use crate::config::{MlfConfig, init_mlf_cache};
use std::io::Write;

pub fn run_init(skip_prompts: bool) -> Result<(), std::io::Error> {
    let current_dir = std::env::current_dir()?;
    let config_path = current_dir.join("mlf.toml");

    if config_path.exists() {
        eprintln!("mlf.toml already exists in current directory");
        eprintln!("Remove it first if you want to reinitialize");
        return Err(std::io::Error::new(
            std::io::ErrorKind::AlreadyExists,
            "mlf.toml already exists",
        ));
    }

    if !skip_prompts {
        println!("Initialize MLF project in {}?", current_dir.display());
        println!("This will create:");
        println!("  - mlf.toml (project configuration)");
        println!("  - .mlf/ (cache directory for fetched lexicons)");
        println!();
        print!("Continue? (y/n): ");
        std::io::stdout().flush()?;

        let mut input = String::new();
        std::io::stdin().read_line(&mut input)?;

        if input.trim().to_lowercase() != "y" {
            println!("Cancelled");
            return Ok(());
        }
    }

    // Collect the package NSID prefix.
    let package_name = if skip_prompts {
        // --yes was passed; derive a best-effort placeholder the user can
        // edit. Tying this to the directory name is a better starting
        // point than a magic constant.
        default_package_name(&current_dir)
    } else {
        prompt_package_name()?
    };

    let config = MlfConfig::create(&config_path, package_name)
        .map_err(|e| std::io::Error::other(e.to_string()))?;

    println!("✓ Created mlf.toml (package `{}`)", config.package.name);

    init_mlf_cache(&current_dir)?;
    println!("✓ Initialized .mlf/ directory");

    println!();
    println!("Project initialized successfully!");
    println!();
    println!("Next steps:");
    println!("  1. Create MLF files in ./lexicons/");
    println!("  2. Fetch dependencies: mlf fetch <namespace> --save");
    println!("  3. Check your lexicons: mlf check");
    println!("  4. Generate code: mlf generate");

    Ok(())
}

fn prompt_package_name() -> Result<String, std::io::Error> {
    loop {
        print!("Package NSID prefix (e.g. com.example.forum): ");
        std::io::stdout().flush()?;
        let mut input = String::new();
        std::io::stdin().read_line(&mut input)?;
        let trimmed = input.trim();
        if trimmed.is_empty() {
            eprintln!("A package name is required (at least two dot-separated segments).");
            continue;
        }
        if !trimmed.contains('.') {
            eprintln!("Expected a dot-separated NSID prefix (e.g. com.example.forum).");
            continue;
        }
        return Ok(trimmed.to_string());
    }
}

fn default_package_name(dir: &std::path::Path) -> String {
    let dir_name = dir
        .file_name()
        .and_then(|s| s.to_str())
        .unwrap_or("package");
    if dir_name.contains('.') {
        dir_name.to_string()
    } else {
        format!("example.{dir_name}")
    }
}