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 GoogleOAuthConfig {
  client_id: string;
  client_secret: string;
  refresh_token: string;
  access_token?: string;
  expires_at?: number; // Timestamp when access_token expires
}

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 get access token from refresh token (OAuth2)
async function getGoogleAccessToken(oauthConfig: GoogleOAuthConfig): Promise<{ access_token: string; expires_in: number }> {
  try {
    console.log("Attempting to exchange refresh token for access token...");
    console.log("Client ID:", oauthConfig.client_id);

    const tokenRequest = {
      client_id: oauthConfig.client_id,
      client_secret: oauthConfig.client_secret,
      refresh_token: oauthConfig.refresh_token,
      grant_type: "refresh_token",
    };

    console.log("Token request payload:", JSON.stringify({
      ...tokenRequest,
      client_secret: "***REDACTED***",
      refresh_token: tokenRequest.refresh_token.substring(0, 20) + "..."
    }));

    const response = await fetch("https://oauth2.googleapis.com/token", {
      method: "POST",
      headers: { "Content-Type": "application/x-www-form-urlencoded" },
      body: new URLSearchParams(tokenRequest),
    });

    const responseText = await response.text();
    console.log("Token response status:", response.status);
    console.log("Token response body:", responseText);

    if (!response.ok) {
      throw new Error(`Token exchange failed: ${responseText}`);
    }

    const data = await response.json();

    if (!data.access_token) {
      throw new Error("No access token in response");
    }

    console.log("Successfully obtained access token");
    return {
      access_token: data.access_token,
      expires_in: data.expires_in || 3600
    };
  } catch (error: any) {
    console.error("Error getting Google access token:", error);
    throw error;
  }
}

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);

    // Clone the request to avoid stream consumption issues
    // Read body text first, then parse JSON
    let body: CreateMeetRequest;
    let debugInfo: any = {
      method: req.method,
      headers: Object.fromEntries(req.headers.entries()),
      contentType: req.headers.get("content-type"),
      bodyConsumed: false
    };

    try {
      debugInfo.bodyReadAttempt = "Starting req.text()";
      const bodyText = await req.text();
      debugInfo.bodyLength = bodyText.length;
      debugInfo.bodyPreview = bodyText.substring(0, 200);
      console.log("Raw body text:", bodyText.substring(0, 100) + "...");
      body = JSON.parse(bodyText);
      debugInfo.parsedBody = body;
    } catch (bodyError) {
      debugInfo.readError = (bodyError as Error).message;
      console.error("Error reading body:", bodyError);
      console.error("Debug info:", JSON.stringify(debugInfo, null, 2));
      return new Response(
        JSON.stringify({
          success: false,
          message: "Invalid request body: " + (bodyError as Error).message,
          debug: debugInfo
        }),
        { status: 400, headers: { ...corsHeaders, "Content-Type": "application/json" } }
      );
    }
    console.log("Creating Google Meet event for slot:", body.slot_id);

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

    if (settingsError) {
      console.error("Error fetching settings:", settingsError);
      throw settingsError;
    }

    const calendarId = settings?.integration_google_calendar_id;

    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 OAuth config from settings
    const oauthConfigJson = settings?.google_oauth_config;

    if (!oauthConfigJson) {
      return new Response(
        JSON.stringify({
          success: false,
          message: "Google OAuth Config belum dikonfigurasi. Tambahkan di Pengaturan > Integrasi. Format: {\"client_id\":\"...\",\"client_secret\":\"...\",\"refresh_token\":\"...\"}"
        }),
        { status: 400, headers: { ...corsHeaders, "Content-Type": "application/json" } }
      );
    }

    // Parse OAuth config JSON
    let oauthConfig: GoogleOAuthConfig;
    try {
      oauthConfig = JSON.parse(oauthConfigJson);
    } catch (error: any) {
      console.error("Failed to parse OAuth config JSON:", error);
      return new Response(
        JSON.stringify({
          success: false,
          message: "Format Google OAuth Config tidak valid: " + error.message
        }),
        { status: 400, headers: { ...corsHeaders, "Content-Type": "application/json" } }
      );
    }

    // Check if we have a valid cached access_token
    let accessToken: string;
    const now = Math.floor(Date.now() / 1000); // Current time in seconds

    if (oauthConfig.access_token && oauthConfig.expires_at && oauthConfig.expires_at > now + 60) {
      // Token is still valid (with 60 second buffer)
      console.log("Using cached access_token (expires at:", new Date(oauthConfig.expires_at * 1000).toISOString(), ")");
      accessToken = oauthConfig.access_token;
    } else {
      // Need to refresh the token
      console.log("Access token expired or missing, refreshing...");
      const tokenData = await getGoogleAccessToken(oauthConfig);
      accessToken = tokenData.access_token;

      // Update the cached token in database with new expiry
      const newExpiresAt = now + tokenData.expires_in;
      const updatedConfig = {
        ...oauthConfig,
        access_token: accessToken,
        expires_at: newExpiresAt
      };

      // Save updated config back to database
      await supabase
        .from("platform_settings")
        .update({ google_oauth_config: JSON.stringify(updatedConfig) })
        .eq("id", settings.id);

      console.log("Updated cached access_token in database");
    }
    console.log("Got access token");

    // 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}`,
      start: {
        dateTime: startDate.toISOString(),
        timeZone: "Asia/Jakarta",
      },
      end: {
        dateTime: endDate.toISOString(),
        timeZone: "Asia/Jakarta",
      },
      conferenceData: {
        createRequest: {
          requestId: body.slot_id,
          conferenceSolutionKey: {
            type: "hangoutsMeet"
          }
        },
      },
    };

    console.log("Creating event in calendar:", calendarId);
    console.log("Event data:", JSON.stringify(eventData, null, 2));

    // Create event via Google Calendar API with better error handling
    let calendarResponse: Response;
    try {
      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",
            "User-Agent": "Deno/1.0 (Supabase Edge Function)",
          },
          body: JSON.stringify(eventData),
        }
      );
    } catch (fetchError: any) {
      console.error("Network error calling Google Calendar API:", fetchError);
      return new Response(
        JSON.stringify({
          success: false,
          message: "Network error calling Google Calendar API: " + fetchError.message
        }),
        { status: 500, headers: { ...corsHeaders, "Content-Type": "application/json" } }
      );
    }

    console.log("Calendar API response status:", calendarResponse.status);

    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();
    console.log("Event created:", eventDataResult.id);
    console.log("Full event response:", JSON.stringify(eventDataResult, null, 2));

    // Check if conference data was created
    if (eventDataResult.conferenceData && eventDataResult.conferenceData.entryPoints) {
      const meetLink = eventDataResult.conferenceData.entryPoints.find((ep: any) => ep.entryPointType === "video")?.uri;

      if (meetLink) {
        await supabase
          .from("consulting_slots")
          .update({ meet_link: meetLink })
          .eq("id", body.slot_id);

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

    // Fallback to hangoutLink for backwards compatibility
    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 || "Unknown error occurred"
      }),
      { status: 500, headers: { ...corsHeaders, "Content-Type": "application/json" } }
    );
  }
});