import Foundation

class HealthAPIService {
    static let shared = HealthAPIService()
    let baseURL = "https://health.digital-home.site"
    
    private var cachedToken: String? {
        get { UserDefaults.standard.string(forKey: "healthJWTToken") }
        set { UserDefaults.standard.set(newValue, forKey: "healthJWTToken") }
    }
    
    // Логин в health сервис (отдельный JWT)
    func ensureToken() async throws -> String {
        if let t = cachedToken { return t }
        return try await refreshToken()
    }
    
    func refreshToken() async throws -> String {
        var req = URLRequest(url: URL(string: "\(baseURL)/api/auth/login")!)
        req.httpMethod = "POST"
        req.setValue("application/json", forHTTPHeaderField: "Content-Type")
        req.httpBody = try? JSONEncoder().encode(["email": "daniilklimov25@gmail.com", "password": "cosmo-health-2026"])
        req.timeoutInterval = 15
        let (data, _) = try await URLSession.shared.data(for: req)
        struct LoginResp: Decodable { let token: String }
        let resp = try JSONDecoder().decode(LoginResp.self, from: data)
        cachedToken = resp.token
        return resp.token
    }

    private func fetch<T: Decodable>(_ path: String) async throws -> T {
        let token = try await ensureToken()
        var req = URLRequest(url: URL(string: "\(baseURL)\(path)")!)
        req.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
        req.setValue("application/json", forHTTPHeaderField: "Content-Type")
        req.timeoutInterval = 15
        let (data, response) = try await URLSession.shared.data(for: req)
        guard let http = response as? HTTPURLResponse else { throw APIError.networkError("No response") }
        if http.statusCode == 401 {
            // Token expired, retry once
            cachedToken = nil
            let newToken = try await refreshToken()
            var req2 = URLRequest(url: URL(string: "\(baseURL)\(path)")!)
            req2.setValue("Bearer \(newToken)", forHTTPHeaderField: "Authorization")
            req2.setValue("application/json", forHTTPHeaderField: "Content-Type")
            req2.timeoutInterval = 15
            let (data2, _) = try await URLSession.shared.data(for: req2)
            return try JSONDecoder().decode(T.self, from: data2)
        }
        if http.statusCode >= 400 {
            throw APIError.serverError(http.statusCode, String(data: data, encoding: .utf8) ?? "")
        }
        return try JSONDecoder().decode(T.self, from: data)
    }

    func getLatest() async throws -> LatestHealthResponse {
        return try await fetch("/api/health/latest")
    }

    func getReadiness() async throws -> ReadinessResponse {
        return try await fetch("/api/health/readiness")
    }

    func getHeatmap(days: Int = 30) async throws -> [HeatmapEntry] {
        let token = try await ensureToken()
        var req = URLRequest(url: URL(string: "\(baseURL)/api/health/heatmap?days=\(days)")!)
        req.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
        req.timeoutInterval = 15
        let (data, _) = try await URLSession.shared.data(for: req)
        if let entries = try? JSONDecoder().decode([HeatmapEntry].self, from: data) { return entries }
        struct HeatmapResponse: Decodable { let data: [HeatmapEntry] }
        let wrapped = try JSONDecoder().decode(HeatmapResponse.self, from: data)
        return wrapped.data
    }

    func sendHealthData(apiKey: String, payload: Data) async throws {
        let url = URL(string: "\(baseURL)/api/health?key=\(apiKey)")!
        var req = URLRequest(url: url)
        req.httpMethod = "POST"
        req.setValue("application/json", forHTTPHeaderField: "Content-Type")
        req.httpBody = payload
        req.timeoutInterval = 30
        let (_, response) = try await URLSession.shared.data(for: req)
        guard let http = response as? HTTPURLResponse, (200...299).contains(http.statusCode) else {
            throw APIError.serverError((response as? HTTPURLResponse)?.statusCode ?? 0, "Ошибка отправки")
        }
    }
}