import Foundation
import Library
import SwiftUI
import UniformTypeIdentifiers

public struct ServiceLogView: View {
    #if os(macOS)
        public static let windowID = "service-log"
    #endif

    @State private var isLoading = true
    @State private var content = ""
    @State private var fileExporterPresented = false
    private let logFont = Font.system(.caption, design: .monospaced)

    public init() {}

    public var body: some View {
        viewBuilder {
            if isLoading {
                ProgressView().onAppear {
                    Task.detached {
                        loadContent()
                    }
                }
            } else {
                if content.isEmpty {
                    Text("Empty content")
                } else {
                    ScrollView {
                        Text(content).font(logFont)
                    }
                    .padding()
                }
            }
        }
        .toolbar {
            Button("Export") {
                fileExporterPresented = true
            }
            .disabled(content.isEmpty)
        }
        .fileExporter(
            isPresented: $fileExporterPresented,
            document: LogDocument(content),
            contentType: .text,
            defaultFilename: "service-log.txt",
            onCompletion: { _ in }
        )
        .navigationTitle("Service Log")
        #if os(iOS)
            .navigationBarTitleDisplayMode(.inline)
        #endif
    }

    private func loadContent() {
        do {
            content = try String(contentsOf: FilePath.cacheDirectory.appendingPathComponent("stderr.log"))
        } catch {}
        if content.isEmpty {
            do {
                content = try String(contentsOf: FilePath.cacheDirectory.appendingPathComponent("stderr.log.old"))
            } catch {}
        }
        isLoading = false
    }

    private struct LogDocument: FileDocument {
        static var readableContentTypes = [UTType.text]

        let content: String

        init(_ content: String) {
            self.content = content
        }

        init(configuration: ReadConfiguration) throws {
            if let data = configuration.file.regularFileContents {
                content = String(decoding: data, as: UTF8.self)
            } else {
                content = ""
            }
        }

        func fileWrapper(configuration _: WriteConfiguration) throws -> FileWrapper {
            FileWrapper(regularFileWithContents: Data(content.utf8))
        }
    }
}