using System.Text.Json;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Npgsql;
using NpgsqlTypes;
using Yuanshen.Gameserver.Options;

namespace Yuanshen.Gameserver.Database;

internal sealed class PostgresPlayerRepository : IPlayerRepository, IAsyncDisposable
{
    private const string CreateTableSql =
        """
        CREATE TABLE IF NOT EXISTS players (
            uid        bigint PRIMARY KEY,
            data       jsonb NOT NULL,
            updated_at timestamptz NOT NULL DEFAULT now()
        )
        """;

    private const string UpsertSql =
        """
        INSERT INTO players (uid, data, updated_at)
        VALUES (@uid, @data, now())
        ON CONFLICT (uid) DO UPDATE
        SET data = EXCLUDED.data, updated_at = now()
        """;

    private const string SelectSql = "SELECT data FROM players WHERE uid = @uid";

    private static readonly JsonSerializerOptions SerializerOptions = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase
    };

    private readonly NpgsqlDataSource _dataSource;
    private readonly ILogger _logger;
    private readonly SemaphoreSlim _schemaLock = new(1, 1);
    private volatile bool _schemaReady;

    public PostgresPlayerRepository(IOptions<DatabaseOptions> options, ILogger<PostgresPlayerRepository> logger)
    {
        _logger = logger;
        _dataSource = new NpgsqlDataSourceBuilder(options.Value.ConnectionString).Build();
    }

    private async ValueTask<bool> EnsureSchemaAsync()
    {
        if (_schemaReady)
            return true;

        await _schemaLock.WaitAsync();
        try
        {
            if (_schemaReady)
                return true;

            await using NpgsqlCommand command = _dataSource.CreateCommand(CreateTableSql);
            await command.ExecuteNonQueryAsync();

            _schemaReady = true;
            _logger.LogInformation("PostgreSQL connected, player storage ready");
            return true;
        }
        catch (Exception exception)
        {
            _logger.LogWarning("PostgreSQL unavailable, persistence disabled for now: {message}", exception.Message);
            return false;
        }
        finally
        {
            _schemaLock.Release();
        }
    }

    public async ValueTask<PlayerRecord?> LoadAsync(uint uid)
    {
        if (!await EnsureSchemaAsync())
            return null;

        try
        {
            await using NpgsqlCommand command = _dataSource.CreateCommand(SelectSql);
            command.Parameters.AddWithValue("uid", (long)uid);

            object? result = await command.ExecuteScalarAsync();
            if (result is not string json)
                return null;

            return JsonSerializer.Deserialize<PlayerRecord>(json, SerializerOptions);
        }
        catch (Exception exception)
        {
            _logger.LogError("Failed to load player {uid}: {message}", uid, exception.Message);
            return null;
        }
    }

    public async ValueTask<bool> SaveAsync(PlayerRecord record)
    {
        if (!await EnsureSchemaAsync())
            return false;

        record.LastSeen = DateTimeOffset.UtcNow;

        try
        {
            await using NpgsqlCommand command = _dataSource.CreateCommand(UpsertSql);
            command.Parameters.AddWithValue("uid", (long)record.Uid);
            command.Parameters.Add(new NpgsqlParameter("data", NpgsqlDbType.Jsonb)
            {
                Value = JsonSerializer.Serialize(record, SerializerOptions)
            });

            await command.ExecuteNonQueryAsync();
            _logger.LogDebug("Saved player {uid}", record.Uid);
            return true;
        }
        catch (Exception exception)
        {
            _logger.LogError("Failed to save player {uid}: {message}", record.Uid, exception.Message);
            return false;
        }
    }

    public ValueTask DisposeAsync()
    {
        _schemaLock.Dispose();
        return _dataSource.DisposeAsync();
    }
}