From 63041a5e62573a442e8a43b43e4c2a9c3c522e8e Mon Sep 17 00:00:00 2001
From: Pelle Nilsson <perni@lysator.liu.se>
Date: Tue, 23 Sep 2014 23:15:00 +0200
Subject: [PATCH] checkgamebook.py now can find unreachable sections in books.

---
 checkgamebook.py | 59 ++++++++++++++++++++++++++++++++++++++++++++++++
 readme.org       | 10 ++++----
 todo.org         |  8 ++++---
 3 files changed, 70 insertions(+), 7 deletions(-)

diff --git a/checkgamebook.py b/checkgamebook.py
index 3a517e3..f046478 100755
--- a/checkgamebook.py
+++ b/checkgamebook.py
@@ -35,8 +35,63 @@ import json
 
 USAGE = "usage: %prog [options] inputfile(s)... outputfile"
 
+def find_section_nr_names(sections):
+    section_nr_to_name = {}
+    for section_name,section_contents in sections.iteritems():
+        section_nr_to_name[section_contents["nr"]] = section_name
+    return section_nr_to_name
+
+def find_references(sections):
+    section_nr_to_name = find_section_nr_names(sections)
+    references = {}
+    for section_name,section_contents in sections.iteritems():
+        references_from_section = []
+        for t in section_contents["text"]:
+            if isinstance(t, dict) and "reference" in t:
+                ref = section_nr_to_name[int(t["reference"])]
+                references_from_section.append(ref)
+        references[section_name] = references_from_section
+    return references
+
+def traverse(sections, references, function, data):
+    stack = ["start"]
+    visited = set()
+    while len(stack) > 0:
+        section = stack.pop()
+        function(section, data)
+        visited.add(section)
+        for reference in references[section]:
+            if reference not in visited:
+                stack.append(reference)
+
+def traverse_add(section, data):
+    data.add(section)
+
+found_errors = False # yay, global state
+def check_error(msg):
+    print "%s: %s" % (sys.argv[1], msg)
+    global found_errors
+    found_errors = True
+
+def check_all_sections_can_be_reached_in_theory(sections, references):
+    reached = set()
+    traverse(sections, references, traverse_add, reached)
+    for section in sections:
+        if section not in reached:
+            check_error("Could not reach section '%s' from start." % section)
+
 def check_gamebook(inputfilename):
     book = json.load(open(inputfilename))
+    sections = book["sections"]
+    if not "start" in sections:
+        check_error("No start section found. Cancelling checks.")
+        sys.exit(1)
+    del sections["IGNORE-debug-json-padding-IGNORE"]
+    for section in sections.keys():
+        if section.startswith("empty-"):
+            del sections[section]
+    references = find_references(sections)
+    check_all_sections_can_be_reached_in_theory(sections, references)
 
 if __name__ == '__main__':
     import argparse
@@ -46,3 +101,7 @@ if __name__ == '__main__':
                     help='input gamebook debug file (eg test.debug)')
     args = ap.parse_args()
     check_gamebook(args.inputfile)
+    if found_errors:
+        sys.exit(1)
+    else:
+        sys.exit(0)
diff --git a/readme.org b/readme.org
index 0bd514a..2fc8fc0 100644
--- a/readme.org
+++ b/readme.org
@@ -90,10 +90,12 @@ on a book and warn about things that do not look right.
 To use it first generate a *debug* output file version of
 the book, using the same flags (eg include-tags) as when
 formatting the real book. Then run *checkgamebook.py bookname.debug*.
-(TODO: Currently does not really test anything. The idea
-is that it should do things like trying to tell you about
-sections that can not be reached, or items that are required
-before they can possibly have been found.)
+Currently only tests that all sections can be reached, in theory,
+from the *start* section. It only looks for existing references,
+and has no idea for instance if a locked door can never be
+unlocked because it is impossible to find enough money to
+pay for a key. Future versions will hopefully catch more
+problems, but never all of them in complex books.
 
 ** Number Map Files
 Whenever formatgamebook.py runs it looks for a file with the same
diff --git a/todo.org b/todo.org
index a7680ba..47af07b 100644
--- a/todo.org
+++ b/todo.org
@@ -1,4 +1,4 @@
-* TODO [62/92] [67%]
+* TODO [64/92] [69%]
 ** DONE Debug output
 ** DONE DOT output
 ** DONE LaTeX output
@@ -79,8 +79,10 @@
    Will be taken care of when implementing JSON output.
 ** DONE checkgamebook.py script, parse debug file JSON
    CLOSED: [2014-09-23 Tue 21:52]
-** TODO checkgamebook.py build internal section graph
-** TODO checkgamebook.py find unreachable sections
+** DONE checkgamebook.py build internal section graph
+   CLOSED: [2014-09-23 Tue 23:10]
+** DONE checkgamebook.py find unreachable sections
+   CLOSED: [2014-09-23 Tue 23:10]
 ** TODO JavaScript improved design/code for what links to enable
    Many strange things can happen when clicking one link changes something
    that should now enable or disable some link. Instead of the current