//! Unified Plugin Host facade
//!
//! Thin wrapper over v2 loader to provide a stable facade
//! with minimal, friendly API for runtime/runner and future transports.

use std::sync::{Arc, RwLock};
use once_cell::sync::Lazy;

use crate::bid::{BidError, BidResult};
use crate::config::nyash_toml_v2::NyashConfigV2;
use crate::runtime::plugin_loader_v2::PluginLoaderV2;

/// Opaque library handle (by name for now)
#[derive(Clone, Debug)]
pub struct PluginLibraryHandle {
    pub name: String,
}

/// Box type descriptor
#[derive(Clone, Debug)]
pub struct PluginBoxType {
    pub lib: String,
    pub name: String,
    pub type_id: u32,
}

/// Resolved method handle
#[derive(Clone, Debug)]
pub struct MethodHandle {
    pub lib: String,
    pub box_type: String,
    pub type_id: u32,
    pub method_id: u32,
    pub returns_result: bool,
}

/// Unified facade
pub struct PluginHost {
    loader: Arc<RwLock<PluginLoaderV2>>, // delegate
    config: Option<NyashConfigV2>,       // cached config for resolution
    config_path: Option<String>,
}

impl PluginHost {
    pub fn new(loader: Arc<RwLock<PluginLoaderV2>>) -> Self {
        Self { loader, config: None, config_path: None }
    }

    /// Load config and dynamic libraries, keeping a local config cache.
    pub fn load_libraries(&mut self, config_path: &str) -> BidResult<()> {
        {
            let mut l = self.loader.write().unwrap();
            l.load_config(config_path)?;
        }

        // Keep our own copy for quick lookups
        let canonical = std::fs::canonicalize(config_path)
            .map(|p| p.to_string_lossy().to_string())
            .unwrap_or_else(|_| config_path.to_string());
        self.config = Some(NyashConfigV2::from_file(&canonical).map_err(|_| BidError::PluginError)?);
        self.config_path = Some(canonical);

        // Delegate actual library loads + pre-birth singletons to v2
        let l = self.loader.read().unwrap();
        l.load_all_plugins()
    }

    /// Register built-ins or user-defined boxes if needed (no-op for now).
    pub fn register_boxes(&self) -> BidResult<()> { Ok(()) }

    /// Expose read-only view of loaded config for callers migrating from v2 paths.
    pub fn config_ref(&self) -> Option<&NyashConfigV2> { self.config.as_ref() }

    /// Resolve a method handle for a given plugin box type and method name.
    pub fn resolve_method(&self, box_type: &str, method_name: &str) -> BidResult<MethodHandle> {
        let cfg = self.config.as_ref().ok_or(BidError::PluginError)?;
        let (lib_name, _lib_def) = cfg.find_library_for_box(box_type).ok_or(BidError::InvalidType)?;
        let cfg_path = self.config_path.as_deref().unwrap_or("nyash.toml");
        let toml_content = std::fs::read_to_string(cfg_path).map_err(|_| BidError::PluginError)?;
        let toml_value: toml::Value = toml::from_str(&toml_content).map_err(|_| BidError::PluginError)?;
        let box_conf = cfg.get_box_config(lib_name, box_type, &toml_value).ok_or(BidError::InvalidType)?;
        let m = box_conf.methods.get(method_name).ok_or(BidError::InvalidMethod)?;
        Ok(MethodHandle {
            lib: lib_name.to_string(),
            box_type: box_type.to_string(),
            type_id: box_conf.type_id,
            method_id: m.method_id,
            returns_result: m.returns_result,
        })
    }

    // --- v2 adapter layer: allow gradual migration of callers ---
    pub fn create_box(&self, box_type: &str, args: &[Box<dyn crate::box_trait::NyashBox>]) -> BidResult<Box<dyn crate::box_trait::NyashBox>> {
        let l = self.loader.read().unwrap();
        l.create_box(box_type, args)
    }

    pub fn invoke_instance_method(
        &self,
        box_type: &str,
        method_name: &str,
        instance_id: u32,
        args: &[Box<dyn crate::box_trait::NyashBox>],
    ) -> BidResult<Option<Box<dyn crate::box_trait::NyashBox>>> {
        let l = self.loader.read().unwrap();
        l.invoke_instance_method(box_type, method_name, instance_id, args)
    }

    pub fn extern_call(
        &self,
        iface_name: &str,
        method_name: &str,
        args: &[Box<dyn crate::box_trait::NyashBox>],
    ) -> BidResult<Option<Box<dyn crate::box_trait::NyashBox>>> {
        let l = self.loader.read().unwrap();
        l.extern_call(iface_name, method_name, args)
    }
}

// Global singleton
static GLOBAL_HOST: Lazy<Arc<RwLock<PluginHost>>> = Lazy::new(|| {
    let loader = crate::runtime::plugin_loader_v2::get_global_loader_v2();
    Arc::new(RwLock::new(PluginHost::new(loader)))
});

pub fn get_global_plugin_host() -> Arc<RwLock<PluginHost>> { GLOBAL_HOST.clone() }

pub fn init_global_plugin_host(config_path: &str) -> BidResult<()> {
    let host = get_global_plugin_host();
    host.write().unwrap().load_libraries(config_path)?;
    host.read().unwrap().register_boxes()?;
    Ok(())
}