using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using PowderCoating.Application.Interfaces;
using PowderCoating.Core.Enums;
using PowderCoating.Infrastructure.Data;
using PowderCoating.Shared.Constants;

namespace PowderCoating.Web.Controllers;

/// <summary>
/// SuperAdmin-only tool for sending platform-wide broadcast emails to tenant
/// company contacts.  Emails are sent one at a time via <see cref="IEmailService"/>
/// rather than bulk API because each message requires a personalised unsubscribe link
/// containing the company's unique <c>MarketingUnsubscribeToken</c>.
/// </summary>
[Authorize(Policy = AppConstants.Policies.SuperAdminOnly)]
public class EmailBroadcastController : Controller
{
    private readonly ApplicationDbContext _db;
    private readonly IEmailService _emailService;
    private readonly ILogger<EmailBroadcastController> _logger;

    public EmailBroadcastController(
        ApplicationDbContext db,
        IEmailService emailService,
        ILogger<EmailBroadcastController> logger)
    {
        _db = db;
        _emailService = emailService;
        _logger = logger;
    }

    /// <summary>
    /// Renders the broadcast compose form, pre-populating ViewBag with plan configs
    /// and the active company list so the targeting dropdowns are populated without
    /// a separate AJAX call.
    /// </summary>
    public async Task<IActionResult> Index()
    {
        await PopulateViewBag();
        return View(new BroadcastForm());
    }

    /// <summary>Returns JSON count of recipients for the current filter — used for the live preview.</summary>
    [HttpGet]
    public async Task<IActionResult> RecipientCount(string target, string? plan, int[]? companyIds)
    {
        var recipients = await BuildRecipientListAsync(target, plan, companyIds);
        return Json(new { count = recipients.Count });
    }

    /// <summary>
    /// Sends the composed broadcast email to all recipients matching the chosen
    /// targeting criteria.  Aborts early (with a validation error) if no recipients
    /// are found, to prevent accidental empty sends.
    /// <para>
    /// Each email body is HTML-encoded (then line-breaks converted to
    /// <c>&lt;br&gt;</c>) and wrapped in a branded container that appends a
    /// per-company unsubscribe footer.  Failures are counted and reported in the
    /// success banner rather than aborting the remainder of the batch, so a single
    /// bad address does not block delivery to every other recipient.
    /// </para>
    /// </summary>
    [HttpPost, ValidateAntiForgeryToken]
    public async Task<IActionResult> Send(BroadcastForm form)
    {
        if (!ModelState.IsValid)
        {
            await PopulateViewBag();
            return View("Index", form);
        }

        var recipients = await BuildRecipientListAsync(form.Target, form.PlanFilter, form.CompanyIds);

        if (recipients.Count == 0)
        {
            TempData["Error"] = "No recipients matched the selected criteria.";
            await PopulateViewBag();
            return View("Index", form);
        }

        int sent = 0, failed = 0;
        var baseUrl = $"{Request.Scheme}://{Request.Host}";
        var encodedBody = System.Net.WebUtility.HtmlEncode(form.Body).Replace("\n", "<br>");

        foreach (var (email, name, unsubToken) in recipients)
        {
            var unsubUrl = $"{baseUrl}/Unsubscribe/BroadcastEmail/{unsubToken}";
            var htmlBody = $@"
<div style=""font-family:sans-serif;max-width:600px;margin:0 auto"">
  <p>{encodedBody}</p>
  <hr style=""border:none;border-top:1px solid #eee;margin:24px 0"">
  <p style=""font-size:12px;color:#999"">
    This message was sent by the Powder Coating Logix platform team.<br>
    <a href=""{unsubUrl}"" style=""color:#999"">Unsubscribe from platform announcements</a>
  </p>
</div>";

            var (success, error) = await _emailService.SendEmailAsync(
                email, name, form.Subject, form.Body, htmlBody);

            if (success) sent++;
            else
            {
                failed++;
                _logger.LogWarning("Broadcast email failed for {Email}: {Error}", email, error);
            }
        }

        TempData["Success"] = $"Broadcast sent: {sent} delivered, {failed} failed. Total recipients: {recipients.Count}.";
        return RedirectToAction(nameof(Index));
    }

    /// <summary>
    /// Builds the list of (email, name, unsubscribe-token) tuples for the given
    /// targeting criteria.  Companies are excluded when <c>MarketingEmailOptOut</c>
    /// is true — honouring prior unsubscribes — or when <c>PrimaryContactEmail</c>
    /// is missing.  The "specific" target requires at least one <c>companyIds</c>
    /// entry and returns an empty list otherwise to prevent accidental all-company sends.
    /// <c>IgnoreQueryFilters()</c> is required because this query spans companies.
    /// </summary>
    private async Task<List<(string Email, string Name, string UnsubToken)>> BuildRecipientListAsync(
        string? target, string? planFilter, int[]? companyIds)
    {
        var companyQuery = _db.Companies.AsNoTracking().IgnoreQueryFilters()
            .Where(c => !c.IsDeleted && c.IsActive && !string.IsNullOrEmpty(c.PrimaryContactEmail)
                        && !c.MarketingEmailOptOut);

        target ??= "active";

        switch (target)
        {
            case "active":
                companyQuery = companyQuery.Where(c =>
                    c.SubscriptionStatus == SubscriptionStatus.Active ||
                    c.SubscriptionStatus == SubscriptionStatus.GracePeriod);
                break;
            case "plan":
                if (!string.IsNullOrWhiteSpace(planFilter) && int.TryParse(planFilter, out var planInt))
                    companyQuery = companyQuery.Where(c => c.SubscriptionPlan == planInt);
                break;
            case "status_grace":
                companyQuery = companyQuery.Where(c => c.SubscriptionStatus == SubscriptionStatus.GracePeriod);
                break;
            case "status_expired":
                companyQuery = companyQuery.Where(c => c.SubscriptionStatus == SubscriptionStatus.Expired);
                break;
            case "specific":
                if (companyIds != null && companyIds.Length > 0)
                    companyQuery = companyQuery.Where(c => companyIds.Contains(c.Id));
                else
                    return new List<(string, string, string)>();
                break;
            case "all":
            default:
                break;
        }

        var companies = await companyQuery
            .Select(c => new { c.PrimaryContactEmail, c.CompanyName, c.MarketingUnsubscribeToken })
            .ToListAsync();

        return companies
            .Where(c => !string.IsNullOrWhiteSpace(c.PrimaryContactEmail))
            .Select(c => (c.PrimaryContactEmail!, c.CompanyName, c.MarketingUnsubscribeToken))
            .ToList();
    }

    /// <summary>
    /// Hydrates ViewBag with the data sets needed by the broadcast compose view:
    /// active subscription plan configs (for the plan-filter dropdown),
    /// all non-deleted active companies (for the specific-company picker),
    /// and a live count of active/grace-period companies shown in the UI summary.
    /// Centralised here so it can be called from both <see cref="Index"/> and the
    /// validation-failure branch of <see cref="Send"/>.
    /// </summary>
    private async Task PopulateViewBag()
    {
        ViewBag.PlanConfigs = await _db.SubscriptionPlanConfigs.AsNoTracking().IgnoreQueryFilters()
            .Where(p => p.IsActive).OrderBy(p => p.SortOrder).ToListAsync();

        ViewBag.Companies = await _db.Companies.AsNoTracking().IgnoreQueryFilters()
            .Where(c => !c.IsDeleted && c.IsActive)
            .OrderBy(c => c.CompanyName)
            .Select(c => new { c.Id, c.CompanyName })
            .ToListAsync();

        ViewBag.ActiveCount = await _db.Companies.AsNoTracking().IgnoreQueryFilters()
            .CountAsync(c => !c.IsDeleted && c.IsActive &&
                (c.SubscriptionStatus == SubscriptionStatus.Active ||
                 c.SubscriptionStatus == SubscriptionStatus.GracePeriod));
    }
}

public class BroadcastForm
{
    public string Target { get; set; } = "active";
    public string? PlanFilter { get; set; }
    public int[]? CompanyIds { get; set; }

    [System.ComponentModel.DataAnnotations.Required]
    public string Subject { get; set; } = string.Empty;

    [System.ComponentModel.DataAnnotations.Required]
    public string Body { get; set; } = string.Empty;
}