use crate::error::{OptimizerError, Result};
use std::path::Path;

/// Simplified ONNX graph wrapper
/// NOTE: The `onnx` crate v0.1.0 has all fields private, making direct graph manipulation impossible.
/// This is a stub implementation. Full implementation requires either:
/// 1. Using a different ONNX manipulation library
/// 2. Writing custom protobuf wrappers with public fields
/// 3. Using ONNX Runtime's SessionOptions for optimization instead
pub struct OnnxGraph {
    // Placeholder - actual implementation would store parsed model
    path: Option<std::path::PathBuf>,
}

impl OnnxGraph {
    /// Load an ONNX model from file
    pub fn load(path: &Path) -> Result<Self> {
        // Verify file exists
        if !path.exists() {
            return Err(OptimizerError::IoError(std::io::Error::new(
                std::io::ErrorKind::NotFound,
                "Model file not found",
            )));
        }

        Ok(Self {
            path: Some(path.to_path_buf()),
        })
    }

    /// Save the ONNX model to file
    pub fn save(&self, output_path: &Path) -> Result<()> {
        // Stub: In real implementation, would serialize model
        if let Some(ref input_path) = self.path {
            // For now, just copy the file
            std::fs::copy(input_path, output_path)?;
        }
        Ok(())
    }

    /// Get the main graph (stub)
    pub fn graph(&self) -> Result<&Self> {
        Ok(self)
    }

    /// Get mutable reference to the main graph (stub)
    pub fn graph_mut(&mut self) -> Result<&mut Self> {
        Ok(self)
    }

    /// Count the number of nodes in the graph (stub)
    pub fn node_count(&self) -> Result<usize> {
        // Stub implementation
        Ok(0)
    }

    /// Remove unused nodes (dead code elimination) - stub
    pub fn remove_unused_nodes(&mut self) -> Result<usize> {
        // Stub implementation - would remove dead code
        log::info!("remove_unused_nodes: stub implementation");
        Ok(0)
    }

    /// Validate graph integrity
    pub fn validate(&self) -> Result<()> {
        // Basic validation - check path exists
        if self.path.is_none() {
            return Err(OptimizerError::InvalidGraph("No model loaded".to_string()));
        }
        Ok(())
    }

    /// Get all node types in the graph (stub)
    pub fn get_node_types(&self) -> Result<std::collections::HashMap<String, usize>> {
        // Stub implementation
        Ok(std::collections::HashMap::new())
    }
}
