/*
   Copyright (C) 2003 - 2015 by David White <dave@whitevine.net>
   Part of the Battle for Wesnoth Project http://www.wesnoth.org/

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY.

   See the COPYING file for more details.
*/

/**
 * @file
 * Show screen with scrolling credits.
 */

#include "about.hpp"

#include "construct_dialog.hpp"
#include "display.hpp"
#include "gettext.hpp"
#include "marked-up_text.hpp"

#include <boost/foreach.hpp>

/**
 * @namespace about
 * Display credits %about all contributors.
 *
 * This module is used from the startup screen. \n
 * When show_about() is called, a list of contributors
 * to the game will be presented to the user.
 */
namespace about
{
	static config about_list = config();
	static std::map<std::string , std::string> images;
	static std::string images_default;

/**
 * Given a vector of strings, and a config representing an [about] section,
 * add all the credits lines from the about section to the list of strings.
 */
static void add_lines(std::vector<std::string> &res, config const &c, bool split_multiline_headers) {
	std::string title = c["title"];
	if (!title.empty()) {
		if(split_multiline_headers) {
			// If the title is multi-line, we need to split it accordingly or we
			// get slight scrolling glitches in the credits screen.
			const std::vector<std::string>& lines = utils::split(c["title"], '\n');
			bool first = true;
			BOOST_FOREACH(const std::string& line, lines) {
				if(first) {
					res.push_back("+" + line);
					first = false;
				} else {
					// Don't convert other lines into headers or they get extra
					// spacing on the credits screen.
					res.push_back(line);
				}
			}
		} else {
			res.push_back("+" + title);
		}
	}

	std::vector<std::string> lines = utils::split(c["text"], '\n');
	BOOST_FOREACH(std::string &line, lines)
	{
		if (line.size() > 1 && line[0] == '+')
			line = "+  " + line.substr(1);
		else
			line = "-  " + line;

		if (!line.empty())
		{
			if (line[0] == '_')
				line = translation::gettext(line.substr(1).c_str());
			res.push_back(line);
		}
	}

	BOOST_FOREACH(const config &entry, c.child_range("entry")) {
		res.push_back("-  "+ entry["name"].str());
	}
}


std::vector<std::string> get_text(const std::string &campaign, bool split_multiline_headers)
{
	std::vector< std::string > res;

	config::child_itors about_entries = about_list.child_range("about");

	if (!campaign.empty()) {
		BOOST_FOREACH(const config &about, about_entries) {
			// just finished a particular campaign
			if (campaign == about["id"]) {
				add_lines(res, about, split_multiline_headers);
			}
		}
	}

	BOOST_FOREACH(const config &about, about_entries) {
		add_lines(res, about, split_multiline_headers);
	}

	return res;
}

void set_about(const config &cfg)
{
	about_list.clear();
	images.clear();
	images_default = "";

	BOOST_FOREACH(const config &about, cfg.child_range("about"))
	{
		about_list.add_child("about", about);
		const std::string &im = about["images"];
		if (!images.empty())
		{
			if (images_default.empty())
				images_default = im;
			else
				images_default += ',' + im;
		}
	}

	BOOST_FOREACH(const config &campaign, cfg.child_range("campaign"))
	{
		config::const_child_itors abouts = campaign.child_range("about");
		if (abouts.first == abouts.second) continue;

		config temp;
		std::ostringstream text;
		const std::string &id = campaign["id"];
		temp["title"] = campaign["name"];
		temp["id"] = id;
		std::string campaign_images;

		BOOST_FOREACH(const config &about, abouts)
		{
			const std::string &subtitle = about["title"];
			if (!subtitle.empty())
			{
				text << '+';
				if (subtitle[0] == '_')
					text << translation::gettext(subtitle.substr(1, subtitle.size() - 1).c_str());
				else
					text << subtitle;
				text << '\n';
			}

			BOOST_FOREACH(const std::string &line, utils::split(about["text"], '\n'))
			{
				text << "    " << line << '\n';
			}

			BOOST_FOREACH(const config &entry, about.child_range("entry"))
			{
				text << "    " << entry["name"] << '\n';
			}

			const std::string &im = about["images"];
			if (!im.empty())
			{
				if (campaign_images.empty())
					campaign_images = im;
				else
					campaign_images += ',' + im;
			}
		}

		images[id] = campaign_images;
		temp["text"] = text.str();
		about_list.add_child("about",temp);
	}
}

/**
 * Show credits with list of contributors.
 *
 * Names of people are shown scrolling up like in movie-credits.\n
 * Uses map from wesnoth or campaign as background.
 */
void show_about(display &disp, const std::string &campaign)
{
	boost::scoped_ptr<cursor::setter> cur(new cursor::setter(cursor::WAIT));
	CVideo &video = disp.video();
	surface screen = video.getSurface();
	if (screen == NULL) return;

	// If the title is multi-line, we need to split it accordingly or we
	// get slight scrolling glitches in the credits screen.
	std::vector<std::string> text = about::get_text(campaign, true);

	SDL_Rect screen_rect = create_rect(0, 0, screen->w, screen->h);

	const surface_restorer restorer(&video, screen_rect);

	cur.reset();

	std::vector<std::string> image_list;
	if(campaign.size() && !images[campaign].empty()){
		image_list = utils::parenthetical_split(images[campaign], ',');
	} else{
		image_list = utils::parenthetical_split(images_default, ',');
	}

	surface map_image, map_image_scaled;

	if(!image_list.empty()) {
		map_image = image::get_image(image_list[0]);
	} else {
		image_list.push_back("");
	}

	if(!map_image){
        image_list[0]=game_config::images::game_title_background;
		map_image=image::get_image(image_list[0]);
	}

	gui::button close(video,_("Close"));
	close.set_location((screen->w/2)-(close.width()/2), screen->h - 30);
	close.set_volatile(true);

	const int def_size = font::SIZE_XLARGE;
	const SDL_Color def_color = font::NORMAL_COLOR;

	//substitute in the correct control characters for '+' and '-'
	std::string before_header(2, ' ');
	before_header[0] = font::LARGE_TEXT;
	for(unsigned i = 0; i < text.size(); ++i) {
		std::string &s = text[i];
		if (s.empty()) continue;
		char &first = s[0];
		if (first == '-')
			first = font::SMALL_TEXT;
		else if (first == '+') {
			first = font::LARGE_TEXT;
			text.insert(text.begin() + i, before_header);
			++i;
		}
	}
	text.insert(text.begin(), 10, before_header);

	int startline = 0;

	//TODO: use values proportional to screen ?
	// distance from top of map image to top of scrolling text
	const int top_margin = 60;
	// distance from bottom of scrolling text to bottom of map image
	const int bottom_margin = 40;
	// distance from left of scrolling text to the frame border
	const int text_left_padding = screen->w/32;

	int offset = 0;
	bool is_new_line = true;

	int first_line_height = 0;

	SDL_Rect frame_area;

	// we use a dialog to contains the text. Strange idea but at least the style
	// will be consistent with the titlescreen
	gui::dialog_frame f(video, "", gui::dialog_frame::titlescreen_style, false);

	// the text area's dimensions
	SDL_Rect text_rect = { 0, 0, 0, 0 };
	// we'll retain a copy to prevent SDL_blit to change its w and h
	SDL_Rect text_rect_blit;

	surface text_surf;

	CKey key;
	bool last_escape;

	int image_count = 0;
	int scroll_speed = 4;	// scroll_speed*50 = speed of scroll in pixel per second

	// Initially redraw all
	bool redraw_mapimage = true;
	bool update_dimensions = true;
	int max_text_width = 0;

	do {
		last_escape = key[SDLK_ESCAPE] != 0;

		// check to see if background image has changed
		if(text.size() && (image_count <
				((startline * static_cast<int>(image_list.size())) /
				static_cast<int>(text.size())))){

			image_count++;
			surface temp=image::get_image(image_list[image_count]);
			map_image=temp?temp:map_image;
			redraw_mapimage = true;
		}

		if (update_dimensions) {
			// rescale the background
			map_image_scaled = scale_surface(map_image, screen->w, screen->h);
			screen_rect = create_rect(0, 0, screen->w, screen->h);
			redraw_mapimage = true;

			// update the frame
			frame_area = create_rect(
						  screen->w * 3 / 32
						, top_margin
						, screen->w * 13 / 16
						, screen->h - top_margin - bottom_margin);

			text_rect = f.layout(frame_area).interior;

			// update the text area
			text_rect.x += text_left_padding;
			text_rect.w -= text_left_padding;
			text_rect_blit = text_rect;

			text_surf = create_compatible_surface(screen, text_rect.w, text_rect.h);
			SDL_SetAlpha(text_surf, SDL_RLEACCEL, SDL_ALPHA_OPAQUE);

			// relocate the close button
			close.set_location((screen->w/2)-(close.width()/2), screen->h - 30);

			update_dimensions = false;
		}

		if (redraw_mapimage) {
			// draw map to screen, thus erasing all text
			sdl_blit(map_image_scaled, NULL, screen, NULL);
			update_rect(screen_rect);

			// redraw the dialog
			f.draw_background();
			f.draw_border();
			// cache the dialog background (alpha blending + blurred map)
			sdl_blit(screen, &text_rect, text_surf, NULL);
			redraw_mapimage = false;
		} else {
			// redraw the saved part of the dialog where text scrolled
			// thus erasing all text
			SDL_Rect modified = create_rect(0, 0, max_text_width, text_rect.h);
			sdl_blit(text_surf, &modified, screen, &text_rect_blit);
			update_rect(text_rect);
		}

		int y = text_rect.y - offset;
		int line = startline;
		max_text_width = 0;

		{
			// clip to keep text into the frame (thus the new code block)
			clip_rect_setter set_clip_rect(screen, &text_rect);

			const int line_spacing = 5;
			do {
				// draw the text (with ellipsis if needed)
				// update the max_text_width for future cleaning
				int w = font::draw_text(&video, text_rect, def_size, def_color,
										text[line], text_rect.x, y).w;
				max_text_width = std::max<int>(max_text_width, w);
				// since the real drawing on screen is clipped,
				// we do a dummy one to get the height of the not clipped line.
				// (each time because special format characters may change it)
				const int line_height = font::draw_text(NULL, text_rect, def_size, def_color,
										text[line], 0,0).h;

				if(is_new_line) {
					is_new_line = false;
					first_line_height = line_height + line_spacing;
				}
				line++;
				if(size_t(line) > text.size()-1)
					line = 0;
				y += line_height + line_spacing;
			} while(y < text_rect.y + text_rect.h);
		}

		// performs the actual scrolling
		offset += scroll_speed;
		if (offset>=first_line_height) {
			offset -= first_line_height;
			is_new_line = true;
			startline++;
			if(size_t(startline) == text.size()){
				startline = 0;
				image_count = -1;
			}
		}

		// handle events
		if (key[SDLK_UP] && scroll_speed < 20) {
			++scroll_speed;
		}
		if (key[SDLK_DOWN] && scroll_speed > 0) {
			--scroll_speed;
		}
		if (screen->w != screen_rect.w || screen->h != screen_rect.h) {
			update_dimensions = true;
		}

		events::pump();
		events::raise_process_event();
		events::raise_draw_event();

		// flip screen and wait, so the text does not scroll too fast
		disp.flip();
		disp.delay(20);

	} while(!close.pressed() && (last_escape || !key[SDLK_ESCAPE]));
}

} // end namespace about