import { serve } from "https://deno.land/std@0.190.0/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",
};

interface GoogleServiceAccount {
  type: string;
  project_id: string;
  private_key_id: string;
  private_key: string;
  client_email: string;
  client_id: string;
  auth_uri: string;
  token_uri: string;
}

interface CreateMeetRequest {
  slot_id: string;
  date: string;
  start_time: string;
  end_time: string;
  client_name: string;
  client_email: string;
  topic: string;
  notes?: string;
}

// Function to create JWT for Google API authentication
async function getGoogleAccessToken(serviceAccount: GoogleServiceAccount): Promise<string> {
  const header = {
    alg: "RS256",
    typ: "JWT",
  };

  const now = Math.floor(Date.now() / 1000);
  const payload = {
    iss: serviceAccount.client_email,
    scope: "https://www.googleapis.com/auth/calendar",
    aud: serviceAccount.token_uri,
    exp: now + 3600,
    iat: now,
  };

  // Import JWT functionality
  const { default: jwt } = await import("https://deno.land/x/jose@v4.14.4/index.ts");

  const privateKey = await crypto.subtle.importKey(
    "pkcs8",
    StringEncoder.encode(serviceAccount.private_key),
    { name: "RSASSA-PKCS1-v1_5", hash: "SHA-256" },
    false,
    ["sign"]
  );

  const token = await jwt.sign(header, payload, privateKey);

  // Exchange JWT for access token
  const response = await fetch(serviceAccount.token_uri, {
    method: "POST",
    headers: { "Content-Type": "application/x-www-form-urlencoded" },
    body: new URLSearchParams({
      grant_type: "urn:ietf:params:oauth:grant-type:jwt-bearer",
      assertion: token,
    }),
  });

  const data = await response.json();
  return data.access_token;
}

// String encoder helper
const StringEncoder = new TextEncoder();

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

  try {
    const supabaseUrl = Deno.env.get("SUPABASE_URL")!;
    const supabaseServiceKey = Deno.env.get("SUPABASE_SERVICE_ROLE_KEY")!;
    const supabase = createClient(supabaseUrl, supabaseServiceKey);

    const body: CreateMeetRequest = await req.json();
    console.log("Creating Google Meet event for slot:", body.slot_id);

    // Get platform settings
    const { data: settings } = await supabase
      .from("platform_settings")
      .select("integration_google_calendar_id, brand_name, google_service_account_json")
      .single();

    const calendarId = settings?.integration_google_calendar_id;
    const brandName = settings?.brand_name || "LearnHub";

    if (!calendarId) {
      return new Response(
        JSON.stringify({
          success: false,
          message: "Google Calendar ID belum dikonfigurasi di Pengaturan > Integrasi"
        }),
        { status: 400, headers: { ...corsHeaders, "Content-Type": "application/json" } }
      );
    }

    // Get service account from settings or environment
    let serviceAccountJson: string | null = null;

    // Priority 1: Check if stored in platform_settings (encrypted field recommended)
    if (settings?.google_service_account_json) {
      serviceAccountJson = settings.google_service_account_json;
    }

    // Priority 2: Check environment variable
    if (!serviceAccountJson) {
      serviceAccountJson = Deno.env.get("GOOGLE_SERVICE_ACCOUNT_JSON") || null;
    }

    if (!serviceAccountJson) {
      return new Response(
        JSON.stringify({
          success: false,
          message: "Google Service Account JSON belum dikonfigurasi. Tambahkan di environment variables atau platform_settings."
        }),
        { status: 400, headers: { ...corsHeaders, "Content-Type": "application/json" } }
      );
    }

    // Parse service account JSON
    let serviceAccount: GoogleServiceAccount;
    try {
      serviceAccount = JSON.parse(serviceAccountJson);
    } catch (error) {
      console.error("Failed to parse service account JSON:", error);
      return new Response(
        JSON.stringify({
          success: false,
          message: "Format Google Service Account JSON tidak valid"
        }),
        { status: 400, headers: { ...corsHeaders, "Content-Type": "application/json" } }
      );
    }

    // Get access token
    const accessToken = await getGoogleAccessToken(serviceAccount);

    // Build event data
    const startDate = new Date(`${body.date}T${body.start_time}`);
    const endDate = new Date(`${body.date}T${body.end_time}`);

    const eventData = {
      summary: `Konsultasi: ${body.topic} - ${body.client_name}`,
      description: `Client: ${body.client_email}\n\nNotes: ${body.notes || '-'}\n\nSlot ID: ${body.slot_id}\nBrand: ${brandName}`,
      start: {
        dateTime: startDate.toISOString(),
        timeZone: "Asia/Jakarta",
      },
      end: {
        dateTime: endDate.toISOString(),
        timeZone: "Asia/Jakarta",
      },
      attendees: [
        { email: body.client_email },
      ],
      conferenceData: {
        createRequest: {
          requestId: body.slot_id,
          conferenceSolutionKey: { type: "hangoutsMeet" },
        },
      },
      sendUpdates: "all",
      guestsCanInviteOthers: false,
      guestsCanModify: false,
      guestsCanSeeOtherGuests: false,
    };

    // Create event via Google Calendar API
    const calendarResponse = await fetch(
      `https://www.googleapis.com/calendar/v3/calendars/${encodeURIComponent(calendarId)}/events?conferenceDataVersion=1`,
      {
        method: "POST",
        headers: {
          "Authorization": `Bearer ${accessToken}`,
          "Content-Type": "application/json",
        },
        body: JSON.stringify(eventData),
      }
    );

    if (!calendarResponse.ok) {
      const errorText = await calendarResponse.text();
      console.error("Google Calendar API error:", errorText);
      return new Response(
        JSON.stringify({
          success: false,
          message: "Gagal membuat event di Google Calendar: " + errorText
        }),
        { status: 500, headers: { ...corsHeaders, "Content-Type": "application/json" } }
      );
    }

    const eventDataResult = await calendarResponse.json();

    // Update the slot with the meet link
    if (eventDataResult.hangoutLink) {
      await supabase
        .from("consulting_slots")
        .update({ meet_link: eventDataResult.hangoutLink })
        .eq("id", body.slot_id);

      return new Response(
        JSON.stringify({
          success: true,
          meet_link: eventDataResult.hangoutLink,
          event_id: eventDataResult.id,
          html_link: eventDataResult.htmlLink,
        }),
        { headers: { ...corsHeaders, "Content-Type": "application/json" } }
      );
    }

    return new Response(
      JSON.stringify({
        success: false,
        message: "Event berhasil dibuat tapi tidak ada meet link"
      }),
      { status: 500, headers: { ...corsHeaders, "Content-Type": "application/json" } }
    );

  } catch (error: any) {
    console.error("Error creating Google Meet event:", error);
    return new Response(
      JSON.stringify({ success: false, message: error.message }),
      { status: 500, headers: { ...corsHeaders, "Content-Type": "application/json" } }
    );
  }
});