//Made by Lumaa

import SwiftUI
import AuthenticationServices

struct AddInstanceView: View {
    @Environment(\.webAuthenticationSession) private var webAuthenticationSession
    @Environment(\.dismiss) private var dismiss
    
    // Instance URL and verify
    @State private var instanceUrl: String = ""
    @State private var verifying: Bool = false
    @State private var verified: Bool = false
    @State private var verifyError: Bool = false
    @State private var instanceInfo: Instance?
    
    @State private var signInClient: Client?
    @Binding public var logged: Bool
    
    var body: some View {
        Form {
            Section {
                TextField("login.mastodon.instance", text: $instanceUrl)
                    .keyboardType(.URL)
                    .textContentType(.URL)
                    .autocorrectionDisabled()
                    .textInputAutocapitalization(.never)
                    .disabled(verifying)
                
                if !verifying {
                    if !verified {
                        Button {
                            verify()
                        } label: {
                            Text("login.mastodon.verify")
                                .disabled(instanceUrl.isEmpty)
                        }
                        .buttonStyle(.bordered)
                        
                        if verifyError == true {
                            Text("login.mastodon.verify-error")
                                .foregroundStyle(.red)
                        }
                    } else {
                        Button {
                            Task {
                                await signIn()
                            }
                        } label: {
                            Text("login.mastodon.login")
                                .disabled(instanceUrl.isEmpty)
                        }
                        .buttonStyle(.bordered)
                    }
                } else {
                    ProgressView()
                        .progressViewStyle(.circular)
                        .tint(Color.white)
                        .foregroundStyle(Color.white)
                }
            }
                
            if verified && instanceInfo != nil {
                Section {
                    VStack(alignment: .leading) {
                        Text(instanceInfo!.title)
                            .font(.headline)
                        Text(instanceInfo!.shortDescription)
                    }
                    
                    VStack(alignment: .leading, spacing: 15) {
                        Text("instance.rules")
                            .font(.headline)
                        
                        if !(instanceInfo!.rules?.isEmpty ?? true) {
                            ForEach(instanceInfo!.rules!) { rule in
                                Text(rule.text)
                            }
                        }
                    }
                }
            }
        }
        .scrollContentBackground(.hidden)
        .background(Color.appBackground)
        .onChange(of: instanceUrl) { _, newValue in
            guard !self.verifying else { return }
            verified = false
        }
    }
    
    func verify() {
        withAnimation {
            verifying = true
            verified = false
            verifyError = false
        }
        
        let cleanInstance = instanceUrl
            .replacingOccurrences(of: "http://", with: "")
            .replacingOccurrences(of: "https://", with: "")
        
        let client = Client(server: cleanInstance)
        
        Task {
            do {
                let instance: Instance = try await client.get(endpoint: Instances.instance)
                
                withAnimation {
                    instanceInfo = instance
                    verifying = false
                    verified = true
                    verifyError = false
                }
            } catch {
                print(error.localizedDescription)
                
                withAnimation {
                    verifying = false
                    verified = false
                    verifyError = true
                }
            }
        }
    }
    
    private func signIn() async {
        let cleanInstance = instanceUrl
            .replacingOccurrences(of: "http://", with: "")
            .replacingOccurrences(of: "https://", with: "")
        
        signInClient = .init(server: cleanInstance)
        if let oauthURL = try? await signInClient?.oauthURL(),
           let url = try? await webAuthenticationSession.authenticate(using: oauthURL, callbackURLScheme: AppInfo.scheme.replacingOccurrences(of: "://", with: "")) {
            await continueSignIn(url: url)
        }
    }
    
    private func continueSignIn(url: URL) async {
        guard let client = signInClient else {
            return
        }
        
        do {
            let oauthToken = try await client.continueOauthFlow(url: url)
            let client = Client(server: client.server, oauthToken: oauthToken)
            let account: Account = try await client.get(endpoint: Accounts.verifyCredentials)
            let appAcc = AppAccount(server: client.server, accountName: "\(account.acct)@\(client.server)", oauthToken: oauthToken)
            try appAcc.saveAsCurrent()
            
            signInClient = client
            logged = true
            dismiss()
        } catch {
            print(error)
        }
    }
}

#Preview {
    AddInstanceView(logged: .constant(false))
}