// widgetDropdown.c — Dropdown (select) widget
//
// A non-editable dropdown list (HTML <select> equivalent). Unlike ComboBox,
// the user cannot type a custom value — they can only choose from the
// predefined items. This simplifies the widget considerably: no text buffer,
// no undo, no cursor, no text editing key handling.
//
// The visual layout is identical to ComboBox (sunken display area + raised
// dropdown button), but the display area shows the selected item's text
// as read-only. A focus rect is drawn inside the display area when focused
// (since there's no cursor to indicate focus).
//
// Keyboard behavior when closed: Up arrow decrements selection immediately
// (inline cycling), Down/Space/Enter opens the popup. This matches the
// Win3.1 dropdown behavior where arrow keys cycle through values without
// opening the full list.
//
// Popup overlay painting and hit testing are shared with ComboBox via
// widgetDropdownPopupRect and widgetPaintPopupList in widgetCore.c.

#include "widgetInternal.h"


// ============================================================
// wgtDropdown
// ============================================================

WidgetT *wgtDropdown(WidgetT *parent) {
    WidgetT *w = widgetAlloc(parent, WidgetDropdownE);

    if (w) {
        w->as.dropdown.selectedIdx = -1;
        w->as.dropdown.hoverIdx    = -1;
    }

    return w;
}


// ============================================================
// wgtDropdownGetSelected
// ============================================================

int32_t wgtDropdownGetSelected(const WidgetT *w) {
    VALIDATE_WIDGET(w, WidgetDropdownE, -1);

    return w->as.dropdown.selectedIdx;
}


// ============================================================
// wgtDropdownSetItems
// ============================================================

void wgtDropdownSetItems(WidgetT *w, const char **items, int32_t count) {
    VALIDATE_WIDGET_VOID(w, WidgetDropdownE);

    w->as.dropdown.items     = items;
    w->as.dropdown.itemCount = count;

    // Cache max item strlen to avoid recomputing in calcMinSize
    int32_t maxLen = 0;

    for (int32_t i = 0; i < count; i++) {
        int32_t slen = (int32_t)strlen(items[i]);

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

    w->as.dropdown.maxItemLen = maxLen;

    if (w->as.dropdown.selectedIdx >= count) {
        w->as.dropdown.selectedIdx = -1;
    }

    wgtInvalidate(w);
}


// ============================================================
// wgtDropdownSetSelected
// ============================================================

void wgtDropdownSetSelected(WidgetT *w, int32_t idx) {
    VALIDATE_WIDGET_VOID(w, WidgetDropdownE);

    w->as.dropdown.selectedIdx = idx;
    wgtInvalidatePaint(w);
}


// ============================================================
// widgetDropdownGetText
// ============================================================

const char *widgetDropdownGetText(const WidgetT *w) {
    if (w->as.dropdown.selectedIdx >= 0 && w->as.dropdown.selectedIdx < w->as.dropdown.itemCount) {
        return w->as.dropdown.items[w->as.dropdown.selectedIdx];
    }

    return "";
}


// ============================================================
// widgetDropdownCalcMinSize
// ============================================================

void widgetDropdownCalcMinSize(WidgetT *w, const BitmapFontT *font) {
    // Width: widest item + button width + border
    int32_t maxItemW = w->as.dropdown.maxItemLen * font->charWidth;
    int32_t minW     = font->charWidth * 8;

    if (maxItemW < minW) {
        maxItemW = minW;
    }

    w->calcMinW = maxItemW + DROPDOWN_BTN_WIDTH + TEXT_INPUT_PAD * 2 + 4;
    w->calcMinH = font->charHeight + TEXT_INPUT_PAD * 2;
}


// ============================================================
// widgetDropdownOnKey
// ============================================================

// Key handling: when popup is open, Up/Down navigate the hover index and
// Enter/Space confirms selection. When closed, Down/Space/Enter opens the
// popup, while Up decrements the selection inline (without opening). This
// two-mode behavior matches the standard Windows combo box UX where quick
// arrow-key cycling doesn't require the popup to be visible.
void widgetDropdownOnKey(WidgetT *w, int32_t key, int32_t mod) {
    (void)mod;

    if (w->as.dropdown.open) {
        // Popup is open — navigate items
        if (key == (0x48 | 0x100)) {
            if (w->as.dropdown.hoverIdx > 0) {
                w->as.dropdown.hoverIdx--;

                if (w->as.dropdown.hoverIdx < w->as.dropdown.scrollPos) {
                    w->as.dropdown.scrollPos = w->as.dropdown.hoverIdx;
                }
            }
        } else if (key == (0x50 | 0x100)) {
            if (w->as.dropdown.hoverIdx < w->as.dropdown.itemCount - 1) {
                w->as.dropdown.hoverIdx++;

                if (w->as.dropdown.hoverIdx >= w->as.dropdown.scrollPos + DROPDOWN_MAX_VISIBLE) {
                    w->as.dropdown.scrollPos = w->as.dropdown.hoverIdx - DROPDOWN_MAX_VISIBLE + 1;
                }
            }
        } else if (key == 0x0D || key == ' ') {
            w->as.dropdown.selectedIdx = w->as.dropdown.hoverIdx;
            w->as.dropdown.open        = false;
            sOpenPopup = NULL;

            if (w->onChange) {
                w->onChange(w);
            }
        }
    } else {
        // Popup is closed
        if (key == (0x50 | 0x100) || key == ' ' || key == 0x0D) {
            w->as.dropdown.open     = true;
            w->as.dropdown.hoverIdx = w->as.dropdown.selectedIdx;
            sOpenPopup = w;

            if (w->as.dropdown.hoverIdx >= w->as.dropdown.scrollPos + DROPDOWN_MAX_VISIBLE) {
                w->as.dropdown.scrollPos = w->as.dropdown.hoverIdx - DROPDOWN_MAX_VISIBLE + 1;
            }

            if (w->as.dropdown.hoverIdx < w->as.dropdown.scrollPos) {
                w->as.dropdown.scrollPos = w->as.dropdown.hoverIdx;
            }
        } else if (key == (0x48 | 0x100)) {
            if (w->as.dropdown.selectedIdx > 0) {
                w->as.dropdown.selectedIdx--;

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

    wgtInvalidatePaint(w);
}


// ============================================================
// widgetDropdownOnMouse
// ============================================================

// Mouse click toggles the popup open/closed. The sClosedPopup guard prevents
// a re-open race condition: when a click outside the popup closes it, the
// widget event dispatcher first closes the popup (setting sClosedPopup),
// then dispatches the click to whatever widget is under the cursor. If that
// happens to be this dropdown's body, we'd immediately re-open without this
// check. The sClosedPopup reference is cleared on the next event cycle.
void widgetDropdownOnMouse(WidgetT *w, WidgetT *root, int32_t vx, int32_t vy) {
    (void)root;
    (void)vx;
    (void)vy;
    w->focused = true;

    // If this dropdown's popup was just closed by click-outside, don't re-open
    if (w == sClosedPopup) {
        return;
    }

    w->as.dropdown.open     = !w->as.dropdown.open;
    w->as.dropdown.hoverIdx = w->as.dropdown.selectedIdx;
    sOpenPopup = w->as.dropdown.open ? w : NULL;
}


// ============================================================
// widgetDropdownPaint
// ============================================================

void widgetDropdownPaint(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;

    // Sunken text area
    int32_t textAreaW = w->w - DROPDOWN_BTN_WIDTH;
    BevelStyleT bevel;
    bevel.highlight = colors->windowShadow;
    bevel.shadow    = colors->windowHighlight;
    bevel.face      = bg;
    bevel.width     = 2;
    drawBevel(d, ops, w->x, w->y, textAreaW, w->h, &bevel);

    // Draw selected item text
    if (w->as.dropdown.selectedIdx >= 0 && w->as.dropdown.selectedIdx < w->as.dropdown.itemCount) {
        int32_t textX = w->x + TEXT_INPUT_PAD;
        int32_t textY = w->y + (w->h - font->charHeight) / 2;

        if (!w->enabled) {
            drawTextEmbossed(d, ops, font, textX, textY, w->as.dropdown.items[w->as.dropdown.selectedIdx], colors);
        } else {
            drawText(d, ops, font, textX, textY, w->as.dropdown.items[w->as.dropdown.selectedIdx], fg, bg, true);
        }
    }

    // Drop button
    BevelStyleT btnBevel;
    btnBevel.highlight = w->as.dropdown.open ? colors->windowShadow : colors->windowHighlight;
    btnBevel.shadow    = w->as.dropdown.open ? colors->windowHighlight : colors->windowShadow;
    btnBevel.face      = colors->buttonFace;
    btnBevel.width     = 2;
    drawBevel(d, ops, w->x + textAreaW, w->y, DROPDOWN_BTN_WIDTH, w->h, &btnBevel);

    // Down arrow glyph in button — a small filled triangle drawn as horizontal
    // lines of decreasing width (7, 5, 3, 1 pixels). This creates a 4-pixel
    // tall downward-pointing triangle centered in the button.
    uint32_t arrowFg = w->enabled ? colors->contentFg : colors->windowShadow;
    int32_t  arrowX  = w->x + textAreaW + DROPDOWN_BTN_WIDTH / 2;
    int32_t  arrowY  = w->y + w->h / 2 - 1;

    for (int32_t i = 0; i < 4; i++) {
        drawHLine(d, ops, arrowX - 3 + i, arrowY + i, 7 - i * 2, arrowFg);
    }

    if (w->focused) {
        drawFocusRect(d, ops, w->x + 3, w->y + 3, textAreaW - 6, w->h - 6, fg);
    }
}


// ============================================================
// widgetDropdownPaintPopup
// ============================================================

// Paint the popup overlay list. Delegates to widgetDropdownPopupRect (which
// computes position, handling screen-edge flip to ensure the popup stays
// on-screen) and widgetPaintPopupList (which renders the bordered, scrollable
// item list with hover highlighting). These shared helpers are also used by
// ComboBox, keeping the popup rendering consistent between both widgets.
void widgetDropdownPaintPopup(WidgetT *w, DisplayT *d, const BlitOpsT *ops, const BitmapFontT *font, const ColorSchemeT *colors) {
    int32_t popX;
    int32_t popY;
    int32_t popW;
    int32_t popH;

    widgetDropdownPopupRect(w, font, d->clipH, &popX, &popY, &popW, &popH);
    widgetPaintPopupList(d, ops, font, colors, popX, popY, popW, popH, w->as.dropdown.items, w->as.dropdown.itemCount, w->as.dropdown.hoverIdx, w->as.dropdown.scrollPos);
}