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namespace FundLab.Api
open System
open System.Collections.Concurrent
open System.Globalization
open System.Threading
/// One point of a fund's real net-value series.
type NavSeriesPoint =
{
NavDate: DateOnly
Nav: decimal
AccumulatedNav: decimal option
}
/// Read-only probe that returns the most recent NAV points for a fund code.
/// Like INavDateProbe there is no synthetic fallback: a failure is surfaced as a
/// MarketDataFailure so the API answers 503 with the underlying reason.
type INavSeriesProbe =
abstract RecentNavSeries: code: string * limit: int * CancellationToken -> Result<NavSeriesPoint list, MarketDataFailure>
/// AKShare-backed series probe. Successful lookups are memoised per code and
/// calendar day (the F# equivalent of functools cache keyed on code + today), so
/// the UI can re-read the curve during one day without re-spawning the collector.
/// Failures are never cached.
type AkshareNavSeriesProbe(collector: IMarketDataCollector) =
let cache = ConcurrentDictionary<string, NavSeriesPoint list>(StringComparer.Ordinal)
let isFundCode (value: string) =
not (String.IsNullOrWhiteSpace value)
&& value.Length = 6
&& value |> Seq.forall Char.IsDigit
let clip limit =
if limit < 1 then 1
elif limit > 250 then 250
else limit
let todayText () =
(ConfirmationPolicy.eventDateFor DateTimeOffset.UtcNow).ToString("yyyy-MM-dd", CultureInfo.InvariantCulture)
member _.Clear() = cache.Clear()
interface INavSeriesProbe with
member _.RecentNavSeries(code, limit, token) =
let normalized = if isNull code then "" else code.Trim()
if not (isFundCode normalized) then
Error(InvalidMarketDataRequest "fund code must contain exactly six digits")
else
let bounded = clip limit
let cacheKey = sprintf "%s|%s" normalized (todayText ())
match cache.TryGetValue cacheKey with
| true, cached -> Ok(cached |> List.truncate bounded)
| _ ->
match collector.FetchNav(normalized, token) with
| Error message -> Error(MarketDataCollectorUnavailable message)
| Ok json ->
match MarketData.parseNavPayload json with
| Error message -> Error(InvalidMarketDataPayload message)
| Ok payload ->
let points =
payload.Observations
|> List.filter (fun observation -> observation.Nav > 0m)
|> List.map (fun observation ->
{
NavDate = observation.NavDate
Nav = observation.Nav
AccumulatedNav = observation.AccumulatedNav
})
|> List.distinctBy (fun point -> point.NavDate)
|> List.sortByDescending (fun point -> point.NavDate)
cache.[cacheKey] <- points
Ok(points |> List.truncate bounded)
|
