/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include "graphics/font.h"

#include "common/array.h"
#include "common/util.h"

namespace Graphics {

int Font::getKerningOffset(uint32 left, uint32 right) const {
	return 0;
}

namespace {

template<class StringType>
int getStringWidthImpl(const Font &font, const StringType &str) {
	int space = 0;
	typename StringType::unsigned_type last = 0;

	for (uint i = 0; i < str.size(); ++i) {
		const typename StringType::unsigned_type cur = str[i];
		space += font.getCharWidth(cur) + font.getKerningOffset(last, cur);
		last = cur;
	}

	return space;
}

template<class StringType>
void drawStringImpl(const Font &font, Surface *dst, const StringType &str, int x, int y, int w, uint32 color, TextAlign align, int deltax) {
	assert(dst != 0);

	const int leftX = x, rightX = x + w;
	int width = font.getStringWidth(str);

	if (align == kTextAlignCenter)
		x = x + (w - width)/2;
	else if (align == kTextAlignRight)
		x = x + w - width;
	x += deltax;

	typename StringType::unsigned_type last = 0;
	for (typename StringType::const_iterator i = str.begin(), end = str.end(); i != end; ++i) {
		const typename StringType::unsigned_type cur = *i;
		x += font.getKerningOffset(last, cur);
		last = cur;
		w = font.getCharWidth(cur);
		if (x+w > rightX)
			break;
		if (x+w >= leftX)
			font.drawChar(dst, cur, x, y, color);
		x += w;
	}
}

template<class StringType>
struct WordWrapper {
	Common::Array<StringType> &lines;
	int actualMaxLineWidth;

	WordWrapper(Common::Array<StringType> &l) : lines(l), actualMaxLineWidth(0) {
	}

	void add(StringType &line, int &w) {
		if (actualMaxLineWidth < w)
			actualMaxLineWidth = w;

		lines.push_back(line);

		line.clear();
		w = 0;
	}
};

template<class StringType>
int wordWrapTextImpl(const Font &font, const StringType &str, int maxWidth, Common::Array<StringType> &lines) {
	WordWrapper<StringType> wrapper(lines);
	StringType line;
	StringType tmpStr;
	int lineWidth = 0;
	int tmpWidth = 0;

	// The rough idea behind this algorithm is as follows:
	// We accumulate characters into the string tmpStr. Whenever a full word
	// has been gathered together this way, we 'commit' it to the line buffer
	// 'line', i.e. we add tmpStr to the end of line, then clear it. Before
	// we do that, we check whether it would cause 'line' to exceed maxWidth;
	// in that case, we first add line to lines, then reset it.
	//
	// If a newline character is read, then we also add line to lines and clear it.
	//
	// Special care has to be taken to account for 'words' that exceed the width
	// of a line. If we encounter such a word, we have to wrap it over multiple
	// lines.

	typename StringType::unsigned_type last = 0;
	for (typename StringType::const_iterator x = str.begin(); x != str.end(); ++x) {
		const typename StringType::unsigned_type c = *x;
		const int w = font.getCharWidth(c) + font.getKerningOffset(last, c);
		last = c;
		const bool wouldExceedWidth = (lineWidth + tmpWidth + w > maxWidth);

		// If this char is a whitespace, then it represents a potential
		// 'wrap point' where wrapping could take place. Everything that
		// came before it can now safely be added to the line, as we know
		// that it will not have to be wrapped.
		if (Common::isSpace(c)) {
			line += tmpStr;
			lineWidth += tmpWidth;

			tmpStr.clear();
			tmpWidth = 0;

			// If we encounter a line break (\n), or if the new space would
			// cause the line to overflow: start a new line
			if (c == '\n' || wouldExceedWidth) {
				wrapper.add(line, lineWidth);
				continue;
			}
		}

		// If the max line width would be exceeded by adding this char,
		// insert a line break.
		if (wouldExceedWidth) {
			// Commit what we have so far, *if* we have anything.
			// If line is empty, then we are looking at a word
			// which exceeds the maximum line width.
			if (lineWidth > 0) {
				wrapper.add(line, lineWidth);
				// Trim left side
				while (tmpStr.size() && Common::isSpace(tmpStr[0])) {
					tmpStr.deleteChar(0);
					// This is not very fast, but it is the simplest way to
					// assure we do not mess something up because of kerning.
					tmpWidth = font.getStringWidth(tmpStr);
				}
			} else {
				wrapper.add(tmpStr, tmpWidth);
			}
		}

		tmpWidth += w;
		tmpStr += c;
	}

	// If some text is left over, add it as the final line
	line += tmpStr;
	lineWidth += tmpWidth;
	if (lineWidth > 0) {
		wrapper.add(line, lineWidth);
	}
	return wrapper.actualMaxLineWidth;
}

} // End of anonymous namespace

int Font::getStringWidth(const Common::String &str) const {
	return getStringWidthImpl(*this, str);
}

int Font::getStringWidth(const Common::U32String &str) const {
	return getStringWidthImpl(*this, str);
}

void Font::drawString(Surface *dst, const Common::String &sOld, int x, int y, int w, uint32 color, TextAlign align, int deltax, bool useEllipsis) const {
	Common::String s = sOld;
	int width = getStringWidth(s);
	Common::String str;

	if (useEllipsis && width > w && s.hasSuffix("...")) {
		// String is too wide. Check whether it ends in an ellipsis
		// ("..."). If so, remove that and try again!
		s.deleteLastChar();
		s.deleteLastChar();
		s.deleteLastChar();
		width = getStringWidth(s);
	}

	if (useEllipsis && width > w) {
		// String is too wide. So we shorten it "intelligently" by
		// replacing parts of the string by an ellipsis. There are
		// three possibilities for this: replace the start, the end, or
		// the middle of the string. What is best really depends on the
		// context; but unless we want to make this configurable,
		// replacing the middle seems to be a good compromise.

		const int ellipsisWidth = getStringWidth("...");

		// SLOW algorithm to remove enough of the middle. But it is good enough
		// for now.
		const int halfWidth = (w - ellipsisWidth) / 2;
		int w2 = 0;
		Common::String::unsigned_type last = 0;
		uint i;

		for (i = 0; i < s.size(); ++i) {
			const Common::String::unsigned_type cur = s[i];
			int charWidth = getCharWidth(cur) + getKerningOffset(last, cur);
			if (w2 + charWidth > halfWidth)
				break;
			last = cur;
			w2 += charWidth;
			str += cur;
		}

		// At this point we know that the first 'i' chars are together 'w2'
		// pixels wide. We took the first i-1, and add "..." to them.
		str += "...";
		last = '.';

		// The original string is width wide. Of those we already skipped past
		// w2 pixels, which means (width - w2) remain.
		// The new str is (w2+ellipsisWidth) wide, so we can accommodate about
		// (w - (w2+ellipsisWidth)) more pixels.
		// Thus we skip ((width - w2) - (w - (w2+ellipsisWidth))) =
		// (width + ellipsisWidth - w)
		int skip = width + ellipsisWidth - w;
		for (; i < s.size() && skip > 0; ++i) {
			const Common::String::unsigned_type cur = s[i];
			skip -= getCharWidth(cur) + getKerningOffset(last, cur);
			last = cur;
		}

		// Append the remaining chars, if any
		for (; i < s.size(); ++i) {
			str += s[i];
		}

		width = getStringWidth(str);
	} else {
		str = s;
	}

	drawStringImpl(*this, dst, str, x, y, w, color, align, deltax);
}

void Font::drawString(Surface *dst, const Common::U32String &str, int x, int y, int w, uint32 color, TextAlign align) const {
	drawStringImpl(*this, dst, str, x, y, w, color, align, 0);
}

int Font::wordWrapText(const Common::String &str, int maxWidth, Common::Array<Common::String> &lines) const {
	return wordWrapTextImpl(*this, str, maxWidth, lines);
}

int Font::wordWrapText(const Common::U32String &str, int maxWidth, Common::Array<Common::U32String> &lines) const {
	return wordWrapTextImpl(*this, str, maxWidth, lines);
}

} // End of namespace Graphics