// Local adjustments: the mask stack, the region overlay, and the subjects the
// model recognised (FR-DEV-3).
//
// The panel is deliberately thin. A mask layer holds an ordinary develop
// chain, so selecting one hands the *existing* adjust panel that chain — there
// are no per-layer sliders here and there must not be, or every operation
// added to `ops/` would need a local twin.

import { Theme } from "theme.slint";
import { Button, Caption, IconButton, Label, PanelHeading, Value } from "widgets.slint";
import { Segmented, SliderRow } from "controls.slint";

/// One layer in the stack.
export struct MaskRow {
    // Identity, opaque to this file — the callbacks hand it straight back.
    id: string,
    label: string,
    /// What kind of mask it is, for the row's second line.
    kind: string,
    enabled: bool,
    /// The layer the develop panel is currently editing.
    selected: bool,
    inverted: bool,
    opacity: float,
    /// Edge transition half-width, as a fraction of the frame's shorter edge.
    feather: float,
    /// Index into `Falloff::ALL`.
    falloff: int,
    /// Index into `Morphology::ALL`.
    morphology: int,
    morph-radius: float,
    /// Whether the edge controls apply. A gradient has its own geometry and
    /// does not go through the distance field, so showing them would offer
    /// controls that do nothing.
    shapeable: bool,
    /// Its region ids came from a different segmentation than the one loaded,
    /// so applying it would produce a confidently wrong shape.
    stale: bool,
    /// Whether it currently changes any pixel. A bare selection does not, and
    /// saying so is what stops it reading as broken.
    adjusted: bool,
}

/// Which part of a gradient a canvas handle drags.
///
/// Named by the job rather than by the field, because the two gradients keep
/// different things in the same place: `edge` is a linear ramp's width and a
/// radial's major semi-axis, and `cross` is the radial's minor one.
export enum HandleRole { centre, edge, cross, rotate }

/// One draggable point on the photograph.
///
/// Positioned in fractions of the image **as it is currently shown** — after
/// the crop, the zoom and the pan — because that is the only space this file
/// can draw in. Rust maps the mask's own source-space geometry into it on
/// every frame, so the handle sits on the mask rather than beside it.
export struct GradientHandle {
    role: HandleRole,
    x: float,
    y: float,
}

/// Something the model found.
export struct SubjectRow {
    index: int,
    label: string,
    /// 0..1. Shown rather than hidden: the detector is a shortcut, not an
    /// authority, and a weak guess presented like a strong one makes the tool
    /// look wrong when it was merely unsure.
    score: float,
}

component MaskEntry inherits Rectangle {
    in property <MaskRow> data;
    in property <bool> enabled: true;
    /// Whether a refine pass is running (for any row — only one runs at a
    /// time), so this row's button can say so and refuse a second press.
    in property <bool> refining: false;

    /// `true` when the click should add this row to the selection rather
    /// than replace it with just this row.
    callback selected(bool);
    callback removed();
    callback toggled(bool);
    callback invert-toggled(bool);
    callback opacity-changed(float);
    callback feather-changed(float);
    callback falloff-picked(int);
    callback morphology-picked(int);
    callback morph-radius-changed(float);
    callback refined();

    height: layout.preferred-height;
    background: root.data.selected ? Theme.surface-raised : transparent;
    border-radius: Theme.radius;

    touch := TouchArea {
        mouse-cursor: pointer;
        enabled: root.enabled;
        // `clicked` carries no modifiers, so a plain click and a
        // multi-select click need the pointer event itself: released, over
        // the row, with control or command held is "add to the selection"
        // rather than "replace it".
        pointer-event(event) => {
            if event.kind == PointerEventKind.up && event.button == PointerEventButton.left {
                root.selected(event.modifiers.control || event.modifiers.meta);
            }
        }
    }

    layout := VerticalLayout {
        padding: Theme.gap-sm;
        spacing: 2px;

        HorizontalLayout {
            spacing: Theme.gap-sm;

            // The eye. Disabling a layer is the A/B a local edit constantly
            // wants, so it is one press away rather than inside the row.
            visibility := TouchArea {
                width: Theme.touch-target;
                height: Theme.touch-target;
                mouse-cursor: pointer;
                enabled: root.enabled;
                clicked => { root.toggled(!root.data.enabled); }

                Label {
                    text: root.data.enabled ? "◉" : "○";
                    emphasised: visibility.has-hover || root.data.enabled;
                    horizontal-alignment: center;
                    vertical-alignment: center;
                }
            }

            VerticalLayout {
                horizontal-stretch: 1;
                alignment: center;
                spacing: 0px;

                Label {
                    text: root.data.label;
                    emphasised: root.data.selected || touch.has-hover;
                    overflow: elide;
                }

                Caption {
                    // Elided rather than wrapped: this sits beside two fixed
                    // targets in a row, and wrapping would give the rows of a
                    // stack different heights for no gain.
                    overflow: elide;
                    // Three states worth distinguishing, and each has a
                    // different remedy: stale needs the segmentation re-run,
                    // unadjusted needs a slider moved, and the ordinary case
                    // needs nothing said about it beyond what it is.
                    text: root.data.stale
                        ? "needs re-segmenting"
                        : (root.data.adjusted
                            ? root.data.kind
                            : root.data.kind + " · no adjustment yet");
                }
            }

            remove := TouchArea {
                width: Theme.touch-target;
                height: Theme.touch-target;
                mouse-cursor: pointer;
                enabled: root.enabled;
                clicked => { root.removed(); }

                Label {
                    text: "×";
                    emphasised: remove.has-hover;
                    horizontal-alignment: center;
                    vertical-alignment: center;
                }
            }
        }

        // Opacity and invert appear only on the selected layer. On every row
        // they would triple the height of a stack of eight and put seven sets
        // of controls in front of the one being worked on.
        if root.data.selected: VerticalLayout {
            spacing: Theme.gap-sm;
            padding-top: Theme.gap-sm;

            SliderRow {
                label: "Opacity";
                value: root.data.opacity;
                default-value: 1.0;
                minimum: 0.0;
                maximum: 1.0;
                changed(v) => { root.opacity-changed(v); }
                reset => { root.opacity-changed(1.0); }
            }

            invert := TouchArea {
                height: Theme.touch-target;
                mouse-cursor: pointer;
                clicked => { root.invert-toggled(!root.data.inverted); }

                Label {
                    text: root.data.inverted ? "Inverted — edit applies outside" : "Invert";
                    emphasised: invert.has-hover || root.data.inverted;
                }
            }

            // Only a subject has a detection behind it worth re-running. A
            // gradient's edge is geometry the photographer placed, and there
            // is nothing for the model to find twice.
            if root.data.kind == "subject": Button {
                text: root.refining ? "Refining…" : "Refine mask";
                enabled: !root.refining;
                clicked => { root.refined(); }
            }

            // The edge. All of it reads one signed distance field, so these
            // are free to move — none of them recomputes anything except a
            // compound morphology.
            if root.data.shapeable: SliderRow {
                label: "Feather";
                hint: "How far the edit fades across the edge.";
                value: root.data.feather * 1000;
                default-value: 4;
                minimum: 0;
                maximum: 60;
                changed(v) => { root.feather-changed(v / 1000); }
                reset => { root.feather-changed(0.004); }
            }

            if root.data.shapeable: Segmented {
                label: "Falloff";
                options: ["Hard", "Linear", "Smooth", "Gaussian", "Expo"];
                selected: root.data.falloff;
                picked(i) => { root.falloff-picked(i); }
            }

            if root.data.shapeable: Segmented {
                label: "Edge";
                hint: "Grow or shrink the outline the model drew. Close fills "
                      + "pinholes; open removes specks.";
                options: ["None", "Grow", "Shrink", "Close", "Open"];
                selected: root.data.morphology;
                picked(i) => { root.morphology-picked(i); }
            }

            if root.data.shapeable && root.data.morphology != 0: SliderRow {
                label: "Amount";
                value: root.data.morph-radius * 1000;
                default-value: 0;
                minimum: 0;
                maximum: 40;
                changed(v) => { root.morph-radius-changed(v / 1000); }
                reset => { root.morph-radius-changed(0); }
            }
        }
    }
}

export component MaskPanel inherits Rectangle {
    in property <bool> enabled: true;
    in property <[MaskRow]> masks;
    in property <[SubjectRow]> subjects;

    /// A region map has been computed for this image.
    in property <bool> segmented: false;
    /// One is being computed now.
    in property <bool> segmenting: false;
    /// A refine pass is running for one subject layer.
    in property <bool> refining: false;

    /// Whether the photographer has hidden the overlay to see the photograph.
    /// Two-way bound to the window's own, so the canvas and this control never
    /// disagree about it.
    in-out property <bool> overlay-hidden: false;


    /// `true` asks for the slower, tiled pass.
    callback segment(bool);

    /// `true` when the click should add the layer to the selection rather
    /// than replace it.
    callback mask-selected(string, bool);
    callback mask-removed(string);
    callback mask-refined(string);
    callback mask-toggled(string, bool);
    callback mask-invert-toggled(string, bool);
    callback mask-opacity-changed(string, float);
    callback mask-feather-changed(string, float);
    callback mask-falloff-picked(string, int);
    callback mask-morphology-picked(string, int);
    callback mask-morph-radius-changed(string, float);

    callback add-gradient(bool);
    callback add-subject(int);

    background: Theme.surface;

    // **Flat, deliberately.** An earlier version grouped each state into its
    // own `if ...: VerticalLayout { ... }`. The nested layout under-reported
    // its height, so the divider and the mask row below it were placed over
    // the "Find regions" button — the sort of fault that is invisible in the
    // source and obvious the moment anyone looks at the panel. Conditioning
    // each child on its own keeps every element a direct child of one layout,
    /// TRACES: FR-UI-2
    /// How wide this panel has to be before it starts clipping itself. The
    /// develop column is the largest of these and nothing else; publishing it
    /// as `min-width` too is what makes the enclosing layout aggregate them
    /// without this panel having to be referenced by name.
    out property <length> content-width: layout.preferred-width;
    min-width: root.content-width;

    // which is the layout that measures them.
    layout := VerticalLayout {
        padding: Theme.gap;
        spacing: Theme.gap-sm;
        alignment: start;

        HorizontalLayout {
            PanelHeading { text: "MASKS"; }
            Rectangle { horizontal-stretch: 1; }
            if root.segmented: Value {                text: root.subjects.length + (root.subjects.length == 1 ? " subject" : " subjects");
            }
        }

        if !root.enabled: Caption { text: "No image"; }

        // --- the region map ---------------------------------------------
        //
        // Segmentation is a thing the user starts. Half a second of watershed
        // and inference is too long to spend on every photograph opened, and
        // most edits never need one.
        if root.enabled && !root.segmented: Caption {
            text: "Find the subjects in this photograph, so a mask can follow one.";
            // Wrapped, or this sentence's single-line width becomes the
            // panel's minimum and levers the fixed 280px develop column open,
            // taking every other panel's controls off the right edge with it.
            wrap: word-wrap;
        }

        if root.enabled && !root.segmented: Button {
            text: root.segmenting ? "Looking…" : "Find subjects";
            enabled: !root.segmenting;
            primary: true;
            clicked => { root.segment(false); }
        }

        // No "Overlay" button and no "Select" button. Both switched on things
        // that are now simply what local mode *is*: entering it draws the
        // region map and makes a click on the photograph mean "select". A mode
        // whose behaviour has to be armed separately is a mode that can be
        // entered and still do nothing, which is what these two allowed.
        if root.enabled && root.segmented: Caption {
            text: "Click a subject in the photograph to mask it.";
            wrap: word-wrap;
        }

        // Hiding the overlay is not the "Overlay" button this panel used to
        // have, and the distinction is the reason it is back. That one *armed*
        // the overlay: local mode could be entered and still show nothing,
        // which is the fault the comment below records. This one only takes an
        // overlay that is already there out of the way for a moment, which is
        // the one thing a photographer needs constantly and had no way to do —
        // a mask is judged against the photograph under it, and you cannot see
        // that photograph through the thing describing it.
        //
        // Reads as its own action rather than its state: "Show the mask" is
        // what pressing it will do, not what is currently true.
        if root.enabled && root.segmented: Button {
            text: root.overlay-hidden ? "Show the mask" : "Hide the mask";
            clicked => { root.overlay-hidden = !root.overlay-hidden; }
        }

        // The second pass, offered rather than taken automatically.
        //
        // The model's input is a fixed 640x640 square and every frame is
        // letterboxed into it, so a subject that is small in the frame reaches
        // the model small — a bird at 200px in a 1600px proxy arrives at 80px,
        // and an outline traced at 80px is what a coarse mask is. Tiling runs
        // the model over overlapping windows instead, so that bird arrives at
        // its own size.
        //
        // It costs one inference per tile: about 2.8s for a 3x2 grid against
        // 470ms for the whole frame. That is the wrong trade for the usual
        // photograph, where the subject fills much of the frame and the first
        // pass is already the best answer available — so it is a button and
        // not a default, and it says what it costs.
        if root.enabled && root.segmented: Button {
            text: root.segmenting ? "Looking closer…" : "Look closer (slower)";
            enabled: !root.segmenting;
            clicked => { root.segment(true); }
        }

        // Granularity, labelled by what it does rather than by its number:
        // "detail" is what a photographer is choosing between, where "300
        // regions" is an implementation detail they would have to learn.
        // --- what the model found ----------------------------------------
        if root.enabled && root.segmented && root.subjects.length > 0: Caption {
            // Says where these came from and how they differ from a region.
            // A list of four beside a count of three thousand invites exactly
            // one question, and the panel should answer it rather than
            // provoke it.
            text: "Click one to mask it. The outline is the model's, so soften or grow it below.";
            wrap: word-wrap;
        }

        if root.enabled && root.segmented: VerticalLayout {
            spacing: 0px;
            for subject in root.subjects: subject-row := TouchArea {
                height: Theme.touch-target;
                mouse-cursor: pointer;
                clicked => { root.add-subject(subject.index); }

                HorizontalLayout {
                    spacing: Theme.gap-sm;

                    Label {
                        text: subject.label;
                        emphasised: subject-row.has-hover;
                        horizontal-stretch: 1;
                        overflow: elide;
                    }
                    Value { text: round(subject.score * 100) + "%"; }
                }
            }
        }

        if root.enabled && root.segmented && root.subjects.length == 0: Caption {
            text: "Nothing recognised. The model knows people, animals and vehicles — "
                  + "a landscape has no subject for it to find. Add a gradient instead.";
            wrap: word-wrap;
        }

        Rectangle {
            height: 1px;
            background: Theme.rule;
        }

        // --- the stack -----------------------------------------------------
        Caption { text: "Masks"; }

        // Gradients need no segmentation, so they are offered whether or not
        // one has been computed — a graduated filter over a sky is a local
        // adjustment that never needed to know what a sky is.
        HorizontalLayout {
            spacing: Theme.gap-sm;

            Button {
                text: "Linear";
                enabled: root.enabled;
                clicked => { root.add-gradient(false); }
            }
            Button {
                text: "Radial";
                enabled: root.enabled;
                clicked => { root.add-gradient(true); }
            }
        }

        if root.enabled && root.masks.length == 0: Caption {
            text: "No local adjustments. Select a region, or add a gradient.";
            wrap: word-wrap;
        }

        for mask in root.masks: MaskEntry {
            data: mask;
            enabled: root.enabled;
            refining: root.refining;
            selected(extend) => { root.mask-selected(mask.id, extend); }
            removed => { root.mask-removed(mask.id); }
            refined => { root.mask-refined(mask.id); }
            toggled(on) => { root.mask-toggled(mask.id, on); }
            invert-toggled(on) => { root.mask-invert-toggled(mask.id, on); }
            opacity-changed(v) => { root.mask-opacity-changed(mask.id, v); }
            feather-changed(v) => { root.mask-feather-changed(mask.id, v); }
            falloff-picked(i) => { root.mask-falloff-picked(mask.id, i); }
            morphology-picked(i) => { root.mask-morphology-picked(mask.id, i); }
            morph-radius-changed(v) => { root.mask-morph-radius-changed(mask.id, v); }
        }

        // No caption saying which chain the sliders below are pointed at.
        //
        // That sentence used to be the *only* indication that selecting a
        // layer had silently re-scoped thirty controls, and describing a
        // hazard in a caption is not the same as removing it. The adjust
        // panel's own heading names the layer it is editing now, which puts
        // the answer on the thing that changed rather than above it.
    }
}

/// TRACES: FR-DEV-3 | FR-UI-3
/// The mask's handles, drawn on the photograph.
///
/// A linear or radial mask could be made and then never moved: there was
/// nothing to grab, so a radial sat at the centre of the frame at its default
/// size for ever.
///
/// **Placed over the fitted image, not the canvas box.** The photograph is
/// letterboxed inside the canvas and Slint does not report the fitted rect, so
/// the develop view derives it and gives this component exactly that rect —
/// which is why everything in here is a plain fraction of `root.width` and
/// `root.height` rather than an offset from someone else's origin. Rust
/// supplies the positions already mapped through the framing — the same map
/// the shader applies — so a handle follows the mask through a zoom, a pan, a
/// crop and a straightening rather than sitting where the mask used to be.
///
/// **Drawn small, grabbed large.** The visible dot is 14px because a bigger
/// one would hide the edge it is placed on, and the `TouchArea` is a full
/// touch target, centred on it — `Button` establishes the same split. These
/// are the first controls in the application meant to be dragged on the
/// photograph, and a 12-inch tablet has no hover to reveal them with and no
/// modifier to qualify them by, so what is drawn is all there is (FR-UI-7).
export component GradientHandles inherits Rectangle {
    in property <[GradientHandle]> handles;

    /// role, from-x, from-y, to-x, to-y — all fractions of this rect.
    callback dragged(HandleRole, float, float, float, float);
    /// One history step per gesture, not per frame.
    callback released();

    background: transparent;

    for handle in root.handles: Rectangle {
        x: handle.x * root.width - self.width / 2;
        y: handle.y * root.height - self.height / 2;
        width: Theme.touch-target;
        height: Theme.touch-target;

        // The centre moves the whole mask, so it is filled; the others shape
        // it and are rings. Shape rather than colour, because the handles sit
        // on a photograph and any colour they carried would be read as part
        // of it.
        property <bool> solid: handle.role == HandleRole.centre;

        Rectangle {
            width: handle.role == HandleRole.rotate ? 12px : 14px;
            height: self.width;
            x: (parent.width - self.width) / 2;
            y: (parent.height - self.height) / 2;
            border-radius: self.width / 2;
            border-width: 2px;
            // White with a dark ring, so the handle is visible against a blown
            // sky and against a black frame — one treatment, both extremes, no
            // theme token because this is drawn over the image and not over
            // the interface.
            border-color: #00000099;
            background: parent.solid ? #ffffff : #ffffff44;
        }

        drag := TouchArea {
            width: 100%;
            height: 100%;
            mouse-cursor: parent.solid
                ? MouseCursor.move
                : MouseCursor.crosshair;

            // Where the press landed, in the same fractions the callback
            // reports in. Captured on the way down so the whole gesture is
            // measured from one origin.
            property <float> from-x;
            property <float> from-y;

            function fraction-x(local-x: length) -> float {
                return (parent.x + local-x) / max(root.width, 1px);
            }
            function fraction-y(local-y: length) -> float {
                return (parent.y + local-y) / max(root.height, 1px);
            }

            pointer-event(ev) => {
                if (ev.kind == PointerEventKind.down) {
                    self.from-x = self.fraction-x(self.pressed-x);
                    self.from-y = self.fraction-y(self.pressed-y);
                }
                if (ev.kind == PointerEventKind.up) {
                    root.released();
                }
            }

            moved => {
                if (self.pressed) {
                    root.dragged(
                        handle.role,
                        self.from-x,
                        self.from-y,
                        self.fraction-x(self.mouse-x),
                        self.fraction-y(self.mouse-y),
                    );
                }
            }
        }
    }
}