using System.Collections.ObjectModel;
using System.Text.Json;
using Snake.Model;

namespace Snake.Persistance;

public class SnakeLevelLoader{

    public readonly string SaveFileName;
    public SnakeLevelLoader(string saveFileName){
        SaveFileName = saveFileName;
        if(!File.Exists(SaveFileName)){
            throw new FileNotFoundException("Save file not found", SaveFileName);
        }
        string file_content = File.ReadAllText(SaveFileName);
        _stored_levels = JsonSerializer.Deserialize<List<StoredSnakeLevel>>(file_content, new JsonSerializerOptions(){PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower})
            ?? throw new JsonException("Failed to deserialize stored levels");
    }

    private List<StoredSnakeLevel> _stored_levels;
    public ReadOnlyCollection<StoredSnakeLevel> StoredLevels => _stored_levels.AsReadOnly();

    public SnakeLevel LoadLevel(StoredSnakeLevel level){
        return new SnakeLevel(level.Size, 
            level.Obstacles.Select(a => new Point(a[0], a[1])),
            level.SnakeStartLength,
            level.NewEggRound,
            level.EggLimit);
    }
}