import SwiftUI

extension AttributedString {
    init(styledMarkdown markdownString: String) throws {
        var output = try AttributedString(
            markdown: markdownString,
            options: .init(
                allowsExtendedAttributes: true,
                interpretedSyntax: .full,
                failurePolicy: .returnPartiallyParsedIfPossible
            ),
            baseURL: nil
        )

        for (intentBlock, intentRange) in output.runs[AttributeScopes.FoundationAttributes.PresentationIntentAttribute.self].reversed() {
            guard let intentBlock = intentBlock else { continue }
            for intent in intentBlock.components {
                switch intent.kind {
                case .header(level: let level):
                    switch level {
                    case 1:
                        output[intentRange].font = .system(.title).bold()
                    case 2:
                        output[intentRange].font = .system(.title2).bold()
                    case 3:
                        output[intentRange].font = .system(.title3).bold()
                    default:
                        break
                    }
                default:
                    break
                }
            }

            if intentRange.lowerBound != output.startIndex {
                output.characters.insert(contentsOf: "\n\n", at: intentRange.lowerBound)
            }
        }

        self = output
    }
}

struct ReleaseNotesView: View {
    @Environment(\.dismiss) private var dismiss

    var body: some View {
        NavigationView {
            ScrollView {
                VStack(alignment: .leading, spacing: 16) {
                    if let attributedString = loadReleaseNotes() {
                        Text(attributedString)
                            .textSelection(.enabled)
                            .padding()
                    } else {
                        Text("Unable to load release notes")
                            .foregroundColor(.secondary)
                            .padding()
                    }
                }
            }
            .navigationTitle("What's New")
            .navigationBarTitleDisplayMode(.large)
            .toolbar {
                ToolbarItem(placement: .confirmationAction) {
                    Button("Done") {
                        dismiss()
                    }
                }
            }
        }
    }

    private func loadReleaseNotes() -> AttributedString? {
        guard let url = Bundle.main.url(forResource: "RELEASE_NOTES", withExtension: "md"),
              let markdownContent = try? String(contentsOf: url),
              let attributedString = try? AttributedString(styledMarkdown: markdownContent) else {
            return nil
        }
        return attributedString
    }
}

#Preview {
    ReleaseNotesView()
}