#! /usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Copyright 2020, Nils Hilbricht, Germany ( https://www.hilbricht.net )

This file is part of the Laborejo Software Suite ( https://www.laborejo.org ),

This is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""

import logging; logger = logging.getLogger(__name__); logger.info("import")

from os import getenv
import os
import pathlib
import re

"""
https://specifications.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html
https://specifications.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html#icon_lookup

$HOME/.icons (for backwards compatibility)
$XDG_DATA_DIRS/icons
/usr/share/pixmaps
"""

SEARCH_DIRECTORIES = [pathlib.Path(pathlib.Path.home(), ".icons")]

XDG_DATA_DIRS = getenv("XDG_DATA_DIRS")  #colon : separated, most likely empty
if XDG_DATA_DIRS:
    SEARCH_DIRECTORIES += [pathlib.Path(p, "icons/hicolor") for p in XDG_DATA_DIRS.split(":")]
    SEARCH_DIRECTORIES += [pathlib.Path(p, "icons/scalable") for p in XDG_DATA_DIRS.split(":")]
else:
    #If $XDG_DATA_DIRS is either not set or empty, a value equal to /usr/local/share/:/usr/share/ should be used.
    SEARCH_DIRECTORIES += [pathlib.Path(p, "icons/hicolor") for p in "/usr/local/share/:/usr/share/".split(":")]
    SEARCH_DIRECTORIES += [pathlib.Path(p, "icons/scalable") for p in "/usr/local/share/:/usr/share/".split(":")]

SEARCH_DIRECTORIES.append(pathlib.Path("/usr/share/pixmaps"))

SEARCH_DIRECTORIES = set(p.resolve() for p in SEARCH_DIRECTORIES) #resolve follows symlinks, set() makes it unique


def run_fast_scandir(dir, ext):
    """
    https://stackoverflow.com/questions/18394147/recursive-sub-folder-search-and-return-files-in-a-list-python
    """
    subfolders, files = [], []

    try:
        for f in os.scandir(dir):
            if f.is_dir():
                subfolders.append(f.path)
            if f.is_file():
                if os.path.splitext(f.name)[1].lower() in ext:
                    files.append(f.path)

        for dir in list(subfolders):
            sf, f = run_fast_scandir(dir, ext)
            subfolders.extend(sf)
            files.extend(f)

    except PermissionError:
        pass

    except FileNotFoundError:
        pass

    return subfolders, files


def _buildCache()->set:
    result = []
    for basePath in SEARCH_DIRECTORIES:
        forget, files = run_fast_scandir(basePath, [".png", ".xpm", ".svg"])
        result += files

    #Convert str to real paths
    result = [pathlib.Path(r) for r in result if pathlib.Path(r).is_file()]

    return set(result)

global _cache
_cache = None
def updateCache(serializedCache:list=None):
    global _cache

    if serializedCache:
        #Convert str to real paths
        logger.info("Filling icon cache with previously serialized data")
        _cache = set([pathlib.Path(r) for r in serializedCache if pathlib.Path(r).is_file()])
    else:
        #Already real paths as a set
        logger.info("Building icon cache from scratch")
        _cache = _buildCache()
    logger.info("Icon cache complete")

def getSerializedCache()->list: #list of strings, not paths. This is for saving in global system config for faster startup
    global _cache
    return [str(p) for p in _cache]

rePattern =  re.compile("\d+x\d+") #we don't put .* around this because we are searching for the subpattern

def findIconPath(executableName:str)->list:
    """Return order is: svg first, then highest resolution first, then the rest unordered.
    so you can use result[0] for the best variant.
    It is not guaranteed that [1], or even [0] exists.
    This is not a sorted list, these extra variants are just added to the front of the list again"""
    global _cache
    if not _cache:
        raise ValueError("You need to call updateCache() first")

    svg = None
    bestr = 0 #resolution
    best = None

    result = []
    for f in _cache:
        if f.stem == executableName:
            if f.suffix == ".svg":
                svg = f
            else:
                match = re.search(rePattern, str(f)) #find resolution dir like /48x48/
                if match:
                    resolutionAsNumber = int(match.group().split("x")[0])
                    if resolutionAsNumber > bestr: #new best one
                        bestr = resolutionAsNumber
                        best = f
            result.append(f)

    if best:
        result.insert(0, best)
    if svg:
        result.insert(0, svg)

    return result

if __name__ == "__main__":
    """Example that tries to find a few icons"""

    updateCache()

    print("Search paths:")
    print(SEARCH_DIRECTORIES)
    print()

    for exe in ("zynaddsubfx", "patroneo", "jack_mixer", "carla", "ardour6", "synthv1"):
        r = findIconPath(exe)
        if r:
            print (f"{exe} Best resolution: {r[0]}")
        else:
            print (f"{exe}: No icon found ")