import Foundation

struct VelocityLeadDTO: Decodable, Identifiable {
    let id: String
    let name: String
    let phone: String?
    let source: String
    let qualification: String
    let score: Int
    let kanbanStatus: String
    let budget: String
    let unitInterest: String
    let createdAt: String?
    let updatedAt: String?

    enum CodingKeys: String, CodingKey {
        case id
        case name
        case phone
        case source
        case qualification
        case score
        case kanbanStatus = "kanban_status"
        case budget
        case unitInterest = "unit_interest"
        case createdAt = "created_at"
        case updatedAt = "updated_at"
    }
}

struct VelocityCommunicationEventDTO: Decodable, Identifiable {
    let eventId: String
    let leadId: String
    let channel: String
    let direction: String
    let provider: String?
    let captureMode: String
    let consentState: String
    let timestamp: String
    let durationSeconds: Int?
    let summary: String?
    let recordingRef: String?
    let createdAt: String

    var id: String { eventId }

    enum CodingKeys: String, CodingKey {
        case eventId = "event_id"
        case leadId = "lead_id"
        case channel
        case direction
        case provider
        case captureMode = "capture_mode"
        case consentState = "consent_state"
        case timestamp
        case durationSeconds = "duration_seconds"
        case summary
        case recordingRef = "recording_ref"
        case createdAt = "created_at"
    }
}

struct VelocityCalendarEventDTO: Decodable, Identifiable {
    let calendarEventId: String
    let leadId: String?
    let title: String
    let description: String?
    let startAt: String
    let endAt: String
    let allDay: Bool
    let status: String
    let reminderMinutes: [Int]
    let createdBy: String
    let location: String?
    let createdAt: String

    var id: String { calendarEventId }

    enum CodingKeys: String, CodingKey {
        case calendarEventId = "calendar_event_id"
        case leadId = "lead_id"
        case title
        case description
        case startAt = "start_at"
        case endAt = "end_at"
        case allDay = "all_day"
        case status
        case reminderMinutes = "reminder_minutes"
        case createdBy = "created_by"
        case location
        case createdAt = "created_at"
    }
}

struct VelocityAlertSnapshotDTO: Decodable {
    let pendingInsights: Int
    let upcomingCalendarEvents24h: Int
    let pendingTranscriptions: Int
    let generatedAt: String

    enum CodingKeys: String, CodingKey {
        case pendingInsights = "pending_insights"
        case upcomingCalendarEvents24h = "upcoming_calendar_events_24h"
        case pendingTranscriptions = "pending_transcriptions"
        case generatedAt = "generated_at"
    }
}

enum VelocityAPIError: LocalizedError {
    case notConfigured(String)
    case invalidResponse
    case api(String)

    var errorDescription: String? {
        switch self {
        case .notConfigured(let message):
            return message
        case .invalidResponse:
            return "Velocity backend returned an invalid response."
        case .api(let message):
            return message
        }
    }
}

actor VelocityAPIClient {
    static let shared = VelocityAPIClient()

    private struct LoginBody: Encodable {
        let email: String
        let password: String
    }

    private struct LoginResponse: Decodable {
        let accessToken: String

        enum CodingKeys: String, CodingKey {
            case accessToken = "access_token"
        }
    }

    private struct LeadsEnvelope: Decodable {
        let data: [VelocityLeadDTO]
    }

    private struct EventsEnvelope: Decodable {
        let events: [VelocityCommunicationEventDTO]
    }

    private struct CalendarEnvelope: Decodable {
        let events: [VelocityCalendarEventDTO]
    }

    private let decoder = JSONDecoder()
    private var cachedToken: String?

    func fetchLeads() async throws -> [VelocityLeadDTO] {
        let request = try await authorizedRequest(path: "/api/leads")
        let response: LeadsEnvelope = try await perform(request)
        return response.data
    }

    func fetchEvents(for leadId: String, limit: Int = 5) async throws -> [VelocityCommunicationEventDTO] {
        let query = URLQueryItem(name: "lead_id", value: leadId)
        let limitItem = URLQueryItem(name: "limit", value: String(limit))
        let request = try await authorizedRequest(path: "/api/mobile-edge/events", queryItems: [query, limitItem])
        let response: EventsEnvelope = try await perform(request)
        return response.events
    }

    func fetchCalendarEvents(limit: Int = 50) async throws -> [VelocityCalendarEventDTO] {
        let request = try await authorizedRequest(
            path: "/api/mobile-edge/calendar",
            queryItems: [URLQueryItem(name: "limit", value: String(limit))]
        )
        let response: CalendarEnvelope = try await perform(request)
        return response.events
    }

    func fetchAlerts() async throws -> VelocityAlertSnapshotDTO {
        let request = try await authorizedRequest(path: "/api/mobile-edge/alerts")
        return try await perform(request)
    }

    private func authorizedRequest(path: String, queryItems: [URLQueryItem] = []) async throws -> URLRequest {
        guard let url = buildURL(path: path, queryItems: queryItems) else {
            throw VelocityAPIError.notConfigured("Velocity backend base URL is invalid.")
        }
        let token = try await getToken()
        var request = URLRequest(url: url)
        request.setValue("application/json", forHTTPHeaderField: "Accept")
        request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
        request.timeoutInterval = 30
        return request
    }

    private func buildURL(path: String, queryItems: [URLQueryItem]) -> URL? {
        guard var components = URLComponents(string: AppConfig.baseURL) else {
            return nil
        }
        components.path = path
        if !queryItems.isEmpty {
            components.queryItems = queryItems
        }
        return components.url
    }

    private func getToken() async throws -> String {
        if let token = AppConfig.apiBearerToken {
            return token
        }
        if let token = cachedToken {
            return token
        }
        guard let email = AppConfig.apiEmail, let password = AppConfig.apiPassword else {
            throw VelocityAPIError.notConfigured(
                "Set API_BEARER_TOKEN or API_EMAIL/API_PASSWORD in the app configuration to use live Velocity data."
            )
        }

        guard let loginURL = buildURL(path: "/api/auth/login", queryItems: []) else {
            throw VelocityAPIError.notConfigured("Velocity backend base URL is invalid.")
        }

        var request = URLRequest(url: loginURL)
        request.httpMethod = "POST"
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        request.setValue("application/json", forHTTPHeaderField: "Accept")
        request.httpBody = try JSONEncoder().encode(LoginBody(email: email, password: password))
        request.timeoutInterval = 30

        let response: LoginResponse = try await perform(request)
        cachedToken = response.accessToken
        return response.accessToken
    }

    private func perform<T: Decodable>(_ request: URLRequest) async throws -> T {
        let (data, response) = try await URLSession.shared.data(for: request)
        guard let http = response as? HTTPURLResponse else {
            throw VelocityAPIError.invalidResponse
        }
        guard 200..<300 ~= http.statusCode else {
            if let apiError = try? decoder.decode(APIErrorPayload.self, from: data), let detail = apiError.detail {
                throw VelocityAPIError.api(detail)
            }
            throw VelocityAPIError.api("Velocity request failed with HTTP \(http.statusCode).")
        }
        do {
            return try decoder.decode(T.self, from: data)
        } catch {
            throw VelocityAPIError.invalidResponse
        }
    }
}

private struct APIErrorPayload: Decodable {
    let detail: String?
}