lanework/Kanban/UI/Card/CardSidebarSections.swift

import AppKit
import SwiftUI

// MARK: - Style

/// The sidebar's **Style** section: the **Background color combo** over the compact **`SymbolPicker`**
/// (05-card-window.md ▸ Style; 03-board-ui.md ▸ Styling ▸ Controls, its 2026-08-06 anchor-ownership
/// rule for the background half, extended to the symbol half on 2026-08-08). Card styling is
/// discoverable here without a context menu — the picker is the same reusable control the board
/// popover's glyph picker beside the rename field already uses (`BoardInfoPopover`).
///
/// ### Why the curated grid left
///
/// `StyleEditorView`'s curated grid used to draw **whole, uncollapsed** in this column
/// (`StyleEditorLayout.sidebar`'s `symbolGridMaximumHeight: nil` — "the sidebar is already a scroll
/// view, and a scroll view inside a scroll view is a scroll view that fights") — a five-to-seven-row
/// grid, permanently open, ahead of every other section the sidebar carries. `SymbolPicker` is the
/// general-purpose control built for precisely this shape of problem (its own header: "a control any
/// caller can aim at one symbol field without wiring up a `BoardStore`, a `StyleTarget`, or the
/// two-dimension batch machinery `StyleEditorView` carries") — one small well at rest, the grid only
/// while its popover is open. This section is the first caller to aim it at a store-backed field
/// rather than a plain binding, which is why it does the store plumbing below that `SymbolPicker`
/// itself deliberately knows nothing about.
///
/// **`StyleEditorView` is no longer instantiated here at all.** It was already `showsBackground:
/// false` — the color combo has owned the background half since 2026-08-06 — so the curated symbol
/// grid was its only remaining job in this section, and that job is what moved. The shared
/// component's `.sidebar` layout variant and `showsBackground` toggle stay in `StyleEditor.swift`
/// regardless: they are still correct and still tested (`StyleEditorLayoutTests`), and that file's own
/// stance is to be anchor-agnostic about callers it does not currently have. Retiring them as dead
/// code is a separate, larger cut this card does not make.
///
/// ### The curated set does not shrink
///
/// `SymbolPicker`'s own default (`SymbolPickerCatalog.defaultSet`, 36 general "boards and projects"
/// glyphs) is deliberately smaller than `CuratedSymbols.cards` (~40, work-item/content-flavored — one
/// of the three level-specific sets `CuratedSymbols` split into, 2026-08-09) — `SymbolPicker.swift`'s
/// own doc comment states why the lists are free to diverge. A card is exactly the level
/// `CuratedSymbols.cards` is grouped for, so this section passes it explicitly (`symbols:
/// CuratedSymbols.availableCards`) rather than taking the picker's domain-agnostic default: the
/// Style… popover's card-level grid and this section now offer the identical curated vocabulary,
/// through two different controls.
///
/// ### Writes still ride the one funnel, on this window's own stack
///
/// `onSelect`/`onSelectColor` below call `StyleCommand.apply(icon:iconColor:to:in:store:recents:on:)`
/// — the same funnel `StyleEditorView`'s wells rode, `on: undo` passed through exactly as before
/// (13-native-undo.md ▸ Rules ▸ two levels: a colour or symbol chosen here is a gesture *issued in
/// this window*, so its step joins the window's session and reaches board history only inside the
/// coarse close step — this section's own note on `undo` below, unchanged by the control swap).
/// Nothing about `BoardStore.applyStyle`'s batch semantics, its no-op skipping, or its `HistoryAnchor`
/// choice moved; only the view that calls it did — `CardSessionUndoTests.sidebarStylingIsASessionGesture`
/// calls that same funnel directly and needed no change.
///
/// ### The target is fixed, and that is the whole difference in behavior
///
/// The Style… popover *tracks*: its target is the selection at the moment the gesture named it,
/// re-resolved against every snapshot, dismissing when it empties (`StyleEditorSession`). This
/// section tracks nothing. Its target is this window's card, always — "the two embedded anchors need
/// none of this and get none: the card sidebar dismisses with its card's window, and the board
/// popover's target is the board itself" (`StyleEditorSession`'s own note). `SymbolPicker`'s own
/// popover presentation is plain view-local `@State`, needing no session for the same reason: the
/// window's card cannot vanish out from under its own window, and when it does the window goes with
/// it (`CardWindowFate`).
struct CardStyleSection: View {

    let store: BoardStore
    let recents: StyleRecents
    let cardID: ItemID
    /// **This window's undo stack** (13-native-undo.md ▸ Rules ▸ two levels): a colour or symbol
    /// chosen here is a gesture *issued in this window*, so its step joins the window's session and
    /// reaches board history only inside the coarse close step. The background combo below and the
    /// symbol picker both take it as a parameter, for the same reason.
    let undo: CardWindowUndo

    /// The trailing debounce on a live colour-panel drag (`ColorComboView`'s `onPanelChange`,
    /// opened from the combo's **Other…** row): cancelled and replaced on every tick, so only the
    /// value the user is still on ~400ms after the last one actually reaches disk. One task for the
    /// section's one combo.
    @State private var backgroundPanelCommit: Task<Void, Never>?

    /// The live body metric, read here rather than passed in — `CardAttachmentsSection`'s pattern,
    /// so every section in this sidebar derives its geometry the same way.
    private var pointSize: CGFloat { CardWindowMetrics.bodyPointSize }

    /// **What this section styles: this card, and nothing else.**
    ///
    /// A one-line seam because it is a claim worth pinning rather than a computation worth reading:
    /// every other anchor derives its target from something that moves (the selection, the board),
    /// and the mistake this window could make is inheriting one of those. `.items` of exactly one id
    /// also means `applyStyle`'s own batch machinery is a no-op here — one subject, so the display is
    /// never mixed and the write bracket holds one file.
    nonisolated static func target(forCard id: ItemID) -> StyleTarget {
        .items([id])
    }

    var body: some View {
        VStack(alignment: .leading, spacing: CardWindowMetrics.sidebarRowSpacing(bodyPointSize: pointSize)) {
            CardSidebarSectionHeader(title: "Style")
            backgroundComboRow
            symbolRow
        }
        .frame(maxWidth: .infinity, alignment: .leading)
    }

    // MARK: - Background combo

    /// The labeled **Background** row, above the well grid — a narrower, single-value alternative
    /// to it (`ColorCombo.swift`'s own doc comment): an inspector row, caption leading and a
    /// compact combo trailing, the arrangement every Xcode inspector uses for exactly this control.
    ///
    /// **No explicit width since 2026-08-09** — the combo used to be stretched to just over half the
    /// row (`CardWindowMetrics.sidebarContentWidth(...) * 0.55`), which was the wide-bar shape the
    /// owner's iteration undid. `ComboFieldMetrics` now carries its own taller, narrower intrinsic
    /// width, so the row hands the combo no frame at all and lets it size itself; the leading
    /// `Spacer(minLength: 8)` still pins it to the row's trailing edge.
    private var backgroundComboRow: some View {
        HStack(spacing: 0) {
            Text("Background")
                .font(.caption)
                .foregroundStyle(.secondary)
            Spacer(minLength: 8)
            ColorComboView(
                role: .background,
                value: currentBackground,
                isEnabled: !store.isReadOnly,
                onChange: { commitBackground($0) },
                onPanelChange: { debounceBackground($0) }
            )
        }
        .frame(maxWidth: .infinity, alignment: .leading)
    }

    /// The card's `background` field, exactly as written — malformed reads as its raw text, missing
    /// reads `nil`, both `StyleFieldState.written`'s own rule (`StyleModel.swift`). The **raw**
    /// string, never a resolved colour: `ColorComboModel`'s matching needs the bytes, not what they
    /// render as.
    private var currentBackground: String? {
        StyleFieldState.written(currentSubject?.background ?? .missing)
    }

    /// A discrete pick — commits immediately. `nil` removes; a name from `Palette.backgrounds` goes
    /// through `StyleCommand.apply` so it feeds `StyleRecents` exactly like a well click would
    /// ("updated on every background application from any anchor", `StyleEditor.swift`); anything
    /// else — the dynamic current-value row re-affirming a foreign name or a custom hex — writes
    /// directly, since it is not the "palette pick" recents was ever meant to remember.
    private func commitBackground(_ newValue: String?) {
        let target = Self.target(forCard: cardID)
        guard let newValue else {
            store.applyStyle(to: target, background: .remove, icon: .keep, on: undo)
            return
        }
        if Palette.backgrounds.contains(where: { $0.name == newValue }) {
            StyleCommand.apply(background: .set(newValue), to: target, in: store, recents: recents, on: undo)
        } else {
            store.applyStyle(to: target, background: .set(newValue), icon: .keep, on: undo)
        }
    }

    /// One tick of a live colour-panel drag: cancels whatever commit was pending and schedules a new
    /// one ~400ms out, so a drag writes once it settles rather than on every pixel it passes through.
    /// Never routed through `StyleCommand.apply` — a drag that passes through a palette-exact hex
    /// mid-gesture must not spam the recents row the way a deliberate pick would.
    private func debounceBackground(_ newValue: String?) {
        backgroundPanelCommit?.cancel()
        let target = Self.target(forCard: cardID)
        backgroundPanelCommit = Task { @MainActor in
            try? await Task.sleep(for: .milliseconds(400))
            guard !Task.isCancelled else { return }
            if let newValue {
                store.applyStyle(to: target, background: .set(newValue), icon: .keep, on: undo)
            } else {
                store.applyStyle(to: target, background: .remove, icon: .keep, on: undo)
            }
        }
    }

    // MARK: - Symbol

    /// The labeled **Symbol** row, below the background combo — `backgroundComboRow`'s own
    /// inspector-row shape, restated: caption leading, the combo trailing, **at the same size**.
    ///
    /// That size used to be the difference between the two rows. The picker was a 20pt bordered
    /// square with one hit zone sitting under a wide two-zone colour combo, and this is the sidebar
    /// where the mismatch was most visible — two adjacent rows setting two adjacent keys, looking
    /// like different kinds of control. Since the 2026-08-09 rework `SymbolPicker` *is* a combo
    /// (`ComboField.swift`), so the two rows need no frame of their own to agree — both controls read
    /// their geometry off the identical `ComboFieldMetrics`, `backgroundComboRow`'s own note.
    private var symbolRow: some View {
        HStack(spacing: 0) {
            Text("Symbol")
                .font(.caption)
                .foregroundStyle(.secondary)
            Spacer(minLength: 8)
            SymbolPicker(
                current: currentSymbol,
                fallback: ItemSymbol.card,
                symbols: CuratedSymbols.availableCards,
                onSelect: { applySymbol($0) },
                currentColor: currentIconColor,
                onSelectColor: { applyIconColor($0) }
            )
            // The same lock `StyleEditorView`'s whole body disabled under
            // (`.disabled(!store.acceptsBoardMutations)`, `StyleEditor.swift`) — the read-only lock
            // and the board's inline-editing rule alike, preserved exactly across the control swap
            // rather than narrowed to `backgroundComboRow`'s plainer `!store.isReadOnly`.
            .disabled(!store.acceptsBoardMutations)
        }
        .frame(maxWidth: .infinity, alignment: .leading)
    }

    /// One `styleSubjects` lookup behind `currentBackground` above and the two properties below —
    /// a card window names exactly one target, so there is exactly one subject to read for all three
    /// fields.
    private var currentSubject: BoardStore.StyleSubject? {
        store.styleSubjects(of: Self.target(forCard: cardID)).first
    }

    /// The card's `icon` field, exactly as written — `currentBackground`'s rule, restated for the
    /// field `SymbolPicker.current` reads. Resolution (an unresolvable name falling back to the level
    /// default) is `SymbolPicker`'s own job, not this property's — `ItemSymbol.name(_:fallback:)`'s
    /// lenient rule, which the picker's `resolvedName` already applies.
    private var currentSymbol: String? {
        StyleFieldState.written(currentSubject?.icon ?? .missing)
    }

    /// The card's `iconColor` field, exactly as written — one dimension over from `currentSymbol`,
    /// feeding `SymbolPicker.currentColor`.
    private var currentIconColor: String? {
        StyleFieldState.written(currentSubject?.iconColor ?? .missing)
    }

    /// `nil` clears back to the card default (`icon` removed); a name sets it — `StyleChange`'s
    /// `set`/`remove` split, `SymbolPicker.onSelect`'s own contract turned into the vocabulary
    /// `StyleCommand.apply` speaks. Routed through the funnel rather than `store.applyStyle` directly
    /// so a symbol pick joins `StyleRecents` exactly as a background pick does — moot today (only
    /// `.set(background:)` records, `StyleCommand.apply`'s own rule), but future-proof against that
    /// rule ever widening to symbols.
    private func applySymbol(_ name: String?) {
        StyleCommand.apply(
            icon: name.map { StyleChange.set($0) } ?? .remove,
            to: Self.target(forCard: cardID),
            in: store,
            recents: recents,
            on: undo
        )
    }

    /// `nil` clears the tint (`iconColor` removed); a palette name sets it — `applySymbol`'s sibling,
    /// one dimension over, exactly as `BoardInfoPopover`'s own `onSelectColor` writes the board's.
    private func applyIconColor(_ name: String?) {
        StyleCommand.apply(
            iconColor: name.map { StyleChange.set($0) } ?? .remove,
            to: Self.target(forCard: cardID),
            in: store,
            recents: recents,
            on: undo
        )
    }
}