using Gateway.Models;
using System.Text.Json;

namespace Gateway.Services;

/// <summary>
/// HTTP client for IntelligenceApi — the spend distribution engine container.
///
/// The Gateway injects clientCategory from ClientContext and provider config
/// before forwarding requests. The client portal never calls IntelligenceApi
/// directly; all routing goes through the Gateway.
///
/// FALLBACK: If IntelligenceApi is unreachable, ForecastController falls back
/// to the local ForecastService (identical to the General engine output).
/// This means a container restart or deployment never breaks the wizard.
/// </summary>
public sealed class IntelligenceApiClient
{
    private readonly IHttpClientFactory _http;
    private readonly IConfiguration _cfg;
    private readonly ILogger<IntelligenceApiClient> _logger;

    private static readonly JsonSerializerOptions _jsonOpts =
        new(JsonSerializerDefaults.Web);

    public IntelligenceApiClient(
        IHttpClientFactory http,
        IConfiguration cfg,
        ILogger<IntelligenceApiClient> logger)
    {
        _http   = http;
        _cfg    = cfg;
        _logger = logger;
    }

    /// <summary>
    /// Forward raw census data for a ZCTA to the Intelligence container for
    /// market analysis derivation (age chips, income tiers, insight strings).
    /// Returns the raw JSON response string, or null if the container is
    /// unreachable — caller falls back to returning raw census data.
    /// </summary>
    public async Task<string?> GetDemographicAnalysisAsync(
        string zcta,
        JsonElement censusData,
        CancellationToken ct)
    {
        var baseUrl = _cfg["INTELLIGENCE_API_URL"]
            ?? Environment.GetEnvironmentVariable("INTELLIGENCE_API_URL");

        if (string.IsNullOrWhiteSpace(baseUrl))
        {
            _logger.LogDebug("[IntelligenceApiClient] INTELLIGENCE_API_URL not configured — skipping demographics analysis");
            return null;
        }

        var internalKey = _cfg["INTELLIGENCE_INTERNAL_KEY"]
            ?? Environment.GetEnvironmentVariable("INTELLIGENCE_INTERNAL_KEY");

        var payload = JsonSerializer.Serialize(new
        {
            zcta,
            census = censusData
        }, _jsonOpts);

        try
        {
            var client = _http.CreateClient();
            using var msg = new HttpRequestMessage(
                HttpMethod.Post,
                $"{baseUrl.TrimEnd('/')}/api/demographics/analyze");

            if (!string.IsNullOrWhiteSpace(internalKey))
                msg.Headers.Add("X-Internal-Key", internalKey);

            msg.Content = new StringContent(payload, System.Text.Encoding.UTF8, "application/json");

            _logger.LogInformation("[IntelligenceApiClient] Demographics analysis | ZCTA={Zcta}", zcta);

            using var resp = await client.SendAsync(msg, ct);
            var body       = await resp.Content.ReadAsStringAsync(ct);

            if (!resp.IsSuccessStatusCode)
            {
                _logger.LogWarning("[IntelligenceApiClient] Demographics non-success {Status}", (int)resp.StatusCode);
                return null;
            }

            return body;
        }
        catch (TaskCanceledException)
        {
            _logger.LogWarning("[IntelligenceApiClient] Demographics analysis timed out | ZCTA={Zcta}", zcta);
            return null;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "[IntelligenceApiClient] Demographics analysis failed | ZCTA={Zcta}", zcta);
            return null;
        }
    }

    /// <summary>
    /// Forward a channel forecast request to IntelligenceApi with
    /// clientCategory injected. Returns null if the service is unreachable
    /// or returns an error — caller should fall back to ForecastService.
    /// </summary>
    public async Task<ChannelForecastResponse?> GetSpendDistributionAsync(
        ChannelForecastRequest request,
        string? clientCategory,
        CancellationToken ct)
    {
        var baseUrl = _cfg["INTELLIGENCE_API_URL"]
            ?? Environment.GetEnvironmentVariable("INTELLIGENCE_API_URL");

        if (string.IsNullOrWhiteSpace(baseUrl))
        {
            _logger.LogDebug("[IntelligenceApiClient] INTELLIGENCE_API_URL not configured — skipping");
            return null;
        }

        var internalKey = _cfg["INTELLIGENCE_INTERNAL_KEY"]
            ?? Environment.GetEnvironmentVariable("INTELLIGENCE_INTERNAL_KEY");

        // Build the IntelligenceApi request — forward everything from the
        // original wizard request, plus inject clientCategory and provider config
        var intelligenceRequest = new
        {
            clientCategory  = clientCategory ?? "General",
            objective       = request.Objective,
            businessCategory = request.BusinessCategory,
            keywords        = request.Keywords,
            geoTargeting    = request.GeoTargeting,
            audience        = request.Audience,
            monthlyBudget   = request.MonthlyBudget,
            channels        = request.Channels,

            // Forward provider URLs so the engine can call providers directly
            providerUrls = new Dictionary<string, string>
            {
                ["google_ads"] = _cfg["GOOGLE_PROVIDER_URL"]
                    ?? Environment.GetEnvironmentVariable("GOOGLE_PROVIDER_URL") ?? ""
            },
            internalKeys = new Dictionary<string, string>
            {
                ["google_ads"] = _cfg["GOOGLE_INTERNAL_KEY"]
                    ?? Environment.GetEnvironmentVariable("GOOGLE_INTERNAL_KEY") ?? ""
            }
        };

        try
        {
            var client = _http.CreateClient();
            using var msg = new HttpRequestMessage(
                HttpMethod.Post,
                $"{baseUrl.TrimEnd('/')}/api/spend-distribution");

            if (!string.IsNullOrWhiteSpace(internalKey))
                msg.Headers.Add("X-Internal-Key", internalKey);

            msg.Content = new StringContent(
                JsonSerializer.Serialize(intelligenceRequest, _jsonOpts),
                System.Text.Encoding.UTF8, "application/json");

            _logger.LogInformation(
                "[IntelligenceApiClient] Calling engine | Category={Category} Budget={Budget}",
                clientCategory, request.MonthlyBudget);

            using var resp = await client.SendAsync(msg, ct);
            var body       = await resp.Content.ReadAsStringAsync(ct);

            if (!resp.IsSuccessStatusCode)
            {
                _logger.LogWarning(
                    "[IntelligenceApiClient] Non-success {Status}: {Body}",
                    (int)resp.StatusCode, body[..Math.Min(body.Length, 200)]);
                return null;
            }

            // Map IntelligenceApi response shape → Gateway ChannelForecastResponse
            // The shapes are intentionally aligned so this is a straight deserialize.
            using var doc  = JsonDocument.Parse(body);
            var root       = doc.RootElement;

            if (!root.TryGetProperty("ok", out var okProp) || !okProp.GetBoolean())
            {
                _logger.LogWarning("[IntelligenceApiClient] Engine returned ok=false");
                return null;
            }

            // Re-serialize then deserialize into the Gateway model
            // (avoids a hard dependency on IntelligenceApi model types in Gateway)
            var result = JsonSerializer.Deserialize<ChannelForecastResponse>(body, _jsonOpts);

            _logger.LogInformation(
                "[IntelligenceApiClient] OK | Engine={Engine} Channels={N}",
                root.TryGetProperty("metadata", out var meta)
                    && meta.TryGetProperty("engine", out var eng)
                    ? eng.GetString() : "?",
                result?.Channels?.Count ?? 0);

            return result;
        }
        catch (TaskCanceledException)
        {
            _logger.LogWarning("[IntelligenceApiClient] Request timed out");
            return null;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "[IntelligenceApiClient] Request failed");
            return null;
        }
    }
}