"""Wiki page titles and Gitea filename encoding."""

from __future__ import annotations

import hashlib
import re
from urllib.parse import quote, unquote

from export1c_help.discover import HelpPage

_INVALID = re.compile(r'[\\/:*?"<>|#\[\]]+')
_SPACES = re.compile(r"\s+")
# Encoded «Slug.md» must leave room under Windows MAX_PATH (~260) for deep
# project roots (e.g. D:\SynologyDrive\projects_syn\…\out\).
_MAX_ENCODED_FILENAME = 100


def sanitize_title(title: str) -> str:
    title = _SPACES.sub(" ", title).strip()
    title = _INVALID.sub(" ", title)
    title = _SPACES.sub(" ", title).strip()
    return title or "untitled"


def _short_hash(s: str) -> str:
    return hashlib.sha1(s.encode("utf-8")).hexdigest()[:8]


def _encoded_filename(slug: str) -> str:
    return quote(slug, safe="-_.") + ".md"


def wiki_filename(title: str, *, meta_key: str | None = None) -> str:
    """
    Gitea wiki stores non-ASCII page names as percent-encoded «Slug.md».

    Encoded length is capped so typical Windows project paths still fit
    under MAX_PATH; when truncated, a short hash of meta_key (or title)
    is appended for stability.
    """
    slug = sanitize_title(title).replace(" ", "-")
    encoded = _encoded_filename(slug)
    if len(encoded) <= _MAX_ENCODED_FILENAME:
        return encoded

    suffix = "-" + _short_hash(meta_key or title)
    # ASCII suffix: encoded length == visible length
    budget = _MAX_ENCODED_FILENAME - len(suffix) - 3  # ".md"
    while slug and len(quote(slug, safe="-_.")) > budget:
        slug = slug[:-1]
    slug = slug.rstrip("-") or "page"
    return quote(slug, safe="-_.") + suffix + ".md"


def decode_wiki_filename(name: str) -> str:
    base = name[:-3] if name.endswith(".md") else name
    return unquote(base)


def assign_titles(
    pages: list[HelpPage],
    h1_by_meta: dict[str, str | None],
) -> tuple[dict[str, str], dict[str, str]]:
    """Returns (meta_key → title, meta_key → filename)."""
    used_title: set[str] = set()
    used_file: set[str] = set()
    titles: dict[str, str] = {}
    files: dict[str, str] = {}

    for p in pages:
        h1 = h1_by_meta.get(p.meta_key)
        base = sanitize_title(h1 or p.synonym or p.meta_key)
        title = base
        n = 2
        while title.casefold() in used_title:
            if p.is_form and p.form_name and n == 2:
                title = sanitize_title(f"{base} — {p.form_name}")
            elif n == 2:
                title = sanitize_title(f"{base} — {p.object_name}")
            else:
                title = sanitize_title(f"{base} ({n})")
            n += 1
            if n > 5000:
                title = sanitize_title(p.meta_key)
                break

        fname = wiki_filename(title, meta_key=p.meta_key)
        if fname.casefold() in used_file:
            fname = wiki_filename(
                f"{title}-{_short_hash(p.meta_key)}",
                meta_key=p.meta_key,
            )
        guard = 0
        while fname.casefold() in used_file:
            fname = _encoded_filename(f"page-{_short_hash(p.meta_key + str(guard))}")
            guard += 1

        used_title.add(title.casefold())
        used_file.add(fname.casefold())
        titles[p.meta_key] = title
        files[p.meta_key] = fname

    return titles, files