import SwiftUI

struct FileView: View {

    @Environment(\.colorScheme) private var colorScheme
    @State private var model: FileViewModel

    init(client: GitbayClient, repo: String, path: String, ref: String?) {
        _model = State(initialValue: FileViewModel(
            client: client, repoPath: repo, filePath: path, ref: ref
        ))
    }

    var body: some View {
        Group {
            if let file = model.state.value {
                content(file)
            } else {
                Color.clear
            }
        }
        .overlay { LoadStateOverlay(state: model.state) }
        .navigationTitle(model.fileName)
        .navigationBarTitleDisplayMode(.inline)
        .task { await model.load() }
    }

    @ViewBuilder
    private func content(_ file: FileContent) -> some View {
        if file.binary {
            ContentUnavailableView {
                Label("Binary file", systemImage: "doc.zipper")
            } description: {
                Text("\(file.file) · \(Int64(file.size).formatted(.byteCount(style: .file)))")
            }
        } else if let text = file.content {
            VStack(spacing: 0) {
                if file.isTruncated {
                    Label(
                        "Truncated — showing the first \(Int64(file.size).formatted(.byteCount(style: .file))).",
                        systemImage: "scissors"
                    )
                    .font(.caption)
                    .frame(maxWidth: .infinity, alignment: .leading)
                    .padding(8)
                    .background(.yellow.opacity(0.15))
                }
                CodeScrollView(text: text, fileName: model.fileName, colorScheme: colorScheme)
            }
        }
    }
}

/// Both-axis scrolling for code, highlighted when the language is known.
private struct CodeScrollView: View {

    let text: String
    let fileName: String
    let colorScheme: ColorScheme

    var body: some View {
        ScrollView([.horizontal, .vertical]) {
            code
                .padding(12)
                .frame(maxWidth: .infinity, alignment: .leading)
        }
        .font(.caption.monospaced())
    }

    private var code: some View {
        let font = UIFont.monospacedSystemFont(
            ofSize: UIFont.preferredFont(forTextStyle: .caption1).pointSize, weight: .regular
        )
        let highlighter = SyntaxHighlighter(colorScheme: colorScheme)
        if let highlighted = highlighter.highlight(text, fileName: fileName, font: font) {
            return Text(AttributedString(highlighted))
        }
        return Text(text)
    }
}