import os
import pygame
from OpenGL.GL import *

class TextureFile(object):
	def __init__(self):
		self.id = None
		self.filename = None
		self.h = None
		self.w = None
		
	def load(self, filename):
		self.filename = filename
		img = pygame.image.load(filename)
		img.convert_alpha()
		glActiveTexture(GL_TEXTURE0)
		texid = glGenTextures(1)
		#print "Generated font texture id %s" % (texid,)
		
		self.id = texid
		
		imgdata = pygame.image.tostring(img, "RGBA")
		imgr = img.get_rect()
		self.h = imgr.h
		self.w = imgr.w
		
		dimension = GL_TEXTURE_2D
		glBindTexture(dimension, texid)
		glTexImage2D(dimension, 0, GL_RGBA8, imgr.w, imgr.h, 0, GL_RGBA, GL_UNSIGNED_BYTE, imgdata)
		glTexParameteri(dimension, GL_TEXTURE_WRAP_S, GL_CLAMP)
		glTexParameteri(dimension, GL_TEXTURE_WRAP_T, GL_CLAMP)
		glTexParameteri(dimension, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
		glTexParameteri(dimension, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
		
class TexFont(object):
	def __init__(self):
		self.image = None
		self.start = None
		self.end = None
		self.rows = None
		self.cols = None
		self.charheight = None
		self.charwidth = None
		self.texwidth = None
		self.texheight = None
		self.gltex = None
		self.monospace = False
		self.charsizes = []
		self.colors = (1.0, 1.0, 1.0, 1.0)
	
	@staticmethod
	def new(fontdir, fontname):
		tf = TexFont()
		tf.load_definition(os.path.join(fontdir, "%s.tfd" % (fontname,)))
		tf.load_texture(os.path.join(fontdir, "%s.png" % (fontname,)))
		return tf
	
	def render(self, text, color=None):
		if color is None:
			color = self.colors
		#print "Binding texture %s" % (self.gltex.id,)
		glActiveTexture(GL_TEXTURE0)
		dimension = GL_TEXTURE_2D
		glBindTexture(GL_TEXTURE_2D, self.gltex.id)
		glTexParameteri(dimension, GL_TEXTURE_WRAP_S, GL_CLAMP)
		glTexParameteri(dimension, GL_TEXTURE_WRAP_T, GL_CLAMP)
		glTexParameteri(dimension, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
		glTexParameteri(dimension, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
		
		glBegin(GL_TRIANGLES)
		glNormal3f(0.0, 0.0, 1.0)
		glColor4f(*color)
		#print "Rendering font"
		offset = 0.0
		for i, letter in enumerate(text):
			offset = self.render_letter(letter, offset)
		
		glEnd()
	
		
	def render_letter(self, letter, offset):
		charidx = self.mapchar(letter)
		x1, y1, x2, y2 = self.get_coordinates(charidx)
		cx, cy = self.charsize(charidx)
		
		#print "Printing letter %s(%s) from %s, %s to %s, %s using texcoords %s, %s, %s, %s" % (letter, charidx, offset, 0.0, offset + cx, cy, x1*128.0, y1*128.0, x2*128.0, y2*128.0)
		glTexCoord2f(x1, y1); glVertex3f( offset + 0.0,  0.0,  0.0)
		glTexCoord2f(x1, y2); glVertex3f( offset + 0.0,   cy,  0.0)
		glTexCoord2f(x2, y1); glVertex3f( offset + cx,   0.0,  0.0)
		glTexCoord2f(x2, y1); glVertex3f( offset + cx,   0.0,  0.0)
		glTexCoord2f(x1, y2); glVertex3f( offset + 0.0,   cy,  0.0)
		glTexCoord2f(x2, y2); glVertex3f( offset + cx,    cy,  0.0)
		glTexCoord2f(0.0, 0.0)
		
		return offset + cx
		
	def charsize(self, idx):
		if self.monospace:
			return (self.charwidth, self.charheight)
		else:
			return self.charsizes[idx]
			
	
	
	def mapchar(self, char):
		"""
		Maps a char to an index.
		
		Takes a character either as ascii ordinal number or as a 1-length string.
		Returns the index of that character in this texture font.
		
		If the character is not valid in this texture font, the index number will
		instead reference the last character in the font, which is usually a
		symbol for unknown characters (either totally blank or a box.)
		"""
		
		if isinstance(char, str):
			char = ord(char)
			
		if char >= self.start and char < self.end:
			return char - self.start
		else:
			return self.end - self.start - 1
		
		
	def get_coordinates(self, idx):
		"""
		Maps an index to their x, y coordinates in the texture.
		
		Invalid indexes will be mapped to the last character in the font.
		"""
		if idx < 0 or idx >= (self.end - self.start):
			idx = (self.end - self.start - 1)
			
		xp1 = (idx % self.cols) * (self.charwidth + 1)
		yp1 = (idx // self.cols) * (self.charheight + 1)
		
		if self.monospace:
			xp2 = xp1 + self.charwidth + 1
			yp2 = yp1 + self.charheight + 1
		else:
			xp2 = xp1 + self.charsizes[idx][0] + 1
			yp2 = yp1 + self.charsizes[idx][1] + 1
		
		xtc1 = (float(xp1) + 0.0) / self.texwidth
		ytc1 = (float(yp1) + 0.0) / self.texheight
		xtc2 = (float(xp2) - 1.0) / self.texwidth
		ytc2 = (float(yp2) - 1.0) / self.texheight
		
		return (xtc1, ytc1, xtc2, ytc2)
		
	def load_definition(self, deffile):
		"""
		Loads a texture font definition (.tfd).
		
		These simple datafiles are generated by fontmaker.py to provide character
		spacing information about the associated texture font.
		
		This should be called before load_texture.
		"""
		dd = open(deffile, 'r')
		
		if dd.readline() != "fontheader\n":
			raise ValueError('"%s" is not a font definition file' % (deffile,))
		
		def nextline(dd):
			return [int(x) for x in dd.readline().rstrip().split(',')]
			
		self.start, self.end = 				nextline(dd)
		self.charwidth, self.charheight = 	nextline(dd)
		self.cols, self.rows = 				nextline(dd)
		self.texwidth, self.texheight =		nextline(dd)
		
		self.charwidth -= 1
		self.charheight -= 1
		
		assert dd.readline() == "charsizes\n"
		
		self.charsizes = [None] * (self.end - self.start)
		monospace = True
		monoheight = True
		
		for i in range(0, (self.end - self.start)):
			x, y = nextline(dd)
			if x != self.charwidth:
				monospace = False
			if y != self.charheight:
				monoheight = False
			self.charsizes[i] = (x, y)
		
		"not yet capable of dealing properly with fonts of variable height"
		assert monoheight
		self.monospace = monospace
			
			
	def load_texture(self, texfile):
		"""
		Loads a texture image (.png)
		
		The PNG image should contain 32-bit color with alpha channel. The image
		will be loaded as an OpenGL texture.
		
		This function must be called after load_definition.
		"""
		tf = TextureFile()
		tf.load(texfile)
		self.gltex = tf
		assert self.gltex.w == self.texwidth
		assert self.gltex.h == self.texheight