#!/usr/bin/env python3
# vim: set et ts=4 sts=4 sw=4:
# Startdate: 2024-11-20-4 12:50
# Title: Library for Graphical Mount Manager
# Dependencies:
#    req-devuan: python3, python3-psutil
import argparse, sys, os, psutil, subprocess, json, configparser

# LOW-LEVEL values
appname = "gmm"
appversion = "0.0.1"
conffile = os.path.join(os.getenv("HOME"),".config",appname,"config")

ABOUT_TEXT = """
gmm "Graphical Mount Manager"
(C) 2024 bgstack15
SPDX-License-Identifier: GPL-3.0-only
"""

# LOW-LEVEL FUNCTIONS
def ferror(*args, **kwargs):
   print(*args, file=sys.stderr, **kwargs)

def debuglev(_numbertocheck):
   # if _numbertocheck <= debuglevel then return truthy
   _debuglev = False
   try:
      if int(_numbertocheck) <= int(debuglevel):
         _debuglev = True
   except Exception as e:
      pass
   return _debuglev

    # APP FUNCTIONS

class Gmm():

    def __init__(self,args=None):
        # Parse config
        self.conffile = conffile
        try:
            if args.conf:
                self.conffile = args.conf
        except:
            pass
        self.mounts = self.list_mounts()
        self.args = args
        self.config = configparser.ConfigParser()
        self.load_config(self.conffile)
        # will be set to False if --no-gui, or some action is given
        self.show_gui = True

    def list_mounts(self):
        """
        Return a python list of FILE,MOUNT pairs
        """
        # get list of devices
        mounts = [
            {
                "device": i.device,
                "mountpoint": i.mountpoint
            } for i in psutil.disk_partitions(False) if i.fstype in ["iso9660"]
        ]
        # use losetup --json,
        losetup_p = subprocess.Popen(
            ["/usr/sbin/losetup","--json"], stdout=subprocess.PIPE
        )
        losetup_o, _ = losetup_p.communicate()
        try:
            losetup_j = json.loads(losetup_o)
        except Exception as e:
            ferror(f"Got error {e} when trying to read losetup output")
            losetup_j = {}
        if losetup_j:
            losetup_j = losetup_j["loopdevices"]
            for i in mounts:
                #for j in losetup_j["loopdevices"]:
                #    if i.device == j.name:
                try:
                    i["source"] = [j["back-file"] for j in losetup_j if j["name"] == i["device"]][0]
                except Exception as e:
                    ferror(f"While looking for {i['device']} in {losetup_j}, got error {e}")
        for i in mounts:
            if "source" in i:
                i.pop("device")
        # Now we have a list of
        # [{'mountpoint': '/mnt/foo', 'source': '/mnt/public/CDROMs/Games/Logical Journey of the Zoombinis.iso'}]
        return mounts

    def mount_iso_to_path(self, isofile, mount_point):
        """
        Mount the isofile to mount_point using sudo. No protections of already-mounted or something-else-mounted.
        """
        mount_p = subprocess.Popen(
            ["sudo","mount","-v",isofile,mount_point], stdout=subprocess.PIPE
        )
        mount_o, mount_e = mount_p.communicate()
        if debuglev(5):
            if mount_e:
                ferror(mount_e)

    def mount_iso_to_default(self,isofile):
        """
        Use the gmm config to determine where to mount this.
        """
        md = self.config[appname]["mounts_dir"]
        # determine next available number. 0-indexed. If you want to make this 1-indexed, set x to 0.
        x = -1
        safe = False
        # safety valve: do not try mount more than 20 mount points.
        while (not safe) or x < 20:
            x = x + 1
            testpath = os.path.join(md,str(x))
            if not os.path.exists(testpath):
                safe = True
                break
            else:
                if os.path.ismount(testpath):
                    if self.iso_is_mounted_to_path(isofile, testpath):
                        if debuglev(2):
                            ferror(f"INFO: Found {isofile} mounted at {testpath} already. Skipping...")
                        # short-circuit
                        return True
                    # if a mountpoint but is not the requested isofile
                    if debuglev(8):
                        ferror(f"DEBUG: Found different mountpoint at {testpath}, continuing to look...")
                    # skip this number
                    continue
                elif os.path.isdir(testpath):
                    if os.listdir(testpath):
                        # not empty so skip it
                        ferror(f"WARNING: non-mountpoint {testpath} is not empty, continuing to look...")
                        continue
                    else:
                        # empty directory, this is what we want
                        safe = True
                        break
                else:
                    # so not a mountpoint and not a dir, so skip
                    ferror(f"WARNING: non-directory {testpath}, continuing to look...")
                    continue
            # end while
            # notably, because of all the continues and breaks, we cannot increment x at bottom of this loop.
        if debuglev(8):
            ferror(f"DEBUG: after loop, testpath is {testpath}")
        if safe:
            if debuglev(1):
                print(f"INFO: will mount {isofile} to {testpath}.")
            try:
                os.mkdir(testpath)
            # FUTUREIMPROVEMENT: might need to catch specific exceptions and pass them, like dir-already-exists.
            except:
                pass
            self.mount_iso_to_path(isofile, testpath)

    def unmount_iso_to_path(self, isofile, mount_point):
        """
        Unmount the isofile to mount_point using sudo.
        This exploits that the "isofile" could be the actual iso file that is mounted, or the mount point. The umount command can either to unmount something.
        """
        params = ["sudo","umount","-v",isofile,mount_point]
        params = [i for i in params if i]
        if debuglev(1):
            ferror(f"Running: {params}")
        mount_p = subprocess.Popen(
            params, stdout=subprocess.PIPE
        )
        mount_o, mount_e = mount_p.communicate()
        if debuglev(5):
            if mount_e:
                ferror(mount_e)
        # and now delete the empty directory
        if not mount_point:
            mount_point = isofile
        if os.path.isdir(mount_point) and (not os.listdir(mount_point)):
            try:
                os.rmdir(mount_point)
            except Exception as e:
                if debuglev(5):
                    ferror(f"INFO: while trying to remove now-empty dir {mount_point}, got error {e}, continuing...")

    def get_iso_mounted_to_path(self, mount_point):
        """
        Return the filename of what is mounted to mount_point.
        """
        if not os.path.ismount(mount_point):
            return False
        if not self.mounts:
            self.mounts = self.list_mounts()
        for i in self.mounts:
            if i["mountpoint"] == mount_point:
                # short-circuit because there can be only one thing mounted to a mount_point
                return i["source"]
        return None

    def iso_is_mounted_to_path(self, iso_file, mount_point):
        """
        Return True if the named iso_file is mounted to mount_point.
        """
        if not os.path.ismount(mount_point):
            return False
        if not self.mounts:
            self.mounts = self.list_mounts()
        for i in self.mounts:
            if i["mountpoint"] == mount_point and i["source"] == iso_file:
                # short-circuit
                return True
        return False

    def load_config(self, configfile):
        if debuglev(1):
            ferror(f"Loading config file {configfile}")
        self.config.read(configfile)
        try:
            #config["gmm"]["mounts_dir"] = os.path.expanduser(config["gmm"]["mounts_dir"])
            self.config.set(appname,"mounts_dir", os.path.expanduser(self.config[appname]["mounts_dir"].strip('"')))
        except:
            pass
        if debuglev(9):
            ferror({section: dict(self.config[section]) for section in self.config.sections()})

    def save_config(self, configfile = None):
        if not configfile:
            configfile = self.conffile
        # un-expand the tilde
        md = self.config[appname]["mounts_dir"]
        # by adding the trailing slash, we make sure it is not just the HOME, but that would be an extreme situation.
        if md.startswith(os.path.expanduser("~")+"/"):
            md = md.replace(os.path.expanduser("~"),"~")
            self.config.set(appname,"mounts_dir",md)
        with open(configfile,"w") as cf:
            config.write(cf)

    def cli_main(self):
        # default behavior is to show the gui, unless --no-gui, or given some paths to mount, or --list
        args = self.args
        paths = args.paths
        umount = args.unmount
        if (args.list) or (paths) or ((not paths) and args.all and umount):
            self.show_gui = False
        if args.gui == False or args.gui == True:
            ferror(f"Setting show_gui to {args.gui}")
            self.show_gui = args.gui
        if args.list:
            if args.output == "json":
                print(json.dumps(self.mounts))
            elif args.output == "tsv":
                if self.mounts:
                    print("source\tpath")
                for i in self.mounts:
                    print(f"{i['source']}\t{i['mountpoint']}")
            else:
                print(self.mounts)
        if paths:
            # calculate if paths.len = 2, then check if paths[0] is a file and paths[1] is a dir or underneath
            if len(paths) == 2:
                left = paths[0]
                right = paths[1]
                if os.path.isfile(left):
                    if os.path.isdir(right) or (not os.path.exists(right)):
                        if os.path.ismount(right):
                            if debuglev(8):
                                ferror(f"DEBUG: Investigating current mount {right} to see if it is same as {left}")
                            if iso_is_mounted_to_path(left, right, self.mounts):
                                if umount:
                                    self.unmount_iso_to_path(left, right)
                                else:
                                    if debuglev(1):
                                        print(f"Already mounted!")
                            else:
                                ferror(f"ERROR: {get_iso_mounted_to_path(right,self.mounts)} is already mounted to {right}.")
                                # FUTUREIMPROVEMENT: If we want to implement --force to umount old, then mount this left, do it here.
                        else:
                            if umount:
                                if debuglev(2):
                                    print(f"INFO: not a mount point, so nothing to do.")
                            else:
                                if debuglev(1):
                                    print(f"INFO: will mount {left} to {right}.")
                                mount_iso_to_path(left, right)
                    elif os.path.isfile(right):
                        for i in paths:
                            self.mount_iso_to_default(i)
                    else:
                        ferror(f"ERROR: second path {right} is not a dir or file. Choose a different spot")
                else:
                    ferror(f"ERROR: first path is not a file: {left}. Skipping...")
            elif len(paths) == 1:
                # main default method; the path to the iso to mount
                isofile = paths[0]
                # not ideal, but figure out that the user wanted "--list"
                if isofile == "list" and not os.path.isfile(isofile):
                    ferror(f"WARNING: please use --list to list mounts. Continuing...")
                    print(self.mounts)
                    sys.exit(0)
                if umount:
                    self.unmount_iso_to_path(isofile,"")
                else:
                    mount_iso_to_default(isofile)
            else:
                # more than one path, so treat each as a file to mount
                for isofile in paths:
                    if umount:
                        self.unmount_iso_to_path(isofile,"")
                    else:
                        self.mount_iso_to_default(isofile)
        else:
            # no paths, so check if --all and --umount
            if umount and args.all:
                for i in self.mounts:
                    self.unmount_iso_to_path(i["source"],i["mountpoint"])

# PARSE ARGUMENTS
parser = argparse.ArgumentParser(description="graphical mount manager",prog=appname,epilog="""        The value-add of this application is to use a configured directory for
mountpoints, for easy mounting, e.g., from a graphical file manager. Run with an
iso filename, and it will mount to ~/mnt/0, for example.""")
parser.add_argument("-d","--debug", nargs='?', default=0, type=int, choices=range(0,11), help="Set debug level.")
parser.add_argument("-V","--version", action="version", version="%(prog)s " + appversion)
parser.add_argument("-g","--gui", action=argparse.BooleanOptionalAction, default=None, help="Show gui, even if also given any other actions.")
parser.add_argument("-l","--list", action="store_true", help="List mounted isos and paths and then exit.")
parser.add_argument("-o","--output", default="tsv", choices=("tsv","raw","json"), help="Change output format for --list.")
parser.add_argument("-u","--unmount","--umount", action="store_true", help="If used with one or more paths, umount them instead of mounting.")
parser.add_argument("-a","--all", action="store_true", help="Used only with --unmount. Unmount all mounted paths in default-configured dir.")
parser.add_argument("paths", nargs="*",help="Positional parameters: ISO_FILE, MOUNT_PATH")
#parser.add_argument("-f","--force", action="store_true", help="Force deploy all confs.")
parser.add_argument("-c","--conf","--config", action="store", default=conffile, help="Use this config file.")
#parser.add_argument("-r","--dry","--dryrun","--dry-run", action="store_true", help="Do not execute. Useful when debugging.")
args = parser.parse_args()
if args.debug is None:
   debuglevel = 5
elif args.debug:
   debuglevel = args.debug
if debuglev(1):
    ferror("debug level", debuglevel)
    ferror(args)
umount = args.unmount