#include "gui.h"
#include "maths.h"
#include "memory.h"
#include "plat.h"
#include "render.h"
#include "standard.h"

void* gui_alloc(GUI* g, int size) {
	GUI_El* e = arena_alloc(g->a, size);
	if (g->prev)
		g->prev->next = e;
	if (!g->first)
		g->first = e;
	g->prev = e;
	e->next = 0;
	return e;
}

void gui_begin(GUI* g, const App* app, Arena* a) {
	g->a = a;
	g->app = app;
	g->pad = 2;
	g->first = 0;
	g->prev = 0;
	g->cursor[0] = 10;
	g->cursor[1] = 10;
}

void gui_get_layout(GUI* g, Rect* r) {
	r->x = g->cursor[0];
	r->y = g->cursor[1];
	g->cursor[1] += r->h;
}

int gui_text_width(const char* text, int len) {
	(void)text;
	return len * 10;
}

int gui_text_height(void) {
	return 10;
}

int mouse_over(const App* app, const Rect* r) {
	return
		app->mx > r->x &&
		app->my > r->y &&
		app->mx < r->x + r->w &&
		app->my < r->y + r->h;
}

Rect gui_viewport(GUI* g) {
	Rect r = { 0 };
	r.w = g->app->w;
	r.h = g->app->h;
	return r;
}

Rect gui_cut_left(Rect* a, int v) {
	Rect r = * a;
	a->x += v;
	a->w -= v;
	r.w -= a->w;
	return r;
}

Rect gui_cut_right(Rect* a, int v) {
	Rect r = *a;
	a->w -= v;
	r.x += v;
	r.w -= v;
	return r;
}

Rect gui_cut_down(Rect* a, int v) {
	Rect r = *a;
	a->h -= v;
	r.y += v;
	r.h -= v;
	return r;
}

Rect gui_cut_up(Rect* a, int v) {
	Rect r = * a;
	a->y += v;
	a->h -= v;
	r.h -= a->h;
	return r;
}

int gui_btn(GUI* g, Rect r, const char* text) {
	int len = string_len(text);
	GUI_Btn* e = gui_alloc(g, sizeof *e);
	e->el.type = gui_el_type_btn;
	e->el.r = r;
	e->text = arena_alloc_aligned(g->a, len + 1, 1);
	string_copy(e->text, text);
	e->hover = mouse_over(g->app, &e->el.r);
	e->active = e->hover &&
		g->app->mbtn_states[mbtn_left] & key_state_pressed;
	return e->hover &&
		g->app->mbtn_states[mbtn_left] & key_state_just_released;
}

void gui_scrollable(
	GUI* g,
	Rect r,
	const int* cs,
	GUI_Scroll_State* state,
	GUI_Scrollable_Draw_Fn fn
) {
	GUI_Scrollable* e = gui_alloc(g, sizeof *e);
	Rect srx, sry;
	int nx, ny, h = mouse_over(g->app, &r);
	int size = 15;
	e->el.type = gui_el_type_scrollable;
	e->el.r = r;
	e->cs[0] = cs[0];
	e->cs[1] = cs[1];
	e->ss = state;
	e->draw = fn;
	e->vp[0] = r.w - 2;
	e->vp[1] = r.h - 2;
	if ((nx = cs[0] - r.w) > 0) {
		srx.h = size;
		srx.w = r.w;
		srx.x = r.x;
		srx.y = r.y + r.h - srx.h;
		e->vp[1] -= srx.h;
		if (h)
			state->x -= g->app->scrollx;
	}
	if ((ny = cs[1] - r.h) > 0) {
		sry.w = size;
		sry.h = r.h;
		sry.x = r.x + r.w - sry.w;
		sry.y = r.y;
		e->vp[0] -= sry.w;
		if (h)
			state->y -= g->app->scrolly;
	}
	if (nx > 0 && ny > 0) {
		srx.w -= size;
		sry.h -= size;
		nx = cs[0] - (r.w - size);
		ny = cs[1] - (r.h - size);
	}
	if (nx > 0) {
		state->x = clamp(state->x, 0, nx);
		gui_scrollbar(g, state, srx, nx, 1);
	}
	if (ny > 0) {
		state->y = clamp(state->y, 0, ny);
		gui_scrollbar(g, state, sry, ny, 0);
	}
}

void gui_scrollbar(
	GUI* g,
	GUI_Scroll_State* state,
	Rect r,
	int diff,
	int horizontal
) {
	GUI_Scrollbar* e = gui_alloc(g, sizeof *e);
	int ls = g->app->mbtn_states[mbtn_left];
	int mh = 30;
	e->el.type = gui_el_type_scrollbar;
	e->el.r = r;
	if (horizontal) {
		e->handle.x = r.x + state->x * (r.w - e->handle.w) / diff;
		e->handle.y = r.y;
		e->handle.w = r.w * r.w / (r.w + diff);
		e->handle.w = maxi(e->handle.w, mh);
		e->handle.h = r.h;
	} else {
		e->handle.x = r.x;
		e->handle.y = r.y + state->y * (r.h - e->handle.h) / diff;
		e->handle.w = r.w;
		e->handle.h = r.h * r.h / (r.h + diff);
		e->handle.h = maxi(e->handle.h, mh);
	}
	e->s = state;
	e->h = horizontal;
	e->hover = 0;
	e->active = 0;
	if (
		mouse_over(g->app, &e->handle) &&
		ls & key_state_just_pressed
	) {
		state->grabbed[horizontal] = 1;
		state->graboff[horizontal] =
			(e->handle.x - g->app->mx);
	}
#define doscroll(a, ad) \
		int scroll = state->a + g->app->dm ## a; \
		scroll = clamp(scroll, 0, diff); \
		state->a = scroll; \
		e->handle.a = scroll * (r.ad - e->handle.ad) / diff + r.a;
	if (state->grabbed[horizontal]) {
		if (horizontal) {
			doscroll(x, w)
		} else {
			doscroll(y, h)
		}
		if (ls & key_state_just_released)
			state->grabbed[horizontal] = 0;
		if (ls & key_state_just_released)
			state->grabbed[horizontal] = 0;
	}
}

void rect_cfit(Rect* r) {
	r->x++;
	r->y++;
	r->w -= 2;
	r->h -= 2;
}

void draw_container(Renderer* r, const Rect* rect, int active) {
	const Colour bg   = make_colour(0xc3c3c3, 0xff);
	Colour out1       = make_colour(0xffffff, 0xff);
	Colour out2       = make_colour(0x000000, 0xff);
	Rect t = *rect;
	if (active) {
		Colour t = out1;
		out1 = out2;
		out2 = t;
	}
	ren_rect(r, bg, rect);
	t.h = 1;
	ren_rect(r, out1, &t);
	t.w = 1;
	t.h = rect->h;
	ren_rect(r, out1, &t);
	t.h--;
	t.x += rect->w - 1;
	t.y++;
	ren_rect(r, out2, &t);
	t.y = rect->y + rect->h - 1;
	t.x = rect->x + 1;
	t.w = rect->w - 1;
	t.h = 1;
	ren_rect(r, out2, &t);
}

void draw_btn(GUI* g, Renderer* r, const GUI_Btn* btn) {
	const Colour txt  = make_colour(0x000000, 0xff);
	int tp[2];
	Rect rect = btn->el.r;
	(void)g;
	tp[0] =
		rect.x + rect.w / 2 -
		gui_text_width(btn->text, string_len(btn->text)) / 2;
	tp[1] =
		rect.y + rect.h / 2 -
		gui_text_height() / 2;
	if (btn->active) {
		tp[0]++;
		tp[1]++;
	}
	draw_container(r, &rect, btn->active);
	rect_cfit(&rect);
	ren_clip(r, &rect);
	ren_text(r, txt, tp[0], tp[1], btn->text);
	ren_clipr(r);
}

void draw_scrollable(
	GUI* g,
	Renderer* r,
	const GUI_Scrollable* s
) {
	Rect rect = s->el.r;
	draw_container(r, &s->el.r, 0);
	rect_cfit(&rect);
	rect.w = s->vp[0];
	rect.h = s->vp[1];
	ren_clip(r, &rect);
	s->draw(g, r, &rect, s->ss);
	ren_clipr(r);
}

void draw_scrollbar(
	GUI* g,
	Renderer* r,
	const GUI_Scrollbar* s
) {
	int a = s->s->grabbed[s->h];
	Colour out1       = make_colour(0xffffff, 0xff);
	Colour out2       = make_colour(0x000000, 0xff);
	Rect rect, h = s->handle;
	(void)g;
	if (a) {
		Colour t = out1;
		out1 = out2;
		out2 = t;
	}
	draw_container(r, &s->el.r, 0);
	if (s->h) {
		int i;
		h.x++;
		h.w -= 2;
		rect.w = 1;
		rect.h = 7;
		rect.x = s->handle.x + s->handle.w / 2 - 7;
		rect.y = s->handle.y + s->handle.h / 2 - rect.h / 2;
		if (a) {
			rect.x++;
			rect.y++;
		}
		draw_container(r, &h, a);
		for (i = 0; i < 3; i++) {
			ren_rect(r, out1, &rect);
			rect.x++;
			ren_rect(r, out2, &rect);
			rect.x += 4;
		}
	} else {
		int i;
		h.y++;
		h.h -= 2;
		rect.w = 7;
		rect.h = 1;
		rect.x = s->handle.x + s->handle.w / 2 - rect.w / 2;
		rect.y = s->handle.y + s->handle.h / 2 - 7;
		if (a) {
			rect.x++;
			rect.y++;
		}
		draw_container(r, &h, a);
		for (i = 0; i < 3; i++) {
			ren_rect(r, out1, &rect);
			rect.y++;
			ren_rect(r, out2, &rect);
			rect.y += 4;
		}
	}
}

void gui_end(GUI* g, Renderer* r) {
	GUI_El* el = g->first;
	while (el) {
		switch (el->type) {
			case gui_el_type_btn:
				draw_btn(g, r, (GUI_Btn*)el);
				break;
			case gui_el_type_scrollable:
				draw_scrollable(g, r, (GUI_Scrollable*)el);
				break;
			case gui_el_type_scrollbar:
				draw_scrollbar(g, r, (GUI_Scrollbar*)el);
				break;
		}
		el = el->next;
	}
}