################################################################################
# coding: utf8
################################################################################

# Std Libs
from __future__ import with_statement

import re
import pprint
import unittest
import threading
import Queue
import os
import functools
import subprocess
import bisect
import time
import mmap

from os.path import join, normpath, dirname
from itertools import izip

################################################################################

TAGS_RE = re.compile (

    '(?P<symbol>[^\t]+)\t'
    '(?P<filename>[^\t]+)\t'
    '(?P<ex_command>.*?);"\t'
    '(?P<type>[^\t]+)'
    '(?:\t(?P<fields>.*))?'
)

SYMBOL = 0
FILENAME = 1

################################################################################

def parse_tag_lines(lines, order_by='symbol'):
    tags_lookup = {}

    for search_obj in (t for t in (TAGS_RE.search(l) for l in lines) if t):
        tag = post_process_tag(search_obj)
        tags_lookup.setdefault(tag[order_by], []).append(tag)

    return tags_lookup


def unescape_ex(ex):
    return re.sub(r"\\(\$|/|\^|\\)", r'\1', ex)

def process_ex_cmd(ex):
    return ex if ex.isdigit() else unescape_ex(ex[2:-2])

def post_process_tag(search_obj):
    tag = search_obj.groupdict()

    fields = tag.get('fields')
    if fields:
        tag.update(process_fields(fields))

    tag['ex_command'] =   process_ex_cmd(tag['ex_command'])

    return tag

def process_fields(fields):
    fields_dict = {}

    for f in fields.split('\t'):
        f = f.split(':')

        # These, if existing, are keys with no values... retarded
        for key in f[:-2]:
            fields_dict[key] = True # Essentially boolean?

        # The last two are actual key value pairs because separated by \t
        key, value =  f[-2:]
        fields_dict[key] = value

    return fields_dict


################################################################################

def resort_ctags(tag_file):
    keys = {}

    with open(tag_file) as fh:
        for l in fh:
            keys.setdefault(l.split('\t')[FILENAME], []).append(l)

    with open(tag_file + '_unsorted', 'w') as fw:
        for k in sorted(keys):
            fw.write(''.join(keys[k]))

# def resort_ctags_mmap(tag_file):
#     with open(tag_file) as read_in:
#         with open(tag_file + '_mmap', 'r+') as fh:
#             mapped = mmap.mmap(fh.fileno(), 0)

#             for l in read_in:
#                 mapped.write(l)

#             mapped.flush()
#             mapped.close()

def build_ctags(ctags_exe, tag_file):
    cmd = [ctags_exe, '-R']

    # cmd = [ctags_exe, '-R']

    # cmds = [cmd] + [cmd[:]]
    # cmds[-1].extend(['--sort=no', '-f', 'tags_unsorted'])
    # cmd = ' && '.join(subprocess.list2cmdline(c) for c in cmds)

    p = subprocess.Popen(cmd, cwd = dirname(tag_file), shell=1)
    p.wait()

    # Faster than ctags.exe again:
    resort_ctags(tag_file)

    return tag_file

################################################################################

def log_divides(f):
    f.accessed = 0
    def wrapped(self, i):
        item = f(self, i)
        f.accessed += 1
        print f.accessed, i, self.fh.tell()
        return item
    return wrapped

class TagFile(object):
    def __init__(self, p, column):
        self.p = p
        self.column = column

    # @log_divides
    def __getitem__(self, index):
        self.fh.seek(index)
        self.fh.readline()
        return self.fh.readline().split('\t')[self.column]

    def __len__(self):
        return os.stat(self.p)[6]

    def get(self, *tags):
        with open(self.p, 'r+') as fh:
            self.fh = mmap.mmap(fh.fileno(), 0)

            for tag in tags:
                b4 = bisect.bisect_left(self, tag)
                fh.seek(b4)

                for l in fh:
                    comp = cmp(l.split('\t')[self.column], tag)

                    if    comp == -1:    continue
                    elif  comp:          break

                    yield l

            self.fh.close()

    def get_tags_dict(self, *tags):
        return parse_tag_lines(self.get(*tags))

################################################################################



def parse_tag_file(tag_file):
    with open(tag_file) as tf:
        tags = parse_tag_lines(tf)

    return tags

# def get_tags_for_file(ctags_exe, a_file):
#     cmd = [ctags_exe, '-f', '-', a_file]

#     p = subprocess.Popen (
#         cmd, stdout = subprocess.PIPE, stderr = subprocess.STDOUT, shell=1 )

#     p.wait()

#     tags = parse_tag_lines(p.stdout)
#     p.stdout.close()

#     return tags

# def index_tag_file(tag_file, column=0):
#     index = {}

#     with open(tag_file, 'rb') as tags:
#         position = 0

#         for l in tags:
#             field = l.split('\t')[column]
#             if field not in index:
#                 index[field] = position

#             position += len(l)

#     return index

# def get_tags_for_field(field, tag_file, index, column=0):
#     position = index.get(field)
#     if not position: return {}

#     with open(tag_file) as fh:
#         fh.seek(position)
#         tag_lines = list(takewhile(lambda l:l.split('\t')[column] == field, fh))

#     return parse_tag_lines(tag_lines)

################################################################################

class Tag(object):
    "dot.syntatic sugar for tag dicts"
    def __init__(self, tag_dict):
        self.__dict__ = tag_dict

    def __repr__(self):
        return pprint.pformat(self.__dict__)

################################################################################

# class CTagsCache(object):
#     cache   = {}
#     pending = {}

#     def __init__(self, status=None):
#         self.Q  = Queue.Queue()
#         self.OQ = Queue.Queue()

#         self.t = threading.Thread(target=self.thread)
#         self.t.setDaemon(1)
#         self.t.start()

#         self.status=status

#     def thread(self):
#         while True:
#             path = self.Q.get()
#             column = 1 if path.endswith('unsorted') else 0

#             self.OQ.put((path, index_tag_file(path, column)))

#             self.Q.task_done()
#             if self.status: self.status(path)

#     def get(self, path):
#         if path not in self.cache:
#             if path not in self.pending:
#                 self.Q.put(path)
#                 self.pending[path] = True

#         while True:
#             try:
#                 tag_path, tag_dict = self.OQ.get_nowait()
#                 self.cache[tag_path] = tag_dict
#                 self.pending.pop(tag_path)
#                 self.OQ.task_done()

#             except Queue.Empty:
#                 break

#         return self.cache.get(path, {})

################################################################################

# - Parse an existing CTAGS file, and implement go-to-tag-under-cursor. CTAGS
# files can get quite large, so representing them efficiently should be a goal.
# Ideally, parsing should also be done in another thread, so the editor isn't
# blocked while reading in a multi-megabyte file. Getting this implemented
# nicely is a fair bit of work.

# Next step would be to automatically run exuberant ctags in the current
# directory, if there isn't a CTAGS file already, or then one that does exist is
# out of date.

# Once we're at a start where symbol definitions are in memory, there's a number
# of other things that can be done, such as listing them in the quick panel, and
# hooking them into auto-complete.

################################################################################


class CTagsTest(unittest.TestCase):
    def test_all_search_strings_work(self):
        os.chdir(os.path.dirname(__file__))
        tags = parse_tag_file('tags')

        failures = []

        for symbol, tag_list in tags.iteritems():
            for tag in (Tag(t) for t in tag_list):
                if not tag.ex_command.isdigit():
                    with open(tag.filename, 'r+') as fh:
                        mapped = mmap.mmap(fh.fileno(), 0)
                        if not mapped.find(tag.ex_command):
                            failures += [tag.ex_command]

        for f in failures:
            print f

        self.assertEqual(len(failures), 0, 'update tag files and try again')

    def test_tags_files(self):
        tags = r"tags"
        tag_file = TagFile(tags, SYMBOL)

        with open(tags, 'r') as fh:
            latest = ''
            lines  = []

            for l in fh:
                symbol = l.split('\t')[SYMBOL]

                if symbol != latest:

                    if latest:
                        tags = list(tag_file.get(latest))
                        self.assertEqual(lines, tags)

                        lines = []

                    latest = symbol

                lines += [l]

# def scribble():
    # raw_input('About to use memory')

    # import time
    # tags = 'C://python25//lib//tags'

    # t1 = time.time()
    # index = index_tag_file(tags)
    # print time.time() - t1

    # t1 = time.time()
    # print get_tags_for_field("struct_GLUnurbs", tags, index)
    # print time.time() - t1

    # raw_input('Press enter')

    # print get_tags_for_file('ctags.exe', 'ctags.py')

def scribble():
    # raw_input('About to use memory')

    import time
    tags = 'C://python25//lib//tags'

    t1 = time.time()

    a =  list(TagFile(tags, SYMBOL).get_tags_dict('Test','Tests'))

    print time.time() - t1

    print len(a)

    # raw_input('Press enter')


if __name__ == '__main__':
    if 0: scribble()
    else: unittest.main()

################################################################################
# TAG FILE FORMAT

# When not running in etags mode, each entry in the tag file consists of a
# separate line, each looking like this in the most general case:

# tag_name<TAB>file_name<TAB>ex_cmd;"<TAB>extension_fields

# The fields and separators of these lines are specified as follows:

# 1.

#     tag name

# 2.

#     single tab character

# 3.

#     name of the file in which the object associated with the tag is located

# 4.

#     single tab character

# 5.

#     EX command used to locate the tag within the file; generally a search
#     pattern (either /pattern/ or ?pattern?) or line number (see −−excmd). Tag
#     file format 2 (see −−format) extends this EX command under certain
#     circumstances to include a set of extension fields (described below)
#     embedded in an EX comment immediately appended to the EX command, which
#     leaves it backward-compatible with original vi(1) implementations.

# A few special tags are written into the tag file for internal purposes. These
# tags are composed in such a way that they always sort to the top of the file.
# Therefore, the first two characters of these tags are used a magic number to
# detect a tag file for purposes of determining whether a valid tag file is
# being overwritten rather than a source file. Note that the name of each source
# file will be recorded in the tag file exactly as it appears on the command
# line.

# Therefore, if the path you specified on the command line was relative to the
# current directory, then it will be recorded in that same manner in the tag
# file. See, however, the −−tag−relative option for how this behavior can be
# modified.

# Extension fields are tab-separated key-value pairs appended to the end of the
# EX command as a comment, as described above. These key value pairs appear in
# the general form "key:value". Their presence in the lines of the tag file are
# controlled by the −−fields option. The possible keys and the meaning of their
# values are as follows:

# access

#     Indicates the visibility of this class member, where value is specific to
#     the language.

# file

#     Indicates that the tag has file-limited visibility. This key has no
#     corresponding value.

# kind

#     Indicates the type, or kind, of tag. Its value is either one of the
#     corresponding one-letter flags described under the various −−<LANG>−kinds
#     options above, or a full name. It is permitted (and is, in fact, the
#     default) for the key portion of this field to be omitted. The optional
#     behaviors are controlled with the −−fields option.

# implementation

# When present, this indicates a limited implementation (abstract vs. concrete)
# of a routine or class, where value is specific to the language ("virtual" or
# "pure virtual" for C++; "abstract" for Java).

# inherits

#     When present, value. is a comma-separated list of classes from which this
#     class is derived (i.e. inherits from).

# signature

#     When present, value is a language-dependent representation of the
#     signature of a routine. A routine signature in its complete form specifies
#     the return type of a routine and its formal argument list. This extension
#     field is presently supported only for C-based languages and does not
#     include the return type.

# In addition, information on the scope of the tag definition may be available,
# with the key portion equal to some language-dependent construct name and its
# value the name declared for that construct in the program. This scope entry
# indicates the scope in which the tag was found. For example, a tag generated
# for a C structure member would have a scope looking like "struct:myStruct".