#include <ft/widgets/flist.h>
#include <ft/util.h>
#include <justui/jwidget-api.h>
#include <stdlib.h>

/* Type identifier for flist */
static int flist_type_id = -1;

/* Events */
uint16_t FLIST_SELECTED;
uint16_t FLIST_VALIDATED;

/* Update the count of visible items after a layout change */
static void update_visible(flist *l);

flist *flist_create(gint_call_t renderer, void *parent)
{
    if(flist_type_id < 0) return NULL;

    flist *l = malloc(sizeof *l);
    if(!l) return NULL;

    jwidget_init(&l->widget, flist_type_id, parent);

    l->renderer = renderer;
    l->rows = 0;
    l->visible = 0;
    l->top = 0;
    l->selected = -1;
    l->row_height = 3;

    return l;
}

void flist_set_renderer(flist *l, gint_call_t renderer)
{
    l->renderer = renderer;
}

//---
// Configuration of rows
//---

void flist_set_rows(flist *l, int rows)
{
    if(l->rows == rows) return;
    l->rows = max(rows, 0);

    if(l->selected < 0 && l->rows > 0)
        l->selected = 0;
    if(l->selected >= l->rows)
        l->selected = l->rows - 1;

    l->widget.dirty = 1;
}

void flist_set_row_height(flist *l, int row_height)
{
    if(l->row_height == row_height) return;

    l->row_height = row_height;
    l->widget.dirty = 1;
}

//---
// Movement
//---

/* Guarantee that the positioning is valid */
static int bound(flist *l, int pos)
{
    pos = max(pos, 0);
    pos = min(pos, flist_end(l));
    return pos;
}

void flist_scroll_to(flist *l, int offset)
{
    l->top = bound(l, offset);
}

void flist_select(flist *l, int entry)
{
    if(entry < -1 || entry >= l->rows) return;
    l->selected = entry;
    l->widget.update = 1;

    /* TODO: flist_select(): Scroll to show selected entry */
}

int flist_end(flist *l)
{
    update_visible(l);
    return max((int)l->rows - (int)l->visible, 0);
}

//---
// Polymorphic widget operations
//---

/* Recompute (visible) based on the current size */
static void update_visible(flist *l)
{
    if(l->visible != 0) return;
    l->visible = max(0, jwidget_content_height(l) / l->row_height);
}

static void flist_poly_csize(void *l0)
{
    flist *l = l0;
    l->widget.w = 64;
    l->widget.h = 32;
}

static void flist_poly_layout(void *l0)
{
    flist *l = l0;
    update_visible(l);
}

static void flist_poly_render(void *l0, int x, int base_y)
{
    flist *l = l0;
    int cw = jwidget_content_width(l);
    int y = base_y;

    for(uint i = 0; l->top + i < l->rows && i < l->visible; i++) {
        l->x = x;
        l->y = y;
        l->row = l->top + i;

        l->renderer.args[0] = (gint_call_arg_t)(void *)l;
        gint_call(l->renderer);

        y += l->row_height;
    }

    /* Scrollbar */
    if(l->visible < l->rows) {
        /* Area where the scroll bar lives */
        int area_w = _(1,2);
        int area_x = x + cw - area_w;
        int area_y = base_y;
        int area_h = jwidget_content_height(l);

        /* Position and size of scroll bar within the area */
        int bar_y = (l->top     * area_h + l->rows/2) / l->rows;
        int bar_h = (l->visible * area_h + l->rows/2) / l->rows;

#ifdef FXCG50
        drect(area_x, area_y, area_x+area_w-1, area_y+area_h-1,
            C_RGB(24,24,24));
#endif
        drect(area_x, area_y + bar_y, area_x + area_w - 1,
            area_y + bar_y + bar_h, C_BLACK);
    }
}

static bool flist_poly_event(void *l0, jevent e)
{
    flist *l = l0;
    update_visible(l);

    if(e.type != JWIDGET_KEY) return false;
    if(e.key.type == KEYEV_UP) return false;

    if(e.key.key == KEY_DOWN && l->selected < l->rows - 1) {
        if(e.key.shift) l->selected = l->rows - 1;
        else l->selected++;

        /* Make sure the selected item remains visible */
        if(l->selected - l->top > l->visible - 1)
            l->top = bound(l, l->selected - l->visible + 1);

        l->widget.update = 1;

        jevent e = { .source = l, .type = FLIST_SELECTED };
        jwidget_emit(l, e);
        return true;
    }
    if(e.key.key == KEY_UP && l->selected > 0) {
        if(e.key.shift) l->selected = 0;
        else l->selected--;

        /* Same thing as before */
        if(l->selected < l->top)
            l->top = bound(l, l->selected);

        jevent e = { .source = l, .type = FLIST_SELECTED };
        jwidget_emit(l, e);
        l->widget.update = 1;
        return true;
    }

    if(e.key.key == KEY_EXE) {
        jevent e = { .source = l, .type = FLIST_VALIDATED };
        jwidget_emit(l, e);
        return true;
    }

    return false;
}

/* flist type definition */
static jwidget_poly type_flist = {
    .name    = "flist",
    .csize   = flist_poly_csize,
    .layout  = flist_poly_layout,
    .render  = flist_poly_render,
    .event   = flist_poly_event,
};

/* Type registration */
__attribute__((constructor(2000)))
static void j_register_flist(void)
{
    flist_type_id = j_register_widget(&type_flist, "jwidget");
    FLIST_SELECTED = j_register_event();
    FLIST_VALIDATED = j_register_event();
}