54 lines
1.6 KiB
TypeScript
54 lines
1.6 KiB
TypeScript
import type { ConditionalRule, FormAnswers, Question } from './types'
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/** Returns true if the question should be shown given the current answers. */
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export function isQuestionVisible(
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question: Question,
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answers: FormAnswers
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): boolean {
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const rules = question.conditional_rules
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if (!rules || rules.length === 0) return true
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// All rules must pass (AND semantics)
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return rules.every((rule) => evaluateRule(rule, answers))
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}
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function evaluateRule(rule: ConditionalRule, answers: FormAnswers): boolean {
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if (rule.op === 'eq') {
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return answers[rule.if_question] === rule.value
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}
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return false
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}
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/**
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* Returns the codes of questions that will become hidden when `triggerCode`
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* changes to `newValue`. Used to clear those answers reactively.
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*/
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export function getHiddenCodes(
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triggerCode: string,
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newValue: string | string[] | number | null,
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questions: Question[],
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currentAnswers: FormAnswers
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): string[] {
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const projected = { ...currentAnswers, [triggerCode]: newValue }
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return questions
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.filter((q) => {
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if (!q.conditional_rules?.length) return false
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const dependsOnTrigger = q.conditional_rules.some(
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(r) => r.if_question === triggerCode
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)
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if (!dependsOnTrigger) return false
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return !isQuestionVisible(q, projected)
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})
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.map((q) => q.code)
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}
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/** All trigger codes in the survey (questions that have dependents). */
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export function getTriggerCodes(questions: Question[]): Set<string> {
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const triggers = new Set<string>()
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for (const q of questions) {
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for (const rule of q.conditional_rules ?? []) {
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triggers.add(rule.if_question)
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}
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}
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return triggers
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}
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