import Foundation
import UIKit

@MainActor
final class StubLeadDetailRemoteService: LeadDetailRemoteService {
    enum Scenario { case success, offline, timeout, http(Int), invalidFile }
    var detailScenario: Scenario = .success
    var fileScenario: Scenario = .success
    var delay: Duration
    private(set) var downloadCount = 0
    private let leads: any LeadRemoteService

    init(leads: (any LeadRemoteService)? = nil,
         delay: Duration = .milliseconds(400)) {
        self.leads = leads ?? StubLeadRemoteService(delay: .zero)
        self.delay = delay
    }

    func fetchDetail(id: String, salesCode: String) async throws -> LeadDetailDTO {
        try await simulate(detailScenario)
        let lead = try await leads.fetchLead(id: id, salesCode: salesCode).toDomain()
        return LeadDetailDTO(detail: LeadDetailSampleData.make(for: lead))
    }

    func download(_ reference: LeadFileReference, leadID: String, salesCode: String) async throws -> Data {
        downloadCount += 1
        try await simulate(fileScenario)
        if case .invalidFile = fileScenario { return Data("not a valid file".utf8) }
        let lead = try await leads.fetchLead(id: leadID, salesCode: salesCode).toDomain()
        let detail = LeadDetailSampleData.make(for: lead)
        switch reference.kind {
        case .pdf:
            guard let document = detail.offers.flatMap(\.documents).first(where: { $0.file == reference }) else {
                throw LeadRemoteError.http(statusCode: 404)
            }
            return makePDF(document: document, customer: lead.displayName)
        case .image:
            guard let photo = detail.photos.first(where: { $0.thumbnail == reference || $0.original == reference }) else {
                throw LeadRemoteError.http(statusCode: 404)
            }
            return makeImage(photo: photo, thumbnail: reference == photo.thumbnail)
        }
    }

    private func simulate(_ scenario: Scenario) async throws {
        try await Task.sleep(for: delay)
        try Task.checkCancellation()
        switch scenario {
        case .success, .invalidFile: break
        case .offline: throw URLError(.notConnectedToInternet)
        case .timeout: throw URLError(.timedOut)
        case .http(let code): throw LeadRemoteError.http(statusCode: code)
        }
    }

    private func makePDF(document: LeadDocument, customer: String) -> Data {
        let renderer = UIGraphicsPDFRenderer(bounds: CGRect(x: 0, y: 0, width: 595, height: 842))
        return renderer.pdfData { context in
            for page in 1...document.pageCount {
                context.beginPage()
                let title = document.title.replacingOccurrences(of: ".pdf", with: "")
                (title as NSString).draw(in: CGRect(x: 48, y: 56, width: 499, height: 100),
                                        withAttributes: [.font: UIFont.boldSystemFont(ofSize: 24)])
                let body = """
                DrachenGas – Beispieldokument
                \(customer)

                Seite \(page) von \(document.pageCount)

                Diese Datei dient ausschließlich zur Vorschau der Download- und PDF-Anzeige.
                Sie enthält keine verbindlichen Vertragsbedingungen.

                Bitte prüfen Sie alle Seiten vor der Unterschrift.
                """
                (body as NSString).draw(in: CGRect(x: 48, y: 180, width: 499, height: 540),
                                       withAttributes: [.font: UIFont.systemFont(ofSize: 15),
                                                        .foregroundColor: UIColor.darkGray])
                if let placement = document.signaturePlacement, placement.pageIndex == page - 1 {
                    let bounds = placement.bounds
                    let field = CGRect(x: bounds.minX, y: 842 - bounds.maxY,
                                       width: bounds.width, height: bounds.height)
                    UIColor.lightGray.setStroke()
                    UIBezierPath(rect: field).stroke()
                    ("Unterschrift Kunde" as NSString).draw(
                        at: CGPoint(x: field.minX, y: field.maxY + 8),
                        withAttributes: [.font: UIFont.systemFont(ofSize: 11),
                                         .foregroundColor: UIColor.darkGray]
                    )
                }
            }
        }
    }

    private func makeImage(photo: LeadPhoto, thumbnail: Bool) -> Data {
        let size = thumbnail ? CGSize(width: 360, height: 220) : CGSize(width: 1200, height: 800)
        let renderer = UIGraphicsImageRenderer(size: size)
        return renderer.pngData { context in
            UIColor.systemTeal.withAlphaComponent(0.14).setFill()
            context.fill(CGRect(origin: .zero, size: size))
            let symbol = UIImage(systemName: photo.isAR ? "arkit" : "photo")?
                .withTintColor(.systemBlue, renderingMode: .alwaysOriginal)
            symbol?.draw(in: CGRect(x: size.width * 0.4, y: size.height * 0.2,
                                   width: size.width * 0.2, height: size.height * 0.35))
            ("Beispiel · \(photo.title)" as NSString).draw(
                in: CGRect(x: 20, y: size.height * 0.72, width: size.width - 40, height: 60),
                withAttributes: [.font: UIFont.systemFont(ofSize: thumbnail ? 16 : 32),
                                 .foregroundColor: UIColor.darkGray]
            )
        }
    }
}