// widgetTreeView.c — TreeView and TreeItem widgets

#include "widgetInternal.h"

// ============================================================
// Prototypes
// ============================================================

static int32_t calcTreeItemsHeight(WidgetT *parent, const BitmapFontT *font);
static int32_t calcTreeItemsMaxWidth(WidgetT *parent, const BitmapFontT *font, int32_t depth);
static void drawTreeHScrollbar(WidgetT *w, DisplayT *d, const BlitOpsT *ops, const ColorSchemeT *colors, int32_t totalW, int32_t innerW, bool hasVSb);
static void drawTreeVScrollbar(WidgetT *w, DisplayT *d, const BlitOpsT *ops, const ColorSchemeT *colors, int32_t totalH, int32_t innerH);
static WidgetT *firstVisibleItem(WidgetT *treeView);
static void layoutTreeItems(WidgetT *parent, const BitmapFontT *font, int32_t x, int32_t *y, int32_t width, int32_t depth);
static WidgetT *nextVisibleItem(WidgetT *item, WidgetT *treeView);
static void paintTreeItems(WidgetT *parent, DisplayT *d, const BlitOpsT *ops, const BitmapFontT *font, const ColorSchemeT *colors, int32_t baseX, int32_t *itemY, int32_t depth, int32_t clipTop, int32_t clipBottom, WidgetT *selectedItem);
static WidgetT *prevVisibleItem(WidgetT *item, WidgetT *treeView);
static void treeCalcScrollbarNeeds(WidgetT *w, const BitmapFontT *font, int32_t *outTotalH, int32_t *outTotalW, int32_t *outInnerH, int32_t *outInnerW, bool *outNeedVSb, bool *outNeedHSb);
static WidgetT *treeItemAtY(WidgetT *parent, int32_t targetY, int32_t *curY, const BitmapFontT *font);
static int32_t treeItemYPos(WidgetT *treeView, WidgetT *target, const BitmapFontT *font);
static int32_t treeItemYPosHelper(WidgetT *parent, WidgetT *target, int32_t *curY, const BitmapFontT *font);

// ============================================================
// calcTreeItemsHeight
// ============================================================

static int32_t calcTreeItemsHeight(WidgetT *parent, const BitmapFontT *font) {
    int32_t totalH = 0;

    for (WidgetT *c = parent->firstChild; c; c = c->nextSibling) {
        if (c->type != WidgetTreeItemE || !c->visible) {
            continue;
        }

        totalH += font->charHeight;

        if (c->as.treeItem.expanded && c->firstChild) {
            totalH += calcTreeItemsHeight(c, font);
        }
    }

    return totalH;
}


// ============================================================
// calcTreeItemsMaxWidth
// ============================================================

static int32_t calcTreeItemsMaxWidth(WidgetT *parent, const BitmapFontT *font, int32_t depth) {
    int32_t maxW = 0;

    for (WidgetT *c = parent->firstChild; c; c = c->nextSibling) {
        if (c->type != WidgetTreeItemE || !c->visible) {
            continue;
        }

        int32_t indent = depth * TREE_INDENT + TREE_EXPAND_SIZE + TREE_ICON_GAP;
        int32_t textW  = (int32_t)strlen(c->as.treeItem.text) * font->charWidth;
        int32_t itemW  = indent + textW;

        if (itemW > maxW) {
            maxW = itemW;
        }

        if (c->as.treeItem.expanded && c->firstChild) {
            int32_t childW = calcTreeItemsMaxWidth(c, font, depth + 1);

            if (childW > maxW) {
                maxW = childW;
            }
        }
    }

    return maxW;
}


// ============================================================
// drawTreeHScrollbar
// ============================================================

static void drawTreeHScrollbar(WidgetT *w, DisplayT *d, const BlitOpsT *ops, const ColorSchemeT *colors, int32_t totalW, int32_t innerW, bool hasVSb) {
    int32_t sbX = w->x + TREE_BORDER;
    int32_t sbY = w->y + w->h - TREE_BORDER - TREE_SB_W;
    int32_t sbW = innerW;

    if (sbW < TREE_SB_W * 3) {
        return;
    }

    // Trough background
    BevelStyleT troughBevel = BEVEL_TROUGH(colors);
    drawBevel(d, ops, sbX, sbY, sbW, TREE_SB_W, &troughBevel);

    // Left arrow button
    BevelStyleT btnBevel = BEVEL_RAISED(colors, 1);
    drawBevel(d, ops, sbX, sbY, TREE_SB_W, TREE_SB_W, &btnBevel);

    // Left arrow triangle
    {
        int32_t  cx = sbX + TREE_SB_W / 2;
        int32_t  cy = sbY + TREE_SB_W / 2;
        uint32_t fg = colors->contentFg;

        for (int32_t i = 0; i < 4; i++) {
            drawVLine(d, ops, cx - 2 + i, cy - i, 1 + i * 2, fg);
        }
    }

    // Right arrow button
    int32_t rightX = sbX + sbW - TREE_SB_W;
    drawBevel(d, ops, rightX, sbY, TREE_SB_W, TREE_SB_W, &btnBevel);

    // Right arrow triangle
    {
        int32_t  cx = rightX + TREE_SB_W / 2;
        int32_t  cy = sbY + TREE_SB_W / 2;
        uint32_t fg = colors->contentFg;

        for (int32_t i = 0; i < 4; i++) {
            drawVLine(d, ops, cx + 2 - i, cy - i, 1 + i * 2, fg);
        }
    }

    // Thumb
    int32_t trackLen = sbW - TREE_SB_W * 2;

    if (trackLen > 0 && totalW > 0) {
        int32_t thumbPos;
        int32_t thumbSize;
        widgetScrollbarThumb(trackLen, totalW, innerW, w->as.treeView.scrollPosH, &thumbPos, &thumbSize);

        drawBevel(d, ops, sbX + TREE_SB_W + thumbPos, sbY, thumbSize, TREE_SB_W, &btnBevel);
    }

    // Fill dead corner when both scrollbars present
    if (hasVSb) {
        rectFill(d, ops, sbX + sbW, sbY, TREE_SB_W, TREE_SB_W, colors->windowFace);
    }
}


// ============================================================
// drawTreeVScrollbar
// ============================================================

static void drawTreeVScrollbar(WidgetT *w, DisplayT *d, const BlitOpsT *ops, const ColorSchemeT *colors, int32_t totalH, int32_t innerH) {
    int32_t sbX = w->x + w->w - TREE_BORDER - TREE_SB_W;
    int32_t sbY = w->y + TREE_BORDER;
    int32_t sbH = innerH;

    if (sbH < TREE_SB_W * 3) {
        return;
    }

    // Trough background
    BevelStyleT troughBevel = BEVEL_TROUGH(colors);
    drawBevel(d, ops, sbX, sbY, TREE_SB_W, sbH, &troughBevel);

    // Up arrow button
    BevelStyleT btnBevel = BEVEL_RAISED(colors, 1);
    drawBevel(d, ops, sbX, sbY, TREE_SB_W, TREE_SB_W, &btnBevel);

    // Up arrow triangle
    {
        int32_t  cx = sbX + TREE_SB_W / 2;
        int32_t  cy = sbY + TREE_SB_W / 2;
        uint32_t fg = colors->contentFg;

        for (int32_t i = 0; i < 4; i++) {
            drawHLine(d, ops, cx - i, cy - 2 + i, 1 + i * 2, fg);
        }
    }

    // Down arrow button
    int32_t downY = sbY + sbH - TREE_SB_W;
    drawBevel(d, ops, sbX, downY, TREE_SB_W, TREE_SB_W, &btnBevel);

    // Down arrow triangle
    {
        int32_t  cx = sbX + TREE_SB_W / 2;
        int32_t  cy = downY + TREE_SB_W / 2;
        uint32_t fg = colors->contentFg;

        for (int32_t i = 0; i < 4; i++) {
            drawHLine(d, ops, cx - i, cy + 2 - i, 1 + i * 2, fg);
        }
    }

    // Thumb
    int32_t trackLen = sbH - TREE_SB_W * 2;

    if (trackLen > 0 && totalH > 0) {
        int32_t thumbPos;
        int32_t thumbSize;
        widgetScrollbarThumb(trackLen, totalH, innerH, w->as.treeView.scrollPos, &thumbPos, &thumbSize);

        drawBevel(d, ops, sbX, sbY + TREE_SB_W + thumbPos, TREE_SB_W, thumbSize, &btnBevel);
    }
}


// ============================================================
// firstVisibleItem
// ============================================================
//
// Return the first visible tree item (depth-first).

static WidgetT *firstVisibleItem(WidgetT *treeView) {
    for (WidgetT *c = treeView->firstChild; c; c = c->nextSibling) {
        if (c->type == WidgetTreeItemE && c->visible) {
            return c;
        }
    }

    return NULL;
}


// ============================================================
// layoutTreeItems
// ============================================================

static void layoutTreeItems(WidgetT *parent, const BitmapFontT *font, int32_t x, int32_t *y, int32_t width, int32_t depth) {
    for (WidgetT *c = parent->firstChild; c; c = c->nextSibling) {
        if (c->type != WidgetTreeItemE || !c->visible) {
            continue;
        }

        c->x = x;
        c->y = *y;
        c->w = width;
        c->h = font->charHeight;
        *y += font->charHeight;

        if (c->as.treeItem.expanded && c->firstChild) {
            layoutTreeItems(c, font, x, y, width, depth + 1);
        }
    }
}


// ============================================================
// nextVisibleItem
// ============================================================
//
// Return the next visible tree item after the given item
// (depth-first order: children first, then siblings, then uncle).

static WidgetT *nextVisibleItem(WidgetT *item, WidgetT *treeView) {
    // If expanded with children, descend
    if (item->as.treeItem.expanded) {
        for (WidgetT *c = item->firstChild; c; c = c->nextSibling) {
            if (c->type == WidgetTreeItemE && c->visible) {
                return c;
            }
        }
    }

    // Try next sibling
    for (WidgetT *s = item->nextSibling; s; s = s->nextSibling) {
        if (s->type == WidgetTreeItemE && s->visible) {
            return s;
        }
    }

    // Walk up parents, looking for their next sibling
    for (WidgetT *p = item->parent; p && p != treeView; p = p->parent) {
        for (WidgetT *s = p->nextSibling; s; s = s->nextSibling) {
            if (s->type == WidgetTreeItemE && s->visible) {
                return s;
            }
        }
    }

    return NULL;
}


// ============================================================
// paintTreeItems
// ============================================================

static void paintTreeItems(WidgetT *parent, DisplayT *d, const BlitOpsT *ops, const BitmapFontT *font, const ColorSchemeT *colors, int32_t baseX, int32_t *itemY, int32_t depth, int32_t clipTop, int32_t clipBottom, WidgetT *selectedItem) {
    for (WidgetT *c = parent->firstChild; c; c = c->nextSibling) {
        if (c->type != WidgetTreeItemE || !c->visible) {
            continue;
        }

        int32_t ix = baseX + depth * TREE_INDENT;
        int32_t iy = *itemY;
        *itemY += font->charHeight;

        // Skip items outside visible area
        if (iy + font->charHeight <= clipTop || iy >= clipBottom) {
            if (c->as.treeItem.expanded && c->firstChild) {
                paintTreeItems(c, d, ops, font, colors, baseX, itemY, depth + 1, clipTop, clipBottom, selectedItem);
            }

            continue;
        }

        // Highlight selected item
        bool isSelected = (c == selectedItem);
        uint32_t fg;
        uint32_t bg;

        if (isSelected) {
            fg = colors->menuHighlightFg;
            bg = colors->menuHighlightBg;
            rectFill(d, ops, baseX, iy, d->clipW, font->charHeight, bg);
        } else {
            fg = c->fgColor ? c->fgColor : colors->contentFg;
            bg = c->bgColor ? c->bgColor : colors->contentBg;
        }

        // Draw expand/collapse icon if item has children
        bool hasChildren = false;

        for (WidgetT *gc = c->firstChild; gc; gc = gc->nextSibling) {
            if (gc->type == WidgetTreeItemE) {
                hasChildren = true;
                break;
            }
        }

        int32_t textX = ix;

        if (hasChildren) {
            int32_t iconX = ix;
            int32_t iconY = iy + (font->charHeight - TREE_EXPAND_SIZE) / 2;

            // Draw box
            rectFill(d, ops, iconX + 1, iconY + 1, TREE_EXPAND_SIZE - 2, TREE_EXPAND_SIZE - 2, colors->contentBg);
            drawHLine(d, ops, iconX, iconY, TREE_EXPAND_SIZE, colors->windowShadow);
            drawHLine(d, ops, iconX, iconY + TREE_EXPAND_SIZE - 1, TREE_EXPAND_SIZE, colors->windowShadow);
            drawVLine(d, ops, iconX, iconY, TREE_EXPAND_SIZE, colors->windowShadow);
            drawVLine(d, ops, iconX + TREE_EXPAND_SIZE - 1, iconY, TREE_EXPAND_SIZE, colors->windowShadow);

            // Draw + or -
            int32_t mid = TREE_EXPAND_SIZE / 2;
            drawHLine(d, ops, iconX + 2, iconY + mid, TREE_EXPAND_SIZE - 4, colors->contentFg);

            if (!c->as.treeItem.expanded) {
                drawVLine(d, ops, iconX + mid, iconY + 2, TREE_EXPAND_SIZE - 4, colors->contentFg);
            }

            textX += TREE_EXPAND_SIZE + TREE_ICON_GAP;
        } else {
            textX += TREE_EXPAND_SIZE + TREE_ICON_GAP;
        }

        // Draw text
        drawText(d, ops, font, textX, iy, c->as.treeItem.text, fg, bg, isSelected);

        // Recurse into expanded children
        if (c->as.treeItem.expanded && c->firstChild) {
            paintTreeItems(c, d, ops, font, colors, baseX, itemY, depth + 1, clipTop, clipBottom, selectedItem);
        }
    }
}


// ============================================================
// prevVisibleItem
// ============================================================
//
// Return the previous visible tree item before the given item
// (depth-first order: last visible descendant of previous sibling,
// or parent).

static WidgetT *prevVisibleItem(WidgetT *item, WidgetT *treeView) {
    // Find previous sibling
    WidgetT *prevSib = NULL;

    for (WidgetT *s = item->parent->firstChild; s && s != item; s = s->nextSibling) {
        if (s->type == WidgetTreeItemE && s->visible) {
            prevSib = s;
        }
    }

    if (prevSib) {
        // Descend to last visible descendant of previous sibling
        WidgetT *node = prevSib;

        while (node->as.treeItem.expanded) {
            WidgetT *last = NULL;

            for (WidgetT *c = node->firstChild; c; c = c->nextSibling) {
                if (c->type == WidgetTreeItemE && c->visible) {
                    last = c;
                }
            }

            if (!last) {
                break;
            }

            node = last;
        }

        return node;
    }

    // No previous sibling — go to parent (if it's a tree item)
    if (item->parent && item->parent != treeView && item->parent->type == WidgetTreeItemE) {
        return item->parent;
    }

    return NULL;
}


// ============================================================
// treeCalcScrollbarNeeds
// ============================================================
//
// Compute content dimensions and determine which scrollbars are
// needed, accounting for the mutual space dependency between them.

static void treeCalcScrollbarNeeds(WidgetT *w, const BitmapFontT *font, int32_t *outTotalH, int32_t *outTotalW, int32_t *outInnerH, int32_t *outInnerW, bool *outNeedVSb, bool *outNeedHSb) {
    int32_t totalH = calcTreeItemsHeight(w, font);
    int32_t totalW = calcTreeItemsMaxWidth(w, font, 0);
    int32_t innerH = w->h - TREE_BORDER * 2;
    int32_t innerW = w->w - TREE_BORDER * 2;
    bool    needVSb = (totalH > innerH);
    bool    needHSb = (totalW > innerW);

    // V scrollbar reduces available width — may trigger H scrollbar
    if (needVSb) {
        innerW -= TREE_SB_W;

        if (!needHSb && totalW > innerW) {
            needHSb = true;
        }
    }

    // H scrollbar reduces available height — may trigger V scrollbar
    if (needHSb) {
        innerH -= TREE_SB_W;

        if (!needVSb && totalH > innerH) {
            needVSb = true;
            innerW -= TREE_SB_W;
        }
    }

    *outTotalH  = totalH;
    *outTotalW  = totalW;
    *outInnerH  = innerH;
    *outInnerW  = innerW;
    *outNeedVSb = needVSb;
    *outNeedHSb = needHSb;
}


// ============================================================
// treeItemAtY
// ============================================================
//
// Find the tree item at a given Y coordinate.

static WidgetT *treeItemAtY(WidgetT *parent, int32_t targetY, int32_t *curY, const BitmapFontT *font) {
    for (WidgetT *c = parent->firstChild; c; c = c->nextSibling) {
        if (c->type != WidgetTreeItemE || !c->visible) {
            continue;
        }

        if (targetY >= *curY && targetY < *curY + font->charHeight) {
            return c;
        }

        *curY += font->charHeight;

        if (c->as.treeItem.expanded && c->firstChild) {
            WidgetT *found = treeItemAtY(c, targetY, curY, font);

            if (found) {
                return found;
            }
        }
    }

    return NULL;
}


// ============================================================
// treeItemYPos
// ============================================================
//
// Return the Y offset (from tree top, 0-based) of a given item,
// or -1 if not found/visible.

static int32_t treeItemYPos(WidgetT *treeView, WidgetT *target, const BitmapFontT *font) {
    int32_t curY = 0;

    if (treeItemYPosHelper(treeView, target, &curY, font)) {
        return curY;
    }

    return -1;
}


// ============================================================
// treeItemYPosHelper
// ============================================================

static int32_t treeItemYPosHelper(WidgetT *parent, WidgetT *target, int32_t *curY, const BitmapFontT *font) {
    for (WidgetT *c = parent->firstChild; c; c = c->nextSibling) {
        if (c->type != WidgetTreeItemE || !c->visible) {
            continue;
        }

        if (c == target) {
            return 1;
        }

        *curY += font->charHeight;

        if (c->as.treeItem.expanded && c->firstChild) {
            if (treeItemYPosHelper(c, target, curY, font)) {
                return 1;
            }
        }
    }

    return 0;
}



// ============================================================
// wgtTreeItem
// ============================================================

WidgetT *wgtTreeItem(WidgetT *parent, const char *text) {
    WidgetT *w = widgetAlloc(parent, WidgetTreeItemE);

    if (w) {
        w->as.treeItem.text     = text;
        w->as.treeItem.expanded = false;
    }

    return w;
}


// ============================================================
// wgtTreeItemIsExpanded
// ============================================================

bool wgtTreeItemIsExpanded(const WidgetT *w) {
    if (!w || w->type != WidgetTreeItemE) {
        return false;
    }

    return w->as.treeItem.expanded;
}


// ============================================================
// wgtTreeItemSetExpanded
// ============================================================

void wgtTreeItemSetExpanded(WidgetT *w, bool expanded) {
    if (!w || w->type != WidgetTreeItemE) {
        return;
    }

    w->as.treeItem.expanded = expanded;
}


// ============================================================
// wgtTreeView
// ============================================================

WidgetT *wgtTreeView(WidgetT *parent) {
    WidgetT *w = widgetAlloc(parent, WidgetTreeViewE);

    if (w) {
        w->weight = 100;
    }

    return w;
}


// ============================================================
// wgtTreeViewGetSelected
// ============================================================

WidgetT *wgtTreeViewGetSelected(const WidgetT *w) {
    if (!w || w->type != WidgetTreeViewE) {
        return NULL;
    }

    return w->as.treeView.selectedItem;
}


// ============================================================
// wgtTreeViewSetSelected
// ============================================================

void wgtTreeViewSetSelected(WidgetT *w, WidgetT *item) {
    if (!w || w->type != WidgetTreeViewE) {
        return;
    }

    w->as.treeView.selectedItem = item;
}


// ============================================================
// widgetTreeViewCalcMinSize
// ============================================================

void widgetTreeViewCalcMinSize(WidgetT *w, const BitmapFontT *font) {
    int32_t minContentW = TREE_INDENT + TREE_EXPAND_SIZE + TREE_ICON_GAP + 6 * font->charWidth;

    w->calcMinW = minContentW + TREE_BORDER * 2 + TREE_SB_W;
    w->calcMinH = TREE_MIN_ROWS * font->charHeight + TREE_BORDER * 2;
}


// ============================================================
// widgetTreeViewOnKey
// ============================================================

void widgetTreeViewOnKey(WidgetT *w, int32_t key) {
    if (!w || w->type != WidgetTreeViewE) {
        return;
    }

    WidgetT *sel = w->as.treeView.selectedItem;

    if (key == (0x50 | 0x100)) {
        // Down arrow — next visible item
        if (!sel) {
            w->as.treeView.selectedItem = firstVisibleItem(w);
        } else {
            WidgetT *next = nextVisibleItem(sel, w);

            if (next) {
                w->as.treeView.selectedItem = next;
            }
        }
    } else if (key == (0x48 | 0x100)) {
        // Up arrow — previous visible item
        if (!sel) {
            w->as.treeView.selectedItem = firstVisibleItem(w);
        } else {
            WidgetT *prev = prevVisibleItem(sel, w);

            if (prev) {
                w->as.treeView.selectedItem = prev;
            }
        }
    } else if (key == (0x4D | 0x100)) {
        // Right arrow — expand if collapsed, else move to first child
        if (sel) {
            bool hasChildren = false;

            for (WidgetT *c = sel->firstChild; c; c = c->nextSibling) {
                if (c->type == WidgetTreeItemE) {
                    hasChildren = true;
                    break;
                }
            }

            if (hasChildren) {
                if (!sel->as.treeItem.expanded) {
                    sel->as.treeItem.expanded = true;

                    if (sel->onChange) {
                        sel->onChange(sel);
                    }
                } else {
                    WidgetT *next = nextVisibleItem(sel, w);

                    if (next) {
                        w->as.treeView.selectedItem = next;
                    }
                }
            }
        }
    } else if (key == (0x4B | 0x100)) {
        // Left arrow — collapse if expanded, else move to parent
        if (sel) {
            if (sel->as.treeItem.expanded) {
                sel->as.treeItem.expanded = false;

                if (sel->onChange) {
                    sel->onChange(sel);
                }
            } else if (sel->parent && sel->parent != w && sel->parent->type == WidgetTreeItemE) {
                w->as.treeView.selectedItem = sel->parent;
            }
        }
    } else if (key == 0x0D) {
        // Enter — toggle expand/collapse for parents, onClick for leaves
        if (sel) {
            bool hasChildren = false;

            for (WidgetT *c = sel->firstChild; c; c = c->nextSibling) {
                if (c->type == WidgetTreeItemE) {
                    hasChildren = true;
                    break;
                }
            }

            if (hasChildren) {
                sel->as.treeItem.expanded = !sel->as.treeItem.expanded;

                if (sel->onChange) {
                    sel->onChange(sel);
                }
            } else {
                if (sel->onClick) {
                    sel->onClick(sel);
                }
            }
        }
    } else {
        return;
    }

    // Scroll to keep selected item visible
    sel = w->as.treeView.selectedItem;

    if (sel) {
        AppContextT *ctx = (AppContextT *)w->window->widgetRoot->userData;
        const BitmapFontT *font = &ctx->font;
        int32_t itemY = treeItemYPos(w, sel, font);

        if (itemY >= 0) {
            int32_t totalH;
            int32_t totalW;
            int32_t innerH;
            int32_t innerW;
            bool    needVSb;
            bool    needHSb;

            treeCalcScrollbarNeeds(w, font, &totalH, &totalW, &innerH, &innerW, &needVSb, &needHSb);

            if (itemY < w->as.treeView.scrollPos) {
                w->as.treeView.scrollPos = itemY;
            } else if (itemY + font->charHeight > w->as.treeView.scrollPos + innerH) {
                w->as.treeView.scrollPos = itemY + font->charHeight - innerH;
            }
        }
    }

    wgtInvalidate(w);
}


// ============================================================
// widgetTreeViewLayout
// ============================================================

void widgetTreeViewLayout(WidgetT *w, const BitmapFontT *font) {
    // Auto-select first item if nothing is selected
    if (!w->as.treeView.selectedItem) {
        w->as.treeView.selectedItem = firstVisibleItem(w);
    }

    int32_t totalH;
    int32_t totalW;
    int32_t innerH;
    int32_t innerW;
    bool    needVSb;
    bool    needHSb;

    treeCalcScrollbarNeeds(w, font, &totalH, &totalW, &innerH, &innerW, &needVSb, &needHSb);

    int32_t itemW  = innerW > totalW ? innerW : totalW;
    int32_t innerX = w->x + TREE_BORDER;
    int32_t innerY = w->y + TREE_BORDER;

    layoutTreeItems(w, font, innerX, &innerY, itemW, 0);
}


// ============================================================
// widgetTreeViewOnMouse
// ============================================================

void widgetTreeViewOnMouse(WidgetT *hit, WidgetT *root, int32_t vx, int32_t vy) {
    AppContextT *ctx = (AppContextT *)root->userData;
    const BitmapFontT *font = &ctx->font;

    int32_t totalH;
    int32_t totalW;
    int32_t innerH;
    int32_t innerW;
    bool    needVSb;
    bool    needHSb;

    treeCalcScrollbarNeeds(hit, font, &totalH, &totalW, &innerH, &innerW, &needVSb, &needHSb);

    // Clamp scroll positions
    int32_t maxScrollV = totalH - innerH;
    int32_t maxScrollH = totalW - innerW;

    if (maxScrollV < 0) {
        maxScrollV = 0;
    }

    if (maxScrollH < 0) {
        maxScrollH = 0;
    }

    hit->as.treeView.scrollPos  = clampInt(hit->as.treeView.scrollPos, 0, maxScrollV);
    hit->as.treeView.scrollPosH = clampInt(hit->as.treeView.scrollPosH, 0, maxScrollH);

    // Check if click is on the vertical scrollbar
    if (needVSb) {
        int32_t sbX = hit->x + hit->w - TREE_BORDER - TREE_SB_W;

        if (vx >= sbX && vy < hit->y + TREE_BORDER + innerH) {
            int32_t sbY      = hit->y + TREE_BORDER;
            int32_t sbH      = innerH;
            int32_t relY     = vy - sbY;
            int32_t trackLen = sbH - TREE_SB_W * 2;
            int32_t pageSize = innerH - font->charHeight;

            if (pageSize < font->charHeight) {
                pageSize = font->charHeight;
            }

            if (relY < TREE_SB_W) {
                // Up arrow — scroll up one row
                hit->as.treeView.scrollPos -= font->charHeight;
            } else if (relY >= sbH - TREE_SB_W) {
                // Down arrow — scroll down one row
                hit->as.treeView.scrollPos += font->charHeight;
            } else if (trackLen > 0) {
                // Track area — page up/down based on thumb position
                int32_t thumbPos;
                int32_t thumbSize;
                widgetScrollbarThumb(trackLen, totalH, innerH, hit->as.treeView.scrollPos, &thumbPos, &thumbSize);

                int32_t trackRelY = relY - TREE_SB_W;

                if (trackRelY < thumbPos) {
                    hit->as.treeView.scrollPos -= pageSize;
                } else if (trackRelY >= thumbPos + thumbSize) {
                    hit->as.treeView.scrollPos += pageSize;
                }
            }

            // Clamp after scroll
            hit->as.treeView.scrollPos = clampInt(hit->as.treeView.scrollPos, 0, maxScrollV);
            return;
        }
    }

    // Check if click is on the horizontal scrollbar
    if (needHSb) {
        int32_t sbY = hit->y + hit->h - TREE_BORDER - TREE_SB_W;

        if (vy >= sbY && vx < hit->x + TREE_BORDER + innerW) {
            int32_t sbX      = hit->x + TREE_BORDER;
            int32_t sbW      = innerW;
            int32_t relX     = vx - sbX;
            int32_t trackLen = sbW - TREE_SB_W * 2;
            int32_t pageSize = innerW - font->charWidth;

            if (pageSize < font->charWidth) {
                pageSize = font->charWidth;
            }

            if (relX < TREE_SB_W) {
                // Left arrow — scroll left
                hit->as.treeView.scrollPosH -= font->charWidth;
            } else if (relX >= sbW - TREE_SB_W) {
                // Right arrow — scroll right
                hit->as.treeView.scrollPosH += font->charWidth;
            } else if (trackLen > 0) {
                // Track area — page left/right based on thumb position
                int32_t thumbPos;
                int32_t thumbSize;
                widgetScrollbarThumb(trackLen, totalW, innerW, hit->as.treeView.scrollPosH, &thumbPos, &thumbSize);

                int32_t trackRelX = relX - TREE_SB_W;

                if (trackRelX < thumbPos) {
                    hit->as.treeView.scrollPosH -= pageSize;
                } else if (trackRelX >= thumbPos + thumbSize) {
                    hit->as.treeView.scrollPosH += pageSize;
                }
            }

            // Clamp after scroll
            hit->as.treeView.scrollPosH = clampInt(hit->as.treeView.scrollPosH, 0, maxScrollH);
            return;
        }
    }

    // Click in dead corner (both scrollbars present) — ignore
    if (needVSb && needHSb) {
        int32_t cornerX = hit->x + hit->w - TREE_BORDER - TREE_SB_W;
        int32_t cornerY = hit->y + hit->h - TREE_BORDER - TREE_SB_W;

        if (vx >= cornerX && vy >= cornerY) {
            return;
        }
    }

    // Tree item click — adjust for scroll offsets
    int32_t curY = hit->y + TREE_BORDER - hit->as.treeView.scrollPos;

    WidgetT *item = treeItemAtY(hit, vy, &curY, font);

    if (!item) {
        return;
    }

    // Set selection
    hit->as.treeView.selectedItem = item;

    // Check if click is on expand/collapse icon
    bool hasChildren = false;

    for (WidgetT *gc = item->firstChild; gc; gc = gc->nextSibling) {
        if (gc->type == WidgetTreeItemE) {
            hasChildren = true;
            break;
        }
    }

    if (hasChildren) {
        // Calculate indent depth
        int32_t  depth = 0;
        WidgetT *p     = item->parent;

        while (p && p->type == WidgetTreeItemE) {
            depth++;
            p = p->parent;
        }

        int32_t iconX = hit->x + TREE_BORDER + depth * TREE_INDENT - hit->as.treeView.scrollPosH;

        if (vx >= iconX && vx < iconX + TREE_EXPAND_SIZE) {
            item->as.treeItem.expanded = !item->as.treeItem.expanded;

            // Clamp scroll positions if collapsing reduced content size
            if (!item->as.treeItem.expanded) {
                int32_t newTotalH;
                int32_t newTotalW;
                int32_t newInnerH;
                int32_t newInnerW;
                bool    newNeedVSb;
                bool    newNeedHSb;

                treeCalcScrollbarNeeds(hit, font, &newTotalH, &newTotalW, &newInnerH, &newInnerW, &newNeedVSb, &newNeedHSb);

                int32_t newMaxScrlV = newTotalH - newInnerH;
                int32_t newMaxScrlH = newTotalW - newInnerW;

                if (newMaxScrlV < 0) {
                    newMaxScrlV = 0;
                }

                if (newMaxScrlH < 0) {
                    newMaxScrlH = 0;
                }

                hit->as.treeView.scrollPos  = clampInt(hit->as.treeView.scrollPos, 0, newMaxScrlV);
                hit->as.treeView.scrollPosH = clampInt(hit->as.treeView.scrollPosH, 0, newMaxScrlH);
            }

            if (item->onChange) {
                item->onChange(item);
            }
        } else {
            if (item->onClick) {
                item->onClick(item);
            }
        }
    } else {
        if (item->onClick) {
            item->onClick(item);
        }
    }
}


// ============================================================
// widgetTreeViewPaint
// ============================================================

void widgetTreeViewPaint(WidgetT *w, DisplayT *d, const BlitOpsT *ops, const BitmapFontT *font, const ColorSchemeT *colors) {
    uint32_t bg = w->bgColor ? w->bgColor : colors->contentBg;

    int32_t totalH;
    int32_t totalW;
    int32_t innerH;
    int32_t innerW;
    bool    needVSb;
    bool    needHSb;

    treeCalcScrollbarNeeds(w, font, &totalH, &totalW, &innerH, &innerW, &needVSb, &needHSb);

    // Clamp scroll positions
    int32_t maxScrollV = totalH - innerH;
    int32_t maxScrollH = totalW - innerW;

    if (maxScrollV < 0) {
        maxScrollV = 0;
    }

    if (maxScrollH < 0) {
        maxScrollH = 0;
    }

    w->as.treeView.scrollPos  = clampInt(w->as.treeView.scrollPos, 0, maxScrollV);
    w->as.treeView.scrollPosH = clampInt(w->as.treeView.scrollPosH, 0, maxScrollH);

    // Sunken border
    BevelStyleT bevel = BEVEL_SUNKEN(colors, bg, 2);
    drawBevel(d, ops, w->x, w->y, w->w, w->h, &bevel);

    // Set clip rect to inner content area (excludes scrollbars)
    int32_t oldClipX = d->clipX;
    int32_t oldClipY = d->clipY;
    int32_t oldClipW = d->clipW;
    int32_t oldClipH = d->clipH;
    setClipRect(d, w->x + TREE_BORDER, w->y + TREE_BORDER, innerW, innerH);

    // Paint tree items offset by both scroll positions
    int32_t itemY = w->y + TREE_BORDER - w->as.treeView.scrollPos;
    int32_t baseX = w->x + TREE_BORDER - w->as.treeView.scrollPosH;

    paintTreeItems(w, d, ops, font, colors,
                   baseX, &itemY, 0,
                   w->y + TREE_BORDER, w->y + TREE_BORDER + innerH,
                   w->as.treeView.selectedItem);

    // Restore clip rect
    setClipRect(d, oldClipX, oldClipY, oldClipW, oldClipH);

    // Draw scrollbars
    if (needVSb) {
        drawTreeVScrollbar(w, d, ops, colors, totalH, innerH);
    }

    if (needHSb) {
        drawTreeHScrollbar(w, d, ops, colors, totalW, innerW, needVSb);
    }

    if (w->focused) {
        uint32_t fg = w->fgColor ? w->fgColor : colors->contentFg;
        drawFocusRect(d, ops, w->x + 1, w->y + 1, w->w - 2, w->h - 2, fg);
    }
}