using StellaOps.Auth.Client;
using StellaOps.Cli.Services;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace StellaOps.Cli.Extensions;

/// <summary>
/// Extension methods for IStellaOpsTokenClient providing compatibility with older CLI patterns.
/// These bridge the gap between the old API (GetTokenAsync, GetAccessTokenAsync) and the
/// new API (RequestClientCredentialsTokenAsync, GetCachedTokenAsync).
/// </summary>
public static class StellaOpsTokenClientExtensions
{
    /// <summary>
    /// Requests an access token using client credentials flow with the specified scopes.
    /// This is a compatibility shim for the old GetAccessTokenAsync pattern.
    /// </summary>
    public static async Task<StellaOpsTokenResult> GetAccessTokenAsync(
        this IStellaOpsTokenClient client,
        IEnumerable<string> scopes,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(client);
        var scope = scopes is not null ? string.Join(" ", scopes.Where(s => !string.IsNullOrWhiteSpace(s))) : null;
        return await client.RequestClientCredentialsTokenAsync(scope, null, cancellationToken).ConfigureAwait(false);
    }

    /// <summary>
    /// Requests an access token using client credentials flow with a single scope.
    /// </summary>
    public static async Task<StellaOpsTokenResult> GetAccessTokenAsync(
        this IStellaOpsTokenClient client,
        string scope,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(client);
        return await client.RequestClientCredentialsTokenAsync(scope, null, cancellationToken).ConfigureAwait(false);
    }

    /// <summary>
    /// Gets a cached access token or requests a new one if not cached or expired.
    /// This is a compatibility shim for the old GetCachedAccessTokenAsync pattern.
    /// Cache key includes effective tenant to prevent cross-tenant cache collisions.
    /// </summary>
    public static async Task<StellaOpsTokenCacheEntry> GetCachedAccessTokenAsync(
        this IStellaOpsTokenClient client,
        IEnumerable<string> scopes,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(client);

        var scopeList = scopes?.Where(s => !string.IsNullOrWhiteSpace(s)).OrderBy(s => s).ToArray() ?? [];
        var scope = string.Join(" ", scopeList);
        var cacheKey = BuildCacheKey(scope);

        // Check cache first
        var cached = await client.GetCachedTokenAsync(cacheKey, cancellationToken).ConfigureAwait(false);
        if (cached is not null && !cached.IsExpired(TimeProvider.System, TimeSpan.FromMinutes(1)))
        {
            return cached;
        }

        // Request new token
        var result = await client.RequestClientCredentialsTokenAsync(scope, null, cancellationToken).ConfigureAwait(false);
        var entry = result.ToCacheEntry();

        // Cache the result
        await client.CacheTokenAsync(cacheKey, entry, cancellationToken).ConfigureAwait(false);

        return entry;
    }

    /// <summary>
    /// Gets a cached access token or requests a new one if not cached or expired.
    /// Single scope version.
    /// </summary>
    public static async Task<StellaOpsTokenCacheEntry> GetCachedAccessTokenAsync(
        this IStellaOpsTokenClient client,
        string scope,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(client);

        var cacheKey = BuildCacheKey(scope ?? "default");

        // Check cache first
        var cached = await client.GetCachedTokenAsync(cacheKey, cancellationToken).ConfigureAwait(false);
        if (cached is not null && !cached.IsExpired(TimeProvider.System, TimeSpan.FromMinutes(1)))
        {
            return cached;
        }

        // Request new token
        var result = await client.RequestClientCredentialsTokenAsync(scope, null, cancellationToken).ConfigureAwait(false);
        var entry = result.ToCacheEntry();

        // Cache the result
        await client.CacheTokenAsync(cacheKey, entry, cancellationToken).ConfigureAwait(false);

        return entry;
    }

    /// <summary>
    /// Requests a token using client credentials. Parameterless version for simple cases.
    /// </summary>
    public static async Task<StellaOpsTokenResult> GetTokenAsync(
        this IStellaOpsTokenClient client,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(client);
        return await client.RequestClientCredentialsTokenAsync(null, null, cancellationToken).ConfigureAwait(false);
    }

    /// <summary>
    /// Builds a cache key that includes the effective tenant to prevent cross-tenant
    /// token cache collisions when users switch tenants between CLI invocations.
    /// </summary>
    private static string BuildCacheKey(string scope)
    {
        var tenant = TenantProfileStore.GetEffectiveTenant(null) ?? "none";
        return $"cc:{tenant}:{scope}";
    }
}