import { serve } from "https://deno.land/std@0.190.0/http/server.ts";
import { createClient } from "https://esm.sh/@supabase/supabase-js@2.57.4";
import { edgeLogger, startRequest, endRequest } from "../_shared/logger.ts";
import { createErrorResponse } from "../_shared/errorSanitizer.ts";

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

interface InboundEmailPayload {
  from: string;
  to: string;
  subject: string;
  text: string;
  html?: string;
  messageId: string;
  inReplyTo?: string;
  references?: string[];
  headers: Record<string, string>;
}

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

  const tracking = startRequest();

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

    const payload: InboundEmailPayload = await req.json();
    const { from, to, subject, text, html, messageId, inReplyTo, references, headers } = payload;

    edgeLogger.info('Inbound email received', {
      requestId: tracking.requestId,
      from,
      to,
      messageId
    });

    // Extract thread ID from headers or inReplyTo
    let threadId = headers['X-Thread-ID'] || 
                   (inReplyTo ? inReplyTo.replace(/<|>/g, '').split('@')[0] : null);

    if (!threadId) {
      edgeLogger.warn('Email missing thread ID', {
        requestId: tracking.requestId,
        messageId
      });
      return new Response(JSON.stringify({ success: false, reason: 'no_thread_id' }), {
        status: 200,
        headers: { ...corsHeaders, 'Content-Type': 'application/json' }
      });
    }

    // Extract ticket number from thread_id (handles multiple formats)
    // Formats: "TW-100000.uuid", "ticket-TW-100000", "TW-100000"
    const ticketMatch = threadId.match(/(?:ticket-)?(TW-\d+)/i);
    const ticketNumber = ticketMatch ? ticketMatch[1] : null;

    edgeLogger.info('Thread ID extracted', {
      requestId: tracking.requestId,
      rawThreadId: threadId,
      ticketNumber
    });

    // Find submission by thread_id or ticket_number
    let submission = null;
    let submissionError = null;

    // Strategy 1: Try exact thread_id match
    const { data: submissionByThreadId, error: error1 } = await supabase
      .from('contact_submissions')
      .select('id, email, status, ticket_number')
      .eq('thread_id', threadId)
      .maybeSingle();

    if (submissionByThreadId) {
      submission = submissionByThreadId;
    } else if (ticketNumber) {
      // Strategy 2: Try ticket_number match
      const { data: submissionByTicket, error: error2 } = await supabase
        .from('contact_submissions')
        .select('id, email, status, ticket_number, thread_id')
        .eq('ticket_number', ticketNumber)
        .maybeSingle();
      
      if (submissionByTicket) {
        submission = submissionByTicket;
        
        // Update thread_id if it's null or in old format
        if (!submissionByTicket.thread_id || submissionByTicket.thread_id !== threadId) {
          await supabase
            .from('contact_submissions')
            .update({ thread_id: threadId })
            .eq('id', submissionByTicket.id);
          
          edgeLogger.info('Updated submission thread_id', {
            requestId: tracking.requestId,
            submissionId: submissionByTicket.id,
            oldThreadId: submissionByTicket.thread_id,
            newThreadId: threadId
          });
        }
      } else {
        submissionError = error2;
      }
    } else {
      submissionError = error1;
    }

    if (submissionError || !submission) {
      edgeLogger.warn('Submission not found for thread ID', {
        requestId: tracking.requestId,
        threadId,
        ticketNumber,
        error: submissionError
      });
      return new Response(JSON.stringify({ success: false, reason: 'submission_not_found' }), {
        status: 200,
        headers: { ...corsHeaders, 'Content-Type': 'application/json' }
      });
    }

    // Verify sender email matches
    const senderEmail = from.match(/<(.+)>/)?.[1] || from;
    if (senderEmail.toLowerCase() !== submission.email.toLowerCase()) {
      edgeLogger.warn('Sender email mismatch', {
        requestId: tracking.requestId,
        expected: submission.email,
        received: senderEmail
      });
      return new Response(JSON.stringify({ success: false, reason: 'email_mismatch' }), {
        status: 200,
        headers: { ...corsHeaders, 'Content-Type': 'application/json' }
      });
    }

    // Insert email thread record
    const { error: insertError } = await supabase
      .from('contact_email_threads')
      .insert({
        submission_id: submission.id,
        message_id: messageId,
        in_reply_to: inReplyTo,
        reference_chain: references || [],
        from_email: senderEmail,
        to_email: to,
        subject,
        body_text: text,
        body_html: html,
        direction: 'inbound',
        metadata: {
          received_at: new Date().toISOString(),
          headers: headers
        }
      });

    if (insertError) {
      edgeLogger.error('Failed to insert inbound email thread', {
        requestId: tracking.requestId,
        error: insertError
      });
      return createErrorResponse(insertError, 500, corsHeaders);
    }

    // Update submission status if pending
    if (submission.status === 'pending') {
      await supabase
        .from('contact_submissions')
        .update({ status: 'in_progress' })
        .eq('id', submission.id);
    }

    edgeLogger.info('Inbound email processed successfully', {
      requestId: tracking.requestId,
      submissionId: submission.id,
      duration: endRequest(tracking)
    });

    return new Response(
      JSON.stringify({ success: true }),
      { status: 200, headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
    );

  } catch (error) {
    edgeLogger.error('Unexpected error in receive-inbound-email', {
      requestId: tracking.requestId,
      error: error instanceof Error ? error.message : String(error)
    });
    return createErrorResponse(error, 500, corsHeaders);
  }
};

serve(handler);