import { serve } from "https://deno.land/std@0.168.0/http/server.ts";
import { createClient } from "https://esm.sh/@supabase/supabase-js@2";

const corsHeaders = {
  "Access-Control-Allow-Origin": "*",
  "Access-Control-Allow-Headers":
    "authorization, x-client-info, apikey, content-type",
  "Access-Control-Allow-Methods": "POST, OPTIONS",
};

serve(async (req) => {
  if (req.method === "OPTIONS") {
    return new Response("ok", { headers: corsHeaders });
  }

  try {
    const supabaseUrl = Deno.env.get("SUPABASE_URL")!;
    const anonKey = Deno.env.get("SUPABASE_ANON_KEY")!;
    const serviceKey = Deno.env.get("SUPABASE_SERVICE_ROLE_KEY")!;
    const resendKey = Deno.env.get("RESEND_API_KEY");

    if (!resendKey) {
      throw new Error("Chýba RESEND_API_KEY.");
    }

    const authorization = req.headers.get("Authorization");

    if (!authorization) {
      throw new Error("Používateľ nie je prihlásený.");
    }

    const userClient = createClient(supabaseUrl, anonKey, {
      global: {
        headers: { Authorization: authorization },
      },
    });

    const {
      data: { user },
      error: userError,
    } = await userClient.auth.getUser();

    if (userError || !user || !user.email) {
      throw new Error("Nepodarilo sa overiť používateľa.");
    }

    const adminClient = createClient(supabaseUrl, serviceKey);

    const body = await req.json();
    const exhibition_id = body.exhibition_id;

    if (!exhibition_id) {
      throw new Error("Chýba výstava.");
    }

    const { data: exhibition, error: exhibitionError } =
      await adminClient
        .from("exhibitions")
        .select("id, name")
        .eq("id", exhibition_id)
        .single();

    if (exhibitionError || !exhibition) {
      throw new Error("Výstava sa nenašla.");
    }

    const { data: animals, error: animalsError } =
      await adminClient
        .from("animals")
        .select("id, category, breed, animal_number")
        .eq("owner_id", user.id);

    if (animalsError) {
      throw new Error("Nepodarilo sa načítať zvieratá.");
    }

    const animalIds = (animals || []).map((a) => a.id);

    if (animalIds.length === 0) {
      throw new Error("Nemáš pridané žiadne zvieratá.");
    }

    const { data: entries, error: entriesError } =
      await adminClient
        .from("entries")
        .select("id, animal_id")
        .eq("exhibition_id", exhibition_id)
        .in("animal_id", animalIds);

    if (entriesError) {
      throw new Error("Nepodarilo sa načítať prihlásené zvieratá.");
    }

    if (!entries || entries.length === 0) {
      throw new Error("Na túto výstavu nemáš prihlásené žiadne zvieratá.");
    }

    const { data: settings } = await adminClient
      .from("app_settings")
      .select("entry_fee")
      .eq("id", 1)
      .maybeSingle();

    const fee = Number(settings?.entry_fee ?? 1);
    const total = entries.length * fee;

    const animalMap = new Map(
      (animals || []).map((a) => [a.id, a])
    );

    const animalList = entries.map((entry, index) => {
      const animal = animalMap.get(entry.animal_id);

      const category = animal?.category || "Zvieratá";
      const breed = animal?.breed || "Neuvedené plemeno";
      const number = animal?.animal_number
        ? ` – č. ${animal.animal_number}`
        : "";

      return `<li>${index + 1}. ${escapeHtml(category)} – ${escapeHtml(breed)}${escapeHtml(number)}</li>`;
    }).join("");

    const { data: profile } = await adminClient
      .from("profiles")
      .select("first_name, last_name")
      .eq("id", user.id)
      .maybeSingle();

    const fullName = [
      profile?.first_name,
      profile?.last_name,
    ].filter(Boolean).join(" ") || user.email;

    const html = `
      <div style="font-family:Arial,sans-serif;max-width:650px;margin:auto;color:#243328">
        <h2 style="color:#245b3b">ZO SZCH Koniarovce</h2>

        <h3>Potvrdenie prijatia prihlášky</h3>

        <p>Dobrý deň, ${escapeHtml(fullName)},</p>

        <p>Vaša prihláška na výstavu bola úspešne prijatá.</p>

        <p><strong>Výstava:</strong> ${escapeHtml(exhibition.name)}</p>

        <p><strong>Prihlásené zvieratá:</strong></p>

        <ul>${animalList}</ul>

        <hr>

        <p>Počet zvierat: <strong>${entries.length} ks</strong></p>
        <p>Poplatok za 1 zviera: <strong>${fee.toFixed(2)} €</strong></p>

        <h3>Celkový poplatok: ${total.toFixed(2)} €</h3>

        <p>Ďakujeme za Vašu prihlášku a tešíme sa na Vašu účasť.</p>

        <p>
          S pozdravom,<br>
          <strong>ZO SZCH Koniarovce</strong>
        </p>
      </div>
    `;

    const resendResponse = await fetch(
      "https://api.resend.com/emails",
      {
        method: "POST",
        headers: {
          "Authorization": `Bearer ${resendKey}`,
          "Content-Type": "application/json",
        },
        body: JSON.stringify({
          from: "ZO SZCH Koniarovce <onboarding@resend.dev>",
          to: [user.email],
          subject: `Potvrdenie prihlášky – ${exhibition.name}`,
          html,
        }),
      }
    );

    const resendResult = await resendResponse.json();

    if (!resendResponse.ok) {
      throw new Error(
        resendResult.message || "Email sa nepodarilo odoslať."
      );
    }

    return new Response(
      JSON.stringify({
        success: true,
        message: "Potvrdzovací email bol odoslaný.",
        count: entries.length,
        total: total,
      }),
      {
        headers: {
          ...corsHeaders,
          "Content-Type": "application/json",
        },
        status: 200,
      }
    );

  } catch (error) {
    return new Response(
      JSON.stringify({
        success: false,
        error: error instanceof Error
          ? error.message
          : "Nastala chyba.",
      }),
      {
        headers: {
          ...corsHeaders,
          "Content-Type": "application/json",
        },
        status: 400,
      }
    );
  }
});

function escapeHtml(value: string): string {
  return value.replace(/[&<>"']/g, (char) => {
    const replacements: Record<string, string> = {
      "&": "&amp;",
      "<": "&lt;",
      ">": "&gt;",
      '"': "&quot;",
      "'": "&#039;",
    };

    return replacements[char];
  });
}