'''
    Onionr - P2P Anonymous Storage Network

    This file contains the OnionrBlocks class which is a class for working with Onionr blocks
'''
'''
    This program 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 <https://www.gnu.org/licenses/>.
'''

import logger, config, onionrexceptions, nacl.exceptions
import json, os, sys, datetime, base64, onionrstorage
from onionrusers import onionrusers
from onionrutils import stringvalidators, epoch
from coredb import blockmetadb
from onionrstorage import removeblock
import onionrblocks
from onionrcrypto import encryption, cryptoutils as cryptoutils, signing
class Block:
    blockCacheOrder = list() # NEVER write your own code that writes to this!
    blockCache = dict() # should never be accessed directly, look at Block.getCache()

    def __init__(self, hash = None, type = None, content = None, expire=None, decrypt=False, bypassReplayCheck=False):
        # take from arguments
        # sometimes people input a bytes object instead of str in `hash`
        if (not hash is None) and isinstance(hash, bytes):
            hash = hash.decode()

        self.hash = hash
        self.btype = type
        self.bcontent = content
        self.expire = expire
        self.bypassReplayCheck = bypassReplayCheck

        # initialize variables
        self.valid = True
        self.raw = None
        self.signed = False
        self.signature = None
        self.signedData = None
        self.blockFile = None
        self.parent = None
        self.bheader = {}
        self.bmetadata = {}
        self.isEncrypted = False
        self.decrypted = False
        self.signer = None
        self.validSig = False
        self.autoDecrypt = decrypt

        self.update()

    def decrypt(self, encodedData = True):
        '''
            Decrypt a block, loading decrypted data into their vars
        '''

        if self.decrypted:
            return True
        retData = False
        # decrypt data
        if self.getHeader('encryptType') == 'asym':
            try:
                self.bcontent = encryption.pub_key_decrypt(self.bcontent, encodedData=encodedData)
                bmeta = encryption.pub_key_decrypt(self.bmetadata, encodedData=encodedData)
                try:
                    bmeta = bmeta.decode()
                except AttributeError:
                    # yet another bytes fix
                    pass
                self.bmetadata = json.loads(bmeta)
                self.signature = encryption.pub_key_decrypt(self.signature, encodedData=encodedData)
                self.signer = encryption.pub_key_decrypt(self.signer, encodedData=encodedData)
                self.bheader['signer'] = self.signer.decode()
                self.signedData =  json.dumps(self.bmetadata) + self.bcontent.decode()

                # Check for replay attacks
                try:
                    if epoch.get_epoch() - blockmetadb.get_block_date(self.hash) > 60:
                        assert cryptoutils.replay_validator(self.bmetadata['rply'])
                except (AssertionError, KeyError, TypeError) as e:
                    if not self.bypassReplayCheck:
                        # Zero out variables to prevent reading of replays
                        self.bmetadata = {}
                        self.signer = ''
                        self.bheader['signer'] = ''
                        self.signedData = ''
                        self.signature = ''
                        raise onionrexceptions.ReplayAttack('Signature is too old. possible replay attack')
                try:
                    assert self.bmetadata['forwardEnc'] is True
                except (AssertionError, KeyError) as e:
                    pass
                else:
                    try:
                        self.bcontent = onionrusers.OnionrUser(self.signer).forwardDecrypt(self.bcontent)
                    except (onionrexceptions.DecryptionError, nacl.exceptions.CryptoError) as e:
                        #logger.error(str(e))
                        pass
            except nacl.exceptions.CryptoError:
                pass
                #logger.debug('Could not decrypt block. Either invalid key or corrupted data')
            except onionrexceptions.ReplayAttack:
                logger.warn('%s is possibly a replay attack' % (self.hash,))
            else:
                retData = True
                self.decrypted = True
        else:
            logger.warn('symmetric decryption is not yet supported by this API')
        return retData

    def verifySig(self):
        '''
            Verify if a block's signature is signed by its claimed signer
        '''

        if signing.ed_verify(data=self.signedData, key=self.signer, sig=self.signature, encodedData=True):
            self.validSig = True
        else:
            self.validSig = False
        return self.validSig


    def update(self, data = None, file = None):
        '''
            Loads data from a block in to the current object.

            Inputs:
            - data (str):
              - if None: will load from file by hash
              - else: will load from `data` string
            - file (str):
              - if None: will load from file specified in this parameter
              - else: will load from wherever block is stored by hash

            Outputs:
            - (bool): indicates whether or not the operation was successful
        '''
        try:
            # import from string
            blockdata = data

            # import from file
            if blockdata is None:
                try:
                    blockdata = onionrstorage.getData(self.getHash()).decode()
                except AttributeError:
                    raise onionrexceptions.NoDataAvailable('Block does not exist')
            else:
                self.blockFile = None
            # parse block
            self.raw = str(blockdata)
            self.bheader = json.loads(self.getRaw()[:self.getRaw().index('\n')])
            self.bcontent = self.getRaw()[self.getRaw().index('\n') + 1:]
            if ('encryptType' in self.bheader) and (self.bheader['encryptType'] in ('asym', 'sym')):
                self.bmetadata = self.getHeader('meta', None)
                self.isEncrypted = True
            else:
                self.bmetadata = json.loads(self.getHeader('meta', None))
            self.parent = self.getMetadata('parent', None)
            self.btype = self.getMetadata('type', None)
            self.signed = ('sig' in self.getHeader() and self.getHeader('sig') != '')
            # TODO: detect if signer is hash of pubkey or not
            self.signer = self.getHeader('signer', None)
            self.signature = self.getHeader('sig', None)
            # signed data is jsonMeta + block content (no linebreak)
            self.signedData = (None if not self.isSigned() else self.getHeader('meta') + self.getContent())
            self.date = blockmetadb.get_block_date(self.getHash())
            self.claimedTime = self.getHeader('time', None)

            if not self.getDate() is None:
                self.date = datetime.datetime.fromtimestamp(self.getDate())

            self.valid = True

            if len(self.getRaw()) <= config.get('allocations.blockCache', 500000):
                self.cache()
            
            if self.autoDecrypt:
                self.decrypt()

            return True
        except Exception as e:
            logger.warn('Failed to parse block %s.' % self.getHash(), error = e, timestamp = False)

            # if block can't be parsed, it's a waste of precious space. Throw it away.
            if not self.delete():
                logger.warn('Failed to delete invalid block %s.' % self.getHash(), error = e)
            else:
                logger.debug('Deleted invalid block %s.' % self.getHash(), timestamp = False)

        self.valid = False
        return False

    def delete(self):
        '''
            Deletes the block's file and records, if they exist

            Outputs:
            - (bool): whether or not the operation was successful
        '''

        if self.exists():
            try:
                os.remove(self.getBlockFile())
            except TypeError:
                pass
            
            removeblock.remove_block(self.getHash())
            return True
        return False

    def save(self, sign = False, recreate = True):
        '''
            Saves a block to file and imports it into Onionr

            Inputs:
            - sign (bool): whether or not to sign the block before saving
            - recreate (bool): if the block already exists, whether or not to recreate the block and save under a new hash

            Outputs:
            - (bool): whether or not the operation was successful
        '''

        try:
            if self.isValid() is True:

                self.hash = onionrblocks.insert(self.getRaw(), header = self.getType(), sign = sign, meta = self.getMetadata(), expire = self.getExpire())
                if self.hash != False:
                    self.update()

                return self.getHash()
            else:
                logger.warn('Not writing block; it is invalid.')
        except Exception as e:
            logger.error('Failed to save block.', error = e, timestamp = False)

        return False

    # getters

    def getExpire(self):
        '''
            Returns the expire time for a block

            Outputs:
            - (int): the expire time for a block, or None
        '''
        return self.expire

    def getHash(self):
        '''
            Returns the hash of the block if saved to file

            Outputs:
            - (str): the hash of the block, or None
        '''

        return self.hash

    def getType(self):
        '''
            Returns the type of the block

            Outputs:
            - (str): the type of the block
        '''
        return self.btype

    def getRaw(self):
        '''
            Returns the raw contents of the block, if saved to file

            Outputs:
            - (str): the raw contents of the block, or None
        '''

        return str(self.raw)

    def getHeader(self, key = None, default = None):
        '''
            Returns the header information

            Inputs:
            - key (str): only returns the value of the key in the header

            Outputs:
            - (dict/str): either the whole header as a dict, or one value
        '''

        if not key is None:
            if key in self.getHeader():
                return self.getHeader()[key]
            return default
        return self.bheader

    def getMetadata(self, key = None, default = None):
        '''
            Returns the metadata information

            Inputs:
            - key (str): only returns the value of the key in the metadata

            Outputs:
            - (dict/str): either the whole metadata as a dict, or one value
        '''

        if not key is None:
            if key in self.getMetadata():
                return self.getMetadata()[key]
            return default
        return self.bmetadata

    def getContent(self):
        '''
            Returns the contents of the block

            Outputs:
            - (str): the contents of the block
        '''

        return str(self.bcontent)

    def getParent(self):
        '''
            Returns the Block's parent Block, or None

            Outputs:
            - (Block): the Block's parent
        '''

        if type(self.parent) == str:
            if self.parent == self.getHash():
                self.parent = self
            elif Block.exists(self.parent):
                self.parent = Block(self.getMetadata('parent'))
            else:
                self.parent = None

        return self.parent

    def getDate(self):
        '''
            Returns the date that the block was received, if loaded from file

            Outputs:
            - (datetime): the date that the block was received
        '''

        return self.date

    def getBlockFile(self):
        '''
            Returns the location of the block file if it is saved

            Outputs:
            - (str): the location of the block file, or None
        '''

        return self.blockFile

    def isValid(self):
        '''
            Checks if the block is valid

            Outputs:
            - (bool): whether or not the block is valid
        '''

        return self.valid

    def isSigned(self):
        '''
            Checks if the block was signed

            Outputs:
            - (bool): whether or not the block is signed
        '''

        return self.signed

    def getSignature(self):
        '''
            Returns the base64-encoded signature

            Outputs:
            - (str): the signature, or None
        '''

        return self.signature

    def getSignedData(self):
        '''
            Returns the data that was signed

            Outputs:
            - (str): the data that was signed, or None
        '''

        return self.signedData

    def isSigner(self, signer, encodedData = True):
        '''
            Checks if the block was signed by the signer inputted

            Inputs:
            - signer (str): the public key of the signer to check against
            - encodedData (bool): whether or not the `signer` argument is base64 encoded

            Outputs:
            - (bool): whether or not the signer of the block is the signer inputted
        '''

        try:
            if (not self.isSigned()) or (not stringvalidators.validate_pub_key(signer)):
                return False

            return bool(signing.ed_verify(self.getSignedData(), signer, self.getSignature(), encodedData = encodedData))
        except:
            return False

    # setters

    def setType(self, btype):
        '''
            Sets the type of the block

            Inputs:
            - btype (str): the type of block to be set to

            Outputs:
            - (Block): the Block instance
        '''

        self.btype = btype
        return self

    def setMetadata(self, key, val):
        '''
            Sets a custom metadata value

            Metadata should not store block-specific data structures.

            Inputs:
            - key (str): the key
            - val: the value (type is irrelevant)

            Outputs:
            - (Block): the Block instance
        '''

        if key == 'parent' and (not val is None) and (not val == self.getParent().getHash()):
            self.setParent(val)
        else:
            self.bmetadata[key] = val
        return self

    def setContent(self, bcontent):
        '''
            Sets the contents of the block

            Inputs:
            - bcontent (str): the contents to be set to

            Outputs:
            - (Block): the Block instance
        '''

        self.bcontent = str(bcontent)
        return self

    def setParent(self, parent):
        '''
            Sets the Block's parent

            Inputs:
            - parent (Block/str): the Block's parent, to be stored in metadata

            Outputs:
            - (Block): the Block instance
        '''

        if type(parent) == str:
            parent = Block(parent)

        self.parent = parent
        self.setMetadata('parent', (None if parent is None else self.getParent().getHash()))
        return self

    # static functions

    def getBlocks(type = None, signer = None, signed = None, parent = None, reverse = False, limit = None):
        '''
            Returns a list of Block objects based on supplied filters

            Inputs:
            - type (str): filters by block type
            - signer (str/list): filters by signer (one in the list has to be a signer)
            - signed (bool): filters out by whether or not the block is signed
            - reverse (bool): reverses the list if True

            Outputs:
            - (list): a list of Block objects that match the input
        '''

        try:

            if (not parent is None) and (not isinstance(parent, Block)):
                parent = Block(hash = parent)

            relevant_blocks = list()
            blocks = (blockmetadb.get_block_list() if type is None else blockmetadb.get_blocks_by_type(type))

            for block in blocks:
                if Block.exists(block):
                    block = Block(block)

                    relevant = True

                    if (not signed is None) and (block.isSigned() != bool(signed)):
                        relevant = False
                    if not signer is None:
                        if isinstance(signer, (str,)):
                            signer = [signer]
                        if isinstance(signer, (bytes,)):
                            signer = [signer.decode()]

                        isSigner = False
                        for key in signer:
                            if block.isSigner(key):
                                isSigner = True
                                break

                        if not isSigner:
                            relevant = False

                    if not parent is None:
                        blockParent = block.getParent()

                        if blockParent is None:
                            relevant = False
                        else:
                            relevant = parent.getHash() == blockParent.getHash()

                    if relevant and (limit is None or len(relevant_Blocks) <= int(limit)):
                        relevant_blocks.append(block)

            if bool(reverse):
                relevant_blocks.reverse()

            return relevant_blocks
        except Exception as e:
            logger.debug('Failed to get blocks.', error = e)

        return list()

    def mergeChain(child, file = None, maximumFollows = 1000):
        '''
            Follows a child Block to its root parent Block, merging content

            Inputs:
            - child (str/Block): the child Block to be followed
            - file (str/file): the file to write the content to, instead of returning it
            - maximumFollows (int): the maximum number of Blocks to follow
        '''

        maximumFollows = max(0, maximumFollows)

        # type conversions
        if type(child) == list:
            child = child[-1]
        if type(child) == str:
            child = Block(child)
        if (not file is None) and (type(file) == str):
            file = open(file, 'ab')

        # only store hashes to avoid intensive memory usage
        blocks = [child.getHash()]

        # generate a list of parent Blocks
        while True:
            # end if the maximum number of follows has been exceeded
            if len(blocks) - 1 >= maximumFollows:
                break

            block = Block(blocks[-1]).getParent()

            # end if there is no parent Block
            if block is None:
                break

            # end if the Block is pointing to a previously parsed Block
            if block.getHash() in blocks:
                break

            # end if the block is not valid
            if not block.isValid():
                break

            blocks.append(block.getHash())

        buffer = b''

        # combine block contents
        for hash in blocks:
            block = Block(hash)
            contents = block.getContent()
            contents = base64.b64decode(contents.encode())

            if file is None:
                try:
                    buffer += contents.encode()
                except AttributeError:
                    buffer += contents
            else:
                file.write(contents)
        if file is not None:
            file.close()

        return (None if not file is None else buffer)

    def exists(bHash):
        '''
            Checks if a block is saved to file or not

            Inputs:
            - hash (str/Block):
              - if (Block): check if this block is saved to file
              - if (str): check if a block by this hash is in file

            Outputs:
            - (bool): whether or not the block file exists
        '''

        # no input data? scrap it.
        if bHash is None:
            return False

        if isinstance(bHash, Block):
            bHash = bHash.getHash()
        
        ret = isinstance(onionrstorage.getData(bHash), type(None))

        return not ret

    def getCache(hash = None):
        # give a list of the hashes of the cached blocks
        if hash is None:
            return list(Block.blockCache.keys())

        # if they inputted self or a Block, convert to hash
        if type(hash) == Block:
            hash = hash.getHash()

        # just to make sure someone didn't put in a bool or something lol
        hash = str(hash)

        # if it exists, return its content
        if hash in Block.getCache():
            return Block.blockCache[hash]

        return None

    def cache(block, override = False):
        # why even bother if they're giving bad data?
        if not type(block) == Block:
            return False

        # only cache if written to file
        if block.getHash() is None:
            return False

        # if it's already cached, what are we here for?
        if block.getHash() in Block.getCache() and not override:
            return False

        # dump old cached blocks if the size exceeds the maximum
        if sys.getsizeof(Block.blockCacheOrder) >= config.get('allocations.block_cache_total', 50000000): # 50MB default cache size
            del Block.blockCache[blockCacheOrder.pop(0)]

        # cache block content
        Block.blockCache[block.getHash()] = block.getRaw()
        Block.blockCacheOrder.append(block.getHash())

        return True