use std::fs;
use std::path::PathBuf;
use tauri::{AppHandle, Manager};

pub fn app_file_path(app: &AppHandle, name: &str) -> Result<PathBuf, String> {
    let dir = app.path().app_data_dir().map_err(|e| e.to_string())?.join("musealpha");
    fs::create_dir_all(&dir).map_err(|e| e.to_string())?;
    Ok(dir.join(name))
}

pub fn save_json<T: serde::Serialize>(app: &AppHandle, name: &str, value: &T) -> Result<(), String> {
    let path = app_file_path(app, name)?;
    let json = serde_json::to_string_pretty(value).map_err(|e| e.to_string())?;
    fs::write(path, json).map_err(|e| e.to_string())
}

pub fn load_json<T: serde::de::DeserializeOwned + Default>(app: &AppHandle, name: &str) -> Result<T, String> {
    let path = app_file_path(app, name)?;
    if !path.exists() {
        return Ok(T::default());
    }
    let json = fs::read_to_string(path).map_err(|e| e.to_string())?;
    serde_json::from_str(&json).map_err(|e| e.to_string())
}

/// Storage info for the settings panel
#[derive(serde::Serialize)]
pub struct StorageInfo {
    pub data_path: String,
    pub total_size_bytes: u64,
    pub file_count: usize,
    pub project_count: usize,
    pub library_count: usize,
    pub library_size_bytes: u64,
    pub projects_size_bytes: u64,
}

#[tauri::command]
pub fn storage_info(app: AppHandle) -> Result<StorageInfo, String> {
    let dir = app.path().app_data_dir().map_err(|e| e.to_string())?.join("musealpha");
    let data_path = dir.to_string_lossy().to_string();

    if !dir.exists() {
        return Ok(StorageInfo { data_path, total_size_bytes: 0, file_count: 0, project_count: 0, library_count: 0, library_size_bytes: 0, projects_size_bytes: 0 });
    }

    let mut total_size: u64 = 0;
    let mut file_count: usize = 0;
    let mut projects_size: u64 = 0;
    let mut project_count: usize = 0;
    let mut library_size: u64 = 0;

    if let Ok(entries) = fs::read_dir(&dir) {
        for entry in entries.flatten() {
            if let Ok(meta) = entry.metadata() {
                if meta.is_file() {
                    let size = meta.len();
                    total_size += size;
                    file_count += 1;
                    let name = entry.file_name().to_string_lossy().to_string();
                    if name.starts_with("project_") && name.ends_with(".json") {
                        projects_size += size;
                        project_count += 1;
                    }
                    if name == "library.json" {
                        library_size = size;
                    }
                }
            }
        }
    }

    // Count library items
    let library_count = load_json::<Vec<serde_json::Value>>(&app, "library.json").map(|v| v.len()).unwrap_or(0);

    Ok(StorageInfo { data_path, total_size_bytes: total_size, file_count, project_count, library_count, library_size_bytes: library_size, projects_size_bytes: projects_size })
}

/// Clear all library data
#[tauri::command]
pub fn storage_clear_library(app: AppHandle) -> Result<(), String> {
    let path = app_file_path(&app, "library.json")?;
    if path.exists() { fs::write(&path, "[]").map_err(|e| e.to_string())?; }
    // Also clear in-memory state
    let state = app.state::<crate::library::LibraryState>();
    let mut items = state.items.lock().map_err(|_| "lock")?;
    items.clear();
    Ok(())
}

/// Delete all project files and reset index
#[tauri::command]
pub fn storage_clear_projects(app: AppHandle) -> Result<(), String> {
    let dir = app.path().app_data_dir().map_err(|e| e.to_string())?.join("musealpha");
    if let Ok(entries) = fs::read_dir(&dir) {
        for entry in entries.flatten() {
            let name = entry.file_name().to_string_lossy().to_string();
            if name.starts_with("project_") && name.ends_with(".json") {
                let _ = fs::remove_file(entry.path());
            }
        }
    }
    // Reset index
    save_json(&app, "projects_index.json", &serde_json::json!({"projects": [], "active_id": null}))?;
    Ok(())
}

/// Reveal app data folder in OS file manager
#[tauri::command]
pub fn storage_reveal_folder(app: AppHandle) -> Result<(), String> {
    let dir = app.path().app_data_dir().map_err(|e| e.to_string())?.join("musealpha");
    fs::create_dir_all(&dir).map_err(|e| e.to_string())?;
    opener::open(dir.to_string_lossy().as_ref()).map_err(|e| format!("Could not open folder: {e}"))
}