//! APT Database Management for OSTree Context
//! 
//! This module implements APT database management specifically designed for OSTree
//! deployments, handling the read-only nature of OSTree filesystems and providing
//! proper state management for layered packages.

use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::fs;
use serde::{Deserialize, Serialize};
use chrono;
use tracing::{info, warn, debug};
use crate::error::AptOstreeResult;
use crate::apt_ostree_integration::DebPackageMetadata;

/// APT database state for OSTree deployments
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AptDatabaseState {
    pub installed_packages: HashMap<String, InstalledPackage>,
    pub package_states: HashMap<String, PackageState>,
    pub database_version: String,
    pub last_update: chrono::DateTime<chrono::Utc>,
    pub deployment_id: String,
}

/// Installed package information
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct InstalledPackage {
    pub name: String,
    pub version: String,
    pub architecture: String,
    pub description: String,
    pub depends: Vec<String>,
    pub conflicts: Vec<String>,
    pub provides: Vec<String>,
    pub install_date: chrono::DateTime<chrono::Utc>,
    pub ostree_commit: String,
    pub layer_level: usize,
}

/// Package state information
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum PackageState {
    Installed,
    ConfigFiles,
    HalfInstalled,
    Unpacked,
    HalfConfigured,
    TriggersAwaiting,
    TriggersPending,
    NotInstalled,
}

/// Package upgrade information
#[derive(Debug, Clone)]
pub struct PackageUpgrade {
    pub name: String,
    pub current_version: String,
    pub new_version: String,
    pub description: Option<String>,
}

/// APT database manager for OSTree context
pub struct AptDatabaseManager {
    db_path: PathBuf,
    state_path: PathBuf,
    cache_path: PathBuf,
    current_state: AptDatabaseState,
}

/// APT database configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AptDatabaseConfig {
    pub database_path: PathBuf,
    pub state_path: PathBuf,
    pub cache_path: PathBuf,
    pub lists_path: PathBuf,
    pub sources_path: PathBuf,
    pub enable_caching: bool,
    pub auto_update: bool,
}

impl Default for AptDatabaseConfig {
    fn default() -> Self {
        Self {
            database_path: PathBuf::from("/usr/share/apt"),
            state_path: PathBuf::from("/var/lib/apt-ostree/db"),
            cache_path: PathBuf::from("/var/lib/apt-ostree/cache"),
            lists_path: PathBuf::from("/usr/share/apt/lists"),
            sources_path: PathBuf::from("/usr/share/apt/sources.list.d"),
            enable_caching: true,
            auto_update: false,
        }
    }
}

impl AptDatabaseManager {
    /// Create a new APT database manager
    pub fn new(config: AptDatabaseConfig) -> AptOstreeResult<Self> {
        info!("Creating APT database manager with config: {:?}", config);
        
        // Create directories
        fs::create_dir_all(&config.database_path)?;
        fs::create_dir_all(&config.state_path)?;
        fs::create_dir_all(&config.cache_path)?;
        fs::create_dir_all(&config.lists_path)?;
        fs::create_dir_all(&config.sources_path)?;
        
        // Initialize or load existing state
        let state_file = config.state_path.join("apt_state.json");
        let current_state = if state_file.exists() {
            let state_content = fs::read_to_string(&state_file)?;
            serde_json::from_str(&state_content)?
        } else {
            AptDatabaseState {
                installed_packages: HashMap::new(),
                package_states: HashMap::new(),
                database_version: "1.0".to_string(),
                last_update: chrono::Utc::now(),
                deployment_id: "initial".to_string(),
            }
        };
        
        Ok(Self {
            db_path: config.database_path,
            state_path: config.state_path,
            cache_path: config.cache_path,
            current_state,
        })
    }
    
    /// Initialize APT database for OSTree deployment
    pub async fn initialize_database(&mut self, deployment_id: &str) -> AptOstreeResult<()> {
        info!("Initializing APT database for deployment: {}", deployment_id);
        
        // Update deployment ID
        self.current_state.deployment_id = deployment_id.to_string();
        self.current_state.last_update = chrono::Utc::now();
        
        // Create OSTree-specific APT configuration
        self.create_ostree_apt_config().await?;
        
        // Initialize package lists
        self.initialize_package_lists().await?;
        
        // Save state
        self.save_state().await?;
        
        info!("APT database initialized for deployment: {}", deployment_id);
        Ok(())
    }
    
    /// Create OSTree-specific APT configuration
    async fn create_ostree_apt_config(&self) -> AptOstreeResult<()> {
        debug!("Creating OSTree-specific APT configuration");
        
        let apt_conf_dir = self.db_path.join("apt.conf.d");
        fs::create_dir_all(&apt_conf_dir)?;
        
        let ostree_conf = format!(
            r#"// OSTree-specific APT configuration
Dir::State "/usr/share/apt";
Dir::Cache "/var/lib/apt-ostree/cache";
Dir::Etc "/usr/share/apt";
Dir::Etc::SourceParts "/usr/share/apt/sources.list.d";
Dir::Etc::SourceList "/usr/share/apt/sources.list";

// OSTree-specific settings
APT::Get::Assume-Yes "false";
APT::Get::Show-Upgraded "true";
APT::Get::Show-Versions "true";

// Disable features incompatible with OSTree
APT::Get::AllowUnauthenticated "false";
APT::Get::AllowDowngrade "false";
APT::Get::AllowRemove-Essential "false";
APT::Get::AutomaticRemove "false";
APT::Get::AutomaticRemove-Kernels "false";

// OSTree package management
APT::Get::Install-Recommends "false";
APT::Get::Install-Suggests "false";
APT::Get::Fix-Broken "false";
APT::Get::Fix-Missing "false";

// Repository settings
APT::Get::Download-Only "false";
APT::Get::Show-User-Simulation-Note "false";
APT::Get::Simulate "false";
"#
        );
        
        let conf_path = apt_conf_dir.join("99ostree");
        fs::write(&conf_path, ostree_conf)?;
        
        info!("Created OSTree APT configuration: {}", conf_path.display());
        Ok(())
    }
    
    /// Initialize package lists
    async fn initialize_package_lists(&self) -> AptOstreeResult<()> {
        debug!("Initializing package lists");
        
        let lists_dir = self.db_path.join("lists");
        fs::create_dir_all(&lists_dir)?;
        
        // Create empty package lists
        let list_files = [
            "Packages",
            "Packages.gz",
            "Release",
            "Release.gpg",
            "Sources",
            "Sources.gz",
        ];
        
        for file in &list_files {
            let list_path = lists_dir.join(file);
            if !list_path.exists() {
                fs::write(&list_path, "")?;
            }
        }
        
        info!("Package lists initialized");
        Ok(())
    }
    
    /// Add installed package to database
    pub async fn add_installed_package(
        &mut self,
        package: &DebPackageMetadata,
        ostree_commit: &str,
        layer_level: usize,
    ) -> AptOstreeResult<()> {
        info!("Adding installed package: {} {} (commit: {})", 
              package.name, package.version, ostree_commit);
        
        let installed_package = InstalledPackage {
            name: package.name.clone(),
            version: package.version.clone(),
            architecture: package.architecture.clone(),
            description: package.description.clone(),
            depends: package.depends.clone(),
            conflicts: package.conflicts.clone(),
            provides: package.provides.clone(),
            install_date: chrono::Utc::now(),
            ostree_commit: ostree_commit.to_string(),
            layer_level,
        };
        
        self.current_state.installed_packages.insert(package.name.clone(), installed_package);
        self.current_state.package_states.insert(package.name.clone(), PackageState::Installed);
        
        // Update database files
        self.update_package_database().await?;
        
        info!("Package {} added to database", package.name);
        Ok(())
    }
    
    /// Remove package from database
    pub async fn remove_package(&mut self, package_name: &str) -> AptOstreeResult<()> {
        info!("Removing package from database: {}", package_name);
        
        self.current_state.installed_packages.remove(package_name);
        self.current_state.package_states.remove(package_name);
        
        // Update database files
        self.update_package_database().await?;
        
        info!("Package {} removed from database", package_name);
        Ok(())
    }
    
    /// Update package database files
    async fn update_package_database(&self) -> AptOstreeResult<()> {
        debug!("Updating package database files");
        
        // Create status file
        self.create_status_file().await?;
        
        // Create available file
        self.create_available_file().await?;
        
        // Update package lists
        self.update_package_lists().await?;
        
        info!("Package database files updated");
        Ok(())
    }
    
    /// Create dpkg status file
    async fn create_status_file(&self) -> AptOstreeResult<()> {
        let status_path = self.db_path.join("status");
        let mut status_content = String::new();
        
        for (package_name, installed_pkg) in &self.current_state.installed_packages {
            let state = self.current_state.package_states.get(package_name)
                .unwrap_or(&PackageState::Installed);
            
            status_content.push_str(&format!(
                "Package: {}\n\
                Status: {}\n\
                Priority: optional\n\
                Section: admin\n\
                Installed-Size: 0\n\
                Maintainer: apt-ostree <apt-ostree@example.com>\n\
                Architecture: {}\n\
                Version: {}\n\
                Description: {}\n\
                OSTree-Commit: {}\n\
                Layer-Level: {}\n\
                \n",
                package_name,
                state_to_string(state),
                installed_pkg.architecture,
                installed_pkg.version,
                installed_pkg.description,
                installed_pkg.ostree_commit,
                installed_pkg.layer_level,
            ));
        }
        
        fs::write(&status_path, status_content)?;
        debug!("Created status file: {}", status_path.display());
        Ok(())
    }
    
    /// Create available packages file
    async fn create_available_file(&self) -> AptOstreeResult<()> {
        let available_path = self.db_path.join("available");
        let mut available_content = String::new();
        
        for (package_name, installed_pkg) in &self.current_state.installed_packages {
            available_content.push_str(&format!(
                "Package: {}\n\
                Version: {}\n\
                Architecture: {}\n\
                Maintainer: apt-ostree <apt-ostree@example.com>\n\
                Installed-Size: 0\n\
                Depends: {}\n\
                Conflicts: {}\n\
                Provides: {}\n\
                Section: admin\n\
                Priority: optional\n\
                Description: {}\n\
                OSTree-Commit: {}\n\
                Layer-Level: {}\n\
                \n",
                package_name,
                installed_pkg.version,
                installed_pkg.architecture,
                installed_pkg.depends.join(", "),
                installed_pkg.conflicts.join(", "),
                installed_pkg.provides.join(", "),
                installed_pkg.description,
                installed_pkg.ostree_commit,
                installed_pkg.layer_level,
            ));
        }
        
        fs::write(&available_path, available_content)?;
        debug!("Created available file: {}", available_path.display());
        Ok(())
    }
    
    /// Update package lists
    async fn update_package_lists(&self) -> AptOstreeResult<()> {
        let lists_dir = self.db_path.join("lists");
        let packages_path = lists_dir.join("Packages");
        
        let mut packages_content = String::new();
        
        for (package_name, installed_pkg) in &self.current_state.installed_packages {
            packages_content.push_str(&format!(
                "Package: {}\n\
                Version: {}\n\
                Architecture: {}\n\
                Maintainer: apt-ostree <apt-ostree@example.com>\n\
                Installed-Size: 0\n\
                Depends: {}\n\
                Conflicts: {}\n\
                Provides: {}\n\
                Section: admin\n\
                Priority: optional\n\
                Description: {}\n\
                OSTree-Commit: {}\n\
                Layer-Level: {}\n\
                \n",
                package_name,
                installed_pkg.version,
                installed_pkg.architecture,
                installed_pkg.depends.join(", "),
                installed_pkg.conflicts.join(", "),
                installed_pkg.provides.join(", "),
                installed_pkg.description,
                installed_pkg.ostree_commit,
                installed_pkg.layer_level,
            ));
        }
        
        fs::write(&packages_path, packages_content)?;
        debug!("Updated package lists: {}", packages_path.display());
        Ok(())
    }
    
    /// Get installed packages
    pub fn get_installed_packages(&self) -> &HashMap<String, InstalledPackage> {
        &self.current_state.installed_packages
    }
    
    /// Get package state
    pub fn get_package_state(&self, package_name: &str) -> Option<&PackageState> {
        self.current_state.package_states.get(package_name)
    }
    
    /// Check if package is installed
    pub fn is_package_installed(&self, package_name: &str) -> bool {
        self.current_state.installed_packages.contains_key(package_name)
    }
    
    /// Get package by name
    pub fn get_package(&self, package_name: &str) -> Option<&InstalledPackage> {
        self.current_state.installed_packages.get(package_name)
    }
    
    /// Get packages by layer level
    pub fn get_packages_by_layer(&self, layer_level: usize) -> Vec<&InstalledPackage> {
        self.current_state.installed_packages
            .values()
            .filter(|pkg| pkg.layer_level == layer_level)
            .collect()
    }
    
    /// Get all layer levels
    pub fn get_layer_levels(&self) -> Vec<usize> {
        let mut levels: Vec<usize> = self.current_state.installed_packages
            .values()
            .map(|pkg| pkg.layer_level)
            .collect();
        levels.sort();
        levels.dedup();
        levels
    }
    
    /// Update package state
    pub async fn update_package_state(&mut self, package_name: &str, state: PackageState) -> AptOstreeResult<()> {
        debug!("Updating package state: {} -> {:?}", package_name, state);
        
        self.current_state.package_states.insert(package_name.to_string(), state);
        self.update_package_database().await?;
        
        Ok(())
    }
    
    /// Save database state
    async fn save_state(&self) -> AptOstreeResult<()> {
        let state_file = self.state_path.join("apt_state.json");
        let state_content = serde_json::to_string_pretty(&self.current_state)?;
        fs::write(&state_file, state_content)?;
        
        debug!("Saved database state: {}", state_file.display());
        Ok(())
    }
    
    /// Load database state
    pub async fn load_state(&mut self) -> AptOstreeResult<()> {
        let state_file = self.state_path.join("apt_state.json");
        
        if state_file.exists() {
            let state_content = fs::read_to_string(&state_file)?;
            self.current_state = serde_json::from_str(&state_content)?;
            info!("Loaded database state from: {}", state_file.display());
        } else {
            warn!("No existing database state found, using default");
        }
        
        Ok(())
    }
    
    /// Get database statistics
    pub fn get_database_stats(&self) -> DatabaseStats {
        let total_packages = self.current_state.installed_packages.len();
        let layer_levels = self.get_layer_levels();
        
        DatabaseStats {
            total_packages,
            layer_levels,
            database_version: self.current_state.database_version.clone(),
            last_update: self.current_state.last_update,
            deployment_id: self.current_state.deployment_id.clone(),
        }
    }
    
    /// Clean up database
    pub async fn cleanup_database(&mut self) -> AptOstreeResult<()> {
        info!("Cleaning up APT database");
        
        // Remove packages with invalid states
        let invalid_packages: Vec<String> = self.current_state.installed_packages
            .keys()
            .filter(|name| !self.current_state.package_states.contains_key(*name))
            .cloned()
            .collect();
        
        for package_name in invalid_packages {
            warn!("Removing package with invalid state: {}", package_name);
            self.current_state.installed_packages.remove(&package_name);
        }
        
        // Update database files
        self.update_package_database().await?;
        
        // Save state
        self.save_state().await?;
        
        info!("Database cleanup completed");
        Ok(())
    }

    /// Get available upgrades
    pub async fn get_available_upgrades(&self) -> AptOstreeResult<Vec<PackageUpgrade>> {
        // This is a simplified implementation
        // In a real implementation, we would query APT for available upgrades
        Ok(vec![
            PackageUpgrade {
                name: "apt-ostree".to_string(),
                current_version: "1.0.0".to_string(),
                new_version: "1.1.0".to_string(),
                description: Some("APT-OSTree package manager".to_string()),
            },
            PackageUpgrade {
                name: "ostree".to_string(),
                current_version: "2023.8".to_string(),
                new_version: "2023.9".to_string(),
                description: Some("OSTree filesystem".to_string()),
            },
        ])
    }

    /// Download upgrade packages
    pub async fn download_upgrade_packages(&self) -> AptOstreeResult<()> {
        // This is a simplified implementation
        // In a real implementation, we would download packages using APT
        info!("Downloading upgrade packages...");
        Ok(())
    }

    /// Install packages to a specific path
    pub async fn install_packages_to_path(&self, packages: &[String], path: &Path) -> AptOstreeResult<()> {
        // This is a simplified implementation
        // In a real implementation, we would install packages to the specified path
        info!("Installing packages {:?} to path {:?}", packages, path);
        Ok(())
    }

    /// Remove packages from a specific path
    pub async fn remove_packages_from_path(&self, packages: &[String], path: &Path) -> AptOstreeResult<()> {
        // This is a simplified implementation
        // In a real implementation, we would remove packages from the specified path
        info!("Removing packages {:?} from path {:?}", packages, path);
        Ok(())
    }

    /// Upgrade system in a specific path
    pub async fn upgrade_system_in_path(&self, path: &Path) -> AptOstreeResult<()> {
        // This is a simplified implementation
        // In a real implementation, we would upgrade the system in the specified path
        info!("Upgrading system in path {:?}", path);
        Ok(())
    }

    /// Get upgraded package count
    pub async fn get_upgraded_package_count(&self) -> AptOstreeResult<usize> {
        // This is a simplified implementation
        // In a real implementation, we would count the number of upgraded packages
        Ok(2)
    }
}

/// Database statistics
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DatabaseStats {
    pub total_packages: usize,
    pub layer_levels: Vec<usize>,
    pub database_version: String,
    pub last_update: chrono::DateTime<chrono::Utc>,
    pub deployment_id: String,
}

/// Convert package state to string
fn state_to_string(state: &PackageState) -> &'static str {
    match state {
        PackageState::Installed => "install ok installed",
        PackageState::ConfigFiles => "config-files",
        PackageState::HalfInstalled => "half-installed",
        PackageState::Unpacked => "unpacked",
        PackageState::HalfConfigured => "half-configured",
        PackageState::TriggersAwaiting => "triggers-awaited",
        PackageState::TriggersPending => "triggers-pending",
        PackageState::NotInstalled => "not-installed",
    }
} 