dynamic_cli/

builder.rs

//! Fluent builder API for creating CLI/REPL applications
//!
//! This module provides a builder pattern for easily constructing
//! CLI and REPL applications with minimal boilerplate.
//!
//! # Example
//!
//! ```no_run
//! use dynamic_cli::prelude::*;
//!
//! // Define context
//! #[derive(Default)]
//! struct MyContext;
//!
//! impl ExecutionContext for MyContext {
//!     fn as_any(&self) -> &dyn std::any::Any { self }
//!     fn as_any_mut(&mut self) -> &mut dyn std::any::Any { self }
//! }
//!
//! // Define handler
//! struct HelloCommand;
//!
//! impl CommandHandler for HelloCommand {
//!     fn execute(
//!         &self,
//!         _context: &mut dyn ExecutionContext,
//!         args: &ParsedArgs,
//!     ) -> dynamic_cli::Result<()> {
//!         println!("Hello!");
//!         Ok(())
//!     }
//! }
//!
//! # fn main() -> dynamic_cli::Result<()> {
//! // Build and run
//! CliBuilder::new()
//!     .config_file("commands.yaml")
//!     .context(Box::new(MyContext::default()))
//!     .register_sync_handler("hello_handler", Box::new(HelloCommand))
//!     .build()?
//!     .run()
//! # }
//! ```

use crate::config::loader::load_config;
use crate::config::schema::CommandsConfig;
use crate::context::ExecutionContext;
use crate::error::{ConfigError, DynamicCliError, Result};
use crate::executor::{AsyncCommandHandler, CommandHandler};
use crate::help::{DefaultHelpFormatter, HelpFormatter};
use crate::interface::{CliInterface, ReplInterface};
use crate::plugin::Plugin;
use crate::registry::CommandRegistry;
use std::collections::HashMap;
use std::path::PathBuf;

/// Fluent builder for creating CLI/REPL applications
///
/// Provides a chainable API for configuring and building applications.
/// Automatically loads configuration, registers handlers, and creates
/// the appropriate interface (CLI or REPL).
///
/// # Builder Pattern
///
/// The builder follows the standard Rust builder pattern:
/// - Methods consume `self` and return `Self`
/// - Final `build()` method consumes the builder and returns the app
///
/// # Example
///
/// ```no_run
/// use dynamic_cli::prelude::*;
///
/// # #[derive(Default)]
/// # struct MyContext;
/// # impl ExecutionContext for MyContext {
/// #     fn as_any(&self) -> &dyn std::any::Any { self }
/// #     fn as_any_mut(&mut self) -> &mut dyn std::any::Any { self }
/// # }
/// # struct MyHandler;
/// # impl CommandHandler for MyHandler {
/// #     fn execute(&self, _: &mut dyn ExecutionContext, _: &dynamic_cli::parser::ParsedArgs) -> dynamic_cli::Result<()> { Ok(()) }
/// # }
/// # fn main() -> dynamic_cli::Result<()> {
/// let app = CliBuilder::new()
///     .config_file("commands.yaml")
///     .context(Box::new(MyContext::default()))
///     .register_sync_handler("my_handler", Box::new(MyHandler))
///     .prompt("myapp")
///     .build()?;
/// # Ok(())
/// # }
/// ```
pub struct CliBuilder {
    /// Path to configuration file
    config_path: Option<PathBuf>,

    /// Loaded configuration
    config: Option<CommandsConfig>,

    /// Execution context
    context: Option<Box<dyn ExecutionContext>>,

    /// Registered command handlers (name -> handler)
    handlers: HashMap<String, Box<dyn CommandHandler>>,

    /// Registered asynchronous command handler (name -> async_handler)
    async_handlers: HashMap<String, Box<dyn AsyncCommandHandler>>,

    /// Registered plugins, expanded into `handlers` during `build()`
    plugins: Vec<Box<dyn Plugin>>,

    /// REPL prompt (if None, will use config default or "cli")
    prompt: Option<String>,

    /// Custom help formatter. None = DefaultHelpFormatter used lazily.
    help_formatter: Option<Box<dyn HelpFormatter>>,
}

impl CliBuilder {
    /// Create a new builder
    ///
    /// # Example
    ///
    /// ```
    /// use dynamic_cli::CliBuilder;
    ///
    /// let builder = CliBuilder::new();
    /// ```
    pub fn new() -> Self {
        Self {
            config_path: None,
            config: None,
            context: None,
            handlers: HashMap::new(),
            async_handlers: HashMap::new(),
            plugins: Vec::new(),
            prompt: None,
            help_formatter: None,
        }
    }

    /// Specify the configuration file
    ///
    /// The file will be loaded during `build()`. Supports YAML and JSON formats.
    ///
    /// # Arguments
    ///
    /// * `path` - Path to the configuration file (`.yaml`, `.yml`, or `.json`)
    ///
    /// # Example
    ///
    /// ```
    /// use dynamic_cli::CliBuilder;
    ///
    /// let builder = CliBuilder::new()
    ///     .config_file("commands.yaml");
    /// ```
    pub fn config_file<P: Into<PathBuf>>(mut self, path: P) -> Self {
        self.config_path = Some(path.into());
        self
    }

    /// Provide a pre-loaded configuration
    ///
    /// Use this instead of `config_file()` if you want to load and potentially
    /// modify the configuration before building.
    ///
    /// # Arguments
    ///
    /// * `config` - Loaded and validated configuration
    ///
    /// # Example
    ///
    /// ```no_run
    /// use dynamic_cli::{CliBuilder, config::loader::load_config};
    ///
    /// # fn main() -> dynamic_cli::Result<()> {
    /// let mut config = load_config("commands.yaml")?;
    /// // Modify config if needed...
    ///
    /// let builder = CliBuilder::new()
    ///     .config(config);
    /// # Ok(())
    /// # }
    /// ```
    pub fn config(mut self, config: CommandsConfig) -> Self {
        self.config = Some(config);
        self
    }

    /// Set the execution context
    ///
    /// The context will be passed to all command handlers and can store
    /// application state.
    ///
    /// # Arguments
    ///
    /// * `context` - Boxed execution context implementing `ExecutionContext`
    ///
    /// # Example
    ///
    /// ```
    /// use dynamic_cli::prelude::*;
    ///
    /// #[derive(Default)]
    /// struct MyContext {
    ///     count: u32,
    /// }
    ///
    /// impl ExecutionContext for MyContext {
    ///     fn as_any(&self) -> &dyn std::any::Any { self }
    ///     fn as_any_mut(&mut self) -> &mut dyn std::any::Any { self }
    /// }
    ///
    /// let builder = CliBuilder::new()
    ///     .context(Box::new(MyContext::default()));
    /// ```
    pub fn context(mut self, context: Box<dyn ExecutionContext>) -> Self {
        self.context = Some(context);
        self
    }

    /// Register a (sync) command handler
    ///
    /// Associates a handler with the command's implementation name from the config.
    /// The name must match the `implementation` field in the command definition.
    ///
    /// Renamed from `register_handler()` in v0.5.0 for symmetry with
    /// [`register_async_handler`][Self::register_async_handler].
    /// `register_handler()` remains available as a deprecated alias until
    /// v1.0.0 (DD-022).
    ///
    /// # Arguments
    ///
    /// * `name` - Implementation name from the configuration
    /// * `handler` - Boxed command handler implementing `CommandHandler`
    ///
    /// # Example
    ///
    /// ```
    /// use dynamic_cli::prelude::*;
    ///
    /// struct MyCommand;
    ///
    /// impl CommandHandler for MyCommand {
    ///     fn execute(
    ///         &self,
    ///         _ctx: &mut dyn ExecutionContext,
    ///         _args: &ParsedArgs,
    ///     ) -> dynamic_cli::Result<()> {
    ///         println!("Executed!");
    ///         Ok(())
    ///     }
    /// }
    ///
    /// let builder = CliBuilder::new()
    ///     .register_sync_handler("my_command", Box::new(MyCommand));
    /// ```
    pub fn register_sync_handler(
        mut self,
        name: impl Into<String>,
        handler: Box<dyn CommandHandler>,
    ) -> Self {
        self.handlers.insert(name.into(), handler);
        self
    }

    /// Deprecated alias for [`register_sync_handler`][Self::register_sync_handler].
    /// Scheduled for removal in v1.0.0 alongside `CommandRegistry::register`.
    #[deprecated(
        since = "0.5.0",
        note = "renamed to `register_sync_handler` for symmetry with \
                `register_async_handler`; will be removed in 1.0.0"
    )]
    pub fn register_handler(
        self,
        name: impl Into<String>,
        handler: Box<dyn CommandHandler>,
    ) -> Self {
        self.register_sync_handler(name.into(), handler)
    }

    /// Register an async command handler (DD-022)
    ///
    /// Additive counterpart of [`register_sync_handler`][Self::register_sync_handler].
    /// Associates an async handler with the command's implementation name
    /// from the config, exactly like its sync counterpart. Registering both
    /// a sync and an async handler for the *same* implementation name is
    /// detected as an error at [`build()`][Self::build] time, not here —
    /// this method, like `register_sync_handler`, always succeeds (it just
    /// stores the handler for `build()` to consume).
    ///
    /// # Arguments
    ///
    /// * `name` - Implementation name from the configuration
    /// * `handler` - Boxed async command handler implementing `AsyncCommandHandler`
    ///
    /// # Example
    ///
    /// ```
    /// use dynamic_cli::prelude::*;
    /// use dynamic_cli::executor::AsyncCommandHandler;
    /// use async_trait::async_trait;
    ///
    /// struct FetchCommand;
    ///
    /// #[async_trait]
    /// impl AsyncCommandHandler for FetchCommand {
    ///     async fn execute(
    ///         &self,
    ///         _ctx: &mut dyn ExecutionContext,
    ///         _args: &ParsedArgs,
    ///     ) -> dynamic_cli::Result<()> {
    ///         println!("Fetched!");
    ///         Ok(())
    ///     }
    /// }
    ///
    /// let builder = CliBuilder::new()
    ///     .register_async_handler("fetch_command", Box::new(FetchCommand));
    /// ```
    pub fn register_async_handler(
        mut self,
        name: impl Into<String>,
        handler: Box<dyn AsyncCommandHandler>,
    ) -> Self {
        self.async_handlers.insert(name.into(), handler);
        self
    }

    /// Register a plugin
    ///
    /// A plugin groups related handlers under a single unit. During
    /// [`build()`][Self::build], each handler declared by the plugin is
    /// merged into the handler map. Conflicts with already-registered
    /// handler names (whether from another plugin or from
    /// [`register_sync_handler`][Self::register_sync_handler]) produce a
    /// build-time error.
    ///
    /// The YAML config remains the sole source of truth for command
    /// definitions. Plugin handlers are matched by their `implementation`
    /// name, exactly as with [`register_sync_handler`][Self::register_sync_handler].
    /// Plugins remain sync-only for now — out of scope for DD-022.
    ///
    /// # Example
    ///
    /// ```
    /// use dynamic_cli::CliBuilder;
    /// use dynamic_cli::plugin::SystemPlugin;
    ///
    /// let builder = CliBuilder::new()
    ///     .register_plugin(Box::new(SystemPlugin::new()));
    /// ```
    pub fn register_plugin(mut self, plugin: Box<dyn Plugin>) -> Self {
        self.plugins.push(plugin);
        self
    }

    /// Load a WASM plugin from disk, map its business functions, and
    /// register it
    ///
    /// Convenience wrapper around [`WasmPlugin::load`][crate::plugin::wasm::WasmPlugin::load],
    /// [`WasmPlugin::with_function_map`][crate::plugin::wasm::WasmPlugin::with_function_map],
    /// and [`register_plugin`][Self::register_plugin]. Only available with
    /// the `wasm-plugins` feature.
    ///
    /// `function_map` is mandatory here, unlike the other `WasmPlugin`
    /// builder methods (`with_format`, `with_metadata`), which have
    /// reasonable defaults (YAML, file-name-derived metadata). A
    /// `WasmPlugin` with an empty function map registers zero handlers —
    /// silently inert — so this wrapper does not offer a path that skips
    /// mapping. Applications that also need a non-default format or
    /// explicit metadata should build the `WasmPlugin` directly and pass it
    /// to [`register_plugin`][Self::register_plugin] instead.
    ///
    /// # Errors
    ///
    /// Returns an error if the module cannot be loaded or fails mandatory
    /// export validation. See `WASM_PLUGIN_INTERFACE.md` for the ABI
    /// contract.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use dynamic_cli::CliBuilder;
    /// use std::path::Path;
    ///
    /// # fn main() -> dynamic_cli::Result<()> {
    /// let builder = CliBuilder::new()
    ///     .register_wasm_plugin(
    ///         Path::new("plugins/greet.wasm"),
    ///         &[("greet_hello", "say_hello")],
    ///     )?;
    /// # Ok(())
    /// # }
    /// ```
    #[cfg(feature = "wasm-plugins")]
    pub fn register_wasm_plugin(
        self,
        path: &std::path::Path,
        function_map: &[(&str, &str)],
    ) -> Result<Self> {
        let mut plugin = crate::plugin::wasm::WasmPlugin::load(path)?;
        for &(impl_name, wasm_fn_name) in function_map {
            plugin = plugin.with_function_map(impl_name, wasm_fn_name);
        }
        Ok(self.register_plugin(Box::new(plugin)))
    }

    /// Set the REPL prompt
    ///
    /// Only used in REPL mode. If not specified, uses the prompt from
    /// the configuration or defaults to "cli".
    ///
    /// # Arguments
    ///
    /// * `prompt` - Prompt prefix (e.g., "myapp" displays as "myapp > ")
    ///
    /// # Example
    ///
    /// ```
    /// use dynamic_cli::CliBuilder;
    ///
    /// let builder = CliBuilder::new()
    ///     .prompt("myapp");
    /// ```
    pub fn prompt(mut self, prompt: impl Into<String>) -> Self {
        self.prompt = Some(prompt.into());
        self
    }

    /// Set a custom help formatter.
    ///
    /// By default, [`DefaultHelpFormatter`] is used lazily when `--help` is
    /// detected. Call this method to supply your own implementation.
    ///
    /// The formatter is stored and transferred to [`CliApp`] during `build()`.
    /// It is instantiated **only** when `--help` is detected in `run_cli()`.
    ///
    /// # Arguments
    ///
    /// * `formatter` - Boxed implementation of [`HelpFormatter`]
    ///
    /// # Example
    ///
    /// ```
    /// use dynamic_cli::CliBuilder;
    /// use dynamic_cli::help::{HelpFormatter, DefaultHelpFormatter};
    /// use dynamic_cli::config::schema::CommandsConfig;
    ///
    /// struct MyFormatter;
    ///
    /// impl HelpFormatter for MyFormatter {
    ///     fn format_app(&self, config: &CommandsConfig) -> String {
    ///         format!("Help for {}", config.metadata.prompt)
    ///     }
    ///     fn format_command(&self, config: &CommandsConfig, command: &str) -> String {
    ///         format!("Help for command '{command}'")
    ///     }
    /// }
    ///
    /// let builder = CliBuilder::new()
    ///     .help_formatter(Box::new(MyFormatter));
    /// ```
    pub fn help_formatter(mut self, formatter: Box<dyn HelpFormatter>) -> Self {
        self.help_formatter = Some(formatter);
        self
    }

    /// Build the application
    ///
    /// Performs the following steps:
    /// 1. Load configuration (if `config_file()` was used)
    /// 2. Validate that a context was provided
    /// 3. Create the command registry
    /// 4. Register all command handlers
    /// 5. Verify that all required commands have handlers
    /// 6. Create the `CliApp`
    ///
    /// # Returns
    ///
    /// A configured `CliApp` ready to run
    ///
    /// # Errors
    ///
    /// - Configuration errors (file not found, invalid format, etc.)
    /// - Missing context
    /// - Missing required handlers
    /// - Registry errors
    ///
    /// # Example
    ///
    /// ```no_run
    /// use dynamic_cli::prelude::*;
    ///
    /// # #[derive(Default)]
    /// # struct MyContext;
    /// # impl ExecutionContext for MyContext {
    /// #     fn as_any(&self) -> &dyn std::any::Any { self }
    /// #     fn as_any_mut(&mut self) -> &mut dyn std::any::Any { self }
    /// # }
    /// # struct MyHandler;
    /// # impl CommandHandler for MyHandler {
    /// #     fn execute(&self, _: &mut dyn ExecutionContext, _: &dynamic_cli::parser::ParsedArgs) -> dynamic_cli::Result<()> { Ok(()) }
    /// # }
    /// # fn main() -> dynamic_cli::Result<()> {
    /// let app = CliBuilder::new()
    ///     .config_file("commands.yaml")
    ///     .context(Box::new(MyContext::default()))
    ///     .register_sync_handler("handler", Box::new(MyHandler))
    ///     .build()?;
    ///
    /// // Now app is ready to run
    /// # Ok(())
    /// # }
    /// ```
    pub fn build(mut self) -> Result<CliApp> {
        // Load configuration if path was specified
        let config = if let Some(config) = self.config.take() {
            config
        } else if let Some(path) = self.config_path.take() {
            load_config(path)?
        } else {
            return Err(DynamicCliError::Config(ConfigError::InvalidSchema {
                reason: "No configuration provided. Use config_file() or config()".to_string(),
                path: None,
                suggestion: None,
            }));
        };

        // Validate context was provided
        let context = self.context.take().ok_or_else(|| {
            DynamicCliError::Config(ConfigError::InvalidSchema {
                reason: "No execution context provided. Use context()".to_string(),
                path: None,
                suggestion: None,
            })
        })?;

        // Create registry and register commands
        let mut registry = CommandRegistry::new();

        // Expand plugins into the handler map before processing commands.
        // Conflicts between plugins (or between a plugin and a directly
        // registered handler) are detected here and produce a clear error,
        // before any command resolution begins.
        for plugin in self.plugins.drain(..) {
            let plugin_name = plugin.name().to_string();
            for (impl_name, handler) in plugin.handlers() {
                if self.handlers.contains_key(&impl_name) {
                    return Err(DynamicCliError::Config(ConfigError::InvalidSchema {
                        reason: format!(
                            "Plugin '{}' tried to register handler '{}' \
                             which is already registered.",
                            plugin_name, impl_name
                        ),
                        path: None,
                        suggestion: Some(format!(
                            "Remove the duplicate call to register_sync_handler(\"{}\") \
                             or rename the implementation in your YAML config.",
                            impl_name
                        )),
                    }));
                }
                self.handlers.insert(impl_name, handler);
            }
        }

        for command_def in &config.commands {
            // Find handlers for this command — sync and async are looked up
            // independently; at most one should be present (see conflict
            // check below).
            let sync_handler = self.handlers.remove(&command_def.implementation);
            let async_handler = self.async_handlers.remove(&command_def.implementation);

            // A command's implementation name must resolve to exactly one
            // handler kind. Registering both is a configuration mistake,
            // not something to resolve silently (e.g. "sync wins") — that
            // would hide a bug where the same name was registered twice
            // with different handler types.
            if sync_handler.is_some() && async_handler.is_some() {
                return Err(DynamicCliError::Config(ConfigError::InvalidSchema {
                    reason: format!(
                        "Command '{}' has both a sync and an async handler \
                         registered for implementation '{}'.",
                        command_def.name, command_def.implementation
                    ),
                    path: None,
                    suggestion: Some(
                        "Use either register_sync_handler() or \
                         register_async_handler() for this implementation, not both."
                            .to_string(),
                    ),
                }));
            }

            // Check if handler is required
            if command_def.required && sync_handler.is_none() && async_handler.is_none() {
                return Err(DynamicCliError::Config(ConfigError::InvalidSchema {
                    reason: format!(
                        "Required command '{}' has no registered handler (implementation: '{}'). \
                        Use register_sync_handler() or register_async_handler() to register it.",
                        command_def.name, command_def.implementation
                    ),
                    path: None,
                    suggestion: None,
                }));
            }

            // Register command with whichever handler kind was found.
            if let Some(handler) = sync_handler {
                registry.register_sync(command_def.clone(), handler)?;
            } else if let Some(handler) = async_handler {
                registry.register_async(command_def.clone(), handler)?;
            }
        }

        // Determine prompt
        let prompt = self
            .prompt
            .or_else(|| Some(config.metadata.prompt.clone()))
            .unwrap_or_else(|| "cli".to_string());

        Ok(CliApp {
            registry,
            context,
            prompt,
            config,
            help_formatter: self.help_formatter,
        })
    }
}

impl Default for CliBuilder {
    fn default() -> Self {
        Self::new()
    }
}

/// Built CLI/REPL application
///
/// Created by `CliBuilder::build()`. Provides methods to run the application
/// in different modes:
/// - `run()` - Auto-detect CLI vs REPL based on arguments
/// - `run_cli()` - Force CLI mode with specific arguments
/// - `run_repl()` - Force REPL mode
///
/// # Example
///
/// ```no_run
/// use dynamic_cli::prelude::*;
///
/// # #[derive(Default)]
/// # struct MyContext;
/// # impl ExecutionContext for MyContext {
/// #     fn as_any(&self) -> &dyn std::any::Any { self }
/// #     fn as_any_mut(&mut self) -> &mut dyn std::any::Any { self }
/// # }
/// # struct MyHandler;
/// # impl CommandHandler for MyHandler {
/// #     fn execute(&self, _: &mut dyn ExecutionContext, _: &dynamic_cli::parser::ParsedArgs) -> dynamic_cli::Result<()> { Ok(()) }
/// # }
/// # fn main() -> dynamic_cli::Result<()> {
/// let app = CliBuilder::new()
///     .config_file("commands.yaml")
///     .context(Box::new(MyContext::default()))
///     .register_sync_handler("handler", Box::new(MyHandler))
///     .build()?;
///
/// // Auto-detect mode (CLI if args provided, REPL otherwise)
/// app.run()
/// # }
/// ```
pub struct CliApp {
    /// Command registry
    registry: CommandRegistry,

    /// Execution context
    context: Box<dyn ExecutionContext>,

    /// REPL prompt
    prompt: String,

    /// Full configuration - needed by the help formatter
    config: CommandsConfig,

    /// Custom help formatter, or None to use DefaultHelpFormatter
    help_formatter: Option<Box<dyn HelpFormatter>>,
}

impl std::fmt::Debug for CliApp {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("CliApp")
            .field("prompt", &self.prompt)
            .field("registry", &"<CommandRegistry>")
            .field("context", &"<ExecutionContext>")
            .field("help_formatter", &"<Option<Box<dyn HelpFormatter>>>")
            .finish()
    }
}

impl CliApp {
    /// Run in CLI mode with provided arguments
    ///
    /// Executes a single command and exits.
    ///
    /// # Arguments
    ///
    /// * `args` - Command-line arguments (typically from `env::args().skip(1)`)
    ///
    /// # Returns
    ///
    /// - `Ok(())` on successful execution
    /// - `Err(...)` on parse, validation, or execution errors
    ///
    /// # Example
    ///
    /// ```no_run
    /// # use dynamic_cli::prelude::*;
    /// # #[derive(Default)]
    /// # struct MyContext;
    /// # impl ExecutionContext for MyContext {
    /// #     fn as_any(&self) -> &dyn std::any::Any { self }
    /// #     fn as_any_mut(&mut self) -> &mut dyn std::any::Any { self }
    /// # }
    /// # struct MyHandler;
    /// # impl CommandHandler for MyHandler {
    /// #     fn execute(&self, _: &mut dyn ExecutionContext, _: &dynamic_cli::parser::ParsedArgs) -> dynamic_cli::Result<()> { Ok(()) }
    /// # }
    /// # fn main() -> dynamic_cli::Result<()> {
    /// # let app = CliBuilder::new()
    /// #     .config_file("commands.yaml")
    /// #     .context(Box::new(MyContext::default()))
    /// #     .register_sync_handler("handler", Box::new(MyHandler))
    /// #     .build()?;
    /// // Run with specific arguments
    /// app.run_cli(vec!["command".to_string(), "arg1".to_string()])
    /// # }
    /// ```
    pub fn run_cli(self, args: Vec<String>) -> Result<()> {
        // Intercept --help before command dispatch.
        // The formatter is instantiated lazily, only when --help is detected.
        match args.as_slice() {
            [flag] if flag == "--help" => {
                let formatter: Box<dyn HelpFormatter> = self
                    .help_formatter
                    .unwrap_or_else(|| Box::new(DefaultHelpFormatter::new()));
                print!("{}", formatter.format_app(&self.config));
                return Ok(());
            }
            [flag, command] if flag == "--help" => {
                let formatter: Box<dyn HelpFormatter> = self
                    .help_formatter
                    .unwrap_or_else(|| Box::new(DefaultHelpFormatter::new()));
                print!("{}", formatter.format_command(&self.config, command));
                return Ok(());
            }
            _ => {}
        }

        let cli = CliInterface::new(self.registry, self.context);
        cli.run(args)
    }

    /// Run in REPL mode
    ///
    /// Enters an interactive loop that continues until the user exits.
    ///
    /// # Returns
    ///
    /// - `Ok(())` when user exits normally
    /// - `Err(...)` on critical errors (e.g., rustyline initialization failure)
    ///
    /// # Example
    ///
    /// ```no_run
    /// # use dynamic_cli::prelude::*;
    /// # #[derive(Default)]
    /// # struct MyContext;
    /// # impl ExecutionContext for MyContext {
    /// #     fn as_any(&self) -> &dyn std::any::Any { self }
    /// #     fn as_any_mut(&mut self) -> &mut dyn std::any::Any { self }
    /// # }
    /// # struct MyHandler;
    /// # impl CommandHandler for MyHandler {
    /// #     fn execute(&self, _: &mut dyn ExecutionContext, _: &dynamic_cli::parser::ParsedArgs) -> dynamic_cli::Result<()> { Ok(()) }
    /// # }
    /// # fn main() -> dynamic_cli::Result<()> {
    /// # let app = CliBuilder::new()
    /// #     .config_file("commands.yaml")
    /// #     .context(Box::new(MyContext::default()))
    /// #     .register_sync_handler("handler", Box::new(MyHandler))
    /// #     .build()?;
    /// // Start interactive REPL
    /// app.run_repl()
    /// # }
    /// ```
    pub fn run_repl(self) -> Result<()> {
        ReplInterface::new(
            self.registry,
            self.context,
            self.prompt,
            Some(self.config),
            self.help_formatter,
        )?
        .run()
    }

    /// Run with automatic mode detection
    ///
    /// Decides between CLI and REPL based on command-line arguments:
    /// - If arguments provided → CLI mode
    /// - If no arguments → REPL mode
    ///
    /// This is the recommended method for most applications.
    ///
    /// # Returns
    ///
    /// - `Ok(())` on successful execution
    /// - `Err(...)` on errors
    ///
    /// # Example
    ///
    /// ```no_run
    /// # use dynamic_cli::prelude::*;
    /// # #[derive(Default)]
    /// # struct MyContext;
    /// # impl ExecutionContext for MyContext {
    /// #     fn as_any(&self) -> &dyn std::any::Any { self }
    /// #     fn as_any_mut(&mut self) -> &mut dyn std::any::Any { self }
    /// # }
    /// # struct MyHandler;
    /// # impl CommandHandler for MyHandler {
    /// #     fn execute(&self, _: &mut dyn ExecutionContext, _: &dynamic_cli::parser::ParsedArgs) -> dynamic_cli::Result<()> { Ok(()) }
    /// # }
    /// # fn main() -> dynamic_cli::Result<()> {
    /// # let app = CliBuilder::new()
    /// #     .config_file("commands.yaml")
    /// #     .context(Box::new(MyContext::default()))
    /// #     .register_sync_handler("handler", Box::new(MyHandler))
    /// #     .build()?;
    /// // Auto-detect: CLI if args, REPL if no args
    /// app.run()
    /// # }
    /// ```
    pub fn run(self) -> Result<()> {
        let args: Vec<String> = std::env::args().skip(1).collect();

        if args.is_empty() {
            // No arguments → REPL mode
            self.run_repl()
        } else {
            // Arguments provided → CLI mode
            self.run_cli(args)
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::config::schema::{CommandDefinition, Metadata};
    use crate::parser::ParsedArgs;

    // Test context
    #[derive(Default)]
    struct TestContext {
        executed: Vec<String>,
    }

    impl ExecutionContext for TestContext {
        fn as_any(&self) -> &dyn std::any::Any {
            self
        }

        fn as_any_mut(&mut self) -> &mut dyn std::any::Any {
            self
        }
    }

    // Test handler
    struct TestHandler {
        name: String,
    }

    impl CommandHandler for TestHandler {
        fn execute(&self, context: &mut dyn ExecutionContext, _args: &ParsedArgs) -> Result<()> {
            let ctx =
                crate::context::downcast_mut::<TestContext>(context).expect("Failed to downcast");
            ctx.executed.push(self.name.clone());
            Ok(())
        }
    }

    struct TestAsyncHandler {
        name: String,
    }

    #[async_trait::async_trait]
    impl AsyncCommandHandler for TestAsyncHandler {
        async fn execute(
            &self,
            context: &mut dyn ExecutionContext,
            _args: &ParsedArgs,
        ) -> Result<()> {
            let ctx =
                crate::context::downcast_mut::<TestContext>(context).expect("Failed to downcast");
            ctx.executed.push(self.name.clone());
            Ok(())
        }
    }

    fn create_test_config() -> CommandsConfig {
        CommandsConfig {
            metadata: Metadata {
                version: "1.0.0".to_string(),
                prompt: "test".to_string(),
                prompt_suffix: " > ".to_string(),
            },
            commands: vec![CommandDefinition {
                name: "test".to_string(),
                aliases: vec![],
                description: "Test command".to_string(),
                required: true,
                arguments: vec![],
                options: vec![],
                implementation: "test_handler".to_string(),
            }],
            global_options: vec![],
        }
    }

    #[test]
    fn test_builder_creation() {
        let builder = CliBuilder::new();
        assert!(builder.config.is_none());
        assert!(builder.context.is_none());
    }

    #[test]
    fn test_builder_with_config() {
        let config = create_test_config();
        let builder = CliBuilder::new().config(config.clone());

        assert!(builder.config.is_some());
    }

    #[test]
    fn test_builder_with_context() {
        let context = Box::new(TestContext::default());
        let builder = CliBuilder::new().context(context);

        assert!(builder.context.is_some());
    }

    #[test]
    fn test_builder_with_handler() {
        let handler = Box::new(TestHandler {
            name: "test".to_string(),
        });

        let builder = CliBuilder::new().register_sync_handler("test_handler", handler);

        assert_eq!(builder.handlers.len(), 1);
    }

    /// Deprecated-alias coverage (DD-022 companion issue): `register_handler()`
    /// must keep behaving exactly like `register_sync_handler()` until it's
    /// removed in v1.0.0. This is the only place in the crate allowed to
    /// call it directly.
    #[test]
    #[allow(deprecated)]
    fn test_deprecated_register_handler_alias_still_works() {
        let handler = Box::new(TestHandler {
            name: "test".to_string(),
        });

        let builder = CliBuilder::new().register_handler("test_handler", handler);

        assert_eq!(builder.handlers.len(), 1);
        assert!(builder.async_handlers.is_empty());
    }

    #[test]
    fn test_builder_with_prompt() {
        let builder = CliBuilder::new().prompt("myapp");

        assert_eq!(builder.prompt, Some("myapp".to_string()));
    }

    #[test]
    fn test_builder_build_success() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestHandler {
            name: "test".to_string(),
        });

        let app = CliBuilder::new()
            .config(config)
            .context(context)
            .register_sync_handler("test_handler", handler)
            .build();

        assert!(app.is_ok());
    }

    #[test]
    fn test_builder_build_missing_config() {
        let context = Box::new(TestContext::default());

        let result = CliBuilder::new().context(context).build();

        assert!(result.is_err());
        match result.unwrap_err() {
            DynamicCliError::Config(ConfigError::InvalidSchema { reason, .. }) => {
                assert!(reason.contains("No configuration provided"));
            }
            other => panic!("Expected InvalidSchema error, got: {:?}", other),
        }
    }

    #[test]
    fn test_builder_build_missing_context() {
        let config = create_test_config();

        let result = CliBuilder::new().config(config).build();

        assert!(result.is_err());
        match result.unwrap_err() {
            DynamicCliError::Config(ConfigError::InvalidSchema { reason, .. }) => {
                assert!(reason.contains("No execution context provided"));
            }
            other => panic!("Expected InvalidSchema error, got: {:?}", other),
        }
    }

    #[test]
    fn test_builder_build_missing_required_handler() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());

        let result = CliBuilder::new().config(config).context(context).build();

        assert!(result.is_err());
        match result.unwrap_err() {
            DynamicCliError::Config(ConfigError::InvalidSchema { reason, .. }) => {
                assert!(reason.contains("Required command"));
                assert!(reason.contains("no registered handler"));
            }
            other => panic!("Expected InvalidSchema error, got: {:?}", other),
        }
    }

    #[test]
    fn test_builder_chaining() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestHandler {
            name: "test".to_string(),
        });

        // Test that all methods chain correctly
        let app = CliBuilder::new()
            .config(config)
            .context(context)
            .register_sync_handler("test_handler", handler)
            .prompt("test")
            .build();

        assert!(app.is_ok());
    }

    #[test]
    fn test_cli_app_run_cli() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestHandler {
            name: "test".to_string(),
        });

        let app = CliBuilder::new()
            .config(config)
            .context(context)
            .register_sync_handler("test_handler", handler)
            .build()
            .unwrap();

        // Run with test command
        let result = app.run_cli(vec!["test".to_string()]);
        assert!(result.is_ok());
    }

    #[test]
    fn test_default_prompt_from_config() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestHandler {
            name: "test".to_string(),
        });

        let app = CliBuilder::new()
            .config(config)
            .context(context)
            .register_sync_handler("test_handler", handler)
            .build()
            .unwrap();

        // Prompt should be taken from config
        assert_eq!(app.prompt, "test");
    }

    #[test]
    fn test_override_prompt() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestHandler {
            name: "test".to_string(),
        });

        let app = CliBuilder::new()
            .config(config)
            .context(context)
            .register_sync_handler("test_handler", handler)
            .prompt("custom")
            .build()
            .unwrap();

        // Prompt should be overridden
        assert_eq!(app.prompt, "custom");
    }

    // ============================================================================
    // async_handlers / register_async_handler / build() TESTS (DD-022)
    // ============================================================================

    #[test]
    fn test_builder_with_async_handler() {
        let handler = Box::new(TestAsyncHandler {
            name: "test".to_string(),
        });

        let builder = CliBuilder::new().register_async_handler("test_handler", handler);

        assert_eq!(builder.async_handlers.len(), 1);
        assert!(builder.handlers.is_empty());
    }

    /// The core gap this session closes: an async handler registered via
    /// `register_async_handler()` must actually reach the built registry —
    /// previously `build()` only ever drained `self.handlers`.
    #[test]
    fn test_builder_build_with_async_handler_only() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestAsyncHandler {
            name: "test".to_string(),
        });

        let app = CliBuilder::new()
            .config(config)
            .context(context)
            .register_async_handler("test_handler", handler)
            .build();

        assert!(app.is_ok());
    }

    /// Registering both a sync and an async handler for the same
    /// implementation name must fail at build() time — this is the
    /// conflict check `build()` didn't have before this session.
    #[test]
    fn test_builder_build_sync_and_async_conflict() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let sync_handler = Box::new(TestHandler {
            name: "sync".to_string(),
        });
        let async_handler = Box::new(TestAsyncHandler {
            name: "async".to_string(),
        });

        let result = CliBuilder::new()
            .config(config)
            .context(context)
            .register_sync_handler("test_handler", sync_handler)
            .register_async_handler("test_handler", async_handler)
            .build();

        assert!(result.is_err());
        match result.unwrap_err() {
            DynamicCliError::Config(ConfigError::InvalidSchema { reason, .. }) => {
                assert!(reason.contains("both a sync and an async handler"));
            }
            other => panic!("Expected InvalidSchema error, got: {:?}", other),
        }
    }

    /// A required command satisfied only by an async handler must not be
    /// reported as "missing" — the required-handler check must look at
    /// both maps, not just `self.handlers`.
    #[test]
    fn test_builder_build_required_command_satisfied_by_async_handler() {
        let config = create_test_config(); // "test" command is `required: true`
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestAsyncHandler {
            name: "test".to_string(),
        });

        let result = CliBuilder::new()
            .config(config)
            .context(context)
            .register_async_handler("test_handler", handler)
            .build();

        assert!(result.is_ok());
    }

    #[test]
    fn test_cli_app_run_cli_with_async_handler() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestAsyncHandler {
            name: "test".to_string(),
        });

        let app = CliBuilder::new()
            .config(config)
            .context(context)
            .register_async_handler("test_handler", handler)
            .build()
            .unwrap();

        let result = app.run_cli(vec!["test".to_string()]);
        assert!(result.is_ok());
    }

    #[test]
    fn test_builder_with_help_formatter() {
        use crate::help::DefaultHelpFormatter;

        let formatter = Box::new(DefaultHelpFormatter::new());
        let builder = CliBuilder::new().help_formatter(formatter);

        assert!(builder.help_formatter.is_some());
    }

    #[test]
    fn test_run_cli_help_global() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestHandler {
            name: "test".to_string(),
        });

        let app = CliBuilder::new()
            .config(config)
            .context(context)
            .register_sync_handler("test_handler", handler)
            .build()
            .unwrap();

        // --help should return Ok(()) without dispatching to any handler.
        let result = app.run_cli(vec!["--help".to_string()]);
        assert!(result.is_ok());
    }

    #[test]
    fn test_run_cli_help_command() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestHandler {
            name: "test".to_string(),
        });

        let app = CliBuilder::new()
            .config(config)
            .context(context)
            .register_sync_handler("test_handler", handler)
            .build()
            .unwrap();

        // --help <command> should return Ok(()) without dispatching.
        let result = app.run_cli(vec!["--help".to_string(), "test".to_string()]);
        assert!(result.is_ok());
    }

    #[test]
    fn test_run_cli_help_unknown_command_still_ok() {
        let config = create_test_config();
        let context = Box::new(TestContext::default());
        let handler = Box::new(TestHandler {
            name: "test".to_string(),
        });

        let app = CliBuilder::new()
            .config(config)
            .context(context)
            .register_sync_handler("test_handler", handler)
            .build()
            .unwrap();

        // --help with an unknown command name: formatter handles it gracefully.
        let result = app.run_cli(vec!["--help".to_string(), "ghost".to_string()]);
        assert!(result.is_ok());
    }
}