#!/usr/bin/env python3
#
#   SPDX-License-Identifier: ISC
#
#   Copyright © 2019 Free Software Foundation of India.
#

import datetime
import os
import os.path
import re
import stat as st
import sys

import mistune

SECTIONS = ["news", "article", "case-study"]

# placeholders
PH = {
    "title": "<!-- ITEM-TITLE -->",
    "author": "<!-- AUTHOR -->",
    "date": "<!-- DATE -->",
    "content": "<!-- MAIN-CONTENT -->",
    "lang": "<!-- LANG-LIST -->",
}


def err(s):
    print("Error: {}".format(s))
    sys.exit(1)


def fok(f):
    p = os.path.basename(f.path)

    if re.search(r"(^[\.\#])|(~$)", p):
        return False

    return True


def files(sec):
    files = os.scandir("md" + "/" + sec)

    fs = []
    for f in files:
        if not fok(f):
            print("Ignoring {}".format(f.path))
        else:
            fs.append(f)

    return fs


def read(f):
    with open(f) as f:
        c = f.read()
    return c


def write(p, c):
    d = os.path.dirname(p)

    if not os.path.exists(d):
        os.makedirs(d)

    with open(p, "w") as f:
        f.write(c)

    os.chmod(
        p,
        st.S_IRUSR
        | st.S_IWUSR
        | st.S_IXUSR
        | st.S_IRGRP
        | st.S_IXGRP
        | st.S_IROTH
        | st.S_IXOTH,
    )


def slug(p):
    m = re.search(r"([0-9a-zA-Z\-]+)(\.([a-z]{2}))?\.md", p)

    if not m:
        err("Unable to get slug")

    return m.group(1, 3)


def title(c):
    m = re.search(r"^\# (.+)$", c, re.M)

    if not m:
        err("Title not found")

    return m.group(1)


def author(c):
    m = re.search(r"<!-- author: ([\w\. ]+) -->", c)

    if not m:
        return ""

    return "By " + m.group(1)


def date(c):
    m = re.search(r"pubdate: ([0-9]{8})", c)

    if not m:
        err("Publication date not found")

    return m.group(1)


def content(c):
    m = re.search(r"^\# (.+)$", c, re.M)

    if not m:
        err("Unable to slurp content")

    return c[m.end() :]


def template(type):
    return read("templates/html/{}.html".format(type))


def datefmt(d):
    return datetime.datetime.strptime(d, "%Y%m%d").strftime("%B %d, %Y")


def markdown(c):
    try:
        r = mistune.markdown(c, False, parse_block_html=True, parse_inline_html=True)
    except Exception as e:
        err("Markdown parsing failed: {}".format(e))

    return r


def lhref(sec, s, l):
    if l == "en":
        return '<a href="/{}/{}">{}</a>'.format(sec, s, l)
    else:
        return '<a href="/{}/{}/{}">{}</a>'.format(sec, s, l, l)


def langhtml(sec, s, lng, lngs):
    lsh = []

    for l in lngs:
        if (l == "en" and lng is None) or (l == lng):
            lsh.append(l)
        else:
            lsh.append(lhref(sec, s, l))

    return template("lang").replace(PH["lang"], " | ".join(lsh), 1)


def html(sec, f, lm):
    c = read(f.path)
    s, l = slug(f.path)

    t = title(c)
    a = author(c)
    d = date(c)
    c = content(c)

    h = template(sec)
    h = h.replace(PH["title"], t, 2)
    h = h.replace(PH["date"], datefmt(d), 1)
    h = h.replace(PH["content"], markdown(c), 1)

    if author:
        h = h.replace(PH["author"], a, 1)

    if len(lm[s]) > 1:
        h = h.replace(PH["lang"], langhtml(sec, s, l, lm[s]), 1)

    return s, h, l


def langmap(sec):
    lm = {}
    for f in files(sec):
        s, l = slug(f.path)

        if not s in lm:
            lm[s] = []

        if not l:
            lm[s].append("en")
        else:
            lm[s].append(l)

        lm[s].sort()

    return lm


def process(sec):
    lm = langmap(sec)

    for f in files(sec):
        s, h, l = html(sec, f, lm)
        if not l:
            write("/".join(["_build", sec, s, "index.html"]), h)
        else:
            write("/".join(["_build", sec, s, l, "index.html"]), h)


def run():
    for sec in SECTIONS:
        process(sec)


if __name__ == "__main__":
    run()