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//
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// Software is furnished to do so, subject to the following conditions:
//
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// DEALINGS IN THE SOFTWARE.

#nullable enable

using System;

namespace Duplicati.Server;

/// <summary>
/// Defines how the task configuration should be stored in the backup.
/// </summary>
public enum StoreTaskConfigMode
{
    /// <summary>
    /// Automatically determine behavior based on encryption settings.
    /// When encryption is enabled, behaves as <see cref="SelfOnly"/>.
    /// When encryption is not enabled, behaves as <see cref="None"/>.
    /// </summary>
    Auto,
    /// <summary>
    /// Include the current job's backup configuration, excluding additional targets.
    /// When encryption is enabled, includes secrets.
    /// When encryption is not enabled, excludes secrets.
    /// </summary>
    SelfOnly,
    /// <summary>
    /// Include the current job's backup configuration.
    /// When encryption is enabled, includes all secrets.
    /// When encryption is not enabled, excludes secrets.
    /// </summary>
    Self,
    /// <summary>
    /// Include all job backup configurations.
    /// When encryption is enabled, includes all secrets.
    /// When encryption is not enabled, excludes secrets.
    /// </summary>
    All,
    /// <summary>
    /// Do not include any task configuration.
    /// </summary>
    None,
    /// <summary>
    /// Include the current job's backup configuration with all secrets included, but excluding additional targets.
    /// </summary>
    SelfOnlyWithUnencryptedSecrets,
    /// <summary>
    /// Include the current job's backup configuration with all secrets included.
    /// </summary>
    SelfWithUnencryptedSecrets,
    /// <summary>
    /// Include all job backup configurations with all secrets included.
    /// </summary>
    AllWithUnencryptedSecrets
}

/// <summary>
/// The resolved mode for storing task configuration.
/// </summary>
/// <param name="IncludeAllTasks">A value indicating whether to include all tasks.</param>
/// <param name="RemoveSecrets">A value indicating whether to remove secrets.</param>
/// <param name="RemoveAdditionalTargets">A value indicating whether to remove additional targets.</param>
public record ResolvedTaskConfigMode(
    bool IncludeAllTasks,
    bool RemoveSecrets,
    bool RemoveAdditionalTargets
);

/// <summary>
/// Extension methods for <see cref="StoreTaskConfigMode"/>.
/// </summary>
public static class StoreTaskConfigModeExtensions
{
    /// <summary>
    /// Resolves the effective mode based on the current mode and encryption settings.
    /// </summary>
    /// <param name="mode">The mode to resolve.</param>
    /// <param name="encryptionEnabled">A flag indicating whether encryption is enabled.</param>
    /// <returns>The effective mode</returns>
    private static StoreTaskConfigMode ResolveEffectiveMode(this StoreTaskConfigMode mode, bool encryptionEnabled)
        => mode switch
        {
            StoreTaskConfigMode.Auto => encryptionEnabled ? StoreTaskConfigMode.SelfOnlyWithUnencryptedSecrets : StoreTaskConfigMode.None,
            StoreTaskConfigMode.SelfOnly when encryptionEnabled => StoreTaskConfigMode.SelfOnlyWithUnencryptedSecrets,
            StoreTaskConfigMode.Self when encryptionEnabled => StoreTaskConfigMode.SelfWithUnencryptedSecrets,
            StoreTaskConfigMode.All when encryptionEnabled => StoreTaskConfigMode.AllWithUnencryptedSecrets,
            _ => mode
        };

    /// <summary>
    /// Resolves the effective mode based on the current mode and encryption settings.
    /// </summary>
    /// <param name="mode">The mode to resolve.</param>
    /// <param name="encryptionEnabled">A flag indicating whether encryption is enabled.</param>
    /// <returns>The effective mode</returns>
    public static ResolvedTaskConfigMode? ResolvedTaskConfigMode(this StoreTaskConfigMode mode, bool encryptionEnabled)
    {
        var effectiveMode = mode.ResolveEffectiveMode(encryptionEnabled);
        if (effectiveMode == StoreTaskConfigMode.None)
            return null;
        if (effectiveMode == StoreTaskConfigMode.Auto)
            throw new InvalidOperationException("Auto mode should have been resolved to a concrete mode");

        return new ResolvedTaskConfigMode(
            effectiveMode.IncludeAllTasks(),
            effectiveMode.RemoveSecrets(),
            effectiveMode.RemoveAdditionalTargets()
        );
    }

    /// <summary>
    /// Determines whether additional targets should be removed based on the current mode.
    /// </summary>
    /// <param name="mode">The mode to check.</param>
    /// <returns><c>true</c> if additional targets should be removed; otherwise, <c>false</c>.</returns>
    private static bool RemoveAdditionalTargets(this StoreTaskConfigMode mode)
        => mode switch
        {
            StoreTaskConfigMode.SelfOnlyWithUnencryptedSecrets or StoreTaskConfigMode.SelfOnly => true,
            _ => false
        };

    /// <summary>
    /// Determines whether secrets should be removed based on the current mode.
    /// </summary>
    /// <param name="mode">The mode to check.</param>
    /// <returns><c>true</c> if secrets should be removed; otherwise, <c>false</c>.</returns>
    private static bool RemoveSecrets(this StoreTaskConfigMode mode)
        => mode switch
        {
            StoreTaskConfigMode.SelfOnlyWithUnencryptedSecrets or StoreTaskConfigMode.SelfWithUnencryptedSecrets or StoreTaskConfigMode.AllWithUnencryptedSecrets => false,
            _ => true
        };

    /// <summary>
    /// Determines whether all tasks should be included based on the current mode.
    /// </summary>
    /// <param name="mode">The mode to check.</param>
    /// <returns><c>true</c> if all tasks should be included; otherwise, <c>false</c>.</returns>
    private static bool IncludeAllTasks(this StoreTaskConfigMode mode)
        => mode switch
        {
            StoreTaskConfigMode.All or StoreTaskConfigMode.AllWithUnencryptedSecrets => true,
            _ => false
        };
}