Prefab Import/Export

/// @function scr_ExportPrefab()
/// @desc Exports all objects and tile data in the current room into a JSON prefab structure.
function scr_ExportPrefab() {
    // === Object Types to Ignore During Export ===
    var skip_objects = [
        oRoomOrigin, oPrefabBuilderControl, oCamera, oNavigation,
        oCursor, oHUD, oItemManager, oInventory, oTech
    ];

    // === Gather Object Data ===
    var prefab_objects = [];

    with (all) {
        if (!array_contains(skip_objects, object_index)) {
            var entry = {
                object_id: object_index,
                type: object_get_name(object_index),
                x: x,
                y: y,
                xscale: image_xscale,
                yscale: image_yscale
            };
            show_debug_message("Exporting object: " + entry.type + " @ " + string(entry.x) + "," + string(entry.y));
            array_push(prefab_objects, entry);
        }
    }

    // === Gather Tile Data from "Tiles_Visual" Layer ===
    var tile_layer = "Tiles_Visual";
    var tile_data = [];

    var tilemap_id = layer_tilemap_get_id(tile_layer);
    if (tilemap_id != -1) {
        var tile_w = tilemap_get_tile_width(tilemap_id);
        var tile_h = tilemap_get_tile_height(tilemap_id);
        var grid_w = room_width div tile_w;
        var grid_h = room_height div tile_h;
        var tile_columns = 8; // Hardcoded: change if tileset changes

        for (var tx = 0; tx < grid_w; tx++) {
            for (var ty = 0; ty < grid_h; ty++) {
                var tile_index = tilemap_get(tilemap_id, tx, ty);
                if (tile_index != 0) {
                    var tile_entry = {
                        x: tx,
                        y: ty,
                        tile_x: tile_index mod tile_columns,
                        tile_y: tile_index div tile_columns
                    };
                    show_debug_message("Exporting tile (" + string(tile_entry.tile_x) + "," + string(tile_entry.tile_y) + ") at " + string(tile_entry.x) + "," + string(tile_entry.y));
                    array_push(tile_data, tile_entry);
                }
            }
        }
    }

    // === Create Final Prefab Structure ===
    var prefab = {
        objects: prefab_objects,
        tiles: tile_data
    };

    // === Write JSON to Disk ===
    var json = json_stringify(prefab, false);
    var file = file_text_open_write("prefab_output.json");
    file_text_write_string(file, json);
    file_text_close(file);

    show_debug_message("Export complete: prefab_output.json");
}


/// @function scr_BuildRoomFromPrefab(prefab, x_offset, y_offset)
/// @desc Builds a room layout from a JSON prefab, placing objects and tiles with pixel offsets.
/// @param prefab {struct} - The parsed JSON prefab data
/// @param x_offset {int} - X pixel offset to position the prefab
/// @param y_offset {int} - Y pixel offset to position the prefab
function scr_BuildRoomFromPrefab(prefab, x_offset, y_offset) {
    show_debug_message("Spawning prefab at offset: " + string(x_offset) + "," + string(y_offset));

    // === OBJECT SPAWN ===
    for (var i = 0; i < array_length(prefab.objects); i++) {
        var obj = prefab.objects[i];

        if (object_exists(obj.object_id)) {
            var inst = instance_create_layer(x_offset + obj.x, y_offset + obj.y, "Instances", obj.object_id);
            inst.image_xscale = obj.xscale;
            inst.image_yscale = obj.yscale;
        } else {
            show_debug_message("WARNING: Invalid object ID " + string(obj.object_id));
        }
    }

    // === TILE PLACEMENT ===
    var tilemap_id = layer_tilemap_get_id("RoomTiles");
    if (tilemap_id == -1) {
        show_debug_message("ERROR: RoomTiles layer not found.");
        return;
    }

    tilemap_clear(tilemap_id, 0);

    var tile_w = tilemap_get_tile_width(tilemap_id);
    var tile_h = tilemap_get_tile_height(tilemap_id);
    var tile_columns = 8;
    var max_tiles = tile_columns * tile_columns;

    for (var j = 0; j < array_length(prefab.tiles); j++) {
        var tile = prefab.tiles[j];

        // Add *pixel* offset to grid cell
        var cx = tile.x + floor(x_offset / tile_w);
        var cy = tile.y + floor(y_offset / tile_h);
        var tile_index = tile.tile_y * tile_columns + tile.tile_x;

        if (tile_index >= 0 && tile_index < max_tiles) {
            tilemap_set(tilemap_id, cx, cy, tile_index);
            show_debug_message("Placed tile (" + string(tile.tile_x) + "," + string(tile.tile_y) + ") → index " + string(tile_index) + " at cell " + string(cx) + "," + string(cy));
        } else {
            show_debug_message("SKIPPED invalid tile index " + string(tile_index));
        }
    }

    show_debug_message("Prefab build complete.");
}