using IntelligenceApi.Engines;
using IntelligenceApi.Models;
using Microsoft.AspNetCore.Mvc;

namespace IntelligenceApi.Controllers;

/// <summary>
/// Spend distribution endpoint — the single public surface of IntelligenceApi.
///
/// Called exclusively by the Gateway (never directly by the client portal).
/// The Gateway injects clientCategory from ClientContext before forwarding.
///
/// POST /api/spend-distribution
/// </summary>
[ApiController]
[Route("api/spend-distribution")]
public sealed class SpendDistributionController : ControllerBase
{
    private readonly EngineRouter _router;
    private readonly ILogger<SpendDistributionController> _log;

    public SpendDistributionController(EngineRouter router, ILogger<SpendDistributionController> log)
    {
        _router = router;
        _log    = log;
    }

    /// <summary>
    /// Generate a spend distribution recommendation.
    /// clientCategory in the request body determines which engine runs.
    /// </summary>
    [HttpPost]
    public async Task<IActionResult> Recommend(
        [FromBody] SpendDistributionRequest? request,
        CancellationToken ct)
    {
        if (request == null)
            return BadRequest(new { ok = false, error = "Request body required" });

        if (request.MonthlyBudget <= 0)
            return BadRequest(new { ok = false, error = "monthlyBudget must be greater than zero" });

        if (request.Keywords.Count == 0)
            return BadRequest(new { ok = false, error = "At least one keyword is required" });

        _log.LogInformation(
            "[SpendDistribution] Request | Category={Category} Budget={Budget} Objective={Obj}",
            request.ClientCategory, request.MonthlyBudget, request.Objective);

        try
        {
            var engine   = _router.Resolve(request.ClientCategory);
            var response = await engine.RecommendAsync(request, ct);

            _log.LogInformation(
                "[SpendDistribution] OK | Engine={Engine} Channels={N}",
                response.Metadata.Engine, response.Channels.Count);

            return Ok(response);
        }
        catch (Exception ex)
        {
            _log.LogError(ex, "[SpendDistribution] Unhandled error");
            return StatusCode(500, new { ok = false, error = "Intelligence service error" });
        }
    }
}