// widgetComboBox.c  -- ComboBox widget (editable text + dropdown list)
//
// Combines a single-line text input with a dropdown list. The text area
// supports full editing (cursor movement, selection, undo, clipboard) via
// the shared widgetTextEditOnKey helper, while the dropdown button opens
// a popup list overlay.
//
// This is a "combo" box in the Windows sense: the user can either type a
// value or select from the list. When an item is selected from the list,
// its text is copied into the edit buffer. The edit buffer is independently
// allocated (malloc'd) so the user can modify the text after selecting.
//
// The popup list is painted as an overlay (widgetComboBoxPaintPopup) that
// renders on top of all other widgets. Popup visibility is coordinated
// through the sOpenPopup global  -- only one popup can be open at a time.
// The sClosedPopup mechanism prevents click-to-close from immediately
// reopening the popup when the close click lands on the dropdown button.
//
// Text selection supports single-click (cursor placement + drag start),
// double-click (word select), and triple-click (select all). Drag-select
// is tracked via the sDragTextSelect global.

#include "widgetInternal.h"


// ============================================================
// wgtComboBox
// ============================================================

// Create a combo box. maxLen controls the edit buffer size (0 = default 256).
// Two buffers are allocated: the edit buffer and an undo buffer (for Ctrl+Z
// single-level undo). Selection indices start at -1 (nothing selected).
// Default weight=100 makes combo boxes expand to fill available space in
// a layout container, which is the typical desired behavior.
WidgetT *wgtComboBox(WidgetT *parent, int32_t maxLen) {
    WidgetT *w = widgetAlloc(parent, WidgetComboBoxE);

    if (w) {
        int32_t bufSize = maxLen > 0 ? maxLen + 1 : 256;
        w->as.comboBox.buf     = (char *)malloc(bufSize);
        w->as.comboBox.undoBuf = (char *)malloc(bufSize);
        w->as.comboBox.bufSize = bufSize;

        if (!w->as.comboBox.buf || !w->as.comboBox.undoBuf) {
            free(w->as.comboBox.buf);
            free(w->as.comboBox.undoBuf);
            w->as.comboBox.buf     = NULL;
            w->as.comboBox.undoBuf = NULL;
        } else {
            w->as.comboBox.buf[0] = '\0';
        }

        w->as.comboBox.selStart    = -1;
        w->as.comboBox.selEnd      = -1;
        w->as.comboBox.selectedIdx = -1;
        w->weight = 100;
    }

    return w;
}


// ============================================================
// wgtComboBoxGetSelected
// ============================================================

int32_t wgtComboBoxGetSelected(const WidgetT *w) {
    VALIDATE_WIDGET(w, WidgetComboBoxE, -1);

    return w->as.comboBox.selectedIdx;
}


// ============================================================
// wgtComboBoxSetItems
// ============================================================

void wgtComboBoxSetItems(WidgetT *w, const char **items, int32_t count) {
    VALIDATE_WIDGET_VOID(w, WidgetComboBoxE);

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

    // Cache max item string length so calcMinSize doesn't need to re-scan
    // the entire item array on every layout pass. Items are stored as
    // external pointers (not copied)  -- the caller owns the string data.
    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.comboBox.maxItemLen = maxLen;

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

    // wgtInvalidate (not wgtInvalidatePaint) triggers a full relayout because
    // changing items may change the widget's minimum width
    wgtInvalidate(w);
}


// ============================================================
// wgtComboBoxSetSelected
// ============================================================

void wgtComboBoxSetSelected(WidgetT *w, int32_t idx) {
    VALIDATE_WIDGET_VOID(w, WidgetComboBoxE);

    w->as.comboBox.selectedIdx = idx;

    // Copy selected item text to buffer
    if (idx >= 0 && idx < w->as.comboBox.itemCount && w->as.comboBox.buf) {
        strncpy(w->as.comboBox.buf, w->as.comboBox.items[idx], w->as.comboBox.bufSize - 1);
        w->as.comboBox.buf[w->as.comboBox.bufSize - 1] = '\0';
        w->as.comboBox.len       = (int32_t)strlen(w->as.comboBox.buf);
        w->as.comboBox.cursorPos = w->as.comboBox.len;
        w->as.comboBox.scrollOff = 0;
        w->as.comboBox.selStart  = -1;
        w->as.comboBox.selEnd    = -1;
    }

    wgtInvalidatePaint(w);
}


// ============================================================
// widgetComboBoxCalcMinSize
// ============================================================

void widgetComboBoxCalcMinSize(WidgetT *w, const BitmapFontT *font) {
    int32_t maxItemW = w->as.comboBox.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;
}


// ============================================================
// widgetComboBoxDestroy
// ============================================================

void widgetComboBoxDestroy(WidgetT *w) {
    free(w->as.comboBox.buf);
    free(w->as.comboBox.undoBuf);
}


// ============================================================
// widgetComboBoxGetText
// ============================================================

const char *widgetComboBoxGetText(const WidgetT *w) {
    return w->as.comboBox.buf ? w->as.comboBox.buf : "";
}


// ============================================================
// widgetComboBoxOnKey
// ============================================================

// Key handling has two modes: when the popup is open, Up/Down navigate the list
// and Enter confirms the selection. When closed, keys go to the text editor
// (via widgetTextEditOnKey) except Down-arrow which opens the popup. This split
// behavior is necessary because the same widget must serve as both a text input
// and a list selector depending on popup state.
// Key codes: 0x48|0x100 = Up, 0x50|0x100 = Down (BIOS scan codes with extended bit).
void widgetComboBoxOnKey(WidgetT *w, int32_t key, int32_t mod) {
    if (w->as.comboBox.open) {
        if (key == (0x48 | 0x100)) {
            if (w->as.comboBox.hoverIdx > 0) {
                w->as.comboBox.hoverIdx--;

                if (w->as.comboBox.hoverIdx < w->as.comboBox.listScrollPos) {
                    w->as.comboBox.listScrollPos = w->as.comboBox.hoverIdx;
                }
            }

            wgtInvalidatePaint(w);
            return;
        }

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

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

            wgtInvalidatePaint(w);
            return;
        }

        if (key == 0x0D) {
            int32_t idx = w->as.comboBox.hoverIdx;

            if (idx >= 0 && idx < w->as.comboBox.itemCount) {
                w->as.comboBox.selectedIdx = idx;

                const char *itemText = w->as.comboBox.items[idx];
                strncpy(w->as.comboBox.buf, itemText, w->as.comboBox.bufSize - 1);
                w->as.comboBox.buf[w->as.comboBox.bufSize - 1] = '\0';
                w->as.comboBox.len       = (int32_t)strlen(w->as.comboBox.buf);
                w->as.comboBox.cursorPos  = w->as.comboBox.len;
                w->as.comboBox.scrollOff  = 0;
                w->as.comboBox.selStart   = -1;
                w->as.comboBox.selEnd     = -1;
            }

            w->as.comboBox.open = false;
            sOpenPopup = NULL;

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

            wgtInvalidatePaint(w);
            return;
        }
    }

    // Down arrow on closed combobox opens the popup
    if (!w->as.comboBox.open && key == (0x50 | 0x100)) {
        w->as.comboBox.open     = true;
        w->as.comboBox.hoverIdx = w->as.comboBox.selectedIdx;
        sOpenPopup = w;

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

        if (w->as.comboBox.hoverIdx < w->as.comboBox.listScrollPos) {
            w->as.comboBox.listScrollPos = w->as.comboBox.hoverIdx;
        }

        wgtInvalidatePaint(w);
        return;
    }

    // Text editing (when popup is closed, or non-navigation keys with popup open)
    if (!w->as.comboBox.buf) {
        return;
    }

    clearOtherSelections(w);

    widgetTextEditOnKey(w, key, mod, w->as.comboBox.buf, w->as.comboBox.bufSize,
                        &w->as.comboBox.len, &w->as.comboBox.cursorPos,
                        &w->as.comboBox.scrollOff,
                        &w->as.comboBox.selStart, &w->as.comboBox.selEnd,
                        w->as.comboBox.undoBuf, &w->as.comboBox.undoLen,
                        &w->as.comboBox.undoCursor);
}


// ============================================================
// widgetComboBoxOnMouse
// ============================================================

void widgetComboBoxOnMouse(WidgetT *w, WidgetT *root, int32_t vx, int32_t vy) {
    w->focused = true;

    // Check if click is on the button area
    int32_t textAreaW = w->w - DROPDOWN_BTN_WIDTH;

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

        // Button click  -- toggle popup
        w->as.comboBox.open     = !w->as.comboBox.open;
        w->as.comboBox.hoverIdx = w->as.comboBox.selectedIdx;
        sOpenPopup = w->as.comboBox.open ? w : NULL;
    } else {
        // Text area click  -- focus for editing
        clearOtherSelections(w);

        AppContextT *ctx = (AppContextT *)root->userData;
        widgetTextEditMouseClick(w, vx, vy, w->x + TEXT_INPUT_PAD, &ctx->font, w->as.comboBox.buf, w->as.comboBox.len, w->as.comboBox.scrollOff, &w->as.comboBox.cursorPos, &w->as.comboBox.selStart, &w->as.comboBox.selEnd, true, true);
    }
}


// ============================================================
// widgetComboBoxPaint
// ============================================================

// Paint: two regions side-by-side  -- a sunken text area (left) and a raised
// dropdown button (right). The text area renders the edit buffer with optional
// selection highlighting (up to 3 text runs: pre-selection, selection,
// post-selection). The dropdown button has a small triangular arrow glyph
// drawn as horizontal lines of decreasing width. When the popup is open,
// the button bevel is inverted (sunken) to show it's active.
void widgetComboBoxPaint(WidgetT *w, DisplayT *d, const BlitOpsT *ops, const BitmapFontT *font, const ColorSchemeT *colors) {
    uint32_t fg = w->enabled ? (w->fgColor ? w->fgColor : colors->contentFg) : colors->windowShadow;
    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 text content
    if (w->as.comboBox.buf) {
        int32_t textX    = w->x + TEXT_INPUT_PAD;
        int32_t textY    = w->y + (w->h - font->charHeight) / 2;
        int32_t maxChars = (textAreaW - TEXT_INPUT_PAD * 2 - 4) / font->charWidth;
        int32_t off      = w->as.comboBox.scrollOff;
        int32_t len      = w->as.comboBox.len - off;

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

        widgetTextEditPaintLine(d, ops, font, colors, textX, textY, w->as.comboBox.buf + off, len, off, w->as.comboBox.cursorPos, w->as.comboBox.selStart, w->as.comboBox.selEnd, fg, bg, w->focused && w->enabled && !w->as.comboBox.open, w->x + TEXT_INPUT_PAD, w->x + textAreaW - TEXT_INPUT_PAD);
    }

    // Drop button
    BevelStyleT btnBevel;
    btnBevel.highlight = w->as.comboBox.open ? colors->windowShadow : colors->windowHighlight;
    btnBevel.shadow    = w->as.comboBox.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
    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);
    }
}


// ============================================================
// widgetComboBoxPaintPopup
// ============================================================

void widgetComboBoxPaintPopup(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.comboBox.items, w->as.comboBox.itemCount, w->as.comboBox.hoverIdx, w->as.comboBox.listScrollPos);
}


// ============================================================
// widgetComboBoxSetText
// ============================================================

void widgetComboBoxSetText(WidgetT *w, const char *text) {
    if (w->as.comboBox.buf) {
        strncpy(w->as.comboBox.buf, text, w->as.comboBox.bufSize - 1);
        w->as.comboBox.buf[w->as.comboBox.bufSize - 1] = '\0';
        w->as.comboBox.len       = (int32_t)strlen(w->as.comboBox.buf);
        w->as.comboBox.cursorPos = w->as.comboBox.len;
        w->as.comboBox.scrollOff = 0;
        w->as.comboBox.selStart  = -1;
        w->as.comboBox.selEnd    = -1;
    }
}