    fn test_template_builder_multiple_placeholders() -> Result<()> {
        let template = TronTemplateBuilder::new()
            .content("@[greeting]@ @[name]@!")
            .set("greeting", "Hello")
            .set("name", "World")
            .build()?;

        assert_eq!(template.render()?, "Hello World!");
        Ok(())
    }

    #[test]
    fn test_template_builder_set_many() -> Result<()> {
        let mut values = HashMap::new();
        values.insert("greeting", "Hello");
        values.insert("name", "World");

        let template = TronTemplateBuilder::new()
            .content("@[greeting]@ @[name]@!")
            .set_many(values)
            .build()?;

        assert_eq!(template.render()?, "Hello World!");
        Ok(())
    }

    #[test]
    fn test_template_builder_no_content_error() {
        let result = TronTemplateBuilder::new().build();
        assert!(matches!(result, Err(TronError::InvalidSyntax(_))));
    }

    #[test]
    fn test_template_builder_invalid_placeholder() {
        let result = TronTemplateBuilder::new()
            .content("Hello @[name]@!")
            .set("nonexistent", "value")
            .build();
        assert!(matches!(result, Err(TronError::MissingPlaceholder(_))));
    }

    #[test]
    fn test_template_ref_builder_basic() -> Result<()> {
        let template_ref = TronRefBuilder::new()
            .content("Hello @[name]@!")
            .set("name", "World")
            .build()?;

        assert_eq!(template_ref.render()?, "Hello World!");
        Ok(())
    }

    #[test]
    fn test_template_ref_builder_with_dependencies() -> Result<()> {
        let template_ref = TronRefBuilder::new()
            .content("fn main() {}")
            .dependency("serde = \"1.0\"")
            .dependency("tokio = \"1.0\"")
            .build()?;

        assert_eq!(template_ref.dependencies().len(), 2);
        assert!(template_ref.dependencies().contains(&"serde = \"1.0\"".to_string()));
        assert!(template_ref.dependencies().contains(&"tokio = \"1.0\"".to_string()));
        Ok(())
    }

    #[test]
    fn test_template_ref_builder_dependencies_method() -> Result<()> {
        let template_ref = TronRefBuilder::new()
            .content("fn main() {}")
            .dependencies(&["serde = \"1.0\"", "tokio = \"1.0\""])
            .build()?;

        assert_eq!(template_ref.dependencies().len(), 2);
        Ok(())
    }

    #[test]
    fn test_template_ref_builder_complex() -> Result<()> {
        let mut values = HashMap::new();
        values.insert("name", "greet");
        values.insert("body", "println!(\"Hello!\");");

        let template_ref = TronRefBuilder::new()
            .content("fn @[name]@() {\n    @[body]@\n}")
            .dependencies(&["serde = \"1.0\"", "tokio = \"1.0\""])
            .set_many(values)
            .build()?;

        let result = template_ref.render()?;
        assert!(result.contains("fn greet()"));
        assert!(result.contains("println!(\"Hello!\");"));
        assert_eq!(template_ref.dependencies().len(), 2);
        Ok(())
    }
}