import SwiftUI

struct EntrySheet: View {
    @EnvironmentObject var store: Store
    @EnvironmentObject var ui: UIState
    @Environment(\.dismiss) private var dismiss

    @State private var entry: Entry
    @State private var date: Date
    @State private var showAll = false

    init(entry: Entry) {
        _entry = State(initialValue: entry)
        _date = State(initialValue: Day.date(entry.date) ?? Date())
    }

    private var task: DutyTask? { store.task(entry.task) }
    private var showPartner: Bool { task?.withPartner == true || !entry.partner.isEmpty }

    private func people(for taskID: String?, keep: String) -> [Person] {
        store.personsSorted.filter { showAll || taskID == nil || $0.may(taskID!) || $0.id == keep }
    }

    private var warnings: [String] {
        var w: [String] = []
        if let t = task, let p = store.person(entry.person), !p.may(t.id) { w.append("\(p.name) ist für „\(t.name)“ nicht freigegeben.") }
        if let pa = store.person(entry.partner), !pa.may("partner") { w.append("\(pa.name) ist nicht als Partner freigegeben.") }
        if !entry.partner.isEmpty, entry.partner == entry.person { w.append("Person und Partner sind gleich.") }
        return w
    }

    var body: some View {
        VStack(alignment: .leading, spacing: 16) {
            Text(entry.isNew ? "Neuer Eintrag" : "Eintrag bearbeiten").font(.title3.weight(.semibold))

            Form {
                DatePicker("Datum", selection: $date, displayedComponents: .date)
                    .datePickerStyle(.field)
                Picker("Aufgabe", selection: $entry.task) {
                    Text("Aufgabe wählen …").tag("")
                    ForEach(TaskGroup.allCases) { g in
                        Section(g.shortTitle) {
                            ForEach(store.db.tasks.filter { $0.group == g && !$0.partnerColumn }) { Text($0.name).tag($0.id) }
                        }
                    }
                }
                Picker("Person", selection: $entry.person) {
                    Text("Person wählen …").tag("")
                    ForEach(people(for: task?.id, keep: entry.person)) { Text($0.name).tag($0.id) }
                }
                Toggle("Alle Personen anzeigen (auch ohne Freigabe)", isOn: $showAll)
                if showPartner {
                    Picker("Partner", selection: $entry.partner) {
                        Text("– kein Partner –").tag("")
                        ForEach(people(for: "partner", keep: entry.partner)) { Text($0.name).tag($0.id) }
                    }
                }
                TextField("Thema / Notiz", text: $entry.note, prompt: Text("optional"))
            }
            .formStyle(.columns)

            ForEach(warnings, id: \.self) { w in
                Label(w, systemImage: "exclamationmark.triangle").foregroundStyle(Theme.kohaku).font(.callout)
            }

            HStack {
                if !entry.isNew {
                    Button("Löschen", role: .destructive) { store.delete(entry: entry.id); dismiss() }
                }
                Spacer()
                Button("Abbrechen", role: .cancel) { dismiss() }.keyboardShortcut(.cancelAction)
                Button(entry.isNew ? "Eintragen" : "Sichern", action: save)
                    .keyboardShortcut(.defaultAction)
                    .buttonStyle(.borderedProminent)
                    .disabled(entry.task.isEmpty || entry.person.isEmpty)
            }
        }
        .padding(22)
        .frame(width: 460)
    }

    private func save() {
        var e = entry
        e.date = Day.string(date)
        if !(task?.withPartner ?? false) && e.partner.isEmpty { e.partner = "" }
        let wasNew = e.isNew
        if wasNew { e.id = newID("e") }
        e.note = e.note.trimmingCharacters(in: .whitespaces)
        store.save(entry: e)
        dismiss()
        ui.show(wasNew ? "Eingetragen: \(store.task(e.task)?.name ?? "") · \(store.name(e.person))" : "Eintrag geändert.")
    }
}