// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Diagnostics.CodeAnalysis;
using Microsoft.Extensions.Configuration;
 
namespace Aspire;
 
internal static class IConfigurationExtensions
{
    /// <summary>
    /// Gets the named configuration value as a boolean.
    /// </summary>
    /// <remarks>
    /// Parses <c>true</c> and <c>false</c>, along with integer values (where non-zero is <see langword="true"/>).
    /// </remarks>
    /// <param name="configuration">The <see cref="IConfiguration"/> this method extends.</param>
    /// <param name="key">The configuration key.</param>
    /// <returns>The parsed value, or <see langword="null"/> if no value exists or it couldn't be parsed.</returns>
    public static bool? GetBool(this IConfiguration configuration, string key)
    {
        var value = configuration[key];
 
        if (value is null or [])
        {
            return null;
        }
        else if (bool.TryParse(value, out var b))
        {
            return b;
        }
        else if (int.TryParse(value, out var i))
        {
            return i != 0;
        }
 
        return null;
    }
 
    /// <summary>
    /// Gets the named configuration value as a boolean.
    /// </summary>
    /// <remarks>
    /// Parses <c>true</c> and <c>false</c>, along with <c>1</c> and <c>0</c>.
    /// </remarks>
    /// <param name="configuration">The <see cref="IConfiguration"/> this method extends.</param>
    /// <param name="key">The configuration key.</param>
    /// <param name="defaultValue">A default value, for when the configuration value is unspecified or white space.</param>
    /// <returns></returns>
    public static bool GetBool(this IConfiguration configuration, string key, bool defaultValue)
    {
        return configuration.GetBool(key) ?? defaultValue;
    }
 
    /// <summary>
    /// Parses a configuration value into a <see cref="Uri"/> object.
    /// </summary>
    /// <param name="configuration">The <see cref="IConfiguration"/> this method extends.</param>
    /// <param name="key">The configuration key.</param>
    /// <param name="defaultValue">A default value, for when the configuration value is unspecified or white space. May be <see langword="null"/>.</param>
    /// <returns>The parsed value, or the default value if specified and parsing failed. Returns <see langword="null"/> if <paramref name="defaultValue"/> is <see langword="null"/> and parsing failed.</returns>
    /// <exception cref="InvalidOperationException">The configuration value could not be accessed, or contained incorrectly formatted data.</exception>
    [return: NotNullIfNotNull(nameof(defaultValue))]
    public static Uri? GetUri(this IConfiguration configuration, string key, Uri? defaultValue = null)
    {
        try
        {
            var uri = configuration[key];
 
            if (string.IsNullOrWhiteSpace(uri))
            {
                return defaultValue;
            }
            else
            {
                return new Uri(uri, UriKind.Absolute);
            }
        }
        catch (Exception ex)
        {
            throw new InvalidOperationException($"Error parsing URIs from configuration value '{key}'.", ex);
        }
    }
 
    /// <summary>
    /// Parses a configuration value's semicolon-delimited value into an array of <see cref="Uri"/> objects.
    /// </summary>
    /// <param name="configuration">The <see cref="IConfiguration"/> this method extends.</param>
    /// <param name="key">The configuration key.</param>
    /// <param name="defaultValue">A default value, for when the configuration value is unspecified or white space. May be <see langword="null"/>.</param>
    /// <returns>The parsed values, or the default value if specified and parsing failed. Returns <see langword="null"/> if <paramref name="defaultValue"/> is <see langword="null"/> and parsing failed.</returns>
    /// <exception cref="InvalidOperationException">The configuration value could not be accessed, or contained incorrectly formatted data.</exception>
    [return: NotNullIfNotNull(nameof(defaultValue))]
    public static Uri[]? GetUris(this IConfiguration configuration, string key, Uri? defaultValue = null)
    {
        try
        {
            var uris = configuration[key];
 
            if (string.IsNullOrWhiteSpace(uris))
            {
                return defaultValue switch
                {
                    not null => [defaultValue],
                    null => null
                };
            }
            else
            {
                return uris
                    .Split(';', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
                    .Select(url => new Uri(url, UriKind.Absolute))
                    .ToArray();
            }
        }
        catch (Exception ex)
        {
            throw new InvalidOperationException($"Error parsing URIs from configuration value '{key}'.", ex);
        }
    }
 
    /// <summary>
    /// Gets the named configuration value as a member of an enum, or <paramref name="defaultValue"/> if the value was null or empty.
    /// </summary>
    /// <remarks>
    /// Parsing is case-insensitive.
    /// </remarks>
    /// <param name="configuration">The <see cref="IConfiguration"/> this method extends.</param>
    /// <param name="key">The configuration key.</param>
    /// <param name="defaultValue">A default value, for when the configuration value is unable to be parsed.</param>
    /// <exception cref="InvalidOperationException">The configuration value is not a valid member of the enum.</exception>
    /// <returns>The parsed enum member, or <paramref name="defaultValue"/> the configuration value was null or empty.</returns>
    [return: NotNullIfNotNull(nameof(defaultValue))]
    public static T? GetEnum<T>(this IConfiguration configuration, string key, T? defaultValue = default)
        where T : struct
    {
        var value = configuration[key];
 
        if (value is null or [])
        {
            return defaultValue;
        }
        else if (Enum.TryParse<T>(value, ignoreCase: true, out var e))
        {
            return e;
        }
 
        throw new InvalidOperationException($"Unknown {typeof(T).Name} value \"{value}\". Valid values are {string.Join(", ", Enum.GetNames(typeof(T)))}.");
    }
 
    /// <summary>
    /// Gets the specified required configuration value as a member of an enum.
    /// </summary>
    /// <remarks>
    /// Parsing is case-insensitive.
    /// </remarks>
    /// <param name="configuration">The <see cref="IConfiguration"/> this method extends.</param>
    /// <param name="key">The configuration key.</param>
    /// <exception cref="InvalidOperationException">The configuration value is empty or not a valid member of the enum.</exception>
    /// <returns>The parsed enum member.</returns>
    public static T GetEnum<T>(this IConfiguration configuration, string key)
        where T : struct
    {
        var value = configuration.GetEnum<T>(key, defaultValue: null);
 
        if (value is null)
        {
            throw new InvalidOperationException($"Missing required configuration for {key}. Valid values are {string.Join(", ", Enum.GetNames(typeof(T)))}.");
        }
 
        return value.Value;
    }
}