# PyCParser caching logic
# by Albert Zeyer, 2011
# code under BSD 2-Clause License

# idea:
#   for each parsed file:
#     keep list of which macros have been used, i.e.
#        the dependency list of macros.
#     keep list of all C-stuff which has been added.
#     check last change time of file and all other files we open from here
#        and also store this list.
#     save all.
#  when opening a new file, macro-dependencies, check the last change time
#     of all files and if everything matches, use the cache.

import sys
import os, os.path
if sys.version_info.major == 2:
    import cparser
    from cparser_utils import *
else:
    from . import cparser
    from .cparser_utils import *
import types

# Note: It might make sense to make this somehow configureable.
# However, for now, I'd like to keep things as simple as possible.
# Using /tmp or (a bit better) /var/tmp might have been another
# possibility. However, it makes sense to keep this more permanent
# because when compiling a lot, it can be very time-critical if
# we just remove all the data.
# If wasted space becomes an issue, it is easy to write a script
# which would remove all old/obsolete entries from the cache.
# It makes sense also to keep this global for the whole system
# because the caching system should be able to handle this
# and it should thus only improve the performance.
# It is saved though in the user directory because most probably
# we wouldn't have write permission otherwise.
CACHING_DIR = os.path.expanduser("~/.cparser_caching/")

def sha1(obj):
    import hashlib
    h = hashlib.sha1()
    if sys.version_info.major == 2:
        def h_update(s): h.update(s)
    else:
        def h_update(s):
            if isinstance(s, str): h.update(s.encode("utf-8"))
            else: h.update(s)
    if isinstance(obj, unicode):
        h_update(obj.encode("utf-8"))
    elif isinstance(obj, str):
        h_update(obj)
    elif isinstance(obj, dict):
        h_update("{")
        for k,v in sorted(obj.items()):
            h_update(sha1(k))
            h_update(":")
            h_update(sha1(v))
            h_update(",")
        h_update("}")
    elif isinstance(obj, (list,tuple)):
        h_update("[")
        for v in sorted(obj):
            h_update(sha1(v))
            h_update(",")
        h_update("]")
    else:
        h_update(str(obj))
    return h.hexdigest()

class MyDict(dict):
    def __setattr__(self, key, value):
        assert isinstance(key, (str,unicode))
        self[key] = value
    def __getattr__(self, key):
        try: return self[key]
        except KeyError: raise AttributeError
    def __repr__(self): return "MyDict(" + dict.__repr__(self) + ")"
    def __str__(self): return "MyDict(" + dict.__str__(self) + ")"

class DbObj:
    @classmethod
    def GetFilePath(cls, key):
        h = sha1(key)
        prefix = CACHING_DIR + cls.Namespace
        return prefix + "/" + h[:2] + "/" + h[2:]
    @classmethod
    def Load(cls, key, create=False):
        fn = cls.GetFilePath(key)
        try: f = open(fn, "b")
        except:
            if create:
                obj = cls()
                obj.__dict__["_key"] = key
                return obj
            else:
                return None
        import pickle
        obj = pickle.load(f)
        f.close()
        return obj
    @classmethod
    def Delete(cls, key):
        fn = cls.GetFilePath(key)
        os.remove(fn)
    def delete(self): self.Delete(self._key)
    def save(self):
        fn = self.GetFilePath(self._key)
        try: os.makedirs(os.path.dirname(fn))
        except: pass # ignore file-exists or other errors
        f = open(fn, "wb")
        import pickle
        pickle.dump(self, f)
        f.close()

def getLastChangeUnixTime(filename):
    import os.path
    return os.path.getmtime(filename)

class FileCacheRef(MyDict):
    @classmethod
    def FromCacheData(cls, cache_data):
        ref = cls()
        ref.filedepslist = map(lambda fn: (fn,getLastChangeUnixTime(fn)), cache_data.filenames)
        ref.macros = {}
        for m in cache_data.macroAccessSet:
            ref.macros[m] = cache_data.oldMacros[m]
        return ref
    def match(self, stateStruct):
        for macro in self.macros:
            if stateStruct.macros[macro] != self.macros[macro]:
                return False
        return True
    def checkFileDepListUpToDate(self):
        for fn,unixtime in self.filedepslist:
            if getLastChangeUnixTime(fn) > unixtime:
                return False
        return True

class FileCacheRefs(DbObj, list):
    Namespace = "file-cache-refs"

class FileCache(DbObj, MyDict):
    Namespace = "file-cache"
    @classmethod
    def FromCacheData(cls, cache_data, key):
        obj = cls()
        obj.__dict__["_key"] = key
        obj.additions = cache_data.additions
        return obj
    def apply(self, stateStruct):
        for k,l in self.additions.items():
            a = getattr(stateStruct, k)
            if isinstance(a, (list,StateListWrapper)):
                a.extend(l)
            elif isinstance(a, (dict,StateDictWrapper)):
                for dk,dv in l:
                    if dv is None:
                        a.pop(dk)
                    else:
                        a[dk] = dv
            else:
                assert False, "unknown attribute " + k + ": " + str(a)

def check_cache(stateStruct, full_filename):
    filecaches = FileCacheRefs.Load(full_filename)
    if filecaches is None: return None

    for filecacheref in filecaches:
        if not filecacheref.match(stateStruct):
            continue
        if not filecacheref.checkFileDepListUpToDate():
            FileCache.Delete(filecacheref)
            filecaches.remove(filecacheref)
            filecaches.save()
            return None
        filecache = FileCache.Load(filecacheref)
        assert filecache is not None, sha1(filecacheref) + " not found in " + FileCache.Namespace
        return filecache

    return None

def save_cache(cache_data, full_filename):
    filecaches = FileCacheRefs.Load(full_filename, create=True)
    filecacheref = FileCacheRef.FromCacheData(cache_data)
    filecaches.append(filecacheref)
    filecaches.save()
    filecache = FileCache.FromCacheData(cache_data, key=filecacheref)
    filecache.save()

# Note: This does more than State.preprocess. In case it hits a cache,
# it applies all effects up to cpre3 and ignores the preprocessing.
# Note also: This is a generator. In the cache hit case, it yields nothing.
# Otherwise, it doesn't do any further processing and it just yields the rest.
def State__cached_preprocess(stateStruct, reader, full_filename, filename):
    if not full_filename:
        # shortcut. we cannot use caching if we don't have the full filename.
        for c in generic_class_method(cparser.State.preprocess)(stateStruct, reader, full_filename, filename):
            yield c
        return

    if stateStruct._cpre3_atBaseLevel:
        try:
            cached_entry = check_cache(stateStruct, full_filename)
            if cached_entry is not None:
                cached_entry.apply(stateStruct)
                return
        except Exception as e:
            print("(Safe to ignore) Error while reading C parser cache for %s : %s" % (filename, str(e)))
            # Try to delete old references if possible. Otherwise we might always hit this.
            try: FileCacheRefs.Delete(full_filename)
            except: pass

    assert isinstance(stateStruct, StateWrapper)
    stateStruct.cache_pushLevel()
    stateStruct._filenames.add(full_filename)
    for c in generic_class_method(cparser.State.preprocess)(stateStruct, reader, full_filename, filename):
        yield c
    cache_data = stateStruct.cache_popLevel()

    save_cache(cache_data, full_filename)

class StateDictWrapper:
    def __init__(self, d, addList, addSet=None, accessSet=None):
        self._addList = addList
        self._addSet = addSet
        self._accessSet = accessSet
        self._dict = d
    def __getattr__(self, k):
        return getattr(self._dict, k)
    def __setitem__(self, k, v):
        assert v is not None
        self._dict[k] = v
        self._addList.append((k,v))
        if self._addSet is not None:
            self._addSet.add(k)
    def __getitem__(self, k):
        if self._accessSet is not None:
            assert self._addSet is not None
            if not k in self._addSet: # we only care about it if we didn't add it ourself
                self._accessSet.add(k)
        return self._dict[k]
    def __contains__(self, k): return self.has_key(k)
    def has_key(self, k):
        haskey = self._dict.__contains__(k)
        if haskey and self._accessSet is not None:
            assert self._addSet is not None
            if not k in self._addSet: # we only care about it if we didn't add it ourself
                self._accessSet.add(k)
        return haskey
    def pop(self, k):
        self._dict.pop(k)
        self._addList.append((k,None))
        if self._addSet is not None:
            self._addSet.discard(k)
    def __repr__(self): return "StateDictWrapper(" + repr(self._dict) + ")"
    def __str__(self): return "StateDictWrapper(" + str(self._dict) + ")"

class StateListWrapper:
    def __init__(self, l, addList):
        self._addList = addList
        self._list = l
    def __getattr__(self, k):
        return getattr(self._list, k)
    def __iadd__(self, l):
        self._list.extend(l)
        self._addList.extend(l)
        return self
    def append(self, v):
        self._list.append(v)
        self._addList.append(v)
    def extend(self, l):
        self._list.extend(l)
        self._addList.extend(l)
    def __repr__(self): return "StateListWrapper(" + repr(self._list) + ")"
    def __str__(self): return "StateListWrapper(" + str(self._list) + ")"

class StateWrapper:
    WrappedDicts = ("macros","typedefs","structs","unions","enums","funcs","vars","enumconsts")
    WrappedLists = ("contentlist",)
    LocalAttribs = ("_stateStruct", "_cache_stack", "_additions", "_macroAccessSet", "_macroAddSet", "_filenames", "_cpre3_atBaseLevel")
    def __init__(self, stateStruct):
        self._stateStruct = stateStruct
        self._cache_stack = []
    def __getattr__(self, k):
        if k in self.LocalAttribs: raise AttributeError # normally we shouldn't get here but just in case
        if len(self._cache_stack) > 0:
            if k in self.WrappedDicts:
                kwattr = {'d': getattr(self._stateStruct, k), 'addList': self._additions[k]}
                if k == "macros":
                    kwattr["accessSet"] = self._macroAccessSet
                    kwattr["addSet"] = self._macroAddSet
                return StateDictWrapper(**kwattr)
            if k in self.WrappedLists:
                return StateListWrapper(getattr(self._stateStruct, k), addList=self._additions[k])
        attr = getattr(self._stateStruct, k)
        if isinstance(attr, types.MethodType):
            attr = rebound_instance_method(attr, self)
        return attr
    def __repr__(self):
        return "<StateWrapper of " + repr(self._stateStruct) + ">"
    def __setattr__(self, k, v):
        if k in self.LocalAttribs:
            self.__dict__[k] = v
            return
        if k in self.WrappedLists and isinstance(v, StateListWrapper): return # ignore. probably iadd or so.
        setattr(self._stateStruct, k, v)
    def cache_pushLevel(self):
        self._additions = {} # dict/list attrib -> addition list
        for k in self.WrappedDicts + self.WrappedLists: self._additions[k] = []
        self._macroAccessSet = set()
        self._macroAddSet = set()
        self._filenames = set()
        self._cache_stack.append(
            MyDict(
                oldMacros = dict(self._stateStruct.macros),
                additions = self._additions,
                macroAccessSet = self._macroAccessSet,
                macroAddSet = self._macroAddSet,
                filenames = self._filenames
            ))
    def cache_popLevel(self):
        cache_data = self._cache_stack.pop()
        if len(self._cache_stack) == 0:
            del self._additions
            del self._macroAccessSet
            del self._macroAddSet
            del self._filenames
        else:
            # recover last
            last = self._cache_stack[-1]
            self._additions = last.additions
            self._macroAccessSet = last.macroAccessSet
            self._macroAddSet = last.macroAddSet
            self._filenames = last.filenames
            # merge with popped frame
            for k in self.WrappedDicts + self.WrappedLists:
                self._additions[k].extend(cache_data.additions[k])
            self._macroAddSet.update(cache_data.macroAddSet)
            for k in cache_data.macroAccessSet:
                if k not in self._macroAddSet:
                    self._macroAccessSet.add(k)
            self._filenames.update(cache_data.filenames)
        return cache_data
    preprocess = State__cached_preprocess
    def __getstate__(self):
        # many C structure objects refer to this as their parent.
        # when we pickle those objects, it should be safe to ignore to safe this.
        # we also don't really have any other option because we don't want to
        # dump this whole object.
        return None

def parse(filename, state = None):
    if state is None:
        state = cparser.State()
        state.autoSetupSystemMacros()

    wrappedState = StateWrapper(state)
    preprocessed = wrappedState.preprocess_file(filename, local=True)
    tokens = cparser.cpre2_parse(wrappedState, preprocessed)
    cparser.cpre3_parse(wrappedState, tokens)

    return state

def test():
    import better_exchook
    better_exchook.install()

    state = parse("/Library/Frameworks/SDL.framework/Headers/SDL.h")

    return state

if __name__ == '__main__':
    print(test())
