namespace StellaOps.AdvisoryAI.Plugin.Unified;

using System.Runtime.CompilerServices;
using StellaOps.AdvisoryAI.Inference.LlmProviders;
using StellaOps.Plugin.Abstractions;
using StellaOps.Plugin.Abstractions.Capabilities;
using StellaOps.Plugin.Abstractions.Context;
using StellaOps.Plugin.Abstractions.Health;
using StellaOps.Plugin.Abstractions.Lifecycle;

// Type aliases to disambiguate between AdvisoryAI and Plugin.Abstractions types
using AdvisoryLlmRequest = StellaOps.AdvisoryAI.Inference.LlmProviders.LlmCompletionRequest;
using AdvisoryLlmResult = StellaOps.AdvisoryAI.Inference.LlmProviders.LlmCompletionResult;
using AdvisoryStreamChunk = StellaOps.AdvisoryAI.Inference.LlmProviders.LlmStreamChunk;
using PluginLlmRequest = StellaOps.Plugin.Abstractions.Capabilities.LlmCompletionRequest;
using PluginLlmResult = StellaOps.Plugin.Abstractions.Capabilities.LlmCompletionResult;
using PluginStreamChunk = StellaOps.Plugin.Abstractions.Capabilities.LlmStreamChunk;

/// <summary>
/// Adapts an existing ILlmProvider to the unified IPlugin and ILlmCapability interfaces.
/// This enables gradual migration of AdvisoryAI LLM providers to the unified plugin architecture.
/// </summary>
public sealed class LlmPluginAdapter : IPlugin, ILlmCapability
{
    private readonly ILlmProvider _inner;
    private readonly ILlmProviderPlugin _plugin;
    private readonly int _priority;
    private IPluginContext? _context;
    private PluginLifecycleState _state = PluginLifecycleState.Discovered;
    private List<LlmModelInfo> _models = new();

    /// <summary>
    /// Creates a new adapter for an existing LLM provider.
    /// </summary>
    /// <param name="inner">The existing LLM provider to wrap.</param>
    /// <param name="plugin">The plugin metadata for this provider.</param>
    /// <param name="priority">Provider priority (higher = preferred).</param>
    public LlmPluginAdapter(ILlmProvider inner, ILlmProviderPlugin plugin, int priority = 10)
    {
        _inner = inner ?? throw new ArgumentNullException(nameof(inner));
        _plugin = plugin ?? throw new ArgumentNullException(nameof(plugin));
        _priority = priority;
    }

    /// <inheritdoc />
    public PluginInfo Info => new(
        Id: $"com.stellaops.llm.{_inner.ProviderId}",
        Name: _plugin.DisplayName,
        Version: "1.0.0",
        Vendor: "Stella Ops",
        Description: _plugin.Description);

    /// <inheritdoc />
    public PluginTrustLevel TrustLevel => PluginTrustLevel.BuiltIn;

    /// <inheritdoc />
    public PluginCapabilities Capabilities => PluginCapabilities.Llm | PluginCapabilities.Network;

    /// <inheritdoc />
    public PluginLifecycleState State => _state;

    #region ILlmCapability

    /// <inheritdoc />
    public string ProviderId => _inner.ProviderId;

    /// <inheritdoc />
    public int Priority => _priority;

    /// <inheritdoc />
    public IReadOnlyList<LlmModelInfo> AvailableModels => _models;

    /// <inheritdoc />
    public Task<bool> IsAvailableAsync(CancellationToken ct)
    {
        return _inner.IsAvailableAsync(ct);
    }

    /// <inheritdoc />
    public async Task<PluginLlmResult> CompleteAsync(PluginLlmRequest request, CancellationToken ct)
    {
        var advisoryRequest = ToAdvisoryRequest(request);
        var result = await _inner.CompleteAsync(advisoryRequest, ct);
        return ToPluginResult(result);
    }

    /// <inheritdoc />
    public IAsyncEnumerable<PluginStreamChunk> CompleteStreamAsync(PluginLlmRequest request, CancellationToken ct)
    {
        var advisoryRequest = ToAdvisoryRequest(request);
        return StreamAdapter(_inner.CompleteStreamAsync(advisoryRequest, ct), ct);
    }

    /// <inheritdoc />
    public Task<LlmEmbeddingResult?> EmbedAsync(string text, CancellationToken ct)
    {
        // Embedding is not supported by the base ILlmProvider interface
        // Specific providers that support embedding would need custom adapters
        return Task.FromResult<LlmEmbeddingResult?>(null);
    }

    #endregion

    #region IPlugin

    /// <inheritdoc />
    public async Task InitializeAsync(IPluginContext context, CancellationToken ct)
    {
        _context = context;
        _state = PluginLifecycleState.Initializing;

        // Check if the provider is available
        var available = await _inner.IsAvailableAsync(ct);
        if (!available)
        {
            _state = PluginLifecycleState.Failed;
            throw new InvalidOperationException($"LLM provider '{_inner.ProviderId}' is not available");
        }

        // Initialize with a default model entry (provider-specific models would be discovered at runtime)
        _models = new List<LlmModelInfo>
        {
            new(
                Id: _inner.ProviderId,
                Name: _plugin.DisplayName,
                Description: _plugin.Description,
                ParameterCount: null,
                ContextLength: null,
                Capabilities: new[] { "chat", "completion" })
        };

        _state = PluginLifecycleState.Active;
        context.Logger.Info("LLM plugin adapter initialized for {ProviderId}", _inner.ProviderId);
    }

    /// <inheritdoc />
    public async Task<HealthCheckResult> HealthCheckAsync(CancellationToken ct)
    {
        try
        {
            var available = await _inner.IsAvailableAsync(ct);

            if (available)
            {
                return HealthCheckResult.Healthy()
                    .WithDetails(new Dictionary<string, object>
                    {
                        ["providerId"] = _inner.ProviderId,
                        ["priority"] = _priority
                    });
            }

            return HealthCheckResult.Unhealthy($"LLM provider '{_inner.ProviderId}' is not available");
        }
        catch (Exception ex)
        {
            return HealthCheckResult.Unhealthy(ex);
        }
    }

    /// <inheritdoc />
    public ValueTask DisposeAsync()
    {
        _state = PluginLifecycleState.Stopped;
        _inner.Dispose();
        return ValueTask.CompletedTask;
    }

    #endregion

    #region Type Mapping

    private static AdvisoryLlmRequest ToAdvisoryRequest(PluginLlmRequest request)
    {
        return new AdvisoryLlmRequest
        {
            UserPrompt = request.UserPrompt,
            SystemPrompt = request.SystemPrompt,
            Model = request.Model,
            Temperature = request.Temperature,
            MaxTokens = request.MaxTokens,
            Seed = request.Seed,
            StopSequences = request.StopSequences,
            RequestId = request.RequestId
        };
    }

    private static PluginLlmResult ToPluginResult(AdvisoryLlmResult result)
    {
        return new PluginLlmResult(
            Content: result.Content,
            ModelId: result.ModelId,
            ProviderId: result.ProviderId,
            InputTokens: result.InputTokens,
            OutputTokens: result.OutputTokens,
            TimeToFirstTokenMs: result.TimeToFirstTokenMs,
            TotalTimeMs: result.TotalTimeMs,
            FinishReason: result.FinishReason,
            Deterministic: result.Deterministic,
            RequestId: result.RequestId);
    }

    private static async IAsyncEnumerable<PluginStreamChunk> StreamAdapter(
        IAsyncEnumerable<AdvisoryStreamChunk> source,
        [EnumeratorCancellation] CancellationToken ct)
    {
        await foreach (var chunk in source.WithCancellation(ct))
        {
            yield return new PluginStreamChunk(
                Content: chunk.Content,
                IsFinal: chunk.IsFinal,
                FinishReason: chunk.FinishReason);
        }
    }

    #endregion
}