// Auteur : Simon-Pierre Boucher — contact@spboucher.ai
// Client de l'API de production Vrai-Prix (https://www.vrai-prix.com).
import Foundation

enum APIError: LocalizedError {
    case server(String)
    case http(Int)

    var errorDescription: String? {
        switch self {
        case .server(let message): return message
        case .http(let code): return "Erreur réseau (\(code)). Réessayez."
        }
    }
}

struct VraiPrixAPI {
    static let shared = VraiPrixAPI()
    let base = URL(string: "https://www.vrai-prix.com")!

    private func decode<T: Decodable>(_ type: T.Type, from data: Data, status: Int) throws -> T {
        guard (200...299).contains(status) else {
            if let payload = try? JSONDecoder().decode(APIErrorPayload.self, from: data) {
                throw APIError.server(payload.error)
            }
            throw APIError.http(status)
        }
        return try JSONDecoder().decode(type, from: data)
    }

    private func get<T: Decodable>(_ type: T.Type, path: String, query: [URLQueryItem]) async throws -> T {
        var comps = URLComponents(url: base.appending(path: path), resolvingAgainstBaseURL: false)!
        comps.queryItems = query
        let (data, response) = try await URLSession.shared.data(from: comps.url!)
        let status = (response as? HTTPURLResponse)?.statusCode ?? 0
        return try decode(type, from: data, status: status)
    }

    // MARK: Endpoints

    func search(_ q: String) async throws -> [SearchResult] {
        try await get(SearchResponse.self, path: "/api/search", query: [.init(name: "q", value: q)]).results
    }

    func nearby(lat: Double, lng: Double, halfLat: Double, halfLng: Double, limit: Int = 250) async throws -> [NearbyUnit] {
        try await get(NearbyResponse.self, path: "/api/nearby", query: [
            .init(name: "lat", value: String(lat)),
            .init(name: "lng", value: String(lng)),
            .init(name: "halfLat", value: String(halfLat)),
            .init(name: "halfLng", value: String(halfLng)),
            .init(name: "limit", value: String(limit)),
        ]).results
    }

    func estimate(id: String) async throws -> UnitEstimate {
        try await get(UnitEstimate.self, path: "/api/estimate", query: [.init(name: "id", value: id)])
    }

    func estimateManual(
        municipality: String,
        typeProp: String,
        floorArea: Double?,
        yearBuilt: Int?,
        landArea: Double?
    ) async throws -> UnitEstimate {
        var body: [String: Any] = ["municipality": municipality, "typeProp": typeProp]
        if let floorArea { body["floorArea"] = floorArea }
        if let yearBuilt { body["yearBuilt"] = yearBuilt }
        if let landArea { body["landArea"] = landArea }

        var request = URLRequest(url: base.appending(path: "/api/estimate"))
        request.httpMethod = "POST"
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        request.httpBody = try JSONSerialization.data(withJSONObject: body)
        let (data, response) = try await URLSession.shared.data(for: request)
        let status = (response as? HTTPURLResponse)?.statusCode ?? 0
        return try decode(UnitEstimate.self, from: data, status: status)
    }

    /// Télécharge un rapport PDF dans un fichier temporaire et retourne son URL locale.
    func downloadReport(path: String, query: [URLQueryItem], fileName: String) async throws -> URL {
        var comps = URLComponents(url: base.appending(path: path), resolvingAgainstBaseURL: false)!
        comps.queryItems = query
        let (data, response) = try await URLSession.shared.data(from: comps.url!)
        let status = (response as? HTTPURLResponse)?.statusCode ?? 0
        guard (200...299).contains(status) else {
            if let payload = try? JSONDecoder().decode(APIErrorPayload.self, from: data) {
                throw APIError.server(payload.error)
            }
            throw APIError.http(status)
        }
        let url = FileManager.default.temporaryDirectory.appending(path: fileName)
        try data.write(to: url)
        return url
    }
}