import Foundation
import UIKit

/// Area-based resize used by the nyris example web app (includes upscaling small sources).
func jpegForSearch(image: UIImage, maxSide: CGFloat = 1024, quality: CGFloat = 0.9) -> Data? {
    let aspect = image.size.width / max(image.size.height, 1)
    let area = maxSide * maxSide
    let width = max(1, (area * aspect).squareRoot().rounded())
    let height = max(1, (width / max(aspect, 0.0001)).rounded())

    let format = UIGraphicsImageRendererFormat.default()
    // default() uses the screen scale (2x/3x); the size below must be pixels.
    format.scale = 1
    format.opaque = true
    let renderer = UIGraphicsImageRenderer(
        size: CGSize(width: width, height: height),
        format: format
    )
    let rendered = renderer.image { ctx in
        UIColor.white.setFill()
        ctx.fill(CGRect(x: 0, y: 0, width: width, height: height))
        image.draw(in: CGRect(x: 0, y: 0, width: width, height: height))
    }
    return rendered.jpegData(compressionQuality: quality)
}

enum FindError: Error {
    case missingKey
    case http(Int)
}

struct FindClient {
    let apiKey: String
    let baseURL = URL(string: "https://api.nyris.io")!

    /// `text` is a multipart field. Do not put it in the URL query.
    func find(jpeg: Data?, text: String?) async throws -> Data {
        guard !apiKey.isEmpty else { throw FindError.missingKey }
        var request = URLRequest(url: baseURL.appendingPathComponent("find/v1.1"))
        request.httpMethod = "POST"
        let boundary = "----nyris\(UUID().uuidString)"
        request.setValue("multipart/form-data; boundary=\(boundary)", forHTTPHeaderField: "Content-Type")
        request.setValue(apiKey, forHTTPHeaderField: "X-Api-Key")
        request.setValue("application/items.complete+json", forHTTPHeaderField: "Accept")

        var body = Data()
        func append(_ string: String) { body.append(Data(string.utf8)) }

        if let jpeg {
            append("--\(boundary)\r\n")
            append("Content-Disposition: form-data; name=\"image\"; filename=\"query.jpg\"\r\n")
            append("Content-Type: image/jpeg\r\n\r\n")
            body.append(jpeg)
            append("\r\n")
        }
        if let text, !text.isEmpty {
            append("--\(boundary)\r\n")
            append("Content-Disposition: form-data; name=\"text\"\r\n\r\n")
            append(text)
            append("\r\n")
        }
        append("--\(boundary)--\r\n")
        request.httpBody = body

        let (data, response) = try await URLSession.shared.data(for: request)
        let status = (response as? HTTPURLResponse)?.statusCode ?? 0
        guard (200..<300).contains(status) else { throw FindError.http(status) }
        return data
    }

    func regions(jpeg: Data) async throws -> Data {
        guard !apiKey.isEmpty else { throw FindError.missingKey }
        var request = URLRequest(url: baseURL.appendingPathComponent("find/v2/regions"))
        request.httpMethod = "POST"
        request.setValue("image/jpeg", forHTTPHeaderField: "Content-Type")
        request.setValue(apiKey, forHTTPHeaderField: "X-Api-Key")
        request.httpBody = jpeg
        let (data, response) = try await URLSession.shared.data(for: request)
        let status = (response as? HTTPURLResponse)?.statusCode ?? 0
        guard (200..<300).contains(status) else { throw FindError.http(status) }
        return data
    }
}