import AppKit
import SwiftUI

// MARK: - Style

/// The sidebar's **Style** section: "the **embedded style editor** — background palette grid (with
/// the leading None well) and curated symbol grid, per 03-board-ui.md ▸ Styling ▸ Controls. Card
/// styling is discoverable here without a context menu; the same component appears in the board
/// popover and behind Style…" (05-card-window.md ▸ Style).
///
/// ### How this anchor differs from the other two — in one word, geometry
///
/// It hosts `StyleEditorView` itself, not a copy of it: the wells, the batch display, the arrow-key
/// grammar, the read-only disabling, the recents the None well deliberately does not record, and the
/// single `applyStyle` bracket every well's click rides are all the shared component's, identical
/// here. The only thing this anchor supplies beyond a target is a `StyleEditorLayout` — the sidebar
/// is narrower than the popover at every text size, so the grids fall in fewer columns and the
/// symbol grid draws whole instead of scrolling inside the sidebar's own scroll view.
///
/// ### 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). Which is why there is no
/// session here to resolve, no popover to dismiss, and no way for a board-side selection change to
/// re-aim the editor a card window is showing: the window's card is the target by construction, and
/// when that card stops existing 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 shared editor takes it as an
    /// anchor's parameter, exactly as it takes the layout — and so does the background combo below,
    /// 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 the editor'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
            // Symbols only: the combo row above is this sidebar's whole background story
            // (03 ▸ Styling ▸ Controls, the 2026-08-06 anchor-ownership rule) — the well grid's
            // background half stays with the other anchors.
            StyleEditorView(
                store: store,
                recents: recents,
                target: Self.target(forCard: cardID),
                layout: .sidebar(
                    contentWidth: CardWindowMetrics.sidebarContentWidth(bodyPointSize: pointSize),
                    bodyPointSize: pointSize
                ),
                undo: undo,
                showsBackground: false
            )
        }
        .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.
    /// The combo takes just over half the row rather than filling it — sized off the same metric
    /// the sidebar's own width comes from, so the pair holds its proportions at every text size.
    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(width: CardWindowMetrics.sidebarContentWidth(bodyPointSize: pointSize) * 0.55)
        }
        .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? {
        let subject = store.styleSubjects(of: Self.target(forCard: cardID)).first
        return StyleFieldState.written(subject?.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: - Actions

/// The sidebar's **Actions** section, at the bottom of the stack (05-card-window.md ▸ Actions):
/// **Delete** — moves the card to the trash — and **Reveal in Finder** — the card's folder.
///
/// ### Delete writes; the window's dismissal is not its business
///
/// The button calls `BoardStore.deleteCard`, which is the ⌫ delete exactly (same write op, same
/// bracket, same stamps). It does not close this window: the card's move into `.trash/` rounds back through
/// the watcher and `CardWindowHost.cardWindowFate` takes the window down, which is the same path a
/// delete from the board — or from an agent — already takes. Dismissing from here as well would be a
/// second rule able to disagree with the first, and 05's own wording is a sequence rather than a
/// pair ("moves the card to the trash; the window then dismisses itself").
///
/// Recovery is the board's trash column, which is why this needs no confirmation: the card is still
/// there to drag out or cut and paste back (03-board-ui.md § Trash — there is no Put Back), and 03
/// reserves the alert for the purge that isn't recoverable.
///
/// ### Reveal is not edit-shaped
///
/// So it stays enabled under the read-only lock, where Delete does not — inspection is a read (04 ▸
/// The trash's posture, shared by the trash row's own Reveal). What it reveals comes from
/// `CardAttachments.revealURLs`, the same rule File ▸ Reveal in Finder's card-window scope answers
/// through: this button is that rule's card-folder branch by construction, since it is the *card's*
/// action rather than the attachment list's.
struct CardActionsSection: View {

    let store: BoardStore
    let cardID: ItemID
    /// The card's own folder — `nil` only where the window has no board to build it from, which is a
    /// window on its way out.
    let cardFolder: URL?

    private var pointSize: CGFloat { CardWindowMetrics.bodyPointSize }

    private var revealURLs: [URL] {
        CardAttachments.revealURLs(cardFolder: cardFolder, selectedURL: nil, isSectionFocused: false)
    }

    var body: some View {
        VStack(alignment: .leading, spacing: CardWindowMetrics.sidebarRowSpacing(bodyPointSize: pointSize)) {
            CardSidebarSectionHeader(title: "Actions")

            // Delete above Reveal, which is the order 05 lists them in. Destructive styling, per 05
            // — the one control in this window that takes the card away. Disabled under the
            // read-only lock like every other mutation (02-architecture.md's every-entry-point
            // predicate); that is the attachments section's `isEditable`, read from the store
            // directly because there is no handle to route it through here and nothing else in this
            // section that would want one.
            Button(role: .destructive) {
                store.deleteCard(cardID)
            } label: {
                // The width is the *label's*, not the button's: a bordered button sizes to its label,
                // so a frame around the button would centre a small pill in a wide row instead of
                // filling it. Both rows do it, so the two are one column rather than two widths.
                Text("Delete").frame(maxWidth: .infinity)
            }
            .tint(.red)
            .disabled(store.isReadOnly)

            Button {
                NSWorkspace.shared.activateFileViewerSelecting(revealURLs)
            } label: {
                Text("Reveal in Finder").frame(maxWidth: .infinity)
            }
            .disabled(revealURLs.isEmpty)
        }
        .buttonStyle(.bordered)
        .frame(maxWidth: .infinity, alignment: .leading)
    }
}
