#!/usr/bin/env python3
"""Static-site sanity checker for the Astrologue website.

Walks every .html file under the given root, then verifies:
  1. every src/href asset reference resolves to a real file;
  2. no external URLs are referenced (the site must be self-contained);
  3. internal page anchors (#id and page#id) point at real ids;
  4. every local page is reachable by some link (orphan check);
  5. quick HTML well-formedness signals (basic tag balance).

Exit code 1 on any failure. Usage: check.py [root]
"""

import re
import sys
from pathlib import Path
from urllib.parse import urlparse, unquote

ROOT = Path(sys.argv[1] if len(sys.argv) > 1 else ".").resolve()
EXTERNAL = re.compile(r"^(https?|ftp|wss?|//):?")

# Reference designs are not part of the deployable site.
EXCLUDE_DIRS = {"Original", "Proposed", ".git"}

# Site-root-relative pages that are linked ahead of their existence because a
# later task in this goal builds them. Remove entries here once the page lands
# so the checker enforces them again.
UPCOMING_PAGES = {"developer/"}


def check() -> int:
    errors: list[str] = []
    pages = sorted(p for p in ROOT.rglob("*.html")
                   if not (set(p.relative_to(ROOT).parts[:-1]) & EXCLUDE_DIRS))
    if not pages:
        errors.append("no .html files found under root")

    ids_by_page: dict[Path, set[str]] = {}
    refs: list[tuple[Path, str, str]] = []  # page, attr value, kind
    linked_pages: set[Path] = set()

    for page in pages:
        text = page.read_text(encoding="utf-8")
        ids_by_page[page] = set(re.findall(r'id="([^"]+)"', text))

        # strip comments so commented-out template rows are not treated as live refs
        body = re.sub(r"<!--.*?-->", "", text, flags=re.S)

        for attr, val in re.findall(r'\b(src|href)="([^"]+)"', body):
            refs.append((page, val, attr))

        # naive tag-balance check for the elements we actually use
        for tag in ("html", "head", "body", "header", "nav", "main", "footer",
                    "section", "article", "figure", "table", "ul", "ol", "div", "a", "p"):
            opens = len(re.findall(rf"<{tag}[\s>]", body))
            closes = len(re.findall(rf"</{tag}>", body))
            if opens != closes:
                errors.append(f"{page.name}: <{tag}> open/close mismatch ({opens}/{closes})")

    for page, val, _attr in refs:
        parsed = urlparse(val)

        if parsed.scheme or val.startswith("//"):
            if not (val.startswith("data:")):
                errors.append(f"{page.name}: EXTERNAL reference '{val}'")
            continue

        if parsed.fragment and not parsed.path:
            # same-page anchor
            if parsed.fragment not in ids_by_page[page]:
                errors.append(f"{page.name}: broken in-page anchor '#{parsed.fragment}'")
            continue

        target = (page.parent / unquote(parsed.path)).resolve()
        if not target.exists():
            rel = unquote(parsed.path).strip("/")
            if parsed.path.startswith("/") and rel in {p.strip("/") for p in UPCOMING_PAGES}:
                continue
            errors.append(f"{page.name}: missing asset '{val}'")
            continue

        if target.suffix == ".html" or target.name == "":
            # a page link; check its fragment if present
            linked_pages.add(target)
            if parsed.fragment:
                tp = target if target.suffix == ".html" else target / "index.html"
                if tp.is_file():
                    if parsed.fragment not in ids_by_page.get(tp, set()):
                        errors.append(f"{page.name}: broken anchor in {val}")

    # orphan check
    for page in pages:
        if page not in linked_pages and page != ROOT / "index.html":
            errors.append(f"orphan page (nothing links to it): {page.relative_to(ROOT)}")

    if errors:
        print(f"FAIL ({len(errors)} problems)")
        for e in errors:
            print("  -", e)
        return 1
    print(f"OK: {len(pages)} page(s), {len(refs)} reference(s), all local, all resolve")
    return 0


if __name__ == "__main__":
    sys.exit(check())