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// license:BSD-3-Clause
// copyright-holders:Nicola Salmoria
/***************************************************************************

  video.c

  Functions to emulate the video hardware of the machine.

***************************************************************************/

#include "emu.h"
#include "includes/galaga.h"
#include "includes/bosco.h"


#define VIDEO_RAM_SIZE 0x400


void bosco_state::bosco_palette(palette_device &palette) const
{
	const uint8_t *color_prom = memregion("proms")->base();

	// core palette
	for (int i = 0; i < 32; i++)
	{
		int bit0, bit1, bit2;

		bit0 = BIT(*color_prom, 0);
		bit1 = BIT(*color_prom, 1);
		bit2 = BIT(*color_prom, 2);
		int const r = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
		bit0 = BIT(*color_prom, 3);
		bit1 = BIT(*color_prom, 4);
		bit2 = BIT(*color_prom, 5);
		int const g = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;
		bit0 = 0;
		bit1 = BIT(*color_prom, 6);
		bit2 = BIT(*color_prom, 7);
		int const b = 0x21 * bit0 + 0x47 * bit1 + 0x97 * bit2;

		palette.set_indirect_color(i, rgb_t(r, g, b));
		color_prom++;
	}

	// palette for the stars
	for (int i = 0; i < 64; i++)
	{
		static constexpr int map[4] = { 0x00, 0x47, 0x97 ,0xde };

		int const r = map[(i >> 0) & 0x03];
		int const g = map[(i >> 2) & 0x03];
		int const b = map[(i >> 4) & 0x03];

		palette.set_indirect_color(32 + i, rgb_t(r, g, b));
	}

	// characters / sprites
	for (int i = 0; i < 64*4; i++)
	{
		palette.set_pen_indirect(i, (color_prom[i] & 0x0f) | 0x10); // chars
		palette.set_pen_indirect(i + 64*4, color_prom[i] & 0x0f); // sprites
	}

	// bullets lookup table
	// they use colors 28-31, I think - PAL 5A controls it
	for (int i = 0; i < 4; i++)
		palette.set_pen_indirect(64*4+64*4+i, 31 - i);

	// now the stars
	for (int i = 0; i < 64; i++)
		palette.set_pen_indirect(64*4+64*4+4+i, 32 + i);
}



/***************************************************************************

  Callbacks for the TileMap code

***************************************************************************/

/* the video RAM has space for 32x32 tiles and is only partially used for the radar */
TILEMAP_MAPPER_MEMBER(bosco_state::fg_tilemap_scan )
{
	return col + (row << 5);
}


inline void bosco_state::get_tile_info_bosco(tile_data &tileinfo,int tile_index,int ram_offs)
{
	uint8_t attr = m_videoram[ram_offs + tile_index + 0x800];
	tileinfo.category = (attr & 0x20) >> 5;
	tileinfo.group = attr & 0x3f;
	tileinfo.set(0,
			m_videoram[ram_offs + tile_index],
			attr & 0x3f,
			TILE_FLIPYX(attr >> 6) ^ TILE_FLIPX);
}

TILE_GET_INFO_MEMBER(bosco_state::bg_get_tile_info )
{
	get_tile_info_bosco(tileinfo,tile_index,0x400);
}

TILE_GET_INFO_MEMBER(bosco_state::fg_get_tile_info )
{
	get_tile_info_bosco(tileinfo,tile_index,0x000);
}



/***************************************************************************

  Start the video hardware emulation.

***************************************************************************/

VIDEO_START_MEMBER(bosco_state,bosco)
{
	m_bg_tilemap = &machine().tilemap().create(*m_gfxdecode, tilemap_get_info_delegate(*this, FUNC(bosco_state::bg_get_tile_info)), TILEMAP_SCAN_ROWS, 8,8, 32,32);
	m_fg_tilemap = &machine().tilemap().create(*m_gfxdecode, tilemap_get_info_delegate(*this, FUNC(bosco_state::fg_get_tile_info)), tilemap_mapper_delegate(*this, FUNC(bosco_state::fg_tilemap_scan)), 8,8, 8,32);

	m_bg_tilemap->configure_groups(*m_gfxdecode->gfx(0), 0x1f);
	m_fg_tilemap->configure_groups(*m_gfxdecode->gfx(0), 0x1f);

	m_bg_tilemap->set_scrolldx(3,3);

	m_spriteram = m_videoram + 0x03d4;
	m_spriteram_size = 0x0c;
	m_spriteram2 = m_spriteram + 0x0800;
	m_bosco_radarx = m_videoram + 0x03f0;
	m_bosco_radary = m_bosco_radarx + 0x0800;

	m_bosco_starclr = 1;

	save_item(NAME(m_bosco_starclr));
}



/***************************************************************************

  Memory handlers

***************************************************************************/

WRITE8_MEMBER( bosco_state::bosco_videoram_w )
{
	m_videoram[offset] = data;
	if (offset & 0x400)
		m_bg_tilemap->mark_tile_dirty(offset & 0x3ff);
	else
		m_fg_tilemap->mark_tile_dirty(offset & 0x3ff);
}

WRITE8_MEMBER( bosco_state::bosco_scrollx_w )
{
	m_bg_tilemap->set_scrollx(0,data);
}

WRITE8_MEMBER( bosco_state::bosco_scrolly_w )
{
	m_bg_tilemap->set_scrolly(0,data);
}

WRITE8_MEMBER( bosco_state::bosco_starclr_w )
{
	// On any write to $9840, turn on starfield
	m_bosco_starclr = 0;
}



/***************************************************************************

  Display refresh

***************************************************************************/

void bosco_state::draw_sprites(bitmap_ind16 &bitmap, const rectangle &cliprect, int flip)
{
	uint8_t *spriteram = m_spriteram;
	uint8_t *spriteram_2 = m_spriteram2;
	int offs;

	for (offs = 0;offs < m_spriteram_size;offs += 2)
	{
		int sx = spriteram[offs + 1] - 1;
		int sy = 240 - spriteram_2[offs];
		int flipx = spriteram[offs] & 1;
		int flipy = spriteram[offs] & 2;
		int color = spriteram_2[offs + 1] & 0x3f;

		if (flip) sx += 32-2;

		m_gfxdecode->gfx(1)->transmask(bitmap,cliprect,
				(spriteram[offs] & 0xfc) >> 2,
				color,
				flipx,flipy,
				sx,sy,
				m_palette->transpen_mask(*m_gfxdecode->gfx(1), color, 0x0f));
	}
}


void bosco_state::draw_bullets(bitmap_ind16 &bitmap, const rectangle &cliprect, int flip)
{
	int offs;

	for (offs = 4; offs < 0x10;offs++)
	{
		int x = m_bosco_radarx[offs] + ((~m_bosco_radarattr[offs] & 0x01) << 8) - 2;
		int y = 251 - m_bosco_radary[offs];

		if (flip)
		{
			x -= 1;
			y += 2;
		}

		m_gfxdecode->gfx(2)->transmask(bitmap,cliprect,
				((m_bosco_radarattr[offs] & 0x0e) >> 1) ^ 0x07,
				0,
				!flip,!flip,
				x,y,0xf0);
	}
}



uint32_t bosco_state::screen_update_bosco(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
	/* the radar tilemap is just 8x32. We rely on the tilemap code to repeat it across
	   the screen, and clip it to only the position where it is supposed to be shown */
	rectangle fg_clip = cliprect;
	rectangle bg_clip = cliprect;
	int flip = flip_screen();
	if (flip)
	{
		bg_clip.min_x = 8*8;
		fg_clip.max_x = 8*8-1;
	}
	else
	{
		bg_clip.max_x = 28*8-1;
		fg_clip.min_x = 28*8;
	}

	bitmap.fill(m_palette->black_pen(), cliprect);
	m_starfield->draw_starfield(bitmap,cliprect,flip);

	m_bg_tilemap->draw(screen, bitmap, bg_clip, 0,0);
	m_fg_tilemap->draw(screen, bitmap, fg_clip, 0,0);

	draw_sprites(bitmap,cliprect,flip);

	/* draw the high priority characters */
	m_bg_tilemap->draw(screen, bitmap, bg_clip, 1,0);
	m_fg_tilemap->draw(screen, bitmap, fg_clip, 1,0);

	draw_bullets(bitmap,cliprect,flip);

	return 0;
}


WRITE_LINE_MEMBER(bosco_state::screen_vblank_bosco)
{
	// falling edge
	if (!state)
	{
		// Bosconian scrolls in X and Y directions
		const uint8_t speed_index_X = m_bosco_starcontrol[0] & 0x07;
		const uint8_t speed_index_Y = (m_bosco_starcontrol[0] & 0x38) >> 3;
		m_starfield->set_scroll_speed(speed_index_X,speed_index_Y);

		m_starfield->set_active_starfield_sets(m_videolatch->q4_r(), m_videolatch->q5_r() | 2);

		// _STARCLR signal enables/disables starfield
		m_starfield->enable_starfield(!m_bosco_starclr);
	}
}