#!/usr/bin/env python3
# Startdate: 2021-01-29 15:35
# Dependencies:
#    devuan-req: python3-exifread
# Reference:
#    https://stackoverflow.com/questions/1192978/python-get-relative-path-of-all-files-and-subfolders-in-a-directory
#    https://stackoverflow.com/questions/3207219/how-do-i-list-all-files-of-a-directory
#    https://stackoverflow.com/questions/600268/mkdir-p-functionality-in-python
from sys import stderr
from exifread import process_file
from os import walk, path, stat, symlink
from pathlib import Path
from datetime import date
from shutil import copy2, move

try:
   if debuglevel is None:
      debuglevel = 0
except:
   debuglevel = 0

# Functions
def eprint(*args, **kwargs):
   print(*args, file=stderr, **kwargs)

def list_files(indir,relative=False,debuglevel=debuglevel, excludes=None):
   x = 0
   f = []
   if debuglevel >= 9:
      eprint(f"Listing all files underneath {indir}")
      if len(excludes) > 0:
         eprint("While excluding path matches:",excludes)
   for (dirpath, dirnames, filenames) in walk(indir):
      for file in filenames:
         x += 1
         fullpath=path.join(dirpath,file)
         relpath=path.join(path.relpath(dirpath,indir),file)
         use = True
         use_pattern = ""
         for e in excludes:
            # simple match, no regex
            if e in relpath:
               use = False
               use_pattern = e
               break # short-circuit
         if use:
            if debuglevel >= 9: eprint(x,fullpath,relpath)
            f.append(relpath if relative else fullpath)
         else:
            if debuglevel >= 9: eprint(x,fullpath,f"ignored per {use_pattern}")
   return f

def limit(listf=None,filters=["image","video"]):
   # available types are "image", "video"
   newlist = []
   for f in listf:
      _, ext = path.splitext(f)
      ext = ext[1:].lower()
      if ext in ["jpg","jpeg","png","svg","tif","tiff","gif"] and "image" in filters:
         newlist.append(f)
      elif ext in ["mp4","webm","avi"] and "video" in filters:
         newlist.append(f)
   return newlist

def get_file_YM(tf,debuglevel=debuglevel,zero_pad=False):
   Y = 0 ; M = 0
   #eprint(f"Debuglevel {debuglevel}")
   try:
      # read exif data
      with open(tf,'rb') as f:
         tags = process_file(f, details=False, stop_tag="Image DateTime")
      if "Image DateTime" in tags:
         #if debuglevel >= 5: eprint(tf,tags["Image DateTime"])
         Y = str(tags["Image DateTime"]).split(' ')[0].split(':')
         if Y == "['']" or Y == ['']:
            Y = ['0','0']
         M = Y[1] ; Y = Y[0];
      # Any other image timestamps could be used here
      #eprint(tags)
   except KeyboardInterrupt:
      return -1, -1
   except:
      if debuglevel >= 1: eprint(f"Unable to extract any exif data for {tf}")
   if int(Y) == 0 or int(M) == 0:
      # need to just use timestamp
      try:
         ts = date.fromtimestamp(stat(tf).st_mtime)
      except KeyboardInterrupt:
         return -1, -1
      except:
         # no timestamp available from filesystem?
         if debuglevel >= 1: eprint(f"No timestamp available for {tf}")
      if int(Y) == 0: Y = ts.year
      if int(M) == 0: M = ts.month
   if zero_pad:
      M = str(M).zfill(2)
   else:
      M = str(int(M))
   if debuglevel >= 3:
      eprint(f"{tf} {Y}/{M}")
   return Y, M

def make_YM_forest(outdir, flist, action = "symlink", dryrun=True, debuglevel=debuglevel, zero_pad=False, relative_symlinks = False):
   """
   For each file in flist, [action] it to outdir, sorting into YYYY/MM subdirs based on exif metadata or timestamp.
   Action may be one of ['symlink', 'copy', 'move'].
   If relative_symlink = True, then make relative symlinks if possible.
   """
   result = 0
   stop = False

   # validate input
   if action not in ['symlink', 'copy', 'move']:
      eprint("make_YM_forest action may be one of ['symlink', 'copy', 'move'].")
      return -1

   # Learn all directories to make
   # and also cache the files with Y/M value
   fdict = {}
   destdirs = []
   for f in flist:
      try:
         Y, M = get_file_YM(f,debuglevel=debuglevel,zero_pad=zero_pad)
         if Y == -1 and M == -1:
            #eprint("Stopping due to keyboard variant 2.")
            stop = True
            break
      except KeyboardInterrupt:
         #eprint("Stopping due to keyboard variant 1.")
         stop = True
         break
      if zero_pad:
         M = str(M).zfill(2)
      else:
         M = str(int(M))
      YM = f"{Y}/{M}"
      if YM not in destdirs: destdirs.append(YM)
      fdict[f] = YM
   # finish the for f in flist

   # short-circuit if keyboard action happened in one of the nested functions
   if stop:
      return -1

   # Make directories
   for d in destdirs:
      dd = path.join(outdir,d)
      if debuglevel >= 3:
         eprint(f"Make dir: {dd}")
      if not dryrun:
         Path(dd).mkdir(parents=True, exist_ok=True)

   # Make symlinks
   for f in fdict:
      ff = f
      basename = path.basename(ff)
      destfile = path.join(outdir,fdict[f],basename)
      if action == "symlink" and relative_symlinks:
         ff = path.relpath(ff,destfile)
      if debuglevel >= 2:
         if action == "copy":
            eprint(f"cp -p {ff} {destfile}")
         elif action == "symlink":
            eprint(f"ln -s {ff} {destfile}")
         elif action == "move":
            eprint(f"mv {ff} {destfile}")

      if not dryrun:
      #if False:
         if action == "copy":
            copy2(ff,destfile)
         elif action == "symlink":
            symlink(ff,destfile)
         elif action == "move":
            move(ff,destfile)

   return result