Invoice Approval Workflow

import { defineWorkflow } from '@dataflows/core'
import { datev } from '@dataflows/datev'
import { email } from '@dataflows/email'
import { openai } from '@dataflows/openai'
import { slack } from '@dataflows/slack'

export const invoiceApproval = defineWorkflow({
  id: 'invoice-approval',
  trigger: email.onReceive({ subject: 'Invoice' }),
  
  async run({ event, step }) {
    // 1. Extract PDF
    const pdf = await step.run('extract-pdf', () => {
      const attachment = event.attachments.find(a => a.type === 'application/pdf')
      if (!attachment) throw new Error('No PDF found')
      return attachment
    })

    // 2. AI Data Extraction
    const invoiceData = await step.run('ai-extract', async () => {
      return openai.extractStructuredData({
        file: pdf,
        schema: z.object({
          amount: z.number(),
          date: z.string(),
          vendor: z.string(),
          costCenter: z.string()
        })
      })
    })

    // 3. Determine Approver
    const approverEmail = await step.run('get-approver', async () => {
      // Logic to find approver based on cost center
      return `manager-${invoiceData.costCenter}@company.com`
    })

    // 4. Request Approval
    const approval = await step.waitForEvent('approval', {
      timeout: '7d',
      action: async () => {
        await email.send({
          to: approverEmail,
          subject: `Approve Invoice from ${invoiceData.vendor}`,
          body: `
            Amount: ${invoiceData.amount}
            Vendor: ${invoiceData.vendor}
            
            Click here to approve: ${step.callbackUrl({ decision: 'approved' })}
            Click here to reject: ${step.callbackUrl({ decision: 'rejected' })}
          `
        })
        
        await slack.postMessage({
          channel: '#finance-alerts',
          text: `New invoice waiting for approval from ${approverEmail}`
        })
      }
    })

    if (approval.payload.decision === 'rejected') {
      await email.send({ to: event.from, subject: 'Invoice Rejected', body: '...' })
      return { status: 'rejected' }
    }

    // 5. Upload to DATEV
    await step.run('upload-datev', async () => {
      await datev.uploadDocument({
        file: pdf,
        metadata: invoiceData
      })
    })
    
    return { status: 'processed', id: invoiceData.id }
  }
})