import csv
import gzip
import os
from math import asin, atan2, cos, degrees, hypot, sin, sqrt

import numpy as np

import pyqtgraph as pg
from pyqtgraph import Point
from pyqtgraph.Qt import QtCore, QtGui


class GlassDB:
    """
    Database of dispersion coefficients for Schott glasses
     + Corning 7980
    """
    def __init__(self, fileName='schott_glasses.csv'):
        path = os.path.dirname(__file__)
        fh = gzip.open(os.path.join(path, 'schott_glasses.csv.gz'), 'rb')
        r = csv.reader(map(str, fh.readlines()))
        lines = [x for x in r]
        self.data = {}
        header = lines[0]
        for l in lines[1:]:
            info = {}
            for i in range(1, len(l)):
                info[header[i]] = l[i]
            self.data[l[0]] = info
        self.data['Corning7980'] = {   ## Thorlabs UV fused silica--not in schott catalog.
            'B1': 0.68374049400,
            'B2': 0.42032361300,
            'B3': 0.58502748000,
            'C1': 0.00460352869,
            'C2': 0.01339688560,
            'C3': 64.49327320000,
            'TAUI25/250': 0.95,    ## transmission data is fabricated, but close.
            'TAUI25/1400': 0.98,
        }
        
        for k in self.data:
            self.data[k]['ior_cache'] = {}
            

    def ior(self, glass, wl):
        """
        Return the index of refraction for *glass* at wavelength *wl*.
        
        The *glass* argument must be a key in self.data.
        """
        info = self.data[glass]
        cache = info['ior_cache']
        if wl not in cache:
            B = list(map(float, [info['B1'], info['B2'], info['B3']]))
            C = list(map(float, [info['C1'], info['C2'], info['C3']]))
            w2 = (wl/1000.)**2
            n = sqrt(1.0 + (B[0]*w2 / (w2-C[0])) + (B[1]*w2 / (w2-C[1])) + (B[2]*w2 / (w2-C[2])))
            cache[wl] = n
        return cache[wl]
        
    def transmissionCurve(self, glass):
        data = self.data[glass]
        keys = [int(x[7:]) for x in data.keys() if 'TAUI25' in x]
        keys.sort()
        curve = np.empty((2,len(keys)))
        for i in range(len(keys)):
            curve[0][i] = keys[i]
            key = 'TAUI25/%d' % keys[i]
            val = data[key]
            if val == '':
                val = 0
            else:
                val = float(val)
            curve[1][i] = val
        return curve
            

GLASSDB = GlassDB()


def wlPen(wl):
    """Return a pen representing the given wavelength"""
    l1 = 400
    l2 = 700
    hue = np.clip(((l2-l1) - (wl-l1)) * 0.8 / (l2-l1), 0, 0.8)
    val = 1.0
    if wl > 700:
        val = 1.0 * (((700-wl)/700.) + 1)
    elif wl < 400:
        val = wl * 1.0/400.
    #print hue, val
    color = pg.hsvColor(hue, 1.0, val)
    pen = pg.mkPen(color)
    return pen


class ParamObj(object):
    # Just a helper for tracking parameters and responding to changes
    def __init__(self):
        self.__params = {}
    
    def __setitem__(self, item, val):
        self.setParam(item, val)
        
    def setParam(self, param, val):
        self.setParams(**{param:val})
        
    def setParams(self, **params):
        """Set parameters for this optic. This is a good function to override for subclasses."""
        self.__params.update(params)
        self.paramStateChanged()

    def paramStateChanged(self):
        pass

    def __getitem__(self, item):
        # bug in pyside 1.2.2 causes getitem to be called inside QGraphicsObject.parentItem:
        return self.getParam(item)  # PySide bug: https://bugreports.qt.io/browse/PYSIDE-671
    
    def __len__(self):
        # Workaround for PySide bug: https://bugreports.qt.io/browse/PYSIDE-671
        return 0

    def getParam(self, param):
        return self.__params[param]


class Optic(pg.GraphicsObject, ParamObj):
    
    sigStateChanged = QtCore.Signal()
    
    
    def __init__(self, gitem, **params):
        ParamObj.__init__(self)
        pg.GraphicsObject.__init__(self) #, [0,0], [1,1])

        self.gitem = gitem
        self.surfaces = gitem.surfaces
        gitem.setParentItem(self)
        
        self.roi = pg.ROI([0,0], [1,1])
        self.roi.addRotateHandle([1, 1], [0.5, 0.5])
        self.roi.setParentItem(self)
        
        defaults = {
            'pos': Point(0,0),
            'angle': 0,
        }
        defaults.update(params)
        self._ior_cache = {}
        self.roi.sigRegionChanged.connect(self.roiChanged)
        self.setParams(**defaults)
        
    def updateTransform(self):
        self.setPos(0, 0)
        tr = QtGui.QTransform()
        self.setTransform(tr.translate(Point(self['pos'])).rotate(self['angle']))
        
    def setParam(self, param, val):
        ParamObj.setParam(self, param, val)

    def paramStateChanged(self):
        """Some parameters of the optic have changed."""
        # Move graphics item
        self.gitem.setPos(Point(self['pos']))
        self.gitem.resetTransform()
        self.gitem.setRotation(self['angle'])
        
        # Move ROI to match
        try:
            self.roi.sigRegionChanged.disconnect(self.roiChanged)
            br = self.gitem.boundingRect()
            o = self.gitem.mapToParent(br.topLeft())
            self.roi.setAngle(self['angle'])
            self.roi.setPos(o)
            self.roi.setSize([br.width(), br.height()])
        finally:
            self.roi.sigRegionChanged.connect(self.roiChanged)
        
        self.sigStateChanged.emit()

    def roiChanged(self, *args):
        pos = self.roi.pos()
        # rotate gitem temporarily so we can decide where it will need to move
        self.gitem.resetTransform()
        self.gitem.setRotation(self.roi.angle())
        br = self.gitem.boundingRect()
        o1 = self.gitem.mapToParent(br.topLeft())
        self.setParams(angle=self.roi.angle(), pos=pos + (self.gitem.pos() - o1))
        
    def boundingRect(self):
        return QtCore.QRectF()
        
    def paint(self, p, *args):
        pass

    def ior(self, wavelength):
        return GLASSDB.ior(self['glass'], wavelength)
        


class Lens(Optic):
    def __init__(self, **params):
        defaults = {
            'dia': 25.4,  ## diameter of lens
            'r1': 50.,    ## positive means convex, use 0 for planar
            'r2': 0,   ## negative means convex
            'd': 4.0,
            'glass': 'N-BK7',
            'reflect': False,
        }
        defaults.update(params)
        d = defaults.pop('d')
        defaults['x1'] = -d/2.
        defaults['x2'] = d/2.
        
        gitem = CircularSolid(brush=(100, 100, 130, 100), **defaults)
        Optic.__init__(self, gitem, **defaults)
        
    def propagateRay(self, ray):
        """Refract, reflect, absorb, and/or scatter ray. This function may create and return new rays"""

        """
        NOTE:: We can probably use this to compute refractions faster: (from GLSL 120 docs)

        For the incident vector I and surface normal N, and the
        ratio of indices of refraction eta, return the refraction
        vector. The result is computed by
        k = 1.0 - eta * eta * (1.0 - dot(N, I) * dot(N, I))
        if (k < 0.0)
            return genType(0.0)
        else
            return eta * I - (eta * dot(N, I) + sqrt(k)) * N
        The input parameters for the incident vector I and the
        surface normal N must already be normalized to get the
        desired results. eta == ratio of IORs


        For reflection:
        For the incident vector I and surface orientation N,
        returns the reflection direction:
        I – 2 ∗ dot(N, I) ∗ N
        N must already be normalized in order to achieve the
        desired result.
        """
        iors = [self.ior(ray['wl']), 1.0]
        for i in [0,1]:
            surface = self.surfaces[i]
            ior = iors[i]
            p1, ai = surface.intersectRay(ray)
            if p1 is None:
                ray.setEnd(None)
                break
            p1 = surface.mapToItem(ray, p1)
            
            rd = ray['dir']

            a1 = atan2(rd[1], rd[0])
            try:
                ar = a1 - ai + asin((sin(ai) * ray['ior'] / ior))
            except ValueError:
                ar = np.nan
            ray.setEnd(p1)
            dp = Point(cos(ar), sin(ar))
            ray = Ray(parent=ray, ior=ior, dir=dp)
        return [ray]
        

class Mirror(Optic):
    def __init__(self, **params):
        defaults = {
            'r1': 0,
            'r2': 0,
            'd': 0.01,
        }
        defaults.update(params)
        d = defaults.pop('d')
        defaults['x1'] = -d/2.
        defaults['x2'] = d/2.
        gitem = CircularSolid(brush=(100,100,100,255), **defaults)
        Optic.__init__(self, gitem, **defaults)
        
    def propagateRay(self, ray):
        """Refract, reflect, absorb, and/or scatter ray. This function may create and return new rays"""
        
        surface = self.surfaces[0]
        p1, ai = surface.intersectRay(ray)
        if p1 is not None:
            p1 = surface.mapToItem(ray, p1)
            rd = ray['dir']
            a1 = atan2(rd[1], rd[0])
            ar = a1 + np.pi - 2 * ai
            ray.setEnd(p1)
            dp = Point(cos(ar), sin(ar))
            ray = Ray(parent=ray, dir=dp)
        else:
            ray.setEnd(None)
        return [ray]


class CircularSolid(pg.GraphicsObject, ParamObj):
    """GraphicsObject with two circular or flat surfaces."""
    def __init__(self, pen=None, brush=None, **opts):
        """
        Arguments for each surface are:
           x1,x2 - position of center of _physical surface_
           r1,r2 - radius of curvature
           d1,d2 - diameter of optic
        """
        defaults = dict(x1=-2, r1=100, d1=25.4, x2=2, r2=100, d2=25.4)
        defaults.update(opts)
        ParamObj.__init__(self)
        self.surfaces = [CircleSurface(defaults['r1'], defaults['d1']), CircleSurface(-defaults['r2'], defaults['d2'])]
        pg.GraphicsObject.__init__(self)
        for s in self.surfaces:
            s.setParentItem(self)
        
        if pen is None:
            self.pen = pg.mkPen((220,220,255,200), width=1, cosmetic=True)
        else:
            self.pen = pg.mkPen(pen)
        
        if brush is None: 
            self.brush = pg.mkBrush((230, 230, 255, 30))
        else:
            self.brush = pg.mkBrush(brush)

        self.setParams(**defaults)

    def paramStateChanged(self):
        self.updateSurfaces()

    def updateSurfaces(self):
        self.surfaces[0].setParams(self['r1'], self['d1'])
        self.surfaces[1].setParams(-self['r2'], self['d2'])
        self.surfaces[0].setPos(self['x1'], 0)
        self.surfaces[1].setPos(self['x2'], 0)
        
        self.path = QtGui.QPainterPath()
        self.path.connectPath(self.surfaces[0].path.translated(self.surfaces[0].pos()))
        self.path.connectPath(self.surfaces[1].path.translated(self.surfaces[1].pos()).toReversed())
        self.path.closeSubpath()
        
    def boundingRect(self):
        return self.path.boundingRect()
        
    def shape(self):
        return self.path
    
    def paint(self, p, *args):
        p.setRenderHints(p.renderHints() | p.RenderHint.Antialiasing)
        p.setPen(self.pen)
        p.fillPath(self.path, self.brush)
        p.drawPath(self.path)
        

class CircleSurface(pg.GraphicsObject):
    def __init__(self, radius=None, diameter=None):
        """center of physical surface is at 0,0
        radius is the radius of the surface. If radius is None, the surface is flat. 
        diameter is of the optic's edge."""
        pg.GraphicsObject.__init__(self)
        
        self.r = radius
        self.d = diameter
        self.mkPath()
        
    def setParams(self, r, d):
        self.r = r
        self.d = d
        self.mkPath()
        
    def mkPath(self):
        self.prepareGeometryChange()
        r = self.r
        d = self.d
        h2 = d/2.
        self.path = QtGui.QPainterPath()
        if r == 0:  ## flat surface
            self.path.moveTo(0, h2)
            self.path.lineTo(0, -h2)
        else:
            ## half-height of surface can't be larger than radius
            h2 = min(h2, abs(r))
            arc = QtCore.QRectF(0, -r, r*2, r*2)
            a1 = degrees(asin(h2/r))
            a2 = -2*a1
            a1 += 180.
            self.path.arcMoveTo(arc, a1)
            self.path.arcTo(arc, a1, a2)
        self.h2 = h2
        
    def boundingRect(self):
        return self.path.boundingRect()
        
    def paint(self, p, *args):
        return  ## usually we let the optic draw.
            
    def intersectRay(self, ray):
        ## return the point of intersection and the angle of incidence
        #print "intersect ray"
        h = self.h2
        r = self.r
        p, dir = ray.currentState(relativeTo=self)  # position and angle of ray in local coords.
        #print "  ray: ", p, dir
        p = p - Point(r, 0)  ## move position so center of circle is at 0,0
        #print "  adj: ", p, r
        
        if r == 0:
            #print "  flat"
            if dir[0] == 0:
                y = 0
            else:
                y = p[1] - p[0] * dir[1]/dir[0]
            if abs(y) > h:
                return None, None
            else:
                return (Point(0, y), atan2(dir[1], dir[0]))
        else:
            #print "  curve"
            ## find intersection of circle and line (quadratic formula)
            dx = dir[0]
            dy = dir[1]
            dr = hypot(dx, dy)  # length
            D = p[0] * (p[1]+dy) - (p[0]+dx) * p[1]
            idr2 = 1.0 / dr**2
            disc = r**2 * dr**2 - D**2
            if disc < 0:
                return None, None
            disc2 = disc**0.5
            if dy < 0:
                sgn = -1
            else:
                sgn = 1

            br = self.path.boundingRect()
            x1 = (D*dy + sgn*dx*disc2) * idr2
            y1 = (-D*dx + abs(dy)*disc2) * idr2
            if br.contains(x1+r, y1):
                pt = Point(x1, y1)
            else:
                x2 = (D*dy - sgn*dx*disc2) * idr2
                y2 = (-D*dx - abs(dy)*disc2) * idr2
                pt = Point(x2, y2)
                if not br.contains(x2+r, y2):
                    return None, None
                
            norm = atan2(pt[1], pt[0])
            if r < 0:
                norm += np.pi
            dp = p - pt
            ang = atan2(dp[1], dp[0]) 
            return pt + Point(r, 0), ang-norm

            
class Ray(pg.GraphicsObject, ParamObj):
    """Represents a single straight segment of a ray"""
    
    sigStateChanged = QtCore.Signal()
    
    def __init__(self, **params):
        ParamObj.__init__(self)
        defaults = {
            'ior': 1.0,
            'wl': 500,
            'end': None,
            'dir': Point(1,0),
        }
        self.params = {}
        pg.GraphicsObject.__init__(self)
        self.children = []
        parent = params.get('parent', None)
        if parent is not None:
            defaults['start'] = parent['end']
            defaults['wl'] = parent['wl']
            self['ior'] = parent['ior']
            self['dir'] = parent['dir']
            parent.addChild(self)
        
        defaults.update(params)
        defaults['dir'] = Point(defaults['dir'])
        self.setParams(**defaults)
        self.mkPath()
        
    def clearChildren(self):
        for c in self.children:
            c.clearChildren()
            c.setParentItem(None)
            self.scene().removeItem(c)
        self.children = []
        
    def paramStateChanged(self):
        pass
        
    def addChild(self, ch):
        self.children.append(ch)
        ch.setParentItem(self)
        
    def currentState(self, relativeTo=None):
        pos = self['start']
        dir = self['dir']
        if relativeTo is None:
            return pos, dir
        else:
            trans = self.itemTransform(relativeTo)[0]
            p1 = trans.map(pos)
            p2 = trans.map(pos + dir)
            return Point(p1), Point(p2-p1)
            
    def setEnd(self, end):
        self['end'] = end
        self.mkPath()

    def boundingRect(self):
        return self.path.boundingRect()
        
    def paint(self, p, *args):
        #p.setPen(pg.mkPen((255,0,0, 150)))
        p.setRenderHints(p.renderHints() | p.RenderHint.Antialiasing)
        p.setCompositionMode(p.CompositionMode.CompositionMode_Plus)
        p.setPen(wlPen(self['wl']))
        p.drawPath(self.path)
        
    def mkPath(self):
        self.prepareGeometryChange()
        self.path = QtGui.QPainterPath()
        self.path.moveTo(self['start'])
        if self['end'] is not None:
            self.path.lineTo(self['end'])
        else:
            self.path.lineTo(self['start']+500*self['dir'])


def trace(rays, optics):
    if len(optics) < 1 or len(rays) < 1:
        return
    for r in rays:
        r.clearChildren()
        o = optics[0]
        r2 = o.propagateRay(r)
        trace(r2, optics[1:])


class Tracer(QtCore.QObject):
    """
    Simple ray tracer. 
    
    Initialize with a list of rays and optics; 
    calling trace() will cause rays to be extended by propagating them through
    each optic in sequence.
    """
    def __init__(self, rays, optics):
        QtCore.QObject.__init__(self)
        self.optics = optics
        self.rays = rays
        for o in self.optics:
            o.sigStateChanged.connect(self.trace)
        self.trace()
            
    def trace(self):
        trace(self.rays, self.optics)
