// widgetListView.c — ListView (multi-column list) widget
//
// A multi-column list with clickable/sortable column headers, horizontal
// and vertical scrolling, column resize by dragging header borders, and
// multi-select support. This is the most complex widget in the toolkit.
//
// Data model: cell data is stored as a flat array of const char* pointers
// in row-major order (cellData[row * colCount + col]). This external data
// model (pointers, not copies) keeps memory usage minimal and avoids
// copying strings that the application already owns.
//
// ListView state is heap-allocated separately (ListViewDataT*) rather than
// inlined in the widget union because the state is too large for a union
// member — it includes per-column resolved widths, sort index, selection
// bits, and numerous scroll/drag state fields.
//
// Sort: clicking a column header toggles sort direction. Sorting uses an
// indirection array (sortIndex) rather than rearranging the cellData. This
// is critical because:
//   1. The application owns cellData and may not expect it to be mutated
//   2. Multi-select selBits are indexed by data row, not display row —
//      rearranging data would invalidate all selection state
//   3. The indirection allows O(1) display↔data row mapping
//
// Insertion sort is used because it's stable (preserves original order for
// equal keys) and has good performance for the typical case of partially-sorted
// data. For the row counts typical in a DOS GUI (hundreds, not millions),
// insertion sort's O(n^2) worst case is acceptable and the constant factors
// are lower than quicksort.
//
// Column widths support four sizing modes via a tagged integer:
//   - 0: auto-size (scan all data for widest string)
//   - positive small: character count (resolved via font->charWidth)
//   - positive large: pixel width
//   - negative: percentage of parent width
// The resolution is done lazily in resolveColumnWidths, which is called on
// first paint or mouse event after data changes.
//
// Column resize: dragging a column header border (3px hot zone) resizes the
// column. The drag is tracked via sResizeListView/sResizeCol/sResizeStartX/
// sResizeOrigW globals. A minimum column width (LISTVIEW_MIN_COL_W) prevents
// columns from collapsing to zero.
//
// Horizontal scrolling is needed when total column width exceeds the widget's
// inner width. Both headers and data rows are offset by scrollPosH. The
// horizontal scrollbar appears automatically when needed, and its presence
// may trigger the vertical scrollbar to appear (and vice versa) — this
// two-pass logic handles the interdependency correctly.

#include "widgetInternal.h"

#include <stdlib.h>
#include <string.h>

#define LISTVIEW_PAD      3
#define LISTVIEW_MIN_ROWS 4
#define LISTVIEW_COL_PAD  6
#define LISTVIEW_SORT_W   10


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

static void allocListViewSelBits(WidgetT *w);
static void listViewBuildSortIndex(WidgetT *w);
static void resolveColumnWidths(WidgetT *w, const BitmapFontT *font);


// ============================================================
// allocListViewSelBits
// ============================================================

// Same allocation strategy as ListBox's selBits — one byte per row,
// only allocated when multiSelect is enabled.
static void allocListViewSelBits(WidgetT *w) {
    if (w->as.listView->selBits) {
        free(w->as.listView->selBits);
        w->as.listView->selBits = NULL;
    }

    int32_t count = w->as.listView->rowCount;

    if (count > 0 && w->as.listView->multiSelect) {
        w->as.listView->selBits = (uint8_t *)calloc(count, 1);
    }
}


// ============================================================
// listViewBuildSortIndex
// ============================================================
//
// Build or rebuild the sortIndex array. Uses insertion sort
// (stable) on the sort column. If no sort is active, frees
// the index so paint uses natural order.

// Build the sort indirection array. Rather than rearranging cellData (which
// the application owns and indexes into), we maintain a separate array that
// maps display-row → data-row. Paint and keyboard navigation work in display-row
// space, then map through sortIndex to get the data row for cell lookups and
// selection operations. This decoupling is essential because selBits are
// indexed by data row — sorting must not invalidate selection state.
static void listViewBuildSortIndex(WidgetT *w) {
    int32_t rowCount = w->as.listView->rowCount;
    int32_t sortCol  = w->as.listView->sortCol;
    int32_t colCount = w->as.listView->colCount;

    // No sort active — clear index
    if (sortCol < 0 || w->as.listView->sortDir == ListViewSortNoneE || rowCount <= 0) {
        if (w->as.listView->sortIndex) {
            free(w->as.listView->sortIndex);
            w->as.listView->sortIndex = NULL;
        }

        return;
    }

    // Allocate or reuse
    int32_t *idx = w->as.listView->sortIndex;

    if (!idx) {
        idx = (int32_t *)malloc(rowCount * sizeof(int32_t));

        if (!idx) {
            return;
        }

        w->as.listView->sortIndex = idx;
    }

    // Initialize identity
    for (int32_t i = 0; i < rowCount; i++) {
        idx[i] = i;
    }

    // Insertion sort — stable (equal elements keep their original order),
    // O(n^2) worst case but with very low constant factors. For typical
    // ListView row counts (10s to low 100s), this beats quicksort because
    // there's no recursion overhead, no stack usage, and the inner loop
    // is a simple pointer chase. On a 486, the predictable memory access
    // pattern also helps since insertion sort is cache-friendly (sequential
    // access to adjacent elements).
    bool ascending = (w->as.listView->sortDir == ListViewSortAscE);

    for (int32_t i = 1; i < rowCount; i++) {
        int32_t key = idx[i];
        const char *keyStr = w->as.listView->cellData[key * colCount + sortCol];

        if (!keyStr) {
            keyStr = "";
        }

        int32_t j = i - 1;

        while (j >= 0) {
            const char *jStr = w->as.listView->cellData[idx[j] * colCount + sortCol];

            if (!jStr) {
                jStr = "";
            }

            int32_t cmp = strcmp(jStr, keyStr);

            if (!ascending) {
                cmp = -cmp;
            }

            if (cmp <= 0) {
                break;
            }

            idx[j + 1] = idx[j];
            j--;
        }

        idx[j + 1] = key;
    }
}


// ============================================================
// resolveColumnWidths
// ============================================================
//
// Resolve tagged column sizes (pixels, chars, percent, or auto)
// to actual pixel widths. Auto-sized columns (width==0) scan
// cellData for the widest string in that column.

// Resolve tagged column widths to actual pixel values. Column widths in the
// ListViewColT definition can be specified as:
//   0          = auto (scan data for widest string, include header)
//   positive   = passed to wgtResolveSize (handles px, chars, or percent)
//
// Auto-sizing scans all rows for the widest string in that column, which
// is O(rows * cols) but only runs once per data change (totalColW is reset
// to 0 when data changes, triggering recalculation on next paint/mouse).
static void resolveColumnWidths(WidgetT *w, const BitmapFontT *font) {
    int32_t colCount = w->as.listView->colCount;
    int32_t parentW  = w->w - LISTVIEW_BORDER * 2;

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

    int32_t totalW = 0;

    for (int32_t c = 0; c < colCount; c++) {
        int32_t taggedW = w->as.listView->cols[c].width;

        if (taggedW == 0) {
            // Auto-size: scan data for widest string in this column
            int32_t maxLen = (int32_t)strlen(w->as.listView->cols[c].title);

            for (int32_t r = 0; r < w->as.listView->rowCount; r++) {
                const char *cell = w->as.listView->cellData[r * colCount + c];

                if (cell) {
                    int32_t slen = (int32_t)strlen(cell);

                    if (slen > maxLen) {
                        maxLen = slen;
                    }
                }
            }

            w->as.listView->resolvedColW[c] = maxLen * font->charWidth + LISTVIEW_COL_PAD;
        } else {
            w->as.listView->resolvedColW[c] = wgtResolveSize(taggedW, parentW, font->charWidth);
        }

        totalW += w->as.listView->resolvedColW[c];
    }

    w->as.listView->totalColW = totalW;
}


// ============================================================
// widgetListViewColBorderHit
// ============================================================
//
// Returns true if (vx, vy) is on a column header border (resize zone).
// Coordinates are in widget/virtual space (scroll-adjusted).

// Test if a point is on a column header border (within 3px). Used by the
// cursor-shape logic to show a resize cursor when hovering over column borders.
// The 3px zone on each side of the border line makes it easy to grab even
// on low-resolution displays where pixel-precise clicking is difficult.
bool widgetListViewColBorderHit(const WidgetT *w, int32_t vx, int32_t vy) {
    if (!w || w->type != WidgetListViewE || w->as.listView->colCount == 0) {
        return false;
    }

    AppContextT       *ctx  = wgtGetContext(w);
    const BitmapFontT *font = &ctx->font;
    int32_t headerH   = font->charHeight + 4;
    int32_t headerTop = w->y + LISTVIEW_BORDER;

    if (vy < headerTop || vy >= headerTop + headerH) {
        return false;
    }

    int32_t colX = w->x + LISTVIEW_BORDER - w->as.listView->scrollPosH;

    for (int32_t c = 0; c < w->as.listView->colCount; c++) {
        int32_t border = colX + w->as.listView->resolvedColW[c];

        if (vx >= border - 3 && vx <= border + 3) {
            return true;
        }

        colX += w->as.listView->resolvedColW[c];
    }

    return false;
}


// ============================================================
// widgetListViewDestroy
// ============================================================

// Free all heap-allocated ListView state. The sortIndex and selBits are
// optional (may be NULL if no sort or single-select), so we check before
// freeing. The ListViewDataT struct itself is always freed.
void widgetListViewDestroy(WidgetT *w) {
    if (w->as.listView->sortIndex) {
        free(w->as.listView->sortIndex);
    }

    if (w->as.listView->selBits) {
        free(w->as.listView->selBits);
    }

    free(w->as.listView);
    w->as.listView = NULL;
}


// ============================================================
// wgtListView
// ============================================================

// Create a ListView widget. The ListViewDataT is heap-allocated separately
// because it's too large for the widget union (it contains fixed-size arrays
// for resolved column widths, plus numerous state fields for scrolling, sorting,
// selection, and drag-reorder). Default weight=100 makes the ListView expand
// to fill available space, which is the typical desired behavior.
WidgetT *wgtListView(WidgetT *parent) {
    WidgetT *w = widgetAlloc(parent, WidgetListViewE);

    if (!w) {
        return NULL;
    }

    w->as.listView = (ListViewDataT *)calloc(1, sizeof(ListViewDataT));

    if (!w->as.listView) {
        free(w);
        return NULL;
    }

    w->as.listView->selectedIdx = -1;
    w->as.listView->anchorIdx   = -1;
    w->as.listView->sortCol     = -1;
    w->as.listView->sortDir     = ListViewSortNoneE;
    w->as.listView->dragIdx     = -1;
    w->as.listView->dropIdx     = -1;
    w->weight                   = 100;

    return w;
}


// ============================================================
// wgtListViewGetSelected
// ============================================================

int32_t wgtListViewGetSelected(const WidgetT *w) {
    VALIDATE_WIDGET(w, WidgetListViewE, -1);

    return w->as.listView->selectedIdx;
}


// ============================================================
// wgtListViewClearSelection
// ============================================================

void wgtListViewClearSelection(WidgetT *w) {
    if (!w || w->type != WidgetListViewE || !w->as.listView->selBits) {
        return;
    }

    memset(w->as.listView->selBits, 0, w->as.listView->rowCount);
    wgtInvalidatePaint(w);
}


// ============================================================
// wgtListViewIsItemSelected
// ============================================================

bool wgtListViewIsItemSelected(const WidgetT *w, int32_t idx) {
    VALIDATE_WIDGET(w, WidgetListViewE, false);

    if (!w->as.listView->multiSelect) {
        return idx == w->as.listView->selectedIdx;
    }

    if (!w->as.listView->selBits || idx < 0 || idx >= w->as.listView->rowCount) {
        return false;
    }

    return w->as.listView->selBits[idx] != 0;
}


// ============================================================
// wgtListViewSelectAll
// ============================================================

void wgtListViewSelectAll(WidgetT *w) {
    if (!w || w->type != WidgetListViewE || !w->as.listView->selBits) {
        return;
    }

    memset(w->as.listView->selBits, 1, w->as.listView->rowCount);
    wgtInvalidatePaint(w);
}


// ============================================================
// wgtListViewSetColumns
// ============================================================

void wgtListViewSetColumns(WidgetT *w, const ListViewColT *cols, int32_t count) {
    VALIDATE_WIDGET_VOID(w, WidgetListViewE);

    if (count > LISTVIEW_MAX_COLS) {
        count = LISTVIEW_MAX_COLS;
    }

    w->as.listView->cols     = cols;
    w->as.listView->colCount = count;
    w->as.listView->totalColW = 0;
    wgtInvalidate(w);
}


// ============================================================
// wgtListViewSetData
// ============================================================

void wgtListViewSetData(WidgetT *w, const char **cellData, int32_t rowCount) {
    VALIDATE_WIDGET_VOID(w, WidgetListViewE);

    // Free old sort index since row count may have changed
    if (w->as.listView->sortIndex) {
        free(w->as.listView->sortIndex);
        w->as.listView->sortIndex = NULL;
    }

    w->as.listView->cellData  = cellData;
    w->as.listView->rowCount  = rowCount;
    w->as.listView->totalColW = 0;

    if (w->as.listView->selectedIdx >= rowCount) {
        w->as.listView->selectedIdx = rowCount > 0 ? 0 : -1;
    }

    if (w->as.listView->selectedIdx < 0 && rowCount > 0) {
        w->as.listView->selectedIdx = 0;
    }

    w->as.listView->anchorIdx = w->as.listView->selectedIdx;

    // Rebuild sort index if sort is active
    listViewBuildSortIndex(w);

    // Reallocate selection bits
    allocListViewSelBits(w);

    if (w->as.listView->selBits && w->as.listView->selectedIdx >= 0) {
        w->as.listView->selBits[w->as.listView->selectedIdx] = 1;
    }

    wgtInvalidate(w);
}


// ============================================================
// wgtListViewSetHeaderClickCallback
// ============================================================

void wgtListViewSetHeaderClickCallback(WidgetT *w, void (*cb)(WidgetT *w, int32_t col, ListViewSortE dir)) {
    VALIDATE_WIDGET_VOID(w, WidgetListViewE);

    w->as.listView->onHeaderClick = cb;
}


// ============================================================
// wgtListViewSetItemSelected
// ============================================================

void wgtListViewSetItemSelected(WidgetT *w, int32_t idx, bool selected) {
    VALIDATE_WIDGET_VOID(w, WidgetListViewE);

    if (!w->as.listView->selBits || idx < 0 || idx >= w->as.listView->rowCount) {
        return;
    }

    w->as.listView->selBits[idx] = selected ? 1 : 0;
    wgtInvalidatePaint(w);
}


// ============================================================
// wgtListViewSetReorderable
// ============================================================

// Enable/disable drag-reorder. When reorderable is enabled, sorting is
// disabled because the two features are fundamentally incompatible: if the
// user manually arranges items, then sorts by a column, the manual order
// is lost. By clearing sortCol and freeing sortIndex, we ensure the display
// shows the natural data order which the user's drag operations will modify.
void wgtListViewSetReorderable(WidgetT *w, bool reorderable) {
    VALIDATE_WIDGET_VOID(w, WidgetListViewE);

    w->as.listView->reorderable = reorderable;

    // Disable sorting when reorderable — sort order conflicts with manual order
    if (reorderable) {
        w->as.listView->sortCol = -1;
        w->as.listView->sortDir = ListViewSortNoneE;

        if (w->as.listView->sortIndex) {
            free(w->as.listView->sortIndex);
            w->as.listView->sortIndex = NULL;
        }
    }
}


// ============================================================
// wgtListViewSetMultiSelect
// ============================================================

void wgtListViewSetMultiSelect(WidgetT *w, bool multi) {
    VALIDATE_WIDGET_VOID(w, WidgetListViewE);

    w->as.listView->multiSelect = multi;
    allocListViewSelBits(w);

    if (w->as.listView->selBits && w->as.listView->selectedIdx >= 0) {
        w->as.listView->selBits[w->as.listView->selectedIdx] = 1;
    }
}


// ============================================================
// wgtListViewSetSelected
// ============================================================

void wgtListViewSetSelected(WidgetT *w, int32_t idx) {
    VALIDATE_WIDGET_VOID(w, WidgetListViewE);

    w->as.listView->selectedIdx = idx;
    w->as.listView->anchorIdx   = idx;

    if (w->as.listView->selBits) {
        memset(w->as.listView->selBits, 0, w->as.listView->rowCount);

        if (idx >= 0 && idx < w->as.listView->rowCount) {
            w->as.listView->selBits[idx] = 1;
        }
    }

    wgtInvalidatePaint(w);
}


// ============================================================
// wgtListViewSetSort
// ============================================================

void wgtListViewSetSort(WidgetT *w, int32_t col, ListViewSortE dir) {
    VALIDATE_WIDGET_VOID(w, WidgetListViewE);

    w->as.listView->sortCol = col;
    w->as.listView->sortDir = dir;
    listViewBuildSortIndex(w);
    wgtInvalidatePaint(w);
}


// ============================================================
// widgetListViewCalcMinSize
// ============================================================

void widgetListViewCalcMinSize(WidgetT *w, const BitmapFontT *font) {
    int32_t headerH = font->charHeight + 4;
    int32_t minW    = font->charWidth * 12 + LISTVIEW_BORDER * 2 + WGT_SB_W;

    w->calcMinW = minW;
    w->calcMinH = headerH + LISTVIEW_MIN_ROWS * font->charHeight + LISTVIEW_BORDER * 2;
}


// ============================================================
// widgetListViewOnKey
// ============================================================

// Key handling must account for the sort indirection layer. Navigation happens
// in display-row space (what the user sees on screen), but selection and data
// access happen in data-row space (the original cellData indices). This means:
//   1. Convert selectedIdx (data row) to display row via linear search in sortIndex
//   2. Navigate in display space (widgetNavigateIndex)
//   3. Convert back to data row via sortIndex[displayRow]
//   4. Update selectedIdx and selBits using data-row indices
//
// Shift-select for sorted views is particularly tricky: the range must be
// computed in display-row space (what the user sees as contiguous) but applied
// to the data-row selBits. This means the selected data rows may not be
// contiguous in the original data order.
void widgetListViewOnKey(WidgetT *w, int32_t key, int32_t mod) {
    if (!w || w->type != WidgetListViewE || w->as.listView->rowCount == 0) {
        return;
    }

    bool     multi    = w->as.listView->multiSelect;
    bool     shift    = (mod & KEY_MOD_SHIFT) != 0;
    bool     ctrl     = (mod & KEY_MOD_CTRL) != 0;
    int32_t  rowCount = w->as.listView->rowCount;
    int32_t *sortIdx  = w->as.listView->sortIndex;

    // Ctrl+A — select all (multi-select only)
    if (multi && ctrl && (key == 'a' || key == 'A' || key == 1)) {
        wgtListViewSelectAll(w);
        return;
    }

    // Space — toggle current item (multi-select only)
    if (multi && key == ' ') {
        int32_t sel = w->as.listView->selectedIdx;

        if (sel >= 0 && w->as.listView->selBits) {
            w->as.listView->selBits[sel] ^= 1;
            w->as.listView->anchorIdx = sel;
        }

        if (w->onChange) {
            w->onChange(w);
        }

        wgtInvalidatePaint(w);
        return;
    }

    // Find current display row from selectedIdx (data row)
    int32_t displaySel = -1;

    if (w->as.listView->selectedIdx >= 0) {
        if (sortIdx) {
            for (int32_t i = 0; i < rowCount; i++) {
                if (sortIdx[i] == w->as.listView->selectedIdx) {
                    displaySel = i;
                    break;
                }
            }
        } else {
            displaySel = w->as.listView->selectedIdx;
        }
    }

    // Compute visible rows for page up/down
    AppContextT       *ctx  = wgtGetContext(w);
    const BitmapFontT *font = &ctx->font;
    int32_t headerH      = font->charHeight + 4;
    int32_t innerH       = w->h - LISTVIEW_BORDER * 2 - headerH;
    int32_t visibleRows  = innerH / font->charHeight;

    if (visibleRows < 1) {
        visibleRows = 1;
    }

    int32_t newDisplaySel = widgetNavigateIndex(key, displaySel, rowCount, visibleRows);

    if (newDisplaySel < 0) {
        return;
    }

    displaySel = newDisplaySel;

    // Convert display row back to data row
    int32_t newDataRow = sortIdx ? sortIdx[displaySel] : displaySel;

    if (newDataRow == w->as.listView->selectedIdx) {
        return;
    }

    w->as.listView->selectedIdx = newDataRow;

    // Update multi-select
    if (multi && w->as.listView->selBits) {
        if (shift) {
            // Shift+arrow: range from anchor to new cursor (in data-row space)
            memset(w->as.listView->selBits, 0, rowCount);

            // Convert anchor to display row, then select display range mapped to data rows
            int32_t anchorDisplay = -1;
            int32_t anchor = w->as.listView->anchorIdx;

            if (sortIdx && anchor >= 0) {
                for (int32_t i = 0; i < rowCount; i++) {
                    if (sortIdx[i] == anchor) {
                        anchorDisplay = i;
                        break;
                    }
                }
            } else {
                anchorDisplay = anchor;
            }

            // Select all display rows in range, mapping to data rows
            int32_t lo = anchorDisplay < displaySel ? anchorDisplay : displaySel;
            int32_t hi = anchorDisplay > displaySel ? anchorDisplay : displaySel;

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

            if (hi >= rowCount) {
                hi = rowCount - 1;
            }

            for (int32_t i = lo; i <= hi; i++) {
                int32_t dr = sortIdx ? sortIdx[i] : i;
                w->as.listView->selBits[dr] = 1;
            }
        }
        // Plain arrow: just move cursor, leave selections untouched
    }

    // Scroll to keep selection visible (in display-row space)
    if (displaySel >= 0) {
        if (displaySel < w->as.listView->scrollPos) {
            w->as.listView->scrollPos = displaySel;
        } else if (displaySel >= w->as.listView->scrollPos + visibleRows) {
            w->as.listView->scrollPos = displaySel - visibleRows + 1;
        }
    }

    if (w->onChange) {
        w->onChange(w);
    }

    wgtInvalidatePaint(w);
}


// ============================================================
// widgetListViewOnMouse
// ============================================================

// Mouse handling is the most complex part of ListView. It handles four
// distinct hit regions (checked in priority order):
//   1. Vertical scrollbar (right edge, if visible)
//   2. Horizontal scrollbar (bottom edge, if visible)
//   3. Dead corner (when both scrollbars present — no action)
//   4. Column headers: resize drag (border +-3px) or sort toggle (click)
//   5. Data rows: item selection with Ctrl/Shift modifiers, double-click,
//      and drag-reorder initiation
//
// The scrollbar visibility calculation is repeated here (matching paint)
// because scrollbar presence depends on content/widget dimensions which
// may have changed since the last paint.
void widgetListViewOnMouse(WidgetT *hit, WidgetT *root, int32_t vx, int32_t vy) {
    hit->focused = true;

    AppContextT       *ctx  = (AppContextT *)root->userData;
    const BitmapFontT *font = &ctx->font;

    // Resolve column widths if needed
    if (hit->as.listView->totalColW == 0 && hit->as.listView->colCount > 0) {
        resolveColumnWidths(hit, font);
    }

    int32_t headerH     = font->charHeight + 4;
    int32_t innerH      = hit->h - LISTVIEW_BORDER * 2 - headerH;
    int32_t innerW      = hit->w - LISTVIEW_BORDER * 2;
    int32_t visibleRows = innerH / font->charHeight;
    int32_t totalColW   = hit->as.listView->totalColW;
    bool    needVSb     = (hit->as.listView->rowCount > visibleRows);
    bool    needHSb     = false;

    // Scrollbar interdependency: adding a vertical scrollbar reduces innerW,
    // which may cause columns to overflow and require a horizontal scrollbar.
    // Adding a horizontal scrollbar reduces innerH, which may require a
    // vertical scrollbar. This two-pass check handles the mutual dependency.
    if (needVSb) {
        innerW -= WGT_SB_W;
    }

    if (totalColW > innerW) {
        needHSb = true;
        innerH -= WGT_SB_W;
        visibleRows = innerH / font->charHeight;

        if (!needVSb && hit->as.listView->rowCount > visibleRows) {
            needVSb = true;
            innerW -= WGT_SB_W;
        }
    }

    if (visibleRows < 1) {
        visibleRows = 1;
    }

    // Clamp scroll positions
    int32_t maxScrollV = hit->as.listView->rowCount - visibleRows;
    int32_t maxScrollH = totalColW - innerW;

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

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

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

    // Check vertical scrollbar
    if (needVSb) {
        int32_t sbX = hit->x + hit->w - LISTVIEW_BORDER - WGT_SB_W;
        int32_t sbY = hit->y + LISTVIEW_BORDER + headerH;

        if (vx >= sbX && vy >= sbY && vy < sbY + innerH) {
            int32_t    relY = vy - sbY;
            ScrollHitE sh   = widgetScrollbarHitTest(innerH, relY, hit->as.listView->rowCount, visibleRows, hit->as.listView->scrollPos);

            if (sh == ScrollHitArrowDecE) {
                if (hit->as.listView->scrollPos > 0) {
                    hit->as.listView->scrollPos--;
                }
            } else if (sh == ScrollHitArrowIncE) {
                if (hit->as.listView->scrollPos < maxScrollV) {
                    hit->as.listView->scrollPos++;
                }
            } else if (sh == ScrollHitPageDecE) {
                hit->as.listView->scrollPos -= visibleRows;
                hit->as.listView->scrollPos = clampInt(hit->as.listView->scrollPos, 0, maxScrollV);
            } else if (sh == ScrollHitPageIncE) {
                hit->as.listView->scrollPos += visibleRows;
                hit->as.listView->scrollPos = clampInt(hit->as.listView->scrollPos, 0, maxScrollV);
            }

            return;
        }
    }

    // Check horizontal scrollbar
    if (needHSb) {
        int32_t sbX = hit->x + LISTVIEW_BORDER;
        int32_t sbY = hit->y + hit->h - LISTVIEW_BORDER - WGT_SB_W;

        if (vy >= sbY && vx >= sbX && vx < sbX + innerW) {
            int32_t relX     = vx - sbX;
            int32_t pageSize = innerW - font->charWidth;

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

            ScrollHitE sh = widgetScrollbarHitTest(innerW, relX, totalColW, innerW, hit->as.listView->scrollPosH);

            if (sh == ScrollHitArrowDecE) {
                hit->as.listView->scrollPosH -= font->charWidth;
            } else if (sh == ScrollHitArrowIncE) {
                hit->as.listView->scrollPosH += font->charWidth;
            } else if (sh == ScrollHitPageDecE) {
                hit->as.listView->scrollPosH -= pageSize;
            } else if (sh == ScrollHitPageIncE) {
                hit->as.listView->scrollPosH += pageSize;
            }

            hit->as.listView->scrollPosH = clampInt(hit->as.listView->scrollPosH, 0, maxScrollH);
            return;
        }
    }

    // Check dead corner (both scrollbars present)
    if (needVSb && needHSb) {
        int32_t cornerX = hit->x + hit->w - LISTVIEW_BORDER - WGT_SB_W;
        int32_t cornerY = hit->y + hit->h - LISTVIEW_BORDER - WGT_SB_W;

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

    // Check column header area
    int32_t headerTop = hit->y + LISTVIEW_BORDER;

    if (vy >= headerTop && vy < headerTop + headerH) {
        // Check for column border resize (3px zone on each side of border)
        int32_t colX = hit->x + LISTVIEW_BORDER - hit->as.listView->scrollPosH;

        for (int32_t c = 0; c < hit->as.listView->colCount; c++) {
            int32_t cw     = hit->as.listView->resolvedColW[c];
            int32_t border = colX + cw;

            if (vx >= border - 3 && vx <= border + 3 && c < hit->as.listView->colCount) {
                // Start column resize drag
                sResizeListView = hit;
                sResizeCol      = c;
                sResizeStartX   = vx;
                sResizeOrigW    = cw;
                return;
            }

            colX += cw;
        }

        // Not on a border — check for sort click (disabled when reorderable
        // since sorting conflicts with manual ordering). Clicking a column
        // toggles between ascending/descending; clicking a different column
        // starts ascending.
        if (!hit->as.listView->reorderable) {
            colX = hit->x + LISTVIEW_BORDER - hit->as.listView->scrollPosH;

            for (int32_t c = 0; c < hit->as.listView->colCount; c++) {
                int32_t cw = hit->as.listView->resolvedColW[c];

                if (vx >= colX && vx < colX + cw) {
                    // Toggle sort direction for this column
                    if (hit->as.listView->sortCol == c) {
                        if (hit->as.listView->sortDir == ListViewSortAscE) {
                            hit->as.listView->sortDir = ListViewSortDescE;
                        } else {
                            hit->as.listView->sortDir = ListViewSortAscE;
                        }
                    } else {
                        hit->as.listView->sortCol = c;
                        hit->as.listView->sortDir = ListViewSortAscE;
                    }

                    listViewBuildSortIndex(hit);

                    if (hit->as.listView->onHeaderClick) {
                        hit->as.listView->onHeaderClick(hit, c, hit->as.listView->sortDir);
                    }

                    wgtInvalidatePaint(hit);
                    return;
                }

                colX += cw;
            }
        }

        return;
    }

    // Click on data area
    int32_t dataTop = headerTop + headerH;
    int32_t relY    = vy - dataTop;

    if (relY < 0) {
        return;
    }

    int32_t clickedRow = relY / font->charHeight;
    int32_t displayRow = hit->as.listView->scrollPos + clickedRow;

    if (displayRow >= 0 && displayRow < hit->as.listView->rowCount) {
        int32_t dataRow = hit->as.listView->sortIndex ? hit->as.listView->sortIndex[displayRow] : displayRow;
        hit->as.listView->selectedIdx = dataRow;

        bool multi = hit->as.listView->multiSelect;
        bool shift = (ctx->keyModifiers & KEY_MOD_SHIFT) != 0;
        bool ctrl  = (ctx->keyModifiers & KEY_MOD_CTRL) != 0;

        if (multi && hit->as.listView->selBits) {
            if (ctrl) {
                // Ctrl+click: toggle item, update anchor
                hit->as.listView->selBits[dataRow] ^= 1;
                hit->as.listView->anchorIdx = dataRow;
            } else if (shift) {
                // Shift+click: range from anchor to clicked (in display-row space)
                memset(hit->as.listView->selBits, 0, hit->as.listView->rowCount);

                int32_t anchorDisplay = -1;
                int32_t anchor = hit->as.listView->anchorIdx;

                if (hit->as.listView->sortIndex && anchor >= 0) {
                    for (int32_t i = 0; i < hit->as.listView->rowCount; i++) {
                        if (hit->as.listView->sortIndex[i] == anchor) {
                            anchorDisplay = i;
                            break;
                        }
                    }
                } else {
                    anchorDisplay = anchor;
                }

                int32_t lo = anchorDisplay < displayRow ? anchorDisplay : displayRow;
                int32_t hi = anchorDisplay > displayRow ? anchorDisplay : displayRow;

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

                if (hi >= hit->as.listView->rowCount) {
                    hi = hit->as.listView->rowCount - 1;
                }

                for (int32_t i = lo; i <= hi; i++) {
                    int32_t dr = hit->as.listView->sortIndex ? hit->as.listView->sortIndex[i] : i;
                    hit->as.listView->selBits[dr] = 1;
                }
            } else {
                // Plain click: select only this item, update anchor
                memset(hit->as.listView->selBits, 0, hit->as.listView->rowCount);
                hit->as.listView->selBits[dataRow] = 1;
                hit->as.listView->anchorIdx = dataRow;
            }
        }

        if (hit->onChange) {
            hit->onChange(hit);
        }

        if (hit->onDblClick && multiClickDetect(vx, vy) >= 2) {
            hit->onDblClick(hit);
        }

        // Initiate drag-reorder if enabled (not from modifier clicks)
        if (hit->as.listView->reorderable && !shift && !ctrl) {
            hit->as.listView->dragIdx = dataRow;
            hit->as.listView->dropIdx = dataRow;
            sDragReorder = hit;
        }
    }

    wgtInvalidatePaint(hit);
}


// ============================================================
// widgetListViewPaint
// ============================================================

// Paint: the most involved paint function in the widget toolkit. Renders
// in layers:
//   1. Outer sunken bevel border
//   2. Column headers (clipped to content width, scrolled by scrollPosH):
//      each header is a raised bevel button with centered text and optional
//      sort indicator (up/down triangle)
//   3. Data rows (clipped to data area, scrolled both H and V):
//      background fill, then per-cell text rendering with alignment, then
//      selection highlight, then cursor focus rect in multi-select mode
//   4. Drag-reorder insertion line (if active)
//   5. Scrollbars (V and/or H, with dead corner fill)
//   6. Outer focus rect
//
// Clip rectangles are saved/restored around the header and data sections to
// prevent rendering from bleeding into the scrollbar or border areas. This
// is cheaper than per-cell clipping and handles horizontal scroll correctly
// (partially visible columns at the edges are clipped by the display's clip
// rect rather than by the draw calls).
void widgetListViewPaint(WidgetT *w, DisplayT *d, const BlitOpsT *ops, const BitmapFontT *font, const ColorSchemeT *colors) {
    uint32_t fg = w->fgColor ? w->fgColor : colors->contentFg;
    uint32_t bg = w->bgColor ? w->bgColor : colors->contentBg;

    // Resolve column widths if needed
    if (w->as.listView->totalColW == 0 && w->as.listView->colCount > 0) {
        resolveColumnWidths(w, font);
    }

    int32_t headerH     = font->charHeight + 4;
    int32_t innerH      = w->h - LISTVIEW_BORDER * 2 - headerH;
    int32_t innerW      = w->w - LISTVIEW_BORDER * 2;
    int32_t visibleRows = innerH / font->charHeight;
    int32_t totalColW   = w->as.listView->totalColW;
    bool    needVSb     = (w->as.listView->rowCount > visibleRows);
    bool    needHSb     = false;

    if (needVSb) {
        innerW -= WGT_SB_W;
    }

    if (totalColW > innerW) {
        needHSb = true;
        innerH -= WGT_SB_W;
        visibleRows = innerH / font->charHeight;

        if (!needVSb && w->as.listView->rowCount > visibleRows) {
            needVSb = true;
            innerW -= WGT_SB_W;
        }
    }

    if (visibleRows < 1) {
        visibleRows = 1;
    }

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

    // Clamp scroll positions
    int32_t maxScrollV = w->as.listView->rowCount - visibleRows;
    int32_t maxScrollH = totalColW - innerW;

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

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

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

    int32_t baseX    = w->x + LISTVIEW_BORDER;
    int32_t baseY    = w->y + LISTVIEW_BORDER;
    int32_t colCount = w->as.listView->colCount;

    // ---- Draw column headers ----
    {
        // Clip headers to the content area width
        int32_t oldClipX = d->clipX;
        int32_t oldClipY = d->clipY;
        int32_t oldClipW = d->clipW;
        int32_t oldClipH = d->clipH;
        setClipRect(d, baseX, baseY, innerW, headerH);

        int32_t hdrX = baseX - w->as.listView->scrollPosH;
        BevelStyleT hdrBevel = BEVEL_RAISED(colors, 1);

        for (int32_t c = 0; c < colCount; c++) {
            int32_t cw = w->as.listView->resolvedColW[c];

            // Draw raised button for header
            drawBevel(d, ops, hdrX, baseY, cw, headerH, &hdrBevel);

            // Header text
            int32_t textX = hdrX + LISTVIEW_PAD;
            int32_t textY = baseY + 2;
            int32_t availTextW = cw - LISTVIEW_PAD * 2;

            // Reserve space for sort indicator if this is the sort column
            if (c == w->as.listView->sortCol && w->as.listView->sortDir != ListViewSortNoneE) {
                availTextW -= LISTVIEW_SORT_W;
            }

            if (w->as.listView->cols[c].title) {
                int32_t titleLen = (int32_t)strlen(w->as.listView->cols[c].title);
                int32_t titleW   = titleLen * font->charWidth;

                if (titleW > availTextW) {
                    titleLen = availTextW / font->charWidth;
                }

                if (titleLen > 0) {
                    drawTextN(d, ops, font, textX, textY, w->as.listView->cols[c].title, titleLen, colors->contentFg, colors->windowFace, true);
                }
            }

            // Sort indicator: a small filled triangle (4px tall) in the header.
            // Up triangle for ascending, down triangle for descending. Drawn as
            // horizontal lines of increasing/decreasing width, same technique as
            // the dropdown arrow glyph.
            if (c == w->as.listView->sortCol && w->as.listView->sortDir != ListViewSortNoneE) {
                int32_t cx = hdrX + cw - LISTVIEW_SORT_W / 2 - LISTVIEW_PAD;
                int32_t cy = baseY + headerH / 2;

                if (w->as.listView->sortDir == ListViewSortAscE) {
                    // Up triangle (ascending)
                    for (int32_t i = 0; i < 4; i++) {
                        drawHLine(d, ops, cx - i, cy - 2 + i, 1 + i * 2, colors->contentFg);
                    }
                } else {
                    // Down triangle (descending)
                    for (int32_t i = 0; i < 4; i++) {
                        drawHLine(d, ops, cx - 3 + i, cy - 1 + i, 7 - i * 2, colors->contentFg);
                    }
                }
            }

            hdrX += cw;
        }

        // Fill any remaining header space to the right of columns
        if (hdrX < baseX + innerW) {
            drawBevel(d, ops, hdrX, baseY, baseX + innerW - hdrX, headerH, &hdrBevel);
        }

        setClipRect(d, oldClipX, oldClipY, oldClipW, oldClipH);
    }

    // ---- Draw data rows ----
    {
        int32_t dataY = baseY + headerH;

        // Set clip rect to data area
        int32_t oldClipX = d->clipX;
        int32_t oldClipY = d->clipY;
        int32_t oldClipW = d->clipW;
        int32_t oldClipH = d->clipH;
        setClipRect(d, baseX, dataY, innerW, innerH);

        int32_t  scrollPos  = w->as.listView->scrollPos;
        int32_t *sortIdx    = w->as.listView->sortIndex;

        // Fill entire data area background first. This is done as a single
        // rectFill rather than per-row because it's cheaper to fill once and
        // then overdraw selected rows than to compute and fill each unselected
        // row's background separately.
        rectFill(d, ops, baseX, dataY, innerW, innerH, bg);

        bool     multi   = w->as.listView->multiSelect;
        uint8_t *selBits = w->as.listView->selBits;

        for (int32_t i = 0; i < visibleRows && (scrollPos + i) < w->as.listView->rowCount; i++) {
            int32_t  displayRow = scrollPos + i;
            int32_t  dataRow    = sortIdx ? sortIdx[displayRow] : displayRow;
            int32_t  iy         = dataY + i * font->charHeight;
            uint32_t ifg        = fg;
            uint32_t ibg        = bg;

            bool selected = false;

            if (multi && selBits) {
                selected = selBits[dataRow] != 0;
            } else {
                selected = (dataRow == w->as.listView->selectedIdx);
            }

            if (selected) {
                ifg = colors->menuHighlightFg;
                ibg = colors->menuHighlightBg;
                rectFill(d, ops, baseX, iy, innerW, font->charHeight, ibg);
            }

            // Draw each cell
            int32_t cellX = baseX - w->as.listView->scrollPosH;

            for (int32_t c = 0; c < colCount; c++) {
                int32_t     cw   = w->as.listView->resolvedColW[c];
                const char *cell = w->as.listView->cellData[dataRow * colCount + c];

                if (cell) {
                    int32_t cellLen  = (int32_t)strlen(cell);
                    int32_t maxChars = (cw - LISTVIEW_PAD * 2) / font->charWidth;

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

                    if (cellLen > maxChars) {
                        cellLen = maxChars;
                    }

                    int32_t tx = cellX + LISTVIEW_PAD;

                    // Column alignment: left (default), right, or center.
                    // Right/center alignment compute the available width and
                    // offset the text start position accordingly. This is done
                    // per-cell rather than using a general-purpose aligned draw
                    // function to keep the inner loop simple and avoid extra
                    // function call overhead per cell.
                    if (w->as.listView->cols[c].align == ListViewAlignRightE) {
                        int32_t renderedW = cellLen * font->charWidth;
                        int32_t availW    = cw - LISTVIEW_PAD * 2;
                        tx = cellX + LISTVIEW_PAD + (availW - renderedW);
                    } else if (w->as.listView->cols[c].align == ListViewAlignCenterE) {
                        int32_t renderedW = cellLen * font->charWidth;
                        int32_t availW    = cw - LISTVIEW_PAD * 2;
                        tx = cellX + LISTVIEW_PAD + (availW - renderedW) / 2;
                    }

                    if (cellLen > 0) {
                        drawTextN(d, ops, font, tx, iy, cell, cellLen, ifg, ibg, true);
                    }
                }

                cellX += cw;
            }

            // Draw cursor focus rect in multi-select mode (on top of text)
            if (multi && dataRow == w->as.listView->selectedIdx && w->focused) {
                drawFocusRect(d, ops, baseX, iy, innerW, font->charHeight, fg);
            }
        }

        // Draw drag-reorder insertion indicator
        if (w->as.listView->reorderable && w->as.listView->dragIdx >= 0 && w->as.listView->dropIdx >= 0) {
            int32_t drop  = w->as.listView->dropIdx;
            int32_t lineY = dataY + (drop - w->as.listView->scrollPos) * font->charHeight;

            if (lineY >= dataY && lineY <= dataY + innerH) {
                drawHLine(d, ops, baseX, lineY, innerW, fg);
                drawHLine(d, ops, baseX, lineY + 1, innerW, fg);
            }
        }

        setClipRect(d, oldClipX, oldClipY, oldClipW, oldClipH);
    }

    // ---- Draw scrollbars ----
    if (needVSb) {
        int32_t sbX = w->x + w->w - LISTVIEW_BORDER - WGT_SB_W;
        int32_t sbY = w->y + LISTVIEW_BORDER + headerH;
        widgetDrawScrollbarV(d, ops, colors, sbX, sbY, innerH, w->as.listView->rowCount, visibleRows, w->as.listView->scrollPos);
    }

    if (needHSb) {
        int32_t sbX = w->x + LISTVIEW_BORDER;
        int32_t sbY = w->y + w->h - LISTVIEW_BORDER - WGT_SB_W;
        widgetDrawScrollbarH(d, ops, colors, sbX, sbY, innerW, totalColW, innerW, w->as.listView->scrollPosH);

        // Fill the dead corner when both scrollbars are present. This is the
        // small square at the intersection of the two scrollbars (bottom-right)
        // that doesn't belong to either. Without filling it, stale content
        // from previous paints would show through.
        if (needVSb) {
            rectFill(d, ops, sbX + innerW, sbY, WGT_SB_W, WGT_SB_W, colors->windowFace);
        }
    }

    if (w->focused) {
        drawFocusRect(d, ops, w->x + 1, w->y + 1, w->w - 2, w->h - 2, fg);
    }
}