import sys
import os
from collections import defaultdict
import json

if __name__ == "__main__":
    if len(sys.argv) != 2:
	print(f"Usage: python {sys.argv[0]} <base_dir>")
	sys.exit(1)
    if not os.path.isdir(basedir := sys.argv[1]):
	print(f"{basedir} is not a valid directory.")
	sys.exit(1)

    basedir = basedir.rstrip("/")

    # dir_name to category string
    categ_dict = {
	"distrib": "分散システム",
	"storage": "ストレージ",
	"virtual": "コンテナ・VM",
	"linux": "Linux",
	"etc": "未分類",
    }
    TITLE_HEAD = "#+TITLE: "
    SUBTITLE_HEAD = "#+SUBTITLE: "
    top_title = "#+TITLE: Personal Wiki Index"

    # Read config.json
    try:
	with open("/".join([basedir, "config.json"])) as f:
	    config = json.load(f)
	    top_title = "#+TITLE: " + config.pop("#+TITLE", top_title)
	    categ_dict = config
    except Exception:
	print("Skip loading config.json")

    # Save README.org if exists
    readme_path = "/".join([basedir, "README.org"])
    readme_bk_path = readme_path + ".bk"
    try:
	os.remove(readme_bk_path)
    except Exception:
	pass
    if os.path.exists(readme_path):
	os.rename(readme_path, readme_bk_path)

    # Create org_dic
    #   category_string: list of (full_path, title) tuples
    #   Note: multiple categories could share the same category_string
    org_dic = defaultdict(list)
    for dpath, _, fnames in os.walk(basedir):
	for fname in fnames:
	    if fname.endswith(".org"):
		full_path = "/".join([dpath, fname])
		categ = categ_str = dpath[dpath.rfind("/") + 1 :].lower()
		try:
		    categ_str = categ_dict[categ]
		except Exception:
		    pass
		with open(full_path, "r") as f:
		    title = "No #+TITLE: header!"
		    subtitles = []
		    for line in f:
			if line.startswith(TITLE_HEAD):
			    title = line[len(TITLE_HEAD) :].rstrip()
			if line.startswith(SUBTITLE_HEAD):
			    subtitles.append(line[len(SUBTITLE_HEAD) :].rstrip())
		link_path = "." + full_path[len(basedir) :]
		org_dic[categ_str].append((link_path, (title, fname, subtitles)))

    # Generate README.org based on org_dic
    with open(readme_path, "w") as f:
	print(top_title, file=f)
	print("\nPersonal memos\n", file=f)
	for categ_str, link_list in org_dic.items():
	    print(f"** {categ_str}", file=f)
	    print("", file=f)
	    for link in link_list:
		print(f"- [[{link[0]}][{link[1][0]}]] ({link[1][1]})", file=f)
		for subttl in link[1][2]:
		    print(f"  - {subttl}", file=f)
	    print("", file=f)