chameleon/Assets/Scripts/MeshPainter.Persistence.cs

using System.Collections.Generic;
using System.IO;
using System.Text;
using UnityEngine;

public partial class MeshPainter
{
    // --- Persistence: named paint slots, saved/loaded explicitly from the HUD ---
    //
    // The painter no longer auto-loads on start or auto-saves on quit; painting is volatile until the
    // player explicitly saves it to a named slot, and a fresh session always starts from the material
    // seed. Saved slots live in a single global library folder (role/object independent), so any avatar
    // can load any saved painting as a camouflage preset.

    // Raw, bit-exact map dump: 'CHMP' magic + version + name + width + height + map count, then each
    // map's canonical Color32 bytes. Raw (not PNG) avoids any sRGB/alpha-premultiply ambiguity and
    // round-trips the exact canonical bytes ReadCanonical produces.
    private const uint PaintFileMagic = 0x504D4843; // 'CHMP' little-endian
    private const int PaintFileVersion = 2;         // v2: added the display-name header
    private const string PaintFileExt = ".paint";

    private static string PaintLibraryDir =>
        Path.Combine(Application.persistentDataPath, "MeshPaint", "Saved");

    private static string SanitizeKey(string s)
    {
        if (string.IsNullOrEmpty(s)) return "unnamed";
        foreach (char c in Path.GetInvalidFileNameChars()) s = s.Replace(c, '_');
        return s.Replace(' ', '_');
    }

    /// <summary>Disk path for a slot. The display name lives inside the file; the file name is a sanitized key.</summary>
    private static string PathForName(string name) =>
        Path.Combine(PaintLibraryDir, SanitizeKey(name) + PaintFileExt);

    /// <summary>True if a slot with this name already exists (used to block overwriting on save).</summary>
    public static bool PaintExists(string name) =>
        !string.IsNullOrWhiteSpace(name) && File.Exists(PathForName(name));

    /// <summary>Display names of every saved slot, sorted alphabetically. Each name is read from the file header.</summary>
    public static List<string> ListSavedPaintings()
    {
        var names = new List<string>();
        try
        {
            if (!Directory.Exists(PaintLibraryDir)) return names;
            foreach (string path in Directory.GetFiles(PaintLibraryDir, "*" + PaintFileExt))
            {
                string n = ReadHeaderName(path);
                if (!string.IsNullOrEmpty(n)) names.Add(n);
            }
        }
        catch (System.Exception e)
        {
            Debug.LogWarning($"[MeshPainter] Listing saved paintings failed: {e.Message}");
        }
        names.Sort(System.StringComparer.CurrentCultureIgnoreCase);
        return names;
    }

    /// <summary>
    /// Writes the current painted maps to a new named slot. Returns false without writing if the painter
    /// is not ready or a slot with this name already exists (no silent overwrite).
    /// </summary>
    public bool SavePaintAs(string name)
    {
        if (!_setupValid || string.IsNullOrWhiteSpace(name)) return false;
        name = name.Trim();
        if (PaintExists(name)) return false;

        try
        {
            Directory.CreateDirectory(PaintLibraryDir);
            int n = textureSize * textureSize;

            using (var fs = new FileStream(PathForName(name), FileMode.Create, FileAccess.Write))
            using (var w = new BinaryWriter(fs))
            {
                w.Write(PaintFileMagic);
                w.Write(PaintFileVersion);
                w.Write(name);                 // length-prefixed UTF8 (BinaryWriter.Write(string))
                w.Write(textureSize);
                w.Write(textureSize);
                w.Write(MAP_COUNT);

                var bytes = new byte[n * 4];
                for (int mi = 0; mi < MAP_COUNT; mi++)
                {
                    Color32[] px = ReadCanonical(mi);
                    int count = Mathf.Min(n, px.Length);
                    for (int i = 0; i < count; i++)
                    {
                        int o = i * 4;
                        bytes[o] = px[i].r;
                        bytes[o + 1] = px[i].g;
                        bytes[o + 2] = px[i].b;
                        bytes[o + 3] = px[i].a;
                    }
                    w.Write(bytes, 0, count * 4);
                }
            }
            return true;
        }
        catch (System.Exception e)
        {
            Debug.LogWarning($"[MeshPainter] Saving paint '{name}' failed: {e.Message}", this);
            return false;
        }
    }

    /// <summary>
    /// Loads a named slot and re-seeds the active backend with it, replacing the current painting.
    /// Returns false if the slot is missing or incompatible (the current painting is left untouched).
    /// </summary>
    public bool LoadPaintByName(string name)
    {
        if (!_setupValid) return false;

        Color32[][] canonical = ReadMaps(PathForName(name));
        if (canonical == null) return false;

        // Re-seed exactly like SwitchBackend / ApplyPaintSnapshot, so the island/dilation seeding path
        // runs and the edge padding is rebuilt correctly for the loaded content.
        if (_gpuActive) TeardownGpu();
        else TeardownCpu();
        SetupBackend(useGpu, canonical);
        _hasLastScreen = false;
        return true;
    }

    /// <summary>Deletes a named slot. Returns true if a file was removed.</summary>
    public static bool DeletePaint(string name)
    {
        try
        {
            string path = PathForName(name);
            if (!File.Exists(path)) return false;
            File.Delete(path);
            return true;
        }
        catch (System.Exception e)
        {
            Debug.LogWarning($"[MeshPainter] Deleting paint '{name}' failed: {e.Message}");
            return false;
        }
    }

    /// <summary>Reads just the display-name header of a slot file (or the file name as a fallback).</summary>
    private static string ReadHeaderName(string path)
    {
        try
        {
            using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read))
            using (var r = new BinaryReader(fs, Encoding.UTF8))
            {
                if (r.ReadUInt32() != PaintFileMagic) return null;
                if (r.ReadInt32() != PaintFileVersion) return null;
                return r.ReadString();
            }
        }
        catch
        {
            return Path.GetFileNameWithoutExtension(path);
        }
    }

    /// <summary>
    /// Reads all maps from a slot file in canonical layout, or null if missing / incompatible. Per-map
    /// null entries are tolerated by both backends (they fall back to the material seed).
    /// </summary>
    private Color32[][] ReadMaps(string path)
    {
        if (!File.Exists(path)) return null;

        try
        {
            using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read))
            using (var r = new BinaryReader(fs, Encoding.UTF8))
            {
                if (r.ReadUInt32() != PaintFileMagic) return null;
                int ver = r.ReadInt32();
                if (ver != PaintFileVersion) return null;
                r.ReadString(); // display name (header only; not needed for the pixel load)
                int w = r.ReadInt32();
                int h = r.ReadInt32();
                int maps = r.ReadInt32();

                // Resolution change -> ignore rather than smear mismatched data; the brush re-seeds
                // from the material instead.
                if (w != textureSize || h != textureSize)
                {
                    Debug.LogWarning($"[MeshPainter] Saved paint ignored (got {w}x{h}, expected " +
                                     $"{textureSize}x{textureSize}).", this);
                    return null;
                }

                int n = textureSize * textureSize;
                var result = new Color32[MAP_COUNT][];
                int load = Mathf.Min(maps, MAP_COUNT);
                for (int mi = 0; mi < load; mi++)
                {
                    byte[] raw = r.ReadBytes(n * 4);
                    if (raw.Length != n * 4) break; // truncated file -> remaining maps stay seeded

                    var px = new Color32[n];
                    for (int i = 0; i < n; i++)
                    {
                        int o = i * 4;
                        px[i] = new Color32(raw[o], raw[o + 1], raw[o + 2], raw[o + 3]);
                    }
                    result[mi] = px;
                }
                return result;
            }
        }
        catch (System.Exception e)
        {
            Debug.LogWarning($"[MeshPainter] Loading paint failed: {e.Message}", this);
            return null;
        }
    }
}