import Foundation

private let BML_API_BASE    = "https://www.bankofmaldives.com.mv/internetbanking"
private let BML_API_UA      = "bml-mobile-banking/348 (Apple; iOS 17.0; iPhone)"
private let BML_API_VERSION = "2.1.44.348"

final class BmlAccountClient {

    private let session: BmlSession
    private let urlSession: URLSession = {
        let cfg = URLSessionConfiguration.default
        cfg.timeoutIntervalForRequest = 30
        return URLSession(configuration: cfg)
    }()

    init(session: BmlSession) {
        self.session = session
    }

    // MARK: - Dashboard / Accounts

    func fetchAccounts(
        loginTag: String,
        profileName: String = "Personal",
        profileId: String = ""
    ) async throws -> [BankAccount] {
        let data = try await apiGet("/api/mobile/dashboard")
        guard let root = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
              root["success"] as? Bool == true,
              let payload = root["payload"] as? [String: Any],
              let dashboard = payload["dashboard"] as? [[String: Any]] else {
            return []
        }
        return parseDashboard(dashboard, loginTag: loginTag, profileName: profileName, profileId: profileId)
    }

    // MARK: - Profile check (lightweight ping to verify session)

    func checkProfile() async throws {
        let data = try await apiGet("/api/mobile/profile")
        if let root = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
           root["success"] as? Bool == false {
            throw BmlError.sessionExpired
        }
    }

    // MARK: - User info

    func fetchUserInfo() async throws -> BmlUserInfo? {
        let data = try await apiGet("/api/mobile/userinfo")
        guard let root = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
              root["success"] as? Bool == true,
              let payload = root["payload"] as? [String: Any],
              let user = payload["user"] as? [String: Any] else { return nil }
        return BmlUserInfo(
            fullName:   (user["fullname"] as? String ?? "").trimmingCharacters(in: .whitespaces),
            email:      (user["email"] as? String ?? "").trimmingCharacters(in: .whitespaces),
            mobile:     (user["mobile_phone"] as? String ?? "").trimmingCharacters(in: .whitespaces),
            customerId: (user["customer_number"] as? String ?? "").trimmingCharacters(in: .whitespaces),
            idCard:     (user["idcard"] as? String ?? "").trimmingCharacters(in: .whitespaces),
            birthdate:  (user["birthdate"] as? String ?? "").trimmingCharacters(in: .whitespaces)
        )
    }

    // MARK: - Loan detail

    func fetchLoanDetail(internalId: String) async throws -> BmlLoanDetail? {
        let data = try await apiGet("/api/mobile/account/\(internalId)")
        guard let root = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
              root["success"] as? Bool == true,
              let p = root["payload"] as? [String: Any] else { return nil }
        return BmlLoanDetail(
            loanAmount:       p["loanAmount"] as? Double ?? 0,
            outstandingAmt:   p["outstandingAmt"] as? Double ?? 0,
            repayAmount:      p["repayAmount"] as? Double ?? 0,
            intRate:          p["intRate"] as? Double ?? 0,
            loanStatus:       p["loanStatus"] as? String ?? "",
            startDate:        p["startDate"] as? String ?? "",
            endDate:          p["endDate"] as? String ?? "",
            noOfRepayOverdue: p["noOfRepayOverdue"] as? Int ?? 0,
            overdueAmount:    p["overdueAmount"] as? Double ?? 0
        )
    }

    // MARK: - Transfer OTP channels

    func fetchTransferChannels() async throws -> [BmlOtpChannel] {
        let data = try await apiGet("/api/mobile/transfer")
        guard let root = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
              root["success"] as? Bool == true,
              let arr = (root["payload"] as? [String: Any])?["transfer"] as? [String: Any],
              let channels = arr["otpChannel"] as? [[String: Any]] else { return [] }
        return channels.map {
            BmlOtpChannel(
                channel:     $0["channel"] as? String ?? "",
                description: $0["description"] as? String ?? "",
                masked:      $0["masked"] as? String ?? ""
            )
        }
    }

    // MARK: - Dashboard parsing

    private func parseDashboard(
        _ dashboard: [[String: Any]],
        loginTag: String,
        profileName: String,
        profileId: String
    ) -> [BankAccount] {
        var casaAccounts: [BankAccount] = []
        var cardAccounts: [BankAccount] = []
        var loanAccounts: [BankAccount] = []

        for item in dashboard {
            let currency    = item["currency"] as? String ?? "MVR"
            let accountType = item["account_type"] as? String ?? "CASA"
            let product     = item["product"] as? String ?? ""
            let accountNum  = Self.stringValue(item["account"])
            let status      = item["account_status"] as? String ?? "Active"
            let internalId  = Self.stringValue(item["id"])

            switch accountType {
            case "CASA":
                let avail = item["availableBalance"] as? Double ?? 0
                casaAccounts.append(BankAccount(
                    id:               "BML_\(accountNum)_\(loginTag)",
                    bank:             "BML",
                    profileName:      profileName,
                    profileType:      "BML",
                    productCode:      item["product_code"] as? String ?? "",
                    accountNumber:    accountNum,
                    accountBriefName: item["alias"] as? String ?? "",
                    currencyName:     currency,
                    accountTypeName:  product,
                    availableBalance: avail,
                    currentBalance:   item["ledgerBalance"] as? Double ?? 0,
                    blockedAmount:    item["lockedAmount"] as? Double ?? 0,
                    mvrBalance:       currency == "MVR" ? avail : nil,
                    statusDesc:       status,
                    profileImageHash: nil,
                    loginTag:         loginTag,
                    profileId:        profileId,
                    internalId:       internalId
                ))

            case "Loan":
                let outstanding = abs(item["availableBalance"] as? Double ?? 0)
                loanAccounts.append(BankAccount(
                    id:               "BML_LOAN_\(accountNum)_\(loginTag)",
                    bank:             "BML",
                    profileName:      profileName,
                    profileType:      "BML_LOAN",
                    productCode:      item["product_code"] as? String ?? "",
                    accountNumber:    accountNum,
                    accountBriefName: item["alias"] as? String ?? "",
                    currencyName:     currency,
                    accountTypeName:  product,
                    availableBalance: outstanding,
                    currentBalance:   outstanding,
                    blockedAmount:    0,
                    mvrBalance:       nil,
                    statusDesc:       status,
                    profileImageHash: nil,
                    loginTag:         loginTag,
                    profileId:        profileId,
                    internalId:       internalId
                ))

            case "Card":
                let isPrepaid   = item["prepaid_card"] as? Bool ?? false
                let isVisible   = item["account_visible"] as? Bool ?? false
                let cardBalance = item["cardBalance"] as? [String: Any]
                let avail       = cardBalance?["AvailableLimit"] as? Double ?? 0
                let current     = cardBalance?["CurrentBalance"] as? Double ?? 0
                let cardType: String = isPrepaid ? "BML_PREPAID" : isVisible ? "BML_CREDIT" : "BML_DEBIT"
                let alias = (item["alias"] as? String ?? "").isEmpty ? product : (item["alias"] as? String ?? product)
                cardAccounts.append(BankAccount(
                    id:               "BML_CARD_\(accountNum)_\(loginTag)",
                    bank:             "BML",
                    profileName:      profileName,
                    profileType:      cardType,
                    productCode:      item["product_code"] as? String ?? "",
                    accountNumber:    accountNum,
                    accountBriefName: alias,
                    currencyName:     currency,
                    accountTypeName:  product,
                    availableBalance: avail,
                    currentBalance:   current,
                    blockedAmount:    0,
                    mvrBalance:       currency == "MVR" ? avail : nil,
                    statusDesc:       status,
                    profileImageHash: nil,
                    loginTag:         loginTag,
                    profileId:        profileId,
                    internalId:       internalId
                ))

            default:
                break
            }
        }

        return casaAccounts + cardAccounts + loanAccounts
    }

    private static func stringValue(_ value: Any?) -> String {
        switch value {
        case let string as String:
            return string
        case let int as Int:
            return String(int)
        case let int64 as Int64:
            return String(int64)
        case let double as Double:
            return double.rounded() == double ? String(Int64(double)) : String(double)
        default:
            return ""
        }
    }

    // MARK: - HTTP

    private func apiGet(_ path: String) async throws -> Data {
        var req = URLRequest(url: URL(string: "\(BML_API_BASE)\(path)")!)
        req.setValue("Bearer \(session.accessToken)", forHTTPHeaderField: "Authorization")
        req.setValue(BML_API_UA, forHTTPHeaderField: "User-Agent")
        req.setValue(BML_API_VERSION, forHTTPHeaderField: "x-app-version")

        let (data, response) = try await urlSession.data(for: req)
        let code = (response as? HTTPURLResponse)?.statusCode ?? 0
        if code == 401 || code == 419 { throw BmlError.sessionExpired }
        if code >= 500 { throw BmlError.networkError("Server error HTTP \(code)") }
        return data
    }
}