add formula placeholder

app/javascript/submission_form/form.vue

@@ -8,6 +8,11 @@
     :current-step="currentStepFields"
     @focus-step="[saveStep(), goToStep($event, false, true), currentField.type !== 'checkbox' ? isFormVisible = true : '']"
   />
+  <FormulaFieldAreas
+    v-if="formulaFields.length"
+    :fields="formulaFields"
+    :values="values"
+  />
   <button
     v-if="!isFormVisible"
     id="expand_form_button"
@@ -396,6 +401,7 @@
 
 <script>
 import FieldAreas from './areas'
+import FormulaFieldAreas from './formula_areas'
 import ImageStep from './image_step'
 import SignatureStep from './signature_step'
 import InitialsStep from './initials_step'
@@ -444,6 +450,7 @@ export default {
     IconArrowsDiagonal,
     TextStep,
     NumberStep,
+    FormulaFieldAreas,
     PhoneStep,
     PaymentStep,
     IconArrowsDiagonalMinimize2,
@@ -636,6 +643,9 @@ export default {
         return acc
       }, [])
     },
+    formulaFields () {
+      return this.fields.filter((f) => f.preferences?.formula)
+    },
     attachmentsIndex () {
       return this.attachments.reduce((acc, a) => {
         acc[a.uuid] = a
@@ -785,7 +795,7 @@ export default {
           this.scrollIntoField(step[0])
         }
 
-        this.$refs.form.querySelector('input[type="date"], input[type="text"], select')?.focus()
+        this.$refs.form.querySelector('input[type="date"], input[type="number"], input[type="text"], select')?.focus()
 
         if (clickUpload && !this.values[this.currentField.uuid] && ['file', 'image'].includes(this.currentField.type)) {
           this.$refs.form.querySelector('input[type="file"]')?.click()

app/javascript/submission_form/formula_areas.vue

@@ -0,0 +1,97 @@
+<template>
+  <template
+    v-for="(field, fieldIndex) in fields"
+    :key="field.uuid"
+  >
+    <template
+      v-for="(area, areaIndex) in field.areas"
+      :key="areaIndex"
+    >
+      <Teleport
+        v-if="findPageElementForArea(area)"
+        :to="findPageElementForArea(area)"
+      >
+        <FieldArea
+          v-if="isMathLoaded"
+          :model-value="calculateFormula(field)"
+          :field="field"
+          :area="area"
+          :submittable="false"
+          :field-index="fieldIndex"
+        />
+      </Teleport>
+    </template>
+  </template>
+</template>
+
+<script>
+import FieldArea from './area'
+
+export default {
+  name: 'FormulaFieldAreas',
+  components: {
+    FieldArea
+  },
+  props: {
+    fields: {
+      type: Array,
+      required: false,
+      default: () => []
+    },
+    values: {
+      type: Object,
+      required: false,
+      default: () => ({})
+    }
+  },
+  data () {
+    return {
+      isMathLoaded: false
+    }
+  },
+  async mounted () {
+    const {
+      create,
+      evaluateDependencies,
+      addDependencies,
+      subtractDependencies,
+      divideDependencies,
+      multiplyDependencies,
+      powDependencies,
+      roundDependencies,
+      absDependencies,
+      sinDependencies,
+      tanDependencies,
+      cosDependencies
+    } = await import('mathjs')
+
+    this.math = create({
+      evaluateDependencies,
+      addDependencies,
+      subtractDependencies,
+      divideDependencies,
+      multiplyDependencies,
+      powDependencies,
+      roundDependencies,
+      absDependencies,
+      sinDependencies,
+      tanDependencies,
+      cosDependencies
+    })
+
+    this.isMathLoaded = true
+  },
+  methods: {
+    findPageElementForArea (area) {
+      return (this.$root.$el?.parentNode?.getRootNode() || document).getElementById(`page-${area.attachment_uuid}-${area.page}`)
+    },
+    calculateFormula (field) {
+      const transformedFormula = field.preferences.formula.replace(/{{(.*?)}}/g, (match, uuid) => {
+        return this.values[uuid] || 0.0
+      })
+
+      return this.math.evaluate(transformedFormula.toLowerCase())
+    }
+  }
+}
+</script>

app/javascript/submission_form/number_step.vue

@@ -59,7 +59,7 @@ export default {
       default: true
     },
     modelValue: {
-      type: String,
+      type: [String, Number],
       required: false,
       default: ''
     }