using Connected.Entities.Annotations;
using Connected.Entities.Storage;
using System.Collections.Concurrent;
using System.Reflection;

namespace Connected.Data.Update;

internal sealed class UpdateCommandBuilder : CommandBuilder
{
    private static readonly ConcurrentDictionary<string, StorageOperation> _cache;

    static UpdateCommandBuilder()
    {
        _cache = new();
    }

    private static ConcurrentDictionary<string, StorageOperation> Cache => _cache;
    private bool SupportsConcurrency { get; set; }
    protected override bool TryGetExisting(out StorageOperation? result)
    {
        return Cache.TryGetValue(Entity.GetType().FullName, out result);
    }

    protected override StorageOperation OnBuild()
    {
        WriteLine($"UPDATE [{Schema.Schema}].[{Schema.Name}] SET");

        WriteAssignments();
        WriteWhere();

        Trim();
        Write(';');

        var result = new StorageOperation { CommandText = CommandText, Concurrency = SupportsConcurrency ? DataConcurrencyMode.Enabled : DataConcurrencyMode.Disabled };

        foreach (var parameter in Parameters)
            result.AddParameter(parameter);

        Cache.TryAdd(Entity.GetType().FullName, result);

        return result;
    }

    private void WriteAssignments()
    {
        foreach (var property in Properties)
        {
            if (property.GetCustomAttribute<PrimaryKeyAttribute>() is not null || IsVersion(property))
            {
                if (IsVersion(property))
                    SupportsConcurrency = true;

                WhereProperties.Add(property);

                continue;
            }

            var parameter = CreateParameter(property);

            WriteLine($"{ColumnName(property)} = {parameter.Name},");
        }

        Trim();
    }

    private void WriteWhere()
    {
        WriteLine(string.Empty);

        for (var i = 0; i < WhereProperties.Count; i++)
        {
            var property = WhereProperties[i];
            var parameter = CreateParameter(property);

            if (i == 0)
                WriteLine($" WHERE {ColumnName(property)} = {parameter.Name}");
            else
                WriteLine($" AND {ColumnName(property)} = {parameter.Name}");
        }
    }
}