use std::env;
use std::fs;
use std::path::Path;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let args: Vec<String> = env::args().collect();
    if args.len() != 4 {
        eprintln!("Usage: {} <proto_file> <descriptor_file> <output_file>", args[0]);
        std::process::exit(1);
    }
    
    let proto_file = &args[1];
    let _descriptor_file = &args[2];  // For future use if needed
    let output_file = &args[3];
    
    // Generate Rust code using proper prost-build
    generate_prost_code(proto_file, output_file)?;
    
    Ok(())
}

fn generate_prost_code(proto_file: &str, output_file: &str) -> Result<(), Box<dyn std::error::Error>> {
    // Create a temporary directory for prost-build output
    let temp_dir = tempfile::tempdir()?;
    let temp_path = temp_dir.path();
    
    // Configure prost-build
    let mut config = prost_build::Config::new();
    
    // Set output directory
    config.out_dir(temp_path);
    
    // Configure derive traits - prost::Message provides Debug automatically  
    config.type_attribute(".", "#[derive(serde::Serialize, serde::Deserialize, schemars::JsonSchema)]");
    
    // Try to find protoc in the environment (Bazel should provide this)
    if let Ok(protoc_path) = env::var("PROTOC") {
        config.protoc_executable(&protoc_path);
    }
    
    // Get the directory containing the proto file for include path
    let proto_path = Path::new(proto_file);
    let include_dir = proto_path.parent().unwrap_or(Path::new("."));
    
    
    // Try to compile the protos
    match config.compile_protos(&[proto_file], &[include_dir]) {
        Ok(_) => {
            // Find and read the generated files
            let generated_content = find_and_read_generated_files(temp_path)?;
            fs::write(output_file, generated_content)?;
        }
        Err(e) => {
            eprintln!("prost-build failed: {}", e);
            eprintln!("Available environment variables:");
            for (key, value) in env::vars() {
                if key.contains("PROTOC") || key.contains("PATH") {
                    eprintln!("  {}: {}", key, value);
                }
            }
            
            // This error should be surfaced to help debug the protoc issue
            return Err(format!("prost-build compilation failed: {}. This indicates protoc is not available in the Bazel sandbox. Consider passing protoc path via environment or simplifying the proto dependencies.", e).into());
        }
    }
    
    Ok(())
}

fn find_and_read_generated_files(dir: &Path) -> Result<String, Box<dyn std::error::Error>> {
    let mut content = String::from("// Generated by prost-build\n\n");
    let mut found_files = false;
    
    for entry in fs::read_dir(dir)? {
        let entry = entry?;
        let path = entry.path();
        
        if path.extension().and_then(|s| s.to_str()) == Some("rs") {
            let file_content = fs::read_to_string(&path)?;
            content.push_str(&file_content);
            content.push('\n');
            found_files = true;
        }
    }
    
    if !found_files {
        return Err("No generated Rust files found from prost-build".into());
    }
    
    Ok(content)
}