using System.Text.RegularExpressions;
using Admin.NET.Core;
using Microsoft.Extensions.Logging;

namespace Admin.NET.Plugin.AiDOP.DataPlatform;

public interface IMdpSourcePasswordResolver
{
    /// <summary>解析数据源口令。返回值不得写入日志、实体或数据库。</summary>
    string Resolve(string sourceCode, string? storedSecret);
}

public sealed class MdpSourceSecretException : Exception
{
    public string Code { get; }

    public MdpSourceSecretException(string code, string message) : base(message)
    {
        Code = code;
    }
}

/// <summary>
/// 口令只在建连时解析：环境变量优先，其次系统密文，最后才是迁移期明文。
/// </summary>
public sealed class MdpSourcePasswordResolver : IMdpSourcePasswordResolver, ITransient
{
    private readonly ILogger<MdpSourcePasswordResolver>? _logger;

    public MdpSourcePasswordResolver(ILogger<MdpSourcePasswordResolver>? logger = null)
    {
        _logger = logger;
    }

    public static string EnvironmentVariableName(string sourceCode)
    {
        if (string.IsNullOrWhiteSpace(sourceCode))
            throw new ArgumentException("sourceCode 不能为空", nameof(sourceCode));
        var token = Regex.Replace(sourceCode.Trim().ToUpperInvariant(), "[^A-Z0-9]", "_");
        return "AIDOP_MDP_SOURCE_" + token + "_PASSWORD";
    }

    public string Resolve(string sourceCode, string? storedSecret)
        => ResolveCore(sourceCode, storedSecret, DecryptStored, _logger);

    internal static string ResolveCore(
        string sourceCode,
        string? storedSecret,
        Func<string, string?> decrypt,
        ILogger? logger)
    {
        var envName = EnvironmentVariableName(sourceCode);
        var fromEnv = Environment.GetEnvironmentVariable(envName);
        if (!string.IsNullOrEmpty(fromEnv))
            return fromEnv;

        if (!string.IsNullOrEmpty(storedSecret))
        {
            if (TryDecrypt(storedSecret, decrypt, out var plain))
                return plain;
            logger?.LogWarning(
                "mdp source {SourceCode} still uses a legacy plaintext secret. Set {EnvName} and clear the stored value.",
                sourceCode, envName);
            return storedSecret;
        }

        throw new MdpSourceSecretException(
            "SECRET_MISSING",
            $"源 {sourceCode} 未配置口令。请设置环境变量 {envName}。");
    }

    private static string? DecryptStored(string stored)
    {
        var decrypted = CryptogramUtil.Decrypt(stored);
        return decrypted;
    }

    private static bool TryDecrypt(string stored, Func<string, string?> decrypt, out string plain)
    {
        plain = "";
        try
        {
            var decrypted = decrypt(stored);
            // 原样返回入参不是解密成功，按迁移期明文处理。
            if (string.IsNullOrEmpty(decrypted) || string.Equals(decrypted, stored, StringComparison.Ordinal))
                return false;
            plain = decrypted;
            return true;
        }
        catch
        {
            return false;
        }
    }
}