#!/usr/bin/env python
# Copyright (c) 2016 Comcast Cable Communications Management, LLC.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Looks for preprocessor macros with struct initializers and siphons them
# off into another file for later parsing; ostensibly to generate
# documentation from struct initializer data.

import os, sys, re, argparse, json

DEFAULT_OUTPUT = "build-root/docs/siphons"
DEFAULT_PREFIX = os.getcwd()

ap = argparse.ArgumentParser()
ap.add_argument("--output", '-o', metavar="directory", default=DEFAULT_OUTPUT,
        help="Output directory for .siphon files [%s]" % DEFAULT_OUTPUT)
ap.add_argument("--input-prefix", metavar="path", default=DEFAULT_PREFIX,
        help="Prefix to strip from input pathnames [%s]" % DEFAULT_PREFIX)
ap.add_argument("input", nargs='+', metavar="input_file",
        help="Input C source files")
args = ap.parse_args()

"""Patterns that match the start of code blocks we want to siphon"""
siphon_patterns = [
    ( re.compile("(?P<m>VLIB_CLI_COMMAND)\s*[(](?P<name>[a-zA-Z0-9_]+)(,[^)]*)?[)]"), "clicmd" ),
]

"""Matches a siphon comment block start"""
siphon_block_start = re.compile("^\s*/\*\?\s*(.*)$")

"""Matches a siphon comment block stop"""
siphon_block_stop = re.compile("^(.*)\s*\?\*/\s*$")

"""Siphon block directive delimiter"""
siphon_block_delimiter = "%%"

"""Matches a siphon block directive such as '%clicmd:group_label Debug CLI%'"""
siphon_block_directive = re.compile("(%s)\s*([a-zA-Z0-9_:]+)\s+(.*)\s*(%s)" % \
        (siphon_block_delimiter, siphon_block_delimiter))

"""Matches the start of an initializer block"""
siphon_initializer = re.compile("\s*=")

"""
count open and close braces in str
return (0, index) when braces were found and count becomes 0.
index indicates the position at which the last closing brace was
found.
return (-1, -1) if a closing brace is found before any opening one.
return (count, -1) if not all opening braces are closed, count is the
current depth
"""
def count_braces(str, count=0, found=False):
    for index in range(0, len(str)):
        if str[index] == '{':
            count += 1;
            found = True
        elif str[index] == '}':
            if count == 0:
                # means we never found an open brace
                return (-1, -1)
            count -= 1;

        if count == 0 and found:
            return (count, index)

    return (count, -1)

# Collated output for each siphon
output = {}

# Pre-process file names in case they indicate a file with
# a list of files
files = []
for filename in args.input:
    if filename.startswith('@'):
        with open(filename[1:], 'r') as fp:
            lines = fp.readlines()
            for line in lines:
                files.append(line.strip())
            lines = None
    else:
        files.append(filename)

# Iterate all the input files we've been given
for filename in files:
    # Strip the current directory off the start of the
    # filename for brevity
    if filename[0:len(args.input_prefix)] == args.input_prefix:
        filename = filename[len(args.input_prefix):]
        if filename[0] == "/":
            filename = filename[1:]

    # Work out the abbreviated directory name
    directory = os.path.dirname(filename)
    if directory[0:2] == "./":
        directory = directory[2:]
    elif directory[0:len(args.input_prefix)] == args.input_prefix:
        directory = directory[len(args.input_prefix):]
    if directory[0] == "/":
    	directory = directory[1:]

    # Open the file and explore its contents...
    sys.stderr.write("Siphoning from %s...\n" % filename)
    directives = {}
    with open(filename) as fd:
        siphon = None
        close_siphon = None
        siphon_block = ""
        in_block = False
        line_num = 0
        siphon_line = 0

        for line in fd:
            line_num += 1
            str = line[:-1] # filter \n

            """See if there is a block directive and if so extract it"""
            def process_block_directive(str, directives):
                m = siphon_block_directive.search(str)
                if m is not None:
                    k = m.group(2)
                    v = m.group(3).strip()
                    directives[k] = v
                    # Return only the parts we did not match
                    return str[0:m.start(1)] + str[m.end(4):]

                return str

            def process_block_prefix(str):
                if str.startswith(" * "):
                    str = str[3:]
                elif str == " *":
                    str = ""
                return str
                
            if not in_block:
                # See if the line contains the start of a siphon doc block
                m = siphon_block_start.search(str)
                if m is not None:
                    in_block = True
                    t = m.group(1)

                    # Now check if the block closes on the same line
                    m = siphon_block_stop.search(t)
                    if m is not None:
                        t = m.group(1)
                        in_block = False

                    # Check for directives
                    t = process_block_directive(t, directives)

                    # Filter for normal comment prefixes
                    t = process_block_prefix(t)

                    # Add what is left
                    siphon_block += t

                    # Skip to next line
                    continue

            else:
                # Check to see if we have an end block marker
                m = siphon_block_stop.search(str)
                if m is not None:
                    in_block = False
                    t = m.group(1)
                else:
                    t = str

                # Check for directives
                t = process_block_directive(t, directives)

                # Filter for normal comment prefixes
                t = process_block_prefix(t)

                # Add what is left
                siphon_block += t + "\n"

                # Skip to next line
                continue


            if siphon is None:
                # Look for blocks we need to siphon
                for p in siphon_patterns:
                    if p[0].match(str):
                        siphon = [ p[1], str + "\n", 0 ]
                        siphon_line = line_num

                        # see if we have an initializer
                        m = siphon_initializer.search(str)
                        if m is not None:
                            # count the braces on this line
                            (count, index) = count_braces(str[m.start():])
                            siphon[2] = count
                            # TODO - it's possible we have the initializer all on the first line
                            # we should check for it, but also account for the possibility that
                            # the open brace is on the next line
                            #if count == 0:
                            #    # braces balanced
                            #    close_siphon = siphon
                            #    siphon = None
                        else:
                            # no initializer: close the siphon right now
                            close_siphon = siphon
                            siphon = None
            else:
                # See if we should end the siphon here - do we have balanced
                # braces?
                (count, index) = count_braces(str, count=siphon[2], found=True)
                if count == 0:
                    # braces balanced - add the substring and close the siphon
                    siphon[1] += str[:index+1] + ";\n"
                    close_siphon = siphon
                    siphon = None
                else:
                    # add the whole string, move on
                    siphon[2] = count
                    siphon[1] += str + "\n"

            if close_siphon is not None:
                # Write the siphoned contents to the right place
                siphon_name = close_siphon[0]
                if siphon_name not in output:
                    output[siphon_name] = {
                        "global": {},
                        "items": [],
                        "file": "%s/%s.siphon" % (args.output, close_siphon[0])
                    }

                # Copy directives for the file
                details = {}
                for key in directives:
                    if ":" in key:
                        (sn, label) = key.split(":")
                        if sn == siphon_name:
                            details[label] = directives[key]
                    else:
                        details[key] = directives[key]

                # Copy details for this block
                details['file'] = filename
                details['line_start'] = siphon_line
                details['line_end'] = line_num
                details['siphon_block'] = siphon_block.strip()

                # Some defaults
                if "group" not in details:
                    if "group_label" in details:
                        # use the filename since group labels are mostly of file scope
                        details['group'] = details['file']
                    else:
			details['group'] = directory

                if "group_label" not in details:
                    details['group_label'] = details['group']

                details["block"] = close_siphon[1]

                # Store the item
                output[siphon_name]['items'].append(details)

                # All done
                close_siphon = None
                siphon_block = ""

        # Update globals
        for key in directives.keys():
            if ':' not in key:
                continue

            if filename.endswith("/dir.dox"):
                # very special! use the parent directory name
                l = directory
            else:
                l = filename

            (sn, label) = key.split(":")

            if sn not in output:
                output[sn] = {}
            if 'global' not in output[sn]:
                output[sn]['global'] = {}
            if l not in output[sn]['global']:
                output[sn]['global'][l] = {}
            if 'file' not in output[sn]:
                output[sn]['file'] = "%s/%s.siphon" % (args.output, sn)
            if 'items' not in output[sn]:
                output[sn]['items'] = []

            output[sn]['global'][l][label] = directives[key]


# Write out the data
for siphon in output.keys():
    sys.stderr.write("Saving siphon %s...\n" % siphon)
    s = output[siphon]
    with open(s['file'], "a") as fp:
        json.dump(s, fp, separators=(',', ': '), indent=4, sort_keys=True)

# All done