using System;
using System.IO;
using System.Text.Json;

namespace BoxPacker3D
{
    /// <summary>
    /// Strongly-typed representation of appsettings.json.
    /// Loaded once at startup via <see cref="Load"/>; falls back to sensible defaults
    /// if the file is missing or malformed.
    /// </summary>
    public class AppSettings
    {
        public DatabaseSettings Database { get; set; } = new();
        public DefaultBoxSettings DefaultBox { get; set; } = new();
        public MaxBoxSettings MaxBox { get; set; } = new();
        public PaddingSettings Padding { get; set; } = new();
        public ViewSettings View { get; set; } = new();
        public UISettings UI { get; set; } = new();

        public class DatabaseSettings
        {
            public string FilePath { get; set; } = "items.db";
        }
        public class DefaultBoxSettings
        {
            public double Width  { get; set; } = 600;
            public double Height { get; set; } = 400;
            public double Depth  { get; set; } = 500;
            public double WallThickness { get; set; } = 20;
        }
        public class MaxBoxSettings
        {
            public double Width  { get; set; } = 1200;
            public double Height { get; set; } = 800;
            public double Depth  { get; set; } = 1000;
        }
        public class PaddingSettings
        {
            public double WallPadding { get; set; } = 10;
            public double ItemPadding { get; set; } = 3;
        }
        public class ViewSettings
        {
            public int InitialRotationX { get; set; } = 30;
            public int InitialRotationY { get; set; } = 30;
            public int InitialZoomPercent { get; set; } = 100;
        }
        public class UISettings
        {
            public int WindowWidth    { get; set; } = 1340;
            public int WindowHeight   { get; set; } = 840;
            public int LeftPanelWidth { get; set; } = 500;
        }

        /// <summary>
        /// Loads appsettings.json from the application directory.
        /// If the file is missing or invalid, returns defaults and writes a warning to stderr.
        /// </summary>
        public static AppSettings Load()
        {
            string path = Path.Combine(AppContext.BaseDirectory, "appsettings.json");
            if (!File.Exists(path))
            {
                Console.Error.WriteLine($"[AppSettings] {path} not found – using defaults.");
                return new AppSettings();
            }
            try
            {
                var json = File.ReadAllText(path);
                var opts = new JsonSerializerOptions
                {
                    PropertyNameCaseInsensitive = true,
                    ReadCommentHandling = JsonCommentHandling.Skip,
                    AllowTrailingCommas = true
                };
                return JsonSerializer.Deserialize<AppSettings>(json, opts) ?? new AppSettings();
            }
            catch (Exception ex)
            {
                Console.Error.WriteLine($"[AppSettings] Failed to parse: {ex.Message} – using defaults.");
                return new AppSettings();
            }
        }

        /// <summary>
        /// Resolves the writable database path.
        ///
        /// Priority:
        ///   1. If FilePath is absolute → use it as-is (developer override).
        ///   2. Otherwise → store in %AppData%\BoxPacker3D\&lt;filename&gt; so the
        ///      file is always user-writable, even when the app is installed in
        ///      Program Files (which is read-only for normal users).
        ///
        /// On first run the seed database is copied from the application directory
        /// to AppData so the user starts with the pre-built item catalogue.
        /// </summary>
        public string ResolvedDatabasePath
        {
            get
            {
                if (Path.IsPathRooted(Database.FilePath))
                    return Database.FilePath;

                // User-writable location: %AppData%\BoxPacker3D\items.db
                string appDataDir = Path.Combine(
                    Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
                    "BoxPacker3D");
                Directory.CreateDirectory(appDataDir);

                string userDbPath = Path.Combine(appDataDir, Path.GetFileName(Database.FilePath));

                // Copy seed database on first run (do not overwrite user's existing data)
                if (!File.Exists(userDbPath))
                {
                    string seedPath = Path.Combine(AppContext.BaseDirectory, Database.FilePath);
                    if (File.Exists(seedPath))
                        File.Copy(seedPath, userDbPath);
                }

                return userDbPath;
            }
        }
    }
}