FinanceUaRevised.fs

module FinanceRevised.Core

open FinanceRevised.Types
open MaybeBuilder

open System
open System.IO
open FSharp.Data
open FSharp.Data.JsonExtensions

let private homeJson =     
    try
        (__SOURCE_DIRECTORY__, "finance_ua.json" ) 
            |> Path.Combine 
            |> File.ReadAllText
            |> JsonValue.Parse 
            |> Some
    with
    | :? System.IO.FileNotFoundException -> None

let private financeUiJson = 
    try
        "http://resources.finance.ua/ru/public/currency-cash.json"
            |> JsonValue.AsyncLoad
            |> Async.RunSynchronously
            |> Some
    with
    | Failure _ -> None
    | :? System.Net.WebException -> None

let private parseJson = function 
    | Home -> homeJson
    | FinanceUa -> financeUiJson     
    
let private tryGetCityId (name: string) json =    
    let byCityName jsonValue = 
        let byName (t:string * JsonValue) = (snd t).AsString().ToLowerInvariant() = name.ToLowerInvariant()
        let takeFirst (t: string * JsonValue) = fst t
        jsonValue?cities.Properties
        |> Array.filter byName
        |> Array.map takeFirst

    let pickFirst (cities: 'a []) = if cities.Length = 0 then None else Some <| Array.head cities    
    json 
    |> byCityName  
    |> pickFirst

let private tryGetOrganizationsById id json =
    let byCityId json = json?cityId.AsString() = id
    let allOrganizations = json?organizations.AsArray()
    allOrganizations |> Array.filter byCityId |> Some

let private getAverageByOrganizations currency operationType organizations = 
    let byCurrency t = fst t = currency
    let forCurrencies v = v?currencies.Properties |> Array.filter byCurrency    
    let byOperationType (t: 'a * JsonValue) = (snd t).GetProperty(operationType).AsFloat()

    organizations 
    |> Array.collect forCurrencies 
    |> Array.map byOperationType
    |> Array.average

let private getAverageByCity path city currency byType =    
    let cityName = City.value city
    let currency = Currency.value currency
    let byType = CurrencyType.value byType
    maybe {
        let! json = parseJson path
        let! cityId = json |> tryGetCityId cityName
        let! organizations = json |> tryGetOrganizationsById cityId
        return organizations |> getAverageByOrganizations currency byType
    } 

let public runFinanceCoreRevised () =    
    let kyivFromFinance = getAverageByCity FinanceUa City.Kyiv Currency.USD
    let kyivUSDAsk = kyivFromFinance CurrencyType.Ask
    let kyivUSDBid = kyivFromFinance CurrencyType.Bid

    printfn "Ask: %A, Bid: %A" kyivUSDAsk kyivUSDBid

    let path = FinanceUa
    let cityName = City.value City.Kyiv
    let currency = Currency.value Currency.USD
    let byType = CurrencyType.value CurrencyType.Ask

    let average = maybe {
        let! json = parseJson path
        let! cityId = json |> tryGetCityId cityName
        let! organizations = json |> tryGetOrganizationsById cityId
        return organizations |> getAverageByOrganizations currency byType
    } 

    printfn "%A" average
    
//    match jsonParsed with
//    | Some json ->
//        let cityId = json |> getCityId cityName
//        match cityId with
//        | Some id -> 
//            json 
//            |> getOrganizationsById id
//            |> Some
//        | None -> None
//    | None -> None