#!/usr/bin/python -tt
"""
dcraw(1) wrapper to generate jpeg thumbnails from raw pictures in parallel

Written by Martin Pelikan, but actually in public domain.
dcraw(1) was written by Dave Coffin, and is available at:

	http://www.cybercom.net/~dcoffin/dcraw/
"""
THUMB_DIR = "_thumbnails"

import errno, os, sys, time
import multiprocessing, subprocess

def generate_thumbnail(rawname):
    jpgname = rawname.rsplit(".", 1)[0] + ".jpg"
    p = jpgname.rsplit("/", 1)
    if len(p) > 1:
        jpgname = p[1]
    jpgname = os.path.join(THUMB_DIR, jpgname)

    start = time.time()
    dcraw_args = [ "dcraw", "-c", rawname ]
    convert_args = [ "convert", "-", "-resize", "50%", jpgname ]
    d = subprocess.Popen(dcraw_args, stdout=subprocess.PIPE)
    c = subprocess.Popen(convert_args, stdin=d.stdout)
    d.stdout.close()
    os.waitpid(d.pid, 0)
    os.waitpid(c.pid, 0)

    total = time.time() - start
    print("finished", rawname, "in", "{0:.2f} seconds".format(total))
    return total

if __name__ == '__main__':
    start = time.time()
    raws = []
    dirs = []
    dirs.append("." if len(sys.argv) == 1 else sys.argv[1])

    while len(dirs) > 0:
        curdir = dirs.pop()
        for file in os.listdir(curdir):
            f = os.path.join(curdir, file)
            if os.path.isdir(f):
                dirs.append(f)
            elif not os.path.isfile(f):
                continue

            arr = file.rsplit(".", 1)
            if len(arr) > 1 and arr[1].lower() == 'cr2':
                raws.append(f)

    try:
        os.mkdir(THUMB_DIR)
    except OSError as e:
        if e.errno != errno.EEXIST:
            print(e)
            sys.exit(e.errno)

    # at the beginning, dcraw(1) does something cpu non-intensive
    # let the kernel scheduler take care of that
    units = multiprocessing.cpu_count() + 2
    pool = multiprocessing.Pool(units)
    times = pool.map(generate_thumbnail, raws)

    total = time.time() - start
    sumtimes = sum(times)
    avg = sumtimes/len(times)
    speedup = sumtimes/total
    print("Average {0:.2f} sec, total {1:.2f} sec, relative speedup {2:.2f}x".format(avg, total, speedup))