using System;
using System.Collections.Generic;
using System.Data.SQLite;
using System.IO;
using System.Text;
using System.Threading.Tasks;
using FileManager;

namespace CookieMonster
{
    internal class Chrome : IBrowser
    {
        public async Task<IEnumerable<CookieValue>> GetAllCookiesAsync()
        {
            var col = new List<CookieValue>();

            var strPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), @"Google\Chrome\User Data\Default\Cookies");
            if (!FileUtility.FileExists(strPath))
                return col;

            //
            // IF WE GET AN ERROR HERE
            //   then add a reference to sqlite core in the project which is ultimately calling this.
            // a project which directly references CookieMonster doesn't need to also ref sqlite.
            // however, for any further number of abstractions, the project needs to directly ref sqlite.
            // eg: this will not work unless the winforms proj adds sqlite to ref.s:
            //     LibationWinForm > AudibleDotComAutomation > CookieMonster
            //
            using (var conn = new SQLiteConnection("Data Source=" + strPath + ";pooling=false"))
            using (var cmd = conn.CreateCommand())
            {
                cmd.CommandText = "SELECT host_key, name, value, encrypted_value, last_access_utc, expires_utc FROM cookies;";

                conn.Open();
                using (var reader = await cmd.ExecuteReaderAsync().ConfigureAwait(false))
                {
                    while (reader.Read())
                    {
                        var host_key = reader.GetString(0);
                        var name = reader.GetString(1);
                        var value = reader.GetString(2);
                        var last_access_utc = reader.GetInt64(4);
                        var expires_utc = reader.GetInt64(5);

                        // https://stackoverflow.com/a/25874366
                        if (string.IsNullOrWhiteSpace(value))
                        {
                            var encrypted_value = (byte[])reader[3];
                            var decodedData = System.Security.Cryptography.ProtectedData.Unprotect(encrypted_value, null, System.Security.Cryptography.DataProtectionScope.CurrentUser);
                            value = Encoding.ASCII.GetString(decodedData);
                        }

                        col.Add(new CookieValue { Browser = "chrome", Domain = host_key, Name = name, Value = value, LastAccess = chromeTimeToDateTimeUtc(last_access_utc), Expires = chromeTimeToDateTimeUtc(expires_utc) });
                    }
                }
            }

            return col;
        }

        // Chrome uses 1601-01-01 00:00:00 UTC as the epoch (ie the starting point for the millisecond time counter).
        // this is the same as "FILETIME" in Win32 except FILETIME uses 100ns ticks instead of ms.
        private static DateTime chromeTimeToDateTimeUtc(long time) => DateTime.SpecifyKind(DateTime.FromFileTime(time * 10), DateTimeKind.Utc);
    }
}