use directories::ProjectDirs;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::fs;
use std::io;
use std::path::PathBuf;
use std::sync::Arc;
use std::sync::RwLock;

use super::api::{Context, ContextConfig};

#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct Config {
    pub context: String,
    pub contexts: HashMap<String, ContextConfig>,
}

impl Default for Config {
    fn default() -> Self {
        let mut contexts = HashMap::new();
        contexts.insert("local".to_string(), ContextConfig::Local);
        Self {
            context: "local".to_string(),
            contexts,
        }
    }
}

/// Helper managing contexts
pub struct ContextManager {
    context: RwLock<Arc<Context>>,
    config_path: PathBuf,
    config: RwLock<Config>,
}

pub static MANAGER: std::sync::LazyLock<ContextManager> =
    std::sync::LazyLock::new(|| ContextManager::new().expect("Cannot setup context manager"));

impl ContextManager {
    fn new() -> io::Result<Self> {
        let proj_dirs = ProjectDirs::from("com", "pkh", "pkh").ok_or_else(|| {
            io::Error::new(
                io::ErrorKind::NotFound,
                "Could not determine config directory",
            )
        })?;
        let config_dir = proj_dirs.config_dir();
        fs::create_dir_all(config_dir)?;
        let config_path = config_dir.join("contexts.json");

        let config = if config_path.exists() {
            // Load existing configuration file
            let content = fs::read_to_string(&config_path)?;
            serde_json::from_str(&content)
                .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?
        } else {
            // Create a new configuration file
            Config::default()
        };

        Ok(Self {
            context: RwLock::new(Arc::new(Self::make_context(
                config.context.as_str(),
                &config,
            ))),
            config_path,
            config: RwLock::new(config),
        })
    }

    /// Obtain current ContextManager configuration
    pub fn get_config(&self) -> std::sync::RwLockReadGuard<'_, Config> {
        self.config.read().unwrap()
    }

    /// Make a ContextManager using a specific configuration path
    pub fn with_path(path: PathBuf) -> Self {
        let config = Config::default();
        Self {
            context: RwLock::new(Arc::new(Self::make_context("local", &config))),
            config_path: path,
            config: RwLock::new(config),
        }
    }

    /// Save current context configuration to disk
    pub fn save(&self) -> io::Result<()> {
        let config = self.config.read().unwrap();
        let content = serde_json::to_string_pretty(&*config)
            .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?;
        fs::write(&self.config_path, content)?;
        Ok(())
    }

    fn make_context(name: &str, config: &Config) -> Context {
        let context_config = config
            .contexts
            .get(name)
            .cloned()
            .expect("Context not found in config");
        Context::new(context_config)
    }

    /// List contexts from configuration
    pub fn list_contexts(&self) -> Vec<String> {
        self.config
            .read()
            .unwrap()
            .contexts
            .keys()
            .cloned()
            .collect()
    }

    /// Add a context to configuration
    pub fn add_context(&self, name: &str, config: ContextConfig) -> io::Result<()> {
        self.config
            .write()
            .unwrap()
            .contexts
            .insert(name.to_string(), config);
        self.save()
    }

    /// Remove context from configuration
    pub fn remove_context(&self, name: &str) -> io::Result<()> {
        let mut config = self.config.write().unwrap();
        if name == "local" {
            return Err(io::Error::new(
                io::ErrorKind::InvalidInput,
                "Cannot remove local context",
            ));
        }
        if config.contexts.remove(name).is_some() {
            // If we are removing the current context, fallback to local
            if name == config.context {
                config.context = "local".to_string();
                self.set_current_ephemeral(Self::make_context("local", &config));
            }

            drop(config); // Drop write lock before saving
            self.save()?;
        }
        Ok(())
    }

    /// Set current context from name (modifying configuration)
    pub fn set_current(&self, name: &str) -> io::Result<()> {
        let mut config = self.config.write().unwrap();
        if config.contexts.contains_key(name) {
            config.context = name.to_string();
            self.set_current_ephemeral(Self::make_context(name, &config));
            drop(config); // Drop write lock before saving
            self.save()?;
            Ok(())
        } else {
            Err(io::Error::new(
                io::ErrorKind::NotFound,
                format!("Context '{}' not found", name),
            ))
        }
    }

    /// Set current context, without modifying configuration
    pub fn set_current_ephemeral(&self, context: Context) {
        *self.context.write().unwrap() = context.into();
    }

    /// Obtain current context handle
    pub fn current(&self) -> Arc<Context> {
        self.context.read().unwrap().clone()
    }

    /// Obtain current context name
    /// Will not work for ephemeral context (obtained from config)
    pub fn current_name(&self) -> String {
        self.config.read().unwrap().context.clone()
    }
}