浅念
56 lines
2.3 KiB
TypeScript
56 lines
2.3 KiB
TypeScript
import type { MonthStat } from '@/api/stats'
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/**
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* Pure derived-stat helpers for the Stats page (Task 6).
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*
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* Extracted from {@link Stats.vue} so the two pieces of trivia that are easy
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* to get wrong — (1) finding the current month's count in a DESC-ordered list
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* and (2) flipping that list to chronological ASC for the line chart — are
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* unit-testable without mounting the component or stubbing ECharts.
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*/
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/**
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* Look up the inquiry count for a given `YYYY-MM` month in the `monthly` list.
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*
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* Used by Stats.vue for the "本月新增" card: it passes
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* `dayjs().format('YYYY-MM')` and we return the matching count, or `0` when
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* there's no data for the current month yet (the backend omits zero-count
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* months entirely, and a fresh month may not have appeared in the trailing
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* 12-month window at all).
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*
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* The lookup is by value equality on `ym`, so input order (DESC vs ASC) is
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* irrelevant. Returns `0` for an empty list — graceful fallback for an empty
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* DB / new install.
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*/
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export function currentMonthCount(
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monthly: readonly MonthStat[],
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ym: string,
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): number {
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// `find` rather than indexing `[0]` — the current month is not guaranteed to
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// be the first entry (DESC newest-first only covers months that have data,
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// and a brand-new month may be ABSENT from the trailing 12-month window).
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const hit = monthly.find((m) => m.ym === ym)
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return hit?.count ?? 0
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}
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/**
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* Return a new array of monthly stats sorted **ascending** by `ym`
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* (chronological order — what the trend line chart needs).
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*
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* The backend returns `monthly` **DESC** (newest first). The line chart's X
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* axis wants oldest → newest, so this flips the order. A fresh copy is always
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* returned (the input is never mutated), even when the input is already ASC —
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* callers can safely pass a `readonly` slice from the API response.
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*
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* String comparison on `YYYY-MM` is lexicographically correct (zero-padded
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* fixed-width format), so no Date parsing is needed.
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*/
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export function sortMonthlyAsc(monthly: readonly MonthStat[]): MonthStat[] {
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// Slice first so `.sort` cannot reorder the caller's array — important
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// because `monthly` may be the live API response object.
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return monthly.slice().sort((a, b) => {
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if (a.ym !== b.ym) return a.ym < b.ym ? -1 : 1
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return 0
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})
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}
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