using System.Diagnostics;
using System.Text.Json;
using Microsoft.AspNetCore.Mvc;
using w4c_workflows.Filters;
using w4c_workflows.Models;
using w4c_workflows.Services;

namespace w4c_workflows.Controllers;

/// <summary>
/// Workflow runtime registry surface (<c>/api/runtimes</c>): which workflow-api
/// instance executes a tenant's workflows. Distinct from
/// <see cref="RuntimesController"/> (<c>/api/languages</c>), which reports
/// execution <em>languages</em>. Authenticates with the tenant operator key.
///
/// Phase 1 covers the platform runtime (always present) and self-hosted runtimes
/// in <b>inbound</b> mode (public URL + API key). Phase 2 adds the outbound
/// runner channel (registration token + WebSocket relay).
/// </summary>
[ApiController]
[Route("api/runtimes")]
public class WorkflowRuntimesController : ControllerBase
{
    private readonly WorkflowRuntimeStore _store;
    private readonly IHttpClientFactory _httpClientFactory;
    private readonly ILogger<WorkflowRuntimesController> _logger;

    public WorkflowRuntimesController(
        WorkflowRuntimeStore store,
        IHttpClientFactory httpClientFactory,
        ILogger<WorkflowRuntimesController> logger)
    {
        _store = store;
        _httpClientFactory = httpClientFactory;
        _logger = logger;
    }

    private string TenantId => (string?)HttpContext.Items["TenantId"]
        ?? throw new InvalidOperationException("TenantId not resolved by auth middleware");

    public sealed record CreateInboundRequest(string? Label = null, string? Endpoint = null, string? ApiKey = null);

    /// <summary>
    /// Lists the tenant's runtimes: the platform runtime first (always present),
    /// then self-hosted runtimes with their cached self-info + online/offline state.
    /// </summary>
    [HttpGet]
    [RequireScope("read")]
    public async Task<IActionResult> List(CancellationToken ct)
    {
        var runtimes = await _store.ListAsync(TenantId, ct);
        return Ok(runtimes.Select(ToDto));
    }

    /// <summary>
    /// Connects a self-hosted runtime in inbound mode (legacy direct-URL model).
    /// The API key is stored hashed and never returned.
    /// </summary>
    [HttpPost]
    [RequireScope("manage")]
    public async Task<IActionResult> Create([FromBody] CreateInboundRequest? request, CancellationToken ct)
    {
        try
        {
            var runtime = await _store.CreateInboundAsync(
                TenantId,
                request?.Label ?? "Self-hosted",
                request?.Endpoint ?? string.Empty,
                request?.ApiKey,
                ct);

            _logger.LogInformation("Connected self-hosted runtime {RuntimeId} for tenant {TenantId} (inbound)",
                runtime.Id, TenantId);
            return Ok(ToDto(runtime));
        }
        catch (ArgumentException ex)
        {
            return BadRequest(new { error = ex.Message });
        }
    }

    /// <summary>Removes a self-hosted runtime. The platform runtime cannot be deleted.</summary>
    [HttpDelete("{id:guid}")]
    [RequireScope("manage")]
    public async Task<IActionResult> Delete(Guid id, CancellationToken ct)
    {
        try
        {
            var deleted = await _store.DeleteAsync(TenantId, id, ct);
            if (!deleted)
                return NotFound(new { error = "Runtime not found." });

            _logger.LogInformation("Removed runtime {RuntimeId} for tenant {TenantId}", id, TenantId);
            return NoContent();
        }
        catch (InvalidOperationException ex)
        {
            return BadRequest(new { error = ex.Message });
        }
    }

    public sealed record TestResultDto(bool Ok, string Message, int? LatencyMs = null);

    /// <summary>
    /// Tests connectivity to a self-hosted runtime (inbound mode) by hitting its
    /// <c>/health</c> endpoint. Always returns 200 with a result object (never
    /// throws on a down/unreachable engine).
    /// </summary>
    [HttpPost("{id:guid}/test")]
    [RequireScope("manage")]
    public async Task<IActionResult> Test(Guid id, CancellationToken ct)
    {
        var runtime = await _store.GetAsync(TenantId, id, ct);
        if (runtime == null)
            return NotFound(new { error = "Runtime not found." });
        if (runtime.Kind == WorkflowRuntimeKind.Platform)
            return Ok(new TestResultDto(true, "Platform runtime is local", 0));
        if (string.IsNullOrWhiteSpace(runtime.Endpoint))
            return Ok(new TestResultDto(false, "This runtime has no inbound endpoint (outbound runner channel)."));

        var sw = Stopwatch.StartNew();
        try
        {
            using var client = _httpClientFactory.CreateClient("runtime-test");
            client.Timeout = TimeSpan.FromSeconds(10);
            using var req = new HttpRequestMessage(HttpMethod.Get, $"{runtime.Endpoint.TrimEnd('/')}/health");
            using var resp = await client.SendAsync(req, ct);
            sw.Stop();
            return Ok(new TestResultDto(
                resp.IsSuccessStatusCode,
                resp.IsSuccessStatusCode
                    ? $"Runtime reachable in {sw.ElapsedMilliseconds} ms"
                    : $"Runtime returned HTTP {(int)resp.StatusCode}",
                (int)sw.ElapsedMilliseconds));
        }
        catch (OperationCanceledException) when (!ct.IsCancellationRequested)
        {
            sw.Stop();
            return Ok(new TestResultDto(false, "Connection timed out", (int)sw.ElapsedMilliseconds));
        }
        catch (Exception ex)
        {
            sw.Stop();
            return Ok(new TestResultDto(false, ex.Message, (int)sw.ElapsedMilliseconds));
        }
    }

    private static object ToDto(WorkflowRuntime r)
    {
        string? name = null, version = null, startedAt = null;
        bool? multiTenant = null;
        if (!string.IsNullOrWhiteSpace(r.InfoJson))
        {
            try
            {
                using var doc = JsonDocument.Parse(r.InfoJson);
                if (doc.RootElement.ValueKind == JsonValueKind.Object)
                {
                    name = doc.RootElement.TryGetProperty("name", out var n) ? n.GetString() : null;
                    version = doc.RootElement.TryGetProperty("version", out var v) ? v.GetString() : null;
                    startedAt = doc.RootElement.TryGetProperty("startedAt", out var s) && s.ValueKind == JsonValueKind.String
                        ? s.GetString()
                        : null;
                    multiTenant = doc.RootElement.TryGetProperty("multiTenant", out var m) && m.ValueKind is JsonValueKind.True or JsonValueKind.False
                        ? m.GetBoolean()
                        : null;
                }
            }
            catch (JsonException)
            {
                // best-effort self-info
            }
        }

        return new
        {
            r.Id,
            r.Label,
            r.Kind,
            r.Endpoint,
            r.Status,
            r.IsDefault,
            r.LastSeenAt,
            r.LastError,
            name,
            version,
            startedAt,
            multiTenant,
        };
    }
}