#!/usr/bin/env python
#
#===- exploded-graph-rewriter.py - ExplodedGraph dump tool -----*- python -*--#
#
# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#
#===-----------------------------------------------------------------------===#


from __future__ import print_function

import argparse
import collections
import difflib
import json
import logging
import os
import re


#===-----------------------------------------------------------------------===#
# These data structures represent a deserialized ExplodedGraph.
#===-----------------------------------------------------------------------===#


# A helper function for finding the difference between two dictionaries.
def diff_dicts(curr, prev):
    removed = [k for k in prev if k not in curr or curr[k] != prev[k]]
    added = [k for k in curr if k not in prev or curr[k] != prev[k]]
    return (removed, added)


# Represents any program state trait that is a dictionary of key-value pairs.
class GenericMap(object):
    def __init__(self, items):
        self.generic_map = collections.OrderedDict(items)

    def diff(self, prev):
        return diff_dicts(self.generic_map, prev.generic_map)

    def is_different(self, prev):
        removed, added = self.diff(prev)
        return len(removed) != 0 or len(added) != 0


# A deserialized source location.
class SourceLocation(object):
    def __init__(self, json_loc):
        super(SourceLocation, self).__init__()
        logging.debug('json: %s' % json_loc)
        self.line = json_loc['line']
        self.col = json_loc['column']
        self.filename = os.path.basename(json_loc['file']) \
            if 'file' in json_loc else '(main file)'
        self.spelling = SourceLocation(json_loc['spelling']) \
            if 'spelling' in json_loc else None

    def is_macro(self):
        return self.spelling is not None


# A deserialized program point.
class ProgramPoint(object):
    def __init__(self, json_pp):
        super(ProgramPoint, self).__init__()
        self.kind = json_pp['kind']
        self.tag = json_pp['tag']
        if self.kind == 'Edge':
            self.src_id = json_pp['src_id']
            self.dst_id = json_pp['dst_id']
        elif self.kind == 'Statement':
            logging.debug(json_pp)
            self.stmt_kind = json_pp['stmt_kind']
            self.cast_kind = json_pp['cast_kind'] \
                if 'cast_kind' in json_pp else None
            self.stmt_point_kind = json_pp['stmt_point_kind']
            self.stmt_id = json_pp['stmt_id']
            self.pointer = json_pp['pointer']
            self.pretty = json_pp['pretty']
            self.loc = SourceLocation(json_pp['location']) \
                if json_pp['location'] is not None else None
        elif self.kind == 'BlockEntrance':
            self.block_id = json_pp['block_id']


# A single expression acting as a key in a deserialized Environment.
class EnvironmentBindingKey(object):
    def __init__(self, json_ek):
        super(EnvironmentBindingKey, self).__init__()
        # CXXCtorInitializer is not a Stmt!
        self.stmt_id = json_ek['stmt_id'] if 'stmt_id' in json_ek \
            else json_ek['init_id']
        self.pretty = json_ek['pretty']
        self.kind = json_ek['kind'] if 'kind' in json_ek else None

    def _key(self):
        return self.stmt_id

    def __eq__(self, other):
        return self._key() == other._key()

    def __hash__(self):
        return hash(self._key())


# Deserialized description of a location context.
class LocationContext(object):
    def __init__(self, json_frame):
        super(LocationContext, self).__init__()
        self.lctx_id = json_frame['lctx_id']
        self.caption = json_frame['location_context']
        self.decl = json_frame['calling']
        self.loc = SourceLocation(json_frame['location']) \
            if json_frame['location'] is not None else None

    def _key(self):
        return self.lctx_id

    def __eq__(self, other):
        return self._key() == other._key()

    def __hash__(self):
        return hash(self._key())


# A group of deserialized Environment bindings that correspond to a specific
# location context.
class EnvironmentFrame(object):
    def __init__(self, json_frame):
        super(EnvironmentFrame, self).__init__()
        self.location_context = LocationContext(json_frame)
        self.bindings = collections.OrderedDict(
            [(EnvironmentBindingKey(b),
              b['value']) for b in json_frame['items']]
            if json_frame['items'] is not None else [])

    def diff_bindings(self, prev):
        return diff_dicts(self.bindings, prev.bindings)

    def is_different(self, prev):
        removed, added = self.diff_bindings(prev)
        return len(removed) != 0 or len(added) != 0


# A deserialized Environment. This class can also hold other entities that
# are similar to Environment, such as Objects Under Construction.
class GenericEnvironment(object):
    def __init__(self, json_e):
        super(GenericEnvironment, self).__init__()
        self.frames = [EnvironmentFrame(f) for f in json_e]

    def diff_frames(self, prev):
        # TODO: It's difficult to display a good diff when frame numbers shift.
        if len(self.frames) != len(prev.frames):
            return None

        updated = []
        for i in range(len(self.frames)):
            f = self.frames[i]
            prev_f = prev.frames[i]
            if f.location_context == prev_f.location_context:
                if f.is_different(prev_f):
                    updated.append(i)
            else:
                # We have the whole frame replaced with another frame.
                # TODO: Produce a nice diff.
                return None

        # TODO: Add support for added/removed.
        return updated

    def is_different(self, prev):
        updated = self.diff_frames(prev)
        return updated is None or len(updated) > 0


# A single binding key in a deserialized RegionStore cluster.
class StoreBindingKey(object):
    def __init__(self, json_sk):
        super(StoreBindingKey, self).__init__()
        self.kind = json_sk['kind']
        self.offset = json_sk['offset']

    def _key(self):
        return (self.kind, self.offset)

    def __eq__(self, other):
        return self._key() == other._key()

    def __hash__(self):
        return hash(self._key())


# A single cluster of the deserialized RegionStore.
class StoreCluster(object):
    def __init__(self, json_sc):
        super(StoreCluster, self).__init__()
        self.base_region = json_sc['cluster']
        self.bindings = collections.OrderedDict(
            [(StoreBindingKey(b), b['value']) for b in json_sc['items']])

    def diff_bindings(self, prev):
        return diff_dicts(self.bindings, prev.bindings)

    def is_different(self, prev):
        removed, added = self.diff_bindings(prev)
        return len(removed) != 0 or len(added) != 0


# A deserialized RegionStore.
class Store(object):
    def __init__(self, json_s):
        super(Store, self).__init__()
        self.ptr = json_s['pointer']
        self.clusters = collections.OrderedDict(
            [(c['pointer'], StoreCluster(c)) for c in json_s['items']])

    def diff_clusters(self, prev):
        removed = [k for k in prev.clusters if k not in self.clusters]
        added = [k for k in self.clusters if k not in prev.clusters]
        updated = [k for k in prev.clusters if k in self.clusters
                   and prev.clusters[k].is_different(self.clusters[k])]
        return (removed, added, updated)

    def is_different(self, prev):
        removed, added, updated = self.diff_clusters(prev)
        return len(removed) != 0 or len(added) != 0 or len(updated) != 0


# Deserialized messages from a single checker in a single program state.
# Basically a list of raw strings.
class CheckerLines(object):
    def __init__(self, json_lines):
        super(CheckerLines, self).__init__()
        self.lines = json_lines

    def diff_lines(self, prev):
        lines = difflib.ndiff(prev.lines, self.lines)
        return [l.strip() for l in lines
                if l.startswith('+') or l.startswith('-')]

    def is_different(self, prev):
        return len(self.diff_lines(prev)) > 0


# Deserialized messages of all checkers, separated by checker.
class CheckerMessages(object):
    def __init__(self, json_m):
        super(CheckerMessages, self).__init__()
        self.items = collections.OrderedDict(
            [(m['checker'], CheckerLines(m['messages'])) for m in json_m])

    def diff_messages(self, prev):
        removed = [k for k in prev.items if k not in self.items]
        added = [k for k in self.items if k not in prev.items]
        updated = [k for k in prev.items if k in self.items
                   and prev.items[k].is_different(self.items[k])]
        return (removed, added, updated)

    def is_different(self, prev):
        removed, added, updated = self.diff_messages(prev)
        return len(removed) != 0 or len(added) != 0 or len(updated) != 0


# A deserialized program state.
class ProgramState(object):
    def __init__(self, state_id, json_ps):
        super(ProgramState, self).__init__()
        logging.debug('Adding ProgramState ' + str(state_id))

        self.state_id = state_id

        self.store = Store(json_ps['store']) \
            if json_ps['store'] is not None else None

        self.environment = \
            GenericEnvironment(json_ps['environment']['items']) \
            if json_ps['environment'] is not None else None

        self.constraints = GenericMap([
            (c['symbol'], c['range']) for c in json_ps['constraints']
        ]) if json_ps['constraints'] is not None else None

        self.dynamic_types = GenericMap([
                (t['region'], '%s%s' % (t['dyn_type'],
                                        ' (or a sub-class)'
                                        if t['sub_classable'] else ''))
                for t in json_ps['dynamic_types']]) \
            if json_ps['dynamic_types'] is not None else None

        self.constructing_objects = \
            GenericEnvironment(json_ps['constructing_objects']) \
            if json_ps['constructing_objects'] is not None else None

        self.checker_messages = CheckerMessages(json_ps['checker_messages']) \
            if json_ps['checker_messages'] is not None else None


# A deserialized exploded graph node. Has a default constructor because it
# may be referenced as part of an edge before its contents are deserialized,
# and in this moment we already need a room for predecessors and successors.
class ExplodedNode(object):
    def __init__(self):
        super(ExplodedNode, self).__init__()
        self.predecessors = []
        self.successors = []

    def construct(self, node_id, json_node):
        logging.debug('Adding ' + node_id)
        self.node_id = json_node['node_id']
        self.ptr = json_node['pointer']
        self.has_report = json_node['has_report']
        self.is_sink = json_node['is_sink']
        self.points = [ProgramPoint(p) for p in json_node['program_points']]
        self.state = ProgramState(json_node['state_id'],
                                  json_node['program_state']) \
            if json_node['program_state'] is not None else None

        assert self.node_name() == node_id

    def node_name(self):
        return 'Node' + self.ptr


# A deserialized ExplodedGraph. Constructed by consuming a .dot file
# line-by-line.
class ExplodedGraph(object):
    # Parse .dot files with regular expressions.
    node_re = re.compile(
        '^(Node0x[0-9a-f]*) \\[shape=record,.*label="{(.*)\\\\l}"\\];$')
    edge_re = re.compile(
        '^(Node0x[0-9a-f]*) -> (Node0x[0-9a-f]*);$')

    def __init__(self):
        super(ExplodedGraph, self).__init__()
        self.nodes = collections.defaultdict(ExplodedNode)
        self.root_id = None
        self.incomplete_line = ''

    def add_raw_line(self, raw_line):
        if raw_line.startswith('//'):
            return

        # Allow line breaks by waiting for ';'. This is not valid in
        # a .dot file, but it is useful for writing tests.
        if len(raw_line) > 0 and raw_line[-1] != ';':
            self.incomplete_line += raw_line
            return
        raw_line = self.incomplete_line + raw_line
        self.incomplete_line = ''

        # Apply regexps one by one to see if it's a node or an edge
        # and extract contents if necessary.
        logging.debug('Line: ' + raw_line)
        result = self.edge_re.match(raw_line)
        if result is not None:
            logging.debug('Classified as edge line.')
            pred = result.group(1)
            succ = result.group(2)
            self.nodes[pred].successors.append(succ)
            self.nodes[succ].predecessors.append(pred)
            return
        result = self.node_re.match(raw_line)
        if result is not None:
            logging.debug('Classified as node line.')
            node_id = result.group(1)
            if len(self.nodes) == 0:
                self.root_id = node_id
            # Note: when writing tests you don't need to escape everything,
            # even though in a valid dot file everything is escaped.
            node_label = result.group(2).replace('\\l', '') \
                                        .replace('&nbsp;', '') \
                                        .replace('\\"', '"') \
                                        .replace('\\{', '{') \
                                        .replace('\\}', '}') \
                                        .replace('\\\\', '\\') \
                                        .replace('\\|', '|') \
                                        .replace('\\<', '\\\\<') \
                                        .replace('\\>', '\\\\>') \
                                        .rstrip(',')
            logging.debug(node_label)
            json_node = json.loads(node_label)
            self.nodes[node_id].construct(node_id, json_node)
            return
        logging.debug('Skipping.')


#===-----------------------------------------------------------------------===#
# Visitors traverse a deserialized ExplodedGraph and do different things
# with every node and edge.
#===-----------------------------------------------------------------------===#


# A visitor that dumps the ExplodedGraph into a DOT file with fancy HTML-based
# syntax highlighing.
class DotDumpVisitor(object):
    def __init__(self, do_diffs, dark_mode, gray_mode,
                 topo_mode, dump_dot_only):
        super(DotDumpVisitor, self).__init__()
        self._do_diffs = do_diffs
        self._dark_mode = dark_mode
        self._gray_mode = gray_mode
        self._topo_mode = topo_mode
        self._dump_dot_only = dump_dot_only
        self._output = []

    def _dump_raw(self, s):
        if self._dump_dot_only:
            print(s, end='')
        else:
            self._output.append(s)

    def output(self):
        assert not self._dump_dot_only
        return ''.join(self._output)

    def _dump(self, s):
        s = s.replace('&', '&amp;') \
             .replace('{', '\\{') \
             .replace('}', '\\}') \
             .replace('\\<', '&lt;') \
             .replace('\\>', '&gt;') \
             .replace('\\l', '<br />') \
             .replace('|', '\\|')
        if self._gray_mode:
            s = re.sub(r'<font color="[a-z0-9]*">', '', s)
            s = re.sub(r'</font>', '', s)
        self._dump_raw(s)

    @staticmethod
    def _diff_plus_minus(is_added):
        if is_added is None:
            return ''
        if is_added:
            return '<font color="forestgreen">+</font>'
        return '<font color="red">-</font>'

    @staticmethod
    def _short_pretty(s):
        if s is None:
            return None
        if len(s) < 20:
            return s
        left = s.find('{')
        right = s.rfind('}')
        if left == -1 or right == -1 or left >= right:
            return s
        candidate = s[0:left + 1] + ' ... ' + s[right:]
        if len(candidate) >= len(s):
            return s
        return candidate

    @staticmethod
    def _make_sloc(loc):
        if loc is None:
            return '<i>Invalid Source Location</i>'

        def make_plain_loc(loc):
            return '%s:<b>%s</b>:<b>%s</b>' \
                % (loc.filename, loc.line, loc.col)

        if loc.is_macro():
            return '%s <font color="royalblue1">' \
                   '(<i>spelling at </i> %s)</font>' \
                % (make_plain_loc(loc), make_plain_loc(loc.spelling))

        return make_plain_loc(loc)

    def visit_begin_graph(self, graph):
        self._graph = graph
        self._dump_raw('digraph "ExplodedGraph" {\n')
        if self._dark_mode:
            self._dump_raw('bgcolor="gray10";\n')
        self._dump_raw('label="";\n')

    def visit_program_point(self, p):
        if p.kind in ['Edge', 'BlockEntrance', 'BlockExit']:
            color = 'gold3'
        elif p.kind in ['PreStmtPurgeDeadSymbols',
                        'PostStmtPurgeDeadSymbols']:
            color = 'red'
        elif p.kind in ['CallEnter', 'CallExitBegin', 'CallExitEnd']:
            color = 'dodgerblue' if self._dark_mode else 'blue'
        elif p.kind in ['Statement']:
            color = 'cyan4'
        else:
            color = 'forestgreen'

        if p.kind == 'Statement':
            # This avoids pretty-printing huge statements such as CompoundStmt.
            # Such statements show up only at [Pre|Post]StmtPurgeDeadSymbols
            skip_pretty = 'PurgeDeadSymbols' in p.stmt_point_kind
            stmt_color = 'cyan3'
            self._dump('<tr><td align="left" width="0">%s:</td>'
                       '<td align="left" width="0"><font color="%s">'
                       '%s</font> </td>'
                       '<td align="left"><i>S%s</i></td>'
                       '<td align="left"><font color="%s">%s</font></td>'
                       '<td align="left">%s</td></tr>'
                       % (self._make_sloc(p.loc), color,
                          '%s (%s)' % (p.stmt_kind, p.cast_kind)
                          if p.cast_kind is not None else p.stmt_kind,
                          p.stmt_id, stmt_color, p.stmt_point_kind,
                          self._short_pretty(p.pretty)
                          if not skip_pretty else ''))
        elif p.kind == 'Edge':
            self._dump('<tr><td width="0"></td>'
                       '<td align="left" width="0">'
                       '<font color="%s">%s</font></td><td align="left">'
                       '[B%d] -\\> [B%d]</td></tr>'
                       % (color, 'BlockEdge', p.src_id, p.dst_id))
        elif p.kind == 'BlockEntrance':
            self._dump('<tr><td width="0"></td>'
                       '<td align="left" width="0">'
                       '<font color="%s">%s</font></td>'
                       '<td align="left">[B%d]</td></tr>'
                       % (color, p.kind, p.block_id))
        else:
            # TODO: Print more stuff for other kinds of points.
            self._dump('<tr><td width="0"></td>'
                       '<td align="left" width="0" colspan="2">'
                       '<font color="%s">%s</font></td></tr>'
                       % (color, p.kind))

        if p.tag is not None:
            self._dump('<tr><td width="0"></td>'
                       '<td colspan="3" align="left">'
                       '<b>Tag: </b> <font color="crimson">'
                       '%s</font></td></tr>' % p.tag)

    def visit_environment(self, e, prev_e=None):
        self._dump('<table border="0">')

        def dump_location_context(lc, is_added=None):
            self._dump('<tr><td>%s</td>'
                       '<td align="left"><b>%s</b></td>'
                       '<td align="left" colspan="2">'
                       '<font color="gray60">%s </font>'
                       '%s</td></tr>'
                       % (self._diff_plus_minus(is_added),
                          lc.caption, lc.decl,
                          ('(%s)' % self._make_sloc(lc.loc))
                          if lc.loc is not None else ''))

        def dump_binding(f, b, is_added=None):
            self._dump('<tr><td>%s</td>'
                       '<td align="left"><i>S%s</i></td>'
                       '%s'
                       '<td align="left">%s</td>'
                       '<td align="left">%s</td></tr>'
                       % (self._diff_plus_minus(is_added),
                          b.stmt_id,
                          '<td align="left"><font color="%s"><i>'
                          '%s</i></font></td>' % (
                              'lavender' if self._dark_mode else 'darkgreen',
                              ('(%s)' % b.kind) if b.kind is not None else ' '
                          ),
                          self._short_pretty(b.pretty), f.bindings[b]))

        frames_updated = e.diff_frames(prev_e) if prev_e is not None else None
        if frames_updated:
            for i in frames_updated:
                f = e.frames[i]
                prev_f = prev_e.frames[i]
                dump_location_context(f.location_context)
                bindings_removed, bindings_added = f.diff_bindings(prev_f)
                for b in bindings_removed:
                    dump_binding(prev_f, b, False)
                for b in bindings_added:
                    dump_binding(f, b, True)
        else:
            for f in e.frames:
                dump_location_context(f.location_context)
                for b in f.bindings:
                    dump_binding(f, b)

        self._dump('</table>')

    def visit_environment_in_state(self, selector, title, s, prev_s=None):
        e = getattr(s, selector)
        prev_e = getattr(prev_s, selector) if prev_s is not None else None
        if e is None and prev_e is None:
            return

        self._dump('<hr /><tr><td align="left"><b>%s: </b>' % title)
        if e is None:
            self._dump('<i> Nothing!</i>')
        else:
            if prev_e is not None:
                if e.is_different(prev_e):
                    self._dump('</td></tr><tr><td align="left">')
                    self.visit_environment(e, prev_e)
                else:
                    self._dump('<i> No changes!</i>')
            else:
                self._dump('</td></tr><tr><td align="left">')
                self.visit_environment(e)

        self._dump('</td></tr>')

    def visit_store(self, s, prev_s=None):
        self._dump('<table border="0">')

        def dump_binding(s, c, b, is_added=None):
            self._dump('<tr><td>%s</td>'
                       '<td align="left">%s</td>'
                       '<td align="left">%s</td>'
                       '<td align="left">%s</td>'
                       '<td align="left">%s</td></tr>'
                       % (self._diff_plus_minus(is_added),
                          s.clusters[c].base_region, b.offset,
                          '(<i>Default</i>)' if b.kind == 'Default'
                          else '',
                          s.clusters[c].bindings[b]))

        if prev_s is not None:
            clusters_removed, clusters_added, clusters_updated = \
                s.diff_clusters(prev_s)
            for c in clusters_removed:
                for b in prev_s.clusters[c].bindings:
                    dump_binding(prev_s, c, b, False)
            for c in clusters_updated:
                bindings_removed, bindings_added = \
                    s.clusters[c].diff_bindings(prev_s.clusters[c])
                for b in bindings_removed:
                    dump_binding(prev_s, c, b, False)
                for b in bindings_added:
                    dump_binding(s, c, b, True)
            for c in clusters_added:
                for b in s.clusters[c].bindings:
                    dump_binding(s, c, b, True)
        else:
            for c in s.clusters:
                for b in s.clusters[c].bindings:
                    dump_binding(s, c, b)

        self._dump('</table>')

    def visit_store_in_state(self, s, prev_s=None):
        st = s.store
        prev_st = prev_s.store if prev_s is not None else None
        if st is None and prev_st is None:
            return

        self._dump('<hr /><tr><td align="left"><b>Store: </b>')
        if st is None:
            self._dump('<i> Nothing!</i>')
        else:
            if self._dark_mode:
                self._dump(' <font color="gray30">(%s)</font>' % st.ptr)
            else:
                self._dump(' <font color="gray">(%s)</font>' % st.ptr)
            if prev_st is not None:
                if s.store.is_different(prev_st):
                    self._dump('</td></tr><tr><td align="left">')
                    self.visit_store(st, prev_st)
                else:
                    self._dump('<i> No changes!</i>')
            else:
                self._dump('</td></tr><tr><td align="left">')
                self.visit_store(st)
        self._dump('</td></tr>')

    def visit_generic_map(self, m, prev_m=None):
        self._dump('<table border="0">')

        def dump_pair(m, k, is_added=None):
            self._dump('<tr><td>%s</td>'
                       '<td align="left">%s</td>'
                       '<td align="left">%s</td></tr>'
                       % (self._diff_plus_minus(is_added),
                          k, m.generic_map[k]))

        if prev_m is not None:
            removed, added = m.diff(prev_m)
            for k in removed:
                dump_pair(prev_m, k, False)
            for k in added:
                dump_pair(m, k, True)
        else:
            for k in m.generic_map:
                dump_pair(m, k, None)

        self._dump('</table>')

    def visit_generic_map_in_state(self, selector, title, s, prev_s=None):
        m = getattr(s, selector)
        prev_m = getattr(prev_s, selector) if prev_s is not None else None
        if m is None and prev_m is None:
            return

        self._dump('<hr />')
        self._dump('<tr><td align="left">'
                   '<b>%s: </b>' % title)
        if m is None:
            self._dump('<i> Nothing!</i>')
        else:
            if prev_m is not None:
                if m.is_different(prev_m):
                    self._dump('</td></tr><tr><td align="left">')
                    self.visit_generic_map(m, prev_m)
                else:
                    self._dump('<i> No changes!</i>')
            else:
                self._dump('</td></tr><tr><td align="left">')
                self.visit_generic_map(m)

        self._dump('</td></tr>')

    def visit_checker_messages(self, m, prev_m=None):
        self._dump('<table border="0">')

        def dump_line(l, is_added=None):
            self._dump('<tr><td>%s</td>'
                       '<td align="left">%s</td></tr>'
                       % (self._diff_plus_minus(is_added), l))

        def dump_chk(chk, is_added=None):
            dump_line('<i>%s</i>:' % chk, is_added)

        if prev_m is not None:
            removed, added, updated = m.diff_messages(prev_m)
            for chk in removed:
                dump_chk(chk, False)
                for l in prev_m.items[chk].lines:
                    dump_line(l, False)
            for chk in updated:
                dump_chk(chk)
                for l in m.items[chk].diff_lines(prev_m.items[chk]):
                    dump_line(l[1:], l.startswith('+'))
            for chk in added:
                dump_chk(chk, True)
                for l in m.items[chk].lines:
                    dump_line(l, True)
        else:
            for chk in m.items:
                dump_chk(chk)
                for l in m.items[chk].lines:
                    dump_line(l)

        self._dump('</table>')

    def visit_checker_messages_in_state(self, s, prev_s=None):
        m = s.checker_messages
        prev_m = prev_s.checker_messages if prev_s is not None else None
        if m is None and prev_m is None:
            return

        self._dump('<hr />')
        self._dump('<tr><td align="left">'
                   '<b>Checker State: </b>')
        if m is None:
            self._dump('<i> Nothing!</i>')
        else:
            if prev_m is not None:
                if m.is_different(prev_m):
                    self._dump('</td></tr><tr><td align="left">')
                    self.visit_checker_messages(m, prev_m)
                else:
                    self._dump('<i> No changes!</i>')
            else:
                self._dump('</td></tr><tr><td align="left">')
                self.visit_checker_messages(m)

        self._dump('</td></tr>')

    def visit_state(self, s, prev_s):
        self.visit_store_in_state(s, prev_s)
        self.visit_environment_in_state('environment', 'Environment',
                                        s, prev_s)
        self.visit_generic_map_in_state('constraints', 'Ranges',
                                        s, prev_s)
        self.visit_generic_map_in_state('dynamic_types', 'Dynamic Types',
                                        s, prev_s)
        self.visit_environment_in_state('constructing_objects',
                                        'Objects Under Construction',
                                        s, prev_s)
        self.visit_checker_messages_in_state(s, prev_s)

    def visit_node(self, node):
        self._dump('%s [shape=record,'
                   % (node.node_name()))
        if self._dark_mode:
            self._dump('color="white",fontcolor="gray80",')
        self._dump('label=<<table border="0">')

        self._dump('<tr><td bgcolor="%s"><b>Node %d (%s) - '
                   'State %s</b></td></tr>'
                   % ("gray20" if self._dark_mode else "gray70",
                      node.node_id, node.ptr, node.state.state_id
                      if node.state is not None else 'Unspecified'))
        if node.has_report:
            self._dump('<tr><td><font color="red"><b>Bug Report Attached'
                       '</b></font></td></tr>')
        if node.is_sink:
            self._dump('<tr><td><font color="cornflowerblue"><b>Sink Node'
                       '</b></font></td></tr>')
        if not self._topo_mode:
            self._dump('<tr><td align="left" width="0">')
            if len(node.points) > 1:
                self._dump('<b>Program points:</b></td></tr>')
            else:
                self._dump('<b>Program point:</b></td></tr>')
        self._dump('<tr><td align="left" width="0">'
                   '<table border="0" align="left" width="0">')
        for p in node.points:
            self.visit_program_point(p)
        self._dump('</table></td></tr>')

        if node.state is not None and not self._topo_mode:
            prev_s = None
            # Do diffs only when we have a unique predecessor.
            # Don't do diffs on the leaf nodes because they're
            # the important ones.
            if self._do_diffs and len(node.predecessors) == 1 \
               and len(node.successors) > 0:
                prev_s = self._graph.nodes[node.predecessors[0]].state
            self.visit_state(node.state, prev_s)
        self._dump_raw('</table>>];\n')

    def visit_edge(self, pred, succ):
        self._dump_raw('%s -> %s%s;\n' % (
            pred.node_name(), succ.node_name(),
            ' [color="white"]' if self._dark_mode else ''
        ))

    def visit_end_of_graph(self):
        self._dump_raw('}\n')

        if not self._dump_dot_only:
            import sys
            import tempfile

            def write_temp_file(suffix, data):
                fd, filename = tempfile.mkstemp(suffix=suffix)
                print('Writing "%s"...' % filename)
                with os.fdopen(fd, 'w') as fp:
                    fp.write(data)
                print('Done! Please remember to remove the file.')
                return filename

            try:
                import graphviz
            except ImportError:
                # The fallback behavior if graphviz is not installed!
                print('Python graphviz not found. Please invoke')
                print('  $ pip install graphviz')
                print('in order to enable automatic conversion to HTML.')
                print()
                print('You may also convert DOT to SVG manually via')
                print('  $ dot -Tsvg input.dot -o output.svg')
                print()
                write_temp_file('.dot', self.output())
                return

            svg = graphviz.pipe('dot', 'svg', self.output())

            filename = write_temp_file(
                '.html', '<html><body bgcolor="%s">%s</body></html>' % (
                             '#1a1a1a' if self._dark_mode else 'white', svg))
            if sys.platform == 'win32':
                os.startfile(filename)
            elif sys.platform == 'darwin':
                os.system('open "%s"' % filename)
            else:
                os.system('xdg-open "%s"' % filename)


#===-----------------------------------------------------------------------===#
# Explorers know how to traverse the ExplodedGraph in a certain order.
# They would invoke a Visitor on every node or edge they encounter.
#===-----------------------------------------------------------------------===#


# BasicExplorer explores the whole graph in no particular order.
class BasicExplorer(object):
    def __init__(self):
        super(BasicExplorer, self).__init__()

    def explore(self, graph, visitor):
        visitor.visit_begin_graph(graph)
        for node in sorted(graph.nodes):
            logging.debug('Visiting ' + node)
            visitor.visit_node(graph.nodes[node])
            for succ in sorted(graph.nodes[node].successors):
                logging.debug('Visiting edge: %s -> %s ' % (node, succ))
                visitor.visit_edge(graph.nodes[node], graph.nodes[succ])
        visitor.visit_end_of_graph()


#===-----------------------------------------------------------------------===#
# Trimmers cut out parts of the ExplodedGraph so that to focus on other parts.
# Trimmers can be combined together by applying them sequentially.
#===-----------------------------------------------------------------------===#


# SinglePathTrimmer keeps only a single path - the leftmost path from the root.
# Useful when the trimmed graph is still too large.
class SinglePathTrimmer(object):
    def __init__(self):
        super(SinglePathTrimmer, self).__init__()

    def trim(self, graph):
        visited_nodes = set()
        node_id = graph.root_id
        while True:
            visited_nodes.add(node_id)
            node = graph.nodes[node_id]
            if len(node.successors) > 0:
                succ_id = node.successors[0]
                succ = graph.nodes[succ_id]
                node.successors = [succ_id]
                succ.predecessors = [node_id]
                if succ_id in visited_nodes:
                    break
                node_id = succ_id
            else:
                break
        graph.nodes = {node_id: graph.nodes[node_id]
                       for node_id in visited_nodes}


# TargetedTrimmer keeps paths that lead to specific nodes and discards all
# other paths. Useful when you cannot use -trim-egraph (e.g. when debugging
# a crash).
class TargetedTrimmer(object):
    def __init__(self, target_nodes):
        super(TargetedTrimmer, self).__init__()
        self._target_nodes = target_nodes

    @staticmethod
    def parse_target_node(node, graph):
        if node.startswith('0x'):
            ret = 'Node' + node
            assert ret in graph.nodes
            return ret
        else:
            for other_id in graph.nodes:
                other = graph.nodes[other_id]
                if other.node_id == int(node):
                    return other_id

    @staticmethod
    def parse_target_nodes(target_nodes, graph):
        return [TargetedTrimmer.parse_target_node(node, graph)
                for node in target_nodes.split(',')]

    def trim(self, graph):
        queue = self._target_nodes
        visited_nodes = set()

        while len(queue) > 0:
            node_id = queue.pop()
            visited_nodes.add(node_id)
            node = graph.nodes[node_id]
            for pred_id in node.predecessors:
                if pred_id not in visited_nodes:
                    queue.append(pred_id)
        graph.nodes = {node_id: graph.nodes[node_id]
                       for node_id in visited_nodes}
        for node_id in graph.nodes:
            node = graph.nodes[node_id]
            node.successors = [succ_id for succ_id in node.successors
                               if succ_id in visited_nodes]
            node.predecessors = [succ_id for succ_id in node.predecessors
                                 if succ_id in visited_nodes]


#===-----------------------------------------------------------------------===#
# The entry point to the script.
#===-----------------------------------------------------------------------===#


def main():
    parser = argparse.ArgumentParser(
        description='Display and manipulate Exploded Graph dumps.')
    parser.add_argument('filename', type=str,
                        help='the .dot file produced by the Static Analyzer')
    parser.add_argument('-v', '--verbose', action='store_const',
                        dest='loglevel', const=logging.DEBUG,
                        default=logging.WARNING,
                        help='enable info prints')
    parser.add_argument('-d', '--diff', action='store_const', dest='diff',
                        const=True, default=False,
                        help='display differences between states')
    parser.add_argument('-t', '--topology', action='store_const',
                        dest='topology', const=True, default=False,
                        help='only display program points, omit states')
    parser.add_argument('-s', '--single-path', action='store_const',
                        dest='single_path', const=True, default=False,
                        help='only display the leftmost path in the graph '
                             '(useful for trimmed graphs that still '
                             'branch too much)')
    parser.add_argument('--to', type=str, default=None,
                        help='only display execution paths from the root '
                             'to the given comma-separated list of nodes '
                             'identified by a pointer or a stable ID; '
                             'compatible with --single-path')
    parser.add_argument('--dark', action='store_const', dest='dark',
                        const=True, default=False,
                        help='dark mode')
    parser.add_argument('--gray', action='store_const', dest='gray',
                        const=True, default=False,
                        help='black-and-white mode')
    parser.add_argument('--dump-dot-only', action='store_const',
                        dest='dump_dot_only', const=True, default=False,
                        help='instead of writing an HTML file and immediately '
                             'displaying it, dump the rewritten dot file '
                             'to stdout')
    args = parser.parse_args()
    logging.basicConfig(level=args.loglevel)

    graph = ExplodedGraph()
    with open(args.filename) as fd:
        for raw_line in fd:
            raw_line = raw_line.strip()
            graph.add_raw_line(raw_line)

    trimmers = []
    if args.to is not None:
        trimmers.append(TargetedTrimmer(
            TargetedTrimmer.parse_target_nodes(args.to, graph)))
    if args.single_path:
        trimmers.append(SinglePathTrimmer())

    explorer = BasicExplorer()

    visitor = DotDumpVisitor(args.diff, args.dark, args.gray, args.topology,
                             args.dump_dot_only)

    for trimmer in trimmers:
        trimmer.trim(graph)

    explorer.explore(graph, visitor)


if __name__ == '__main__':
    main()