import SwiftUI

/// The issue and MR lists' filter sheet. A `Form` with the fields both
/// lists share — author and milestone — plus an `extra` slot for the
/// rows each list adds: the label picker on both, and an assignee field
/// on issues only, since `mr list` takes no `--assignee`.
struct FilterSheet<Extra: View>: View {

    let title: String
    @Binding var author: String?
    @Binding var milestone: String?
    let milestones: [Milestone]
    let onClear: () -> Void
    @ViewBuilder var extra: Extra

    @Environment(\.dismiss) private var dismiss

    var body: some View {
        NavigationStack {
            Form {
                extra
                Section("Author") {
                    TextField("Username", text: $author.orEmpty)
                        .autocorrectionDisabled()
                        .textInputAutocapitalization(.never)
                        .accessibilityIdentifier("filter-author")
                }
                Section("Milestone") {
                    Menu {
                        Button("Any milestone") { milestone = nil }
                        Button("No milestone") { milestone = "none" }
                        ForEach(milestones) { entry in
                            Button(entry.title) { milestone = entry.title }
                        }
                    } label: {
                        HStack {
                            Text(milestone ?? "Any milestone")
                            Spacer()
                            Image(systemName: "chevron.up.chevron.down")
                                .font(.gbSans(.caption2))
                                .foregroundStyle(.secondary)
                        }
                    }
                    .accessibilityIdentifier("filter-milestone-menu")
                }
                Section {
                    Button("Clear filters", role: .destructive, action: onClear)
                }
            }
            .navigationTitle(title)
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .confirmationAction) {
                    Button("Done") { dismiss() }
                }
            }
        }
    }
}

/// The label picker both lists' sheets add through `FilterSheet`'s
/// `extra` slot.
struct LabelFilterSection: View {

    @Binding var label: String?
    let labels: [IssueLabel]
    let colors: LabelColors

    var body: some View {
        Section("Label") {
            Menu {
                Button("Any label") { label = nil }
                ForEach(labels) { entry in
                    Button {
                        label = entry.name
                    } label: {
                        Text(entry.name)
                    }
                }
            } label: {
                HStack {
                    if let label {
                        GBChip(label, colors.color(label))
                    } else {
                        Text("Any label")
                    }
                    Spacer()
                    Image(systemName: "chevron.up.chevron.down")
                        .font(.gbSans(.caption2))
                        .foregroundStyle(.secondary)
                }
            }
            .accessibilityIdentifier("filter-label-menu")
        }
    }
}

/// The label and assignee rows the issue list's sheet adds through
/// `FilterSheet`'s `extra` slot.
struct IssueFilterExtra: View {

    @Binding var label: String?
    @Binding var assignee: String?
    let labels: [IssueLabel]
    let colors: LabelColors

    var body: some View {
        LabelFilterSection(label: $label, labels: labels, colors: colors)
        Section("Assignee") {
            TextField("Username", text: $assignee.orEmpty)
                .autocorrectionDisabled()
                .textInputAutocapitalization(.never)
                .accessibilityIdentifier("filter-assignee")
        }
    }
}

extension Binding where Value == String? {
    /// Bridges an optional filter field to a plain `TextField`: empty
    /// text writes back `nil` rather than `""`, since the two are
    /// distinct filter values (no flag sent versus `--flag ""`).
    var orEmpty: Binding<String> {
        Binding<String>(
            get: { self.wrappedValue ?? "" },
            set: { self.wrappedValue = $0.isEmpty ? nil : $0 }
        )
    }
}