import ast
import codegen
import logging
import os.path
import bb.utils, bb.data
from itertools import chain
from pysh import pyshyacc, pyshlex, sherrors
from bb.cache import MultiProcessCache


logger = logging.getLogger('BitBake.CodeParser')

try:
    import cPickle as pickle
except ImportError:
    import pickle
    logger.info('Importing cPickle failed.  Falling back to a very slow implementation.')


def check_indent(codestr):
    """If the code is indented, add a top level piece of code to 'remove' the indentation"""

    i = 0
    while codestr[i] in ["\n", "\t", " "]:
        i = i + 1

    if i == 0:
        return codestr

    if codestr[i-1] == "\t" or codestr[i-1] == " ":
        return "if 1:\n" + codestr

    return codestr


# Basically pickle, in python 2.7.3 at least, does badly with data duplication 
# upon pickling and unpickling. Combine this with duplicate objects and things
# are a mess.
#
# When the sets are originally created, python calls intern() on the set keys
# which significantly improves memory usage. Sadly the pickle/unpickle process
# doesn't call intern() on the keys and results in the same strings being duplicated
# in memory. This also means pickle will save the same string multiple times in
# the cache file.
#
# By having shell and python cacheline objects with setstate/getstate, we force
# the object creation through our own routine where we can call intern (via internSet).
#
# We also use hashable frozensets and ensure we use references to these so that
# duplicates can be removed, both in memory and in the resulting pickled data.
#
# By playing these games, the size of the cache file shrinks dramatically
# meaning faster load times and the reloaded cache files also consume much less
# memory. Smaller cache files, faster load times and lower memory usage is good.
#
# A custom getstate/setstate using tuples is actually worth 15% cachesize by
# avoiding duplication of the attribute names!

class SetCache(object):
    def __init__(self):
        self.setcache = {}

    def internSet(self, items):
        
        new = []
        for i in items:
            new.append(intern(i))
        s = frozenset(new)
        if hash(s) in self.setcache:
            return self.setcache[hash(s)]
        self.setcache[hash(s)] = s
        return s

codecache = SetCache()

class pythonCacheLine(object):
    def __init__(self, refs, execs, contains):
        self.refs = codecache.internSet(refs)
        self.execs = codecache.internSet(execs)
        self.contains = {}
        for c in contains:
            self.contains[c] = codecache.internSet(contains[c])

    def __getstate__(self):
        return (self.refs, self.execs, self.contains)

    def __setstate__(self, state):
        (refs, execs, contains) = state
        self.__init__(refs, execs, contains)
    def __hash__(self):
        l = (hash(self.refs), hash(self.execs))
        for c in sorted(self.contains.keys()):
            l = l + (c, hash(self.contains[c]))
        return hash(l)

class shellCacheLine(object):
    def __init__(self, execs):
        self.execs = codecache.internSet(execs)

    def __getstate__(self):
        return (self.execs)

    def __setstate__(self, state):
        (execs) = state
        self.__init__(execs)
    def __hash__(self):
        return hash(self.execs)

class CodeParserCache(MultiProcessCache):
    cache_file_name = "bb_codeparser.dat"
    CACHE_VERSION = 7

    def __init__(self):
        MultiProcessCache.__init__(self)
        self.pythoncache = self.cachedata[0]
        self.shellcache = self.cachedata[1]
        self.pythoncacheextras = self.cachedata_extras[0]
        self.shellcacheextras = self.cachedata_extras[1]

        # To avoid duplication in the codeparser cache, keep
        # a lookup of hashes of objects we already have
        self.pythoncachelines = {}
        self.shellcachelines = {}

    def newPythonCacheLine(self, refs, execs, contains):
        cacheline = pythonCacheLine(refs, execs, contains)
        h = hash(cacheline)
        if h in self.pythoncachelines:
            return self.pythoncachelines[h]
        self.pythoncachelines[h] = cacheline
        return cacheline

    def newShellCacheLine(self, execs):
        cacheline = shellCacheLine(execs)
        h = hash(cacheline)
        if h in self.shellcachelines:
            return self.shellcachelines[h]
        self.shellcachelines[h] = cacheline
        return cacheline

    def init_cache(self, d):
        MultiProcessCache.init_cache(self, d)

        # cachedata gets re-assigned in the parent
        self.pythoncache = self.cachedata[0]
        self.shellcache = self.cachedata[1]

    def create_cachedata(self):
        data = [{}, {}]
        return data

codeparsercache = CodeParserCache()

def parser_cache_init(d):
    codeparsercache.init_cache(d)

def parser_cache_save(d):
    codeparsercache.save_extras(d)

def parser_cache_savemerge(d):
    codeparsercache.save_merge(d)

Logger = logging.getLoggerClass()
class BufferedLogger(Logger):
    def __init__(self, name, level=0, target=None):
        Logger.__init__(self, name)
        self.setLevel(level)
        self.buffer = []
        self.target = target

    def handle(self, record):
        self.buffer.append(record)

    def flush(self):
        for record in self.buffer:
            self.target.handle(record)
        self.buffer = []

class PythonParser():
    getvars = (".getVar", ".appendVar", ".prependVar")
    containsfuncs = ("bb.utils.contains", "base_contains", "bb.utils.contains_any")
    execfuncs = ("bb.build.exec_func", "bb.build.exec_task")

    def warn(self, func, arg):
        """Warn about calls of bitbake APIs which pass a non-literal
        argument for the variable name, as we're not able to track such
        a reference.
        """

        try:
            funcstr = codegen.to_source(func)
            argstr = codegen.to_source(arg)
        except TypeError:
            self.log.debug(2, 'Failed to convert function and argument to source form')
        else:
            self.log.debug(1, self.unhandled_message % (funcstr, argstr))

    def visit_Call(self, node):
        name = self.called_node_name(node.func)
        if name and name.endswith(self.getvars) or name in self.containsfuncs:
            if isinstance(node.args[0], ast.Str):
                varname = node.args[0].s
                if name in self.containsfuncs and isinstance(node.args[1], ast.Str):
                    if varname not in self.contains:
                        self.contains[varname] = set()
                    self.contains[varname].add(node.args[1].s)
                else:                      
                    self.references.add(node.args[0].s)
            else:
                self.warn(node.func, node.args[0])
        elif name in self.execfuncs:
            if isinstance(node.args[0], ast.Str):
                self.var_execs.add(node.args[0].s)
            else:
                self.warn(node.func, node.args[0])
        elif name and isinstance(node.func, (ast.Name, ast.Attribute)):
            self.execs.add(name)

    def called_node_name(self, node):
        """Given a called node, return its original string form"""
        components = []
        while node:
            if isinstance(node, ast.Attribute):
                components.append(node.attr)
                node = node.value
            elif isinstance(node, ast.Name):
                components.append(node.id)
                return '.'.join(reversed(components))
            else:
                break

    def __init__(self, name, log):
        self.var_execs = set()
        self.contains = {}
        self.execs = set()
        self.references = set()
        self.log = BufferedLogger('BitBake.Data.PythonParser', logging.DEBUG, log)

        self.unhandled_message = "in call of %s, argument '%s' is not a string literal"
        self.unhandled_message = "while parsing %s, %s" % (name, self.unhandled_message)

    def parse_python(self, node):
        h = hash(str(node))

        if h in codeparsercache.pythoncache:
            self.references = set(codeparsercache.pythoncache[h].refs)
            self.execs = set(codeparsercache.pythoncache[h].execs)
            self.contains = {}
            for i in codeparsercache.pythoncache[h].contains:
                self.contains[i] = set(codeparsercache.pythoncache[h].contains[i])
            return

        if h in codeparsercache.pythoncacheextras:
            self.references = set(codeparsercache.pythoncacheextras[h].refs)
            self.execs = set(codeparsercache.pythoncacheextras[h].execs)
            self.contains = {}
            for i in codeparsercache.pythoncacheextras[h].contains:
                self.contains[i] = set(codeparsercache.pythoncacheextras[h].contains[i])
            return

        code = compile(check_indent(str(node)), "<string>", "exec",
                       ast.PyCF_ONLY_AST)

        for n in ast.walk(code):
            if n.__class__.__name__ == "Call":
                self.visit_Call(n)

        self.execs.update(self.var_execs)

        codeparsercache.pythoncacheextras[h] = codeparsercache.newPythonCacheLine(self.references, self.execs, self.contains)

class ShellParser():
    def __init__(self, name, log):
        self.funcdefs = set()
        self.allexecs = set()
        self.execs = set()
        self.log = BufferedLogger('BitBake.Data.%s' % name, logging.DEBUG, log)
        self.unhandled_template = "unable to handle non-literal command '%s'"
        self.unhandled_template = "while parsing %s, %s" % (name, self.unhandled_template)

    def parse_shell(self, value):
        """Parse the supplied shell code in a string, returning the external
        commands it executes.
        """

        h = hash(str(value))

        if h in codeparsercache.shellcache:
            self.execs = set(codeparsercache.shellcache[h].execs)
            return self.execs

        if h in codeparsercache.shellcacheextras:
            self.execs = set(codeparsercache.shellcacheextras[h].execs)
            return self.execs

        self._parse_shell(value)
        self.execs = set(cmd for cmd in self.allexecs if cmd not in self.funcdefs)

        codeparsercache.shellcacheextras[h] = codeparsercache.newShellCacheLine(self.execs)

        return self.execs

    def _parse_shell(self, value):
        try:
            tokens, _ = pyshyacc.parse(value, eof=True, debug=False)
        except pyshlex.NeedMore:
            raise sherrors.ShellSyntaxError("Unexpected EOF")

        for token in tokens:
            self.process_tokens(token)

    def process_tokens(self, tokens):
        """Process a supplied portion of the syntax tree as returned by
        pyshyacc.parse.
        """

        def function_definition(value):
            self.funcdefs.add(value.name)
            return [value.body], None

        def case_clause(value):
            # Element 0 of each item in the case is the list of patterns, and
            # Element 1 of each item in the case is the list of commands to be
            # executed when that pattern matches.
            words = chain(*[item[0] for item in value.items])
            cmds  = chain(*[item[1] for item in value.items])
            return cmds, words

        def if_clause(value):
            main = chain(value.cond, value.if_cmds)
            rest = value.else_cmds
            if isinstance(rest, tuple) and rest[0] == "elif":
                return chain(main, if_clause(rest[1]))
            else:
                return chain(main, rest)

        def simple_command(value):
            return None, chain(value.words, (assign[1] for assign in value.assigns))

        token_handlers = {
            "and_or": lambda x: ((x.left, x.right), None),
            "async": lambda x: ([x], None),
            "brace_group": lambda x: (x.cmds, None),
            "for_clause": lambda x: (x.cmds, x.items),
            "function_definition": function_definition,
            "if_clause": lambda x: (if_clause(x), None),
            "pipeline": lambda x: (x.commands, None),
            "redirect_list": lambda x: ([x.cmd], None),
            "subshell": lambda x: (x.cmds, None),
            "while_clause": lambda x: (chain(x.condition, x.cmds), None),
            "until_clause": lambda x: (chain(x.condition, x.cmds), None),
            "simple_command": simple_command,
            "case_clause": case_clause,
        }

        for token in tokens:
            name, value = token
            try:
                more_tokens, words = token_handlers[name](value)
            except KeyError:
                raise NotImplementedError("Unsupported token type " + name)

            if more_tokens:
                self.process_tokens(more_tokens)

            if words:
                self.process_words(words)

    def process_words(self, words):
        """Process a set of 'words' in pyshyacc parlance, which includes
        extraction of executed commands from $() blocks, as well as grabbing
        the command name argument.
        """

        words = list(words)
        for word in list(words):
            wtree = pyshlex.make_wordtree(word[1])
            for part in wtree:
                if not isinstance(part, list):
                    continue

                if part[0] in ('`', '$('):
                    command = pyshlex.wordtree_as_string(part[1:-1])
                    self._parse_shell(command)

                    if word[0] in ("cmd_name", "cmd_word"):
                        if word in words:
                            words.remove(word)

        usetoken = False
        for word in words:
            if word[0] in ("cmd_name", "cmd_word") or \
               (usetoken and word[0] == "TOKEN"):
                if "=" in word[1]:
                    usetoken = True
                    continue

                cmd = word[1]
                if cmd.startswith("$"):
                    self.log.debug(1, self.unhandled_template % cmd)
                elif cmd == "eval":
                    command = " ".join(word for _, word in words[1:])
                    self._parse_shell(command)
                else:
                    self.allexecs.add(cmd)
                break
