# mkxref.py
#
# Generate crossreferences.asc
# as a global include file for all text files here.
#

import os, sys, re

# find all work package files, like
# B6.wp02_cpython_to_python.txt

START_STR = "B6.7.wp".lower()

def get_wps_from_dir(as_html=False):
    res = {}
    for fname in os.listdir("."):
        flow = fname.lower()
        pre, ext = os.path.splitext(flow)
        if flow.startswith(START_STR) and ext == ".txt":
            num = flow[len(START_STR):].split("_", 1)[0]
            if len(num)==2 and num.isdigit():
                if as_html:
                    pre, ext = os.path.splitext(fname)
                    newfname = pre + ".html"
                else:
                    newfname = fname
                res["WP"+num] = newfname
    return res

REF_FILE = "B6.5_workpackage_list.txt"

def get_wps_from_file():
    # read the file and find all WPnn_ references
    txt = file(REF_FILE).read()
    res = {}
    for piece in txt.split("WP"):
        num = piece.split("_", 1)[0]
        if len(num)==2 and num.isdigit():
            res["WP"+num] = ""
    return res

# read the existing xref file, find the WP section and replace it.

XREF_FILE = "crossreferences.asc"

def split_xref_text():
    """ split the xref file into three parts:
        before, in, and after the workpackages
    """
    try:
        lines = file(XREF_FILE).readlines()
    except IOError:
        lines = []
    pre = []
    pat = "..\s+_WP\d\d\:|.. attention::"
    for line in lines:
        if re.match(pat, line):
            break
        pre.append(line)
    post = lines[len(pre):]
    mid = []
    for line in post[:]:
        if re.match(pat, line):
            mid.append(post.pop(0))
        else:
            break
    return pre, mid, post

def build_xref_file():
    pre, old, post = split_xref_text()
    wps = get_wps_from_file()
    wps.update(get_wps_from_dir(as_html=True))
    wplist = wps.items()
    wplist.sort()
    mid = [ ".. _%s: %s\n" % (name, url) for name, url in wplist]
    empties = [name for name, url in wplist if not url]
    if empties:
        n = len(empties)
        mid.append(".. attention:: **%d file%s missing: %s**\n" %
                   (n, "s"[0:n>1], " ".join(empties)))
    if mid != old:
        file(XREF_FILE, "w").writelines( pre + mid + post)

if __name__ == "__main__":
    build_xref_file()