// Copyright (C) 2024 Rubén Beltrán del Río

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see https://map.tranquil.systems.

use std::fs;
use std::path::PathBuf;

use crate::constants;

use super::models::{UserPreferences, UserPreferencesJson};

/// Returns the XDG config directory path for preferences
pub fn config_dir() -> PathBuf {
    dirs::config_dir()
        .unwrap_or_else(|| PathBuf::from("."))
        .join(constants::APP_ID)
}

/// Returns the preferences file path
pub fn preferences_path() -> PathBuf {
    config_dir().join("preferences.json")
}

/// Loads preferences from disk, returning defaults if not found
pub fn load() -> UserPreferences {
    let path = preferences_path();

    if path.exists() {
        match fs::read_to_string(&path) {
            Ok(content) => serde_json::from_str(&content).unwrap_or_default(),
            Err(_) => UserPreferences::default(),
        }
    } else {
        UserPreferences::default()
    }
}

/// Saves preferences to disk
pub fn save(prefs: &UserPreferences) -> Result<(), std::io::Error> {
    let path = preferences_path();

    if let Some(parent) = path.parent() {
        fs::create_dir_all(parent)?;
    }

    let content = serde_json::to_string_pretty(prefs).map_err(std::io::Error::other)?;

    fs::write(path, content)
}

/// Exports preferences to JSON string (for file export)
pub fn export_json(prefs: &UserPreferences) -> Option<String> {
    let json_prefs = prefs.to_json();
    serde_json::to_string_pretty(&json_prefs).ok()
}

/// Imports preferences from JSON string (partial updates supported)
/// Returns true on success, false on parse error
pub fn import_json(prefs: &mut UserPreferences, json: &str) -> bool {
    match serde_json::from_str::<UserPreferencesJson>(json) {
        Ok(imported) => {
            prefs.update_from_json(&imported);
            true
        }
        Err(_) => false,
    }
}

/// Saves preferences to a specific file path (for export dialog)
pub fn export_to_file(prefs: &UserPreferences, path: &PathBuf) -> Result<(), std::io::Error> {
    let content =
        export_json(prefs).ok_or_else(|| std::io::Error::other("Serialization failed"))?;
    fs::write(path, content)
}

/// Loads preferences from a specific file path (for import dialog)
pub fn import_from_file(prefs: &mut UserPreferences, path: &PathBuf) -> Result<(), std::io::Error> {
    let content = fs::read_to_string(path)?;
    if import_json(prefs, &content) {
        Ok(())
    } else {
        Err(std::io::Error::new(
            std::io::ErrorKind::InvalidData,
            "Invalid preferences format",
        ))
    }
}