using WxAgent.Core;

namespace WxAgent.Windows;

public sealed record AccountDatabaseFile(string FullPath, string RelativePath, byte[] FirstPage, string Salt);

public sealed record AccountDatabaseRoot(string AccountRootPath, string Fingerprint, IReadOnlyList<AccountDatabaseFile> Databases);

public static class WechatDatabaseDiscovery
{
    public static IReadOnlyList<AccountDatabaseRoot> FindAccountRoots(
        string? xwechatFilesRoot = null,
        CancellationToken cancellationToken = default)
    {
        cancellationToken.ThrowIfCancellationRequested();
        var root = xwechatFilesRoot ?? Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "xwechat_files");
        if (!Directory.Exists(root))
        {
            return [];
        }

        var accounts = new List<AccountDatabaseRoot>();
        foreach (var accountDirectory in Directory.EnumerateDirectories(root))
        {
            cancellationToken.ThrowIfCancellationRequested();
            var dbStorage = Path.Combine(accountDirectory, "db_storage");
            if (!Directory.Exists(dbStorage))
            {
                continue;
            }

            var databases = new List<AccountDatabaseFile>();
            foreach (var path in Directory.EnumerateFiles(dbStorage, "*.db", SearchOption.AllDirectories))
            {
                cancellationToken.ThrowIfCancellationRequested();
                try
                {
                    var page = new byte[SqlCipherPageVerifier.PageSize];
                    using var stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete);
                    stream.ReadExactly(page);

                    var relativePath = Path.GetRelativePath(dbStorage, path).Replace('\\', '/');
                    databases.Add(new AccountDatabaseFile(path, relativePath, page, Convert.ToHexString(page.AsSpan(0, SqlCipherPageVerifier.SaltSize)).ToLowerInvariant()));
                }
                catch (IOException)
                {
                }
                catch (UnauthorizedAccessException)
                {
                }
            }

            accounts.Add(new AccountDatabaseRoot(dbStorage, AccountRootFingerprint.Create(dbStorage), databases));
        }

        return accounts;
    }
}