#!/usr/bin/env python

# RandPod version 0.2, 2005Jul21
# Copyright 2005 by Mark Damon Hughes <mark@markdamonhughes.com>
# Use and modify freely, but do not redistribute, always refer others
# back to <http://markdamonhughes.com/RandPod/>

import os, shutil, sys
from random import randint
from os.path import join, getsize
from Tkinter import *

NODESIZE=4096

class RandPod:
    def __init__(self, root):
        # path
        self.pathvar = StringVar()
        Label(root, text="Path:").grid(row=0, column=0, sticky=W)
        Entry(root, width=80, textvariable=self.pathvar).grid(row=0, column=1, sticky=W)
        self.pathvar.set(os.getcwd())

        # size
        self.sizevar = StringVar()
        Label(root, text="Max Size (MB):").grid(row=1, column=0, sticky=W)
        Entry(root, width=6, textvariable=self.sizevar).grid(row=1, column=1, sticky=W)
        self.sizevar.set("512")

        # dest
        self.destvar = StringVar()
        Label(root, text="Destination:").grid(row=2, column=0, sticky=W)
        Entry(root, width=80, textvariable=self.destvar).grid(row=2, column=1, sticky=W)
        self.destvar.set(os.getcwd())

        # command buttons
        buttonFrame = Frame(root)
        Button(buttonFrame, text="Randomize", command=self.randomizeButton).pack(side=LEFT)
        Button(buttonFrame, text="Copy", command=self.copyButton).pack(side=LEFT)
        Button(buttonFrame, text="Exit", command=self.exitButton).pack(side=LEFT)
        buttonFrame.grid(row=3, column=0, columnspan=2, sticky=W)

        # output
        self.chosen = []
        outputFrame = Frame(root)
        self.output = Text(outputFrame, width=120, height=16)
        scroll = Scrollbar(outputFrame, command=self.output.yview)
        self.output.configure(yscrollcommand=scroll.set)
        self.output.pack(side=LEFT)
        scroll.pack(side=RIGHT, fill=Y)
        outputFrame.grid(row=4, column=0, columnspan=2, sticky=W)

        # status
        self.labelvar = StringVar()
        Label(root, textvariable=self.labelvar).grid(row=5, column=0, columnspan=2, sticky=W)
        self.labelvar.set("")

        root.title("RandPod")

    def randomizeButton(self, *args):
        path = self.pathvar.get()
        maxnodes = int(self.sizevar.get()) * 1024 * 1024 // NODESIZE
        dest = self.destvar.get()
        self.chosen = randpod(maxnodes, path)
        self.output.delete("0.0", END)
        for pathname in self.chosen:
            self.output.insert(END, pathname+"\n")
        self.labelvar.set("Selected %d random files" % (len(self.chosen),) )

    def copyButton(self, *args):
        dest = self.destvar.get()
        docopy(self.chosen, dest)
        self.labelvar.set("Copied %d files!" % (len(self.chosen),) )

    def exitButton(self, *args):
        sys.exit(0)

#________________________________________
def randomize(list):
    """Randomly shuffles the contents of list and returns the list.
    As maximally shuffled as possible."""
    size = len(list)
    for i in range(size):
        a = randint(0, size-1)
        tmp = list[i]
        list[i] = list[a]
        list[a] = tmp

def randpod(maxnodes, path):
    """Returns a list of randomly-chosen files under path which use less
    than maxnodes.
        maxnodes: Maximum number of nodes (4K each).
        path: Starting path.
    """
    list = []  # := [pathname, size]
    for root, dirs, files in os.walk(path):
        for filename in files:
            if filename.endswith(".mp3"):
                pathname = join(root, filename)
                nodes = (getsize(pathname) + NODESIZE-1) // NODESIZE
                list.append( [pathname, nodes] )
    randomize(list)
    total = 0
    chosen = [] # := pathname
    for pathname, nodes in list:
        if total + nodes <= maxnodes:
            chosen.append(pathname)
            total += nodes
        if total >= maxnodes:
            break
    return chosen

def docopy(chosen, dest):
    """Copies pathnames listed in chosen (a list) to directory dest."""
    if not os.path.isdir(dest):
        os.makedirs(dest)
    for pathname in chosen:
        print pathname
        shutil.copy(pathname, dest)

#________________________________________
def main(argv):
    if len(sys.argv) == 1:
        # GUI user
        root = Tk()
        randpod = RandPod(root)
        root.mainloop()
    elif len(sys.argv) == 4:
        # command line user
        maxnodes = int(sys.argv[1]) * 1024 * 1024 // NODESIZE
        path = sys.argv[2]
        dest = sys.argv[3]
        chosen = randpod(maxnodes, path)
        docopy(chosen, dest)
    else:
        print >>sys.stderr, "Usage: randpod.py MAXSIZE(MB) PATH DEST"
        sys.exit(1)

#________________________________________
if __name__ == "__main__":
    main(sys.argv)