// The Swift Programming Language
// https://docs.swift.org/swift-book

import Foundation

public class OpenFoodFactsClient {
    let version: Int = 0
    public var prod: Bool = false
    var baseURL: URL? {
        if prod {
            return URL(string: "https://world.openfoodfacts.org/api/v\(version)")
        } else {
            return URL(string: "https://world.openfoodfacts.net/api/v\(version)")
        }
    }

    public init() {}

    public func getProductByBarcode(_ barcode: String) async throws -> ProductResponse {
        guard let endpoint = baseURL?.appendingPathComponent("product/\(barcode)") else { throw OFFError.invalidURL }
        var request = URLRequest(url: endpoint)
        request.setValue("application/json", forHTTPHeaderField: "accept")
        let (data, response) = try await URLSession.shared.data(for: request)

        guard let response = response as? HTTPURLResponse, response.statusCode == 200 else {
            throw OFFError.invalidResponse
        }
        do {
            return try JSONDecoder().decode(ProductResponse.self, from: data)
        }
    }

    public struct SearchQuery {
        public let additivesTags: String?
        public let allergensTags: String?
        public let brandsTags: String?
        public let categoriesTags: String?
        public let countriesTagsEn: String?
        public let embCodesTags: String?
        public let labelsTags: String?
        public let manufacturingPlacesTags: String?
        public let nutritionGradesTags: String?
        public let originsTags: String?
        public let packagingTagsDe: String?
        public let purchasePlacesTags: String?
    }

    public func search(_ productName: String, queryParams: SearchQuery? = nil) async throws -> SearchResponse {
        let qp = Mirror(reflecting: queryParams ?? {})
        var s: String = "?product_name=\(productName)&"
        for case let (label?, value) in qp.children {
            s += label.camelCaseToSnakeCase() + "=" + (value as! String) + "&"
        }
        guard let endpoint = baseURL?.appendingPathComponent("search\(s)") else { throw OFFError.invalidURL }
        var request = URLRequest(url: endpoint)
        request.setValue("application/json", forHTTPHeaderField: "accept")

        let (data, response) = try await URLSession.shared.data(for: request)
        guard let response = response as? HTTPURLResponse, response.statusCode == 200 else {
            throw OFFError.invalidResponse
        }
        do {
            return try JSONDecoder().decode(SearchResponse.self, from: data)
        }
    }
}

enum OFFError: Error {
    case invalidURL, invalidResponse
}