//
// Copyright 2022 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
import SwiftUI

struct FormattedBodyText: View {
    let attributedComponents: [AttributedStringBuilderComponent]
    
    var body: some View {
        VStack(alignment: .leading, spacing: 8.0) {
            ForEach(attributedComponents, id: \.self) { component in
                if component.isBlockquote {
                    Text(component.attributedString.mergingAttributes(blockquoteAttributes))
                        .fixedSize(horizontal: false, vertical: true)
                        .foregroundColor(.element.primaryContent)
                        .padding(EdgeInsets(top: 6, leading: 12, bottom: 6, trailing: 12))
                        .clipped()
                        .background(Color.element.systemGray4)
                        .cornerRadius(13)
                } else {
                    Text(component.attributedString)
                        .fixedSize(horizontal: false, vertical: true)
                        .foregroundColor(.element.primaryContent)
                }
            }
        }
        .tint(.element.accent)
    }

    private var blockquoteAttributes: AttributeContainer {
        var container = AttributeContainer()
        container.font = .element.caption1
        return container
    }
}

extension FormattedBodyText {
    init(text: String) {
        attributedComponents = [.init(attributedString: AttributedString(text), isBlockquote: false)]
    }
}

struct FormattedBodyText_Previews: PreviewProvider {
    static var previews: some View {
        body.preferredColorScheme(.light)
        body.preferredColorScheme(.dark)
    }
    
    @ViewBuilder
    static var body: some View {
        let htmlStrings = [
            """
            Text before blockquote
            <blockquote>
            <b>bold</b> <i>italic</i>
            </blockquote>
            Text after blockquote
            """,
            """
            <blockquote>First blockquote with a <a href=\"https://www.matrix.org/\">link</a> in it</blockquote>
            <blockquote>Second blockquote with a <a href=\"https://www.matrix.org/\">link</a> in it</blockquote>
            <blockquote>Third blockquote with a <a href=\"https://www.matrix.org/\">link</a> in it</blockquote>
            """,
            """
            <code>Hello world</code>
            <p>Text</p>
            <code><b>Hello</b> <i>world</i></code>
            <p>Text</p>
            <code>Hello world</code>
            """
        ]
        
        let attributedStringBuilder = AttributedStringBuilder()
        
        VStack(alignment: .leading, spacing: 24.0) {
            ForEach(htmlStrings, id: \.self) { htmlString in
                let attributedString = attributedStringBuilder.fromHTML(htmlString)
                
                if let components = attributedStringBuilder.blockquoteCoalescedComponentsFrom(attributedString) {
                    FormattedBodyText(attributedComponents: components)
                        .fixedSize()
                }
            }
            FormattedBodyText(text: "Some plain text that's not an attributed component.")
        }
    }
}