// 
// Copyright 2020 New Vector Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import Foundation

/// `HomeserverConfigurationBuilder` build `HomeserverConfiguration` objects according to injected inputs
@objcMembers
final class HomeserverConfigurationBuilder: NSObject {

    // MARK: - Properties
    
    private let vectorWellKnownParser = VectorWellKnownParser()
    
    // MARK: - Public
    
    /// Create an `HomeserverConfiguration` from an HS Well-Known when possible otherwise it takes hardcoded values from BuildSettings by default.
    func build(from wellKnown: MXWellKnown?) -> HomeserverConfiguration {
                
        let isE2EEByDefaultEnabled: Bool
        let jitsiPreferredDomain: String
        
        var vectorWellKnownEncryptionConfiguration: VectorWellKnownEncryptionConfiguration?
        var vectorWellKnownJitsiConfiguration: VectorWellKnownJitsiConfiguration?
        
        if let wellKnown = wellKnown, let vectorWellKnown = self.vectorWellKnownParser.parse(jsonDictionary: wellKnown.jsonDictionary()) {
            vectorWellKnownEncryptionConfiguration = self.getEncryptionConfiguration(from: vectorWellKnown)
            vectorWellKnownJitsiConfiguration = self.getJitsiConfiguration(from: vectorWellKnown)
        }
        
        // Encryption configuration
        if let vectorWellKnownEncryptionConfig = vectorWellKnownEncryptionConfiguration {
            isE2EEByDefaultEnabled = vectorWellKnownEncryptionConfig.isE2EEByDefaultEnabled
        } else {
            // Enable E2EE by default when there is no value
            isE2EEByDefaultEnabled = true
        }
        
        // Jitsi configuration
        let jitsiServerURL: URL
        let hardcodedJitsiServerURL: URL = BuildSettings.jitsiServerUrl
        
        if let vectorWellKnownJitsiConfig = vectorWellKnownJitsiConfiguration {
            jitsiPreferredDomain = vectorWellKnownJitsiConfig.preferredDomain
            jitsiServerURL = self.jitsiServerURL(from: jitsiPreferredDomain) ?? hardcodedJitsiServerURL
        } else {
            guard let hardcodedJitsiDomain = hardcodedJitsiServerURL.host else {
                fatalError("[HomeserverConfigurationBuilder] Fail to get Jitsi domain from hardcoded Jitsi URL")
            }
            jitsiPreferredDomain = hardcodedJitsiDomain
            jitsiServerURL = hardcodedJitsiServerURL
        }
        
        // Create HomeserverConfiguration
        
        let jitsiConfiguration = HomeserverJitsiConfiguration(serverDomain: jitsiPreferredDomain,
                                                              serverURL: jitsiServerURL)
                
        return HomeserverConfiguration(jitsi: jitsiConfiguration, isE2EEByDefaultEnabled: isE2EEByDefaultEnabled)
    }
    
    // MARK: - Private
    
    private func getJitsiConfiguration(from vectorWellKnown: VectorWellKnown) -> VectorWellKnownJitsiConfiguration? {
                
        let jitsiConfiguration: VectorWellKnownJitsiConfiguration?
        
        if let lastJitsiConfiguration = vectorWellKnown.jitsi {
            jitsiConfiguration = lastJitsiConfiguration
        } else if let deprecatedJitsiConfiguration = vectorWellKnown.deprecatedJitsi {
            NSLog("[HomeserverConfigurationBuilder] getJitsiConfiguration - Use deprecated configuration")
            jitsiConfiguration = deprecatedJitsiConfiguration
        } else {
            NSLog("[HomeserverConfigurationBuilder] getJitsiConfiguration - No configuration found")
            jitsiConfiguration = nil
        }
        
        return jitsiConfiguration
    }
    
    private func getEncryptionConfiguration(from vectorWellKnown: VectorWellKnown) -> VectorWellKnownEncryptionConfiguration? {
        
        let encryptionConfiguration: VectorWellKnownEncryptionConfiguration?
        
        if let lastEncryptionConfiguration = vectorWellKnown.encryption {
            encryptionConfiguration = lastEncryptionConfiguration
        } else if let deprecatedEncryptionConfiguration = vectorWellKnown.deprecatedEncryption {
            NSLog("[HomeserverConfigurationBuilder] getEncryptionConfiguration - Use deprecated configuration")
            encryptionConfiguration = deprecatedEncryptionConfiguration
        } else {
            NSLog("[HomeserverConfigurationBuilder] getEncryptionConfiguration - No configuration found")
            encryptionConfiguration = nil
        }
        
        return encryptionConfiguration
    }
    
    private func jitsiServerURL(from jitsiServerDomain: String) -> URL? {
        let jitsiStringURL: String
        if jitsiServerDomain.starts(with: "http") {
            jitsiStringURL = jitsiServerDomain
        } else {
            jitsiStringURL = "https://\(jitsiServerDomain)"
        }
        
        guard let jitsiServerURL = URL(string: jitsiStringURL) else {
            NSLog("[HomeserverConfigurationBuilder] Jitsi server URL is not valid")
            return nil
        }
        
        return jitsiServerURL
    }
}