// widgetCore.c — Core widget infrastructure (alloc, tree ops, helpers)

#include "widgetInternal.h"

// ============================================================
// Global state for drag and popup tracking
// ============================================================

bool     sDebugLayout   = false;
WidgetT *sOpenPopup     = NULL;
WidgetT *sPressedButton = NULL;
WidgetT *sDragSlider    = NULL;
WidgetT *sDrawingCanvas  = NULL;
WidgetT *sDragTextSelect = NULL;
int32_t  sDragOffset     = 0;


// ============================================================
// widgetAddChild
// ============================================================

void widgetAddChild(WidgetT *parent, WidgetT *child) {
    child->parent      = parent;
    child->nextSibling = NULL;

    if (parent->lastChild) {
        parent->lastChild->nextSibling = child;
        parent->lastChild = child;
    } else {
        parent->firstChild = child;
        parent->lastChild  = child;
    }
}


// ============================================================
// widgetAlloc
// ============================================================

WidgetT *widgetAlloc(WidgetT *parent, WidgetTypeE type) {
    WidgetT *w = (WidgetT *)malloc(sizeof(WidgetT));

    if (!w) {
        return NULL;
    }

    memset(w, 0, sizeof(*w));
    w->type    = type;
    w->wclass  = widgetClassTable[type];
    w->visible = true;
    w->enabled = true;

    if (parent) {
        w->window = parent->window;
        widgetAddChild(parent, w);
    }

    return w;
}


// ============================================================
// widgetClearFocus
// ============================================================

void widgetClearFocus(WidgetT *root) {
    if (!root) {
        return;
    }

    root->focused = false;

    for (WidgetT *c = root->firstChild; c; c = c->nextSibling) {
        widgetClearFocus(c);
    }
}


// ============================================================
// widgetCountVisibleChildren
// ============================================================

int32_t widgetCountVisibleChildren(const WidgetT *w) {
    int32_t count = 0;

    for (const WidgetT *c = w->firstChild; c; c = c->nextSibling) {
        if (c->visible) {
            count++;
        }
    }

    return count;
}


// ============================================================
// widgetDestroyChildren
// ============================================================

void widgetDestroyChildren(WidgetT *w) {
    WidgetT *child = w->firstChild;

    while (child) {
        WidgetT *next = child->nextSibling;
        widgetDestroyChildren(child);

        if (child->wclass && child->wclass->destroy) {
            child->wclass->destroy(child);
        }

        // Clear popup/drag references if they point to destroyed widgets
        if (sOpenPopup == child) {
            sOpenPopup = NULL;
        }

        if (sPressedButton == child) {
            sPressedButton = NULL;
        }

        if (sDragSlider == child) {
            sDragSlider = NULL;
        }

        if (sDrawingCanvas == child) {
            sDrawingCanvas = NULL;
        }

        free(child);
        child = next;
    }

    w->firstChild = NULL;
    w->lastChild  = NULL;
}


// ============================================================
// widgetDropdownPopupRect
// ============================================================
//
// Calculate the rectangle for a dropdown/combobox popup list.

void widgetDropdownPopupRect(WidgetT *w, const BitmapFontT *font, int32_t contentH, int32_t *popX, int32_t *popY, int32_t *popW, int32_t *popH) {
    int32_t itemCount = 0;

    if (w->type == WidgetDropdownE) {
        itemCount = w->as.dropdown.itemCount;
    } else if (w->type == WidgetComboBoxE) {
        itemCount = w->as.comboBox.itemCount;
    }

    int32_t visibleItems = itemCount;

    if (visibleItems > DROPDOWN_MAX_VISIBLE) {
        visibleItems = DROPDOWN_MAX_VISIBLE;
    }

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

    *popX = w->x;
    *popW = w->w;
    *popH = visibleItems * font->charHeight + 4; // 2px border each side

    // Try below first, then above if no room
    if (w->y + w->h + *popH <= contentH) {
        *popY = w->y + w->h;
    } else {
        *popY = w->y - *popH;

        if (*popY < 0) {
            *popY = 0;
        }
    }
}


// ============================================================
// widgetFindByAccel
// ============================================================

WidgetT *widgetFindByAccel(WidgetT *root, char key) {
    if (!root || !root->enabled) {
        return NULL;
    }

    // Invisible tab pages: match the page itself (for tab switching)
    // but don't recurse into children (their accels shouldn't be active)
    if (!root->visible) {
        if (root->type == WidgetTabPageE && root->accelKey == key) {
            return root;
        }

        return NULL;
    }

    if (root->accelKey == key) {
        return root;
    }

    for (WidgetT *c = root->firstChild; c; c = c->nextSibling) {
        WidgetT *found = widgetFindByAccel(c, key);

        if (found) {
            return found;
        }
    }

    return NULL;
}


// ============================================================
// widgetFindNextFocusable
// ============================================================
//
// Depth-first walk of the widget tree. Returns the first focusable
// widget found after 'after'. If 'after' is NULL, returns the first
// focusable widget. Wraps around to the beginning if needed.

static WidgetT *findNextFocusableImpl(WidgetT *w, WidgetT *after, bool *pastAfter) {
    if (!w->visible || !w->enabled) {
        return NULL;
    }

    if (after == NULL) {
        *pastAfter = true;
    }

    if (w == after) {
        *pastAfter = true;
    } else if (*pastAfter && widgetIsFocusable(w->type)) {
        return w;
    }

    for (WidgetT *c = w->firstChild; c; c = c->nextSibling) {
        WidgetT *found = findNextFocusableImpl(c, after, pastAfter);

        if (found) {
            return found;
        }
    }

    return NULL;
}

WidgetT *widgetFindNextFocusable(WidgetT *root, WidgetT *after) {
    bool pastAfter = false;
    WidgetT *found = findNextFocusableImpl(root, after, &pastAfter);

    if (found) {
        return found;
    }

    // Wrap around — search from the beginning
    pastAfter = true;
    return findNextFocusableImpl(root, NULL, &pastAfter);
}


// ============================================================
// widgetFindPrevFocusable
// ============================================================
//
// Depth-first walk collecting all visible+enabled focusable widgets,
// then returns the one before 'before'. Wraps around if needed.

WidgetT *widgetFindPrevFocusable(WidgetT *root, WidgetT *before) {
    WidgetT *list[128];
    int32_t  count = 0;

    // Collect all focusable widgets via depth-first traversal
    WidgetT *stack[64];
    int32_t  top = 0;
    stack[top++] = root;

    while (top > 0) {
        WidgetT *w = stack[--top];

        if (!w->visible || !w->enabled) {
            continue;
        }

        if (widgetIsFocusable(w->type) && count < 128) {
            list[count++] = w;
        }

        // Push children in reverse order so first child is processed first
        WidgetT *children[64];
        int32_t  childCount = 0;

        for (WidgetT *c = w->firstChild; c; c = c->nextSibling) {
            if (childCount < 64) {
                children[childCount++] = c;
            }
        }

        for (int32_t i = childCount - 1; i >= 0; i--) {
            if (top < 64) {
                stack[top++] = children[i];
            }
        }
    }

    if (count == 0) {
        return NULL;
    }

    // Find 'before' in the list
    int32_t idx = -1;

    for (int32_t i = 0; i < count; i++) {
        if (list[i] == before) {
            idx = i;
            break;
        }
    }

    if (idx <= 0) {
        return list[count - 1]; // Wrap to last
    }

    return list[idx - 1];
}


// ============================================================
// widgetFrameBorderWidth
// ============================================================

int32_t widgetFrameBorderWidth(const WidgetT *w) {
    if (w->type != WidgetFrameE) {
        return 0;
    }

    if (w->as.frame.style == FrameFlatE) {
        return FRAME_FLAT_BORDER;
    }

    return FRAME_BEVEL_BORDER;
}


// ============================================================
// widgetHitTest
// ============================================================

WidgetT *widgetHitTest(WidgetT *w, int32_t x, int32_t y) {
    if (!w->visible) {
        return NULL;
    }

    if (x < w->x || x >= w->x + w->w || y < w->y || y >= w->y + w->h) {
        return NULL;
    }

    // Widgets with WCLASS_NO_HIT_RECURSE manage their own children
    if (w->wclass && (w->wclass->flags & WCLASS_NO_HIT_RECURSE)) {
        return w;
    }

    // Check children — take the last match (topmost in Z-order)
    WidgetT *hit = NULL;

    for (WidgetT *c = w->firstChild; c; c = c->nextSibling) {
        WidgetT *childHit = widgetHitTest(c, x, y);

        if (childHit) {
            hit = childHit;
        }
    }

    return hit ? hit : w;
}


// ============================================================
// widgetIsFocusable
// ============================================================

bool widgetIsFocusable(WidgetTypeE type) {
    return (widgetClassTable[type]->flags & WCLASS_FOCUSABLE) != 0;
}


// ============================================================
// widgetIsBoxContainer
// ============================================================
//
// Returns true for widget types that use the generic box layout.

bool widgetIsBoxContainer(WidgetTypeE type) {
    return (widgetClassTable[type]->flags & WCLASS_BOX_CONTAINER) != 0;
}


// ============================================================
// widgetIsHorizContainer
// ============================================================
//
// Returns true for container types that lay out children horizontally.

bool widgetIsHorizContainer(WidgetTypeE type) {
    return (widgetClassTable[type]->flags & WCLASS_HORIZ_CONTAINER) != 0;
}


// ============================================================
// widgetScrollbarThumb
// ============================================================

void widgetScrollbarThumb(int32_t trackLen, int32_t totalSize, int32_t visibleSize, int32_t scrollPos, int32_t *thumbPos, int32_t *thumbSize) {
    *thumbSize = (trackLen * visibleSize) / totalSize;

    if (*thumbSize < SB_MIN_THUMB) {
        *thumbSize = SB_MIN_THUMB;
    }

    if (*thumbSize > trackLen) {
        *thumbSize = trackLen;
    }

    int32_t maxScroll = totalSize - visibleSize;

    if (maxScroll > 0) {
        *thumbPos = ((trackLen - *thumbSize) * scrollPos) / maxScroll;
    } else {
        *thumbPos = 0;
    }
}


// ============================================================
// widgetRemoveChild
// ============================================================

void widgetRemoveChild(WidgetT *parent, WidgetT *child) {
    WidgetT *prev = NULL;

    for (WidgetT *c = parent->firstChild; c; c = c->nextSibling) {
        if (c == child) {
            if (prev) {
                prev->nextSibling = c->nextSibling;
            } else {
                parent->firstChild = c->nextSibling;
            }

            if (parent->lastChild == child) {
                parent->lastChild = prev;
            }

            child->nextSibling = NULL;
            child->parent      = NULL;
            return;
        }

        prev = c;
    }
}