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// 
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// Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in 
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// 
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
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#nullable enable
using System.Collections.Generic;
using Duplicati.Library.Interface;

namespace Duplicati.Library.Utility.Options;

/// <summary>
/// Helper class for unified use of authentication settings
/// </summary>
public static class AuthOptionsHelper
{
    /// <summary>
    /// The authentication username option, without a prefix
    /// </summary>
    public const string AuthUsernameOption = "auth-username";
    /// <summary>
    /// The authentication password option, without a prefix
    /// </summary>
    public const string AuthPasswordOption = "auth-password";

    /// <summary>
    /// Gets the authentication options
    /// </summary>
    /// <param name="prefix">An optional prefix for the options</param>
    /// <returns>The authentication options</returns>
    public static CommandLineArgument[] GetOptions(string? prefix = null) =>
    [
        new CommandLineArgument($"{prefix}{AuthUsernameOption}", CommandLineArgument.ArgumentType.String, Strings.AuthSettingsHelper.DescriptionAuthUsernameShort, Strings.AuthSettingsHelper.DescriptionAuthUsernameLong),
        new CommandLineArgument($"{prefix}{AuthPasswordOption}", CommandLineArgument.ArgumentType.Password, Strings.AuthSettingsHelper.DescriptionAuthPasswordShort, Strings.AuthSettingsHelper.DescriptionAuthPasswordLong)
    ];

    /// <summary>
    /// Parses the authentication options from a dictionary
    /// </summary>
    /// <param name="options">The dictionary to parse</param>
    /// <param name="uri">The URI to get the default values from</param>
    /// <param name="username">The name of the username options</param>
    /// <param name="password">The name of the password options</param>
    /// <returns>The parsed authentication options</returns>
    public static AuthOptions ParseWithAlias(IReadOnlyDictionary<string, string?> options, Uri uri, string username, string password)
    {
        // Prefer the primary name, if set
        var optionUsername = options.GetValueOrDefault(username);
        var optionPassword = options.GetValueOrDefault(password);
        var parsedOptions = Parse(options, uri);

        if (string.IsNullOrWhiteSpace(optionUsername))
            optionUsername = parsedOptions.Username;
        if (string.IsNullOrWhiteSpace(optionPassword))
            optionPassword = parsedOptions.Password;

        return new AuthOptions(optionUsername, optionPassword);
    }

    /// <summary>
    /// Parses the authentication options from a dictionary
    /// </summary>
    /// <param name="options">The dictionary to parse</param>
    /// <param name="uri">The URI to get the default values from</param>
    /// <param name="prefix">An optional prefix for the options</param>
    /// <returns>The parsed authentication options</returns>
    public static AuthOptions Parse(IReadOnlyDictionary<string, string?> options, Uri uri, string? prefix = null)
    {
        var optionUsername = options.GetValueOrDefault($"{prefix}{AuthUsernameOption}");
        var optionPassword = options.GetValueOrDefault($"{prefix}{AuthPasswordOption}");

        // Prefer the URL values, if set
        string? username = null;
        string? password = null;
        if (!string.IsNullOrEmpty(uri.Username))
        {
            username = uri.Username;
            if (!string.IsNullOrEmpty(uri.Password))
                password = uri.Password;
            else if (!string.IsNullOrWhiteSpace(optionPassword))
                password = optionPassword;
        }
        else
        {
            if (!string.IsNullOrWhiteSpace(optionUsername))
            {
                username = optionUsername;
                if (!string.IsNullOrWhiteSpace(optionPassword))
                    password = optionPassword;
            }
        }

        return new AuthOptions(username, password);
    }

    /// <summary>
    /// Structure to hold the authentication options
    /// </summary>
    /// <param name="Username">The username</param>
    /// <param name="Password">The password</param>
    public sealed record AuthOptions(string? Username, string? Password)
    {
        /// <summary>
        /// Checks if the username has a value
        /// </summary>
        public bool HasUsername => !string.IsNullOrWhiteSpace(Username);
        /// <summary>
        /// Checks if the password has a value
        /// </summary>
        public bool HasPassword => !string.IsNullOrWhiteSpace(Password);

        /// <summary>
        /// Checks if the username and password are set
        /// </summary>
        /// <returns>True if the username and password are set</returns>
        public bool IsValid() => HasUsername && HasPassword;

        /// <summary>
        /// Throws an exception if the username and password are not set
        /// </summary>
        public AuthOptions RequireCredentials()
        {
            if (!IsValid())
                throw new UserInformationException(Strings.AuthSettingsHelper.UsernameAndPasswordRequired, "UsernameAndPasswordRequired");

            return this;
        }

        /// <summary>
        /// Returns the username and password after checking that they are set
        /// </summary>
        /// <returns>The username and password</returns>
        public (string Username, string Password) GetCredentials()
        {
            RequireCredentials();
            return (Username!, Password!);
        }
    }

}