# -----------------------------------------------------------------------------
# VENDORED COPY — DO NOT EDIT THIS FILE BY HAND.
#
# Canonical source of truth:
#   git.chemavx.xyz/chemavx/chemavx-seo-tools  ->  seo_rules.py
#   (local working copy: ~/seo-tools/seo_rules.py)
#
# The bot reuses the shared SEO rule engine inside the container, where
# seo-tools is not installed. Everything below the BEGIN marker is a
# byte-for-byte copy of the canonical file.
#
# To update:   edit the canonical, then run  `make sync-seo`  (re-copies here).
# Drift guard: CI step "Verify vendored SEO engine" clones the canonical and
#              diffs it against the content below the marker; the build FAILS on
#              any divergence. Locally, `make check-seo-sync` does the same.
# -----------------------------------------------------------------------------
# ===== BEGIN VENDORED seo_rules.py (exact copy of canonical; do not edit below) =====
"""
Reusable SEO rule engine for The Exclusion Zone (EN) — theexclusionzone.com (Ghost).

Pure functions, NO I/O. Feed it a Ghost Admin API post dict (with `html` format
included) and it returns a list of Violation(rule, severity, message, fix).

Shared by:
  - seo_audit.py        — Tool A, site-wide auditor (this engine, run over all posts)
  - (future) seo_validate.py — Tool C, pre-publish validator (same engine, one draft)

Design note: every check is an independent function registered in RULES. To add a
rule, write a function (post) -> list[Violation] and append it to RULES. The auditor
and the validator both just call check_post(); they never re-implement a check.
"""
import re
from collections import namedtuple

SITE_HOST = "theexclusionzone.com"

# ---- thresholds (single source of truth, reused by validator) -------------
META_TITLE_MAX     = 60
META_DESC_MAX      = 145
CUSTOM_EXCERPT_MAX = 300
MIN_INTERNAL_LINKS = 2

# ---- severity weights (used to rank "worst first") ------------------------
HIGH, MED, LOW, INFO = 3, 2, 1, 0
SEV_NAME = {HIGH: "HIGH", MED: "MED", LOW: "LOW", INFO: "INFO"}

# The Edition-main theme injects BlogPosting JSON-LD globally in default.hbs
# ({{#is "post"}} ... <script type="application/ld+json"> @type BlogPosting),
# plus Ghost's own {{ghost_head}}. So JSON-LD is handled site-wide and is NOT a
# per-post rule. Flip to False only if that theme block is ever removed.
THEME_HANDLES_JSONLD = True

Violation = namedtuple("Violation", "rule severity message fix")


def _s(v):
    return v if isinstance(v, str) else ""


def _empty(v):
    return not (isinstance(v, str) and v.strip())


# First path segments that are NOT article posts on a Ghost site (tags, authors,
# pagination, static content, etc.). Keeps root-relative link counting from
# treating /tag/foo or /content/images/... as an internal article link.
NON_POST_PREFIXES = {
    "tag", "tags", "author", "page", "p", "content", "assets",
    "rss", "ghost", "members", "404", "sitemap",
}


def _internal_slug(href, self_slug):
    """Return the article slug an href points to if it's an internal POST link,
    else None. Accepts both absolute (contains SITE_HOST) and root-relative
    ("/slug/") forms; rejects protocol-relative ("//host"), anchors, mailto,
    external links, static assets, and known non-post sections."""
    if SITE_HOST in href:
        path = re.sub(r"^https?://[^/]+/", "", href)
    elif href.startswith("/") and not href.startswith("//"):
        path = href[1:]
    else:
        return None
    slug = path.strip("/").split("/")[0]
    if not slug or slug == self_slug:
        return None
    if slug in NON_POST_PREFIXES or "." in slug:  # section page or static asset
        return None
    return slug


def internal_links(post):
    """Distinct internal article slugs linked from the body, excluding self-links.

    Counts BOTH absolute internal links (href containing SITE_HOST) and
    root-relative links ("/slug/"), so a Ghost-relative link isn't miscounted as
    "too few". Tool A (auditor) and Tool C (validator) share this, staying in sync.
    """
    html = _s(post.get("html"))
    self_slug = post.get("slug")
    out = set()
    for m in re.finditer(r'href="([^"#]+)"', html):
        slug = _internal_slug(m.group(1), self_slug)
        if slug:
            out.add(slug)
    return out


# --- individual rules -------------------------------------------------------

def r_meta_title(p):
    mt = _s(p.get("meta_title"))
    title = _s(p.get("title"))
    if _empty(mt):
        sev = MED if len(title) > META_TITLE_MAX else LOW
        return [Violation("meta_title.missing", sev,
                          f"meta_title missing → falls back to title ({len(title)} chars"
                          + (f", which is >{META_TITLE_MAX}!" if len(title) > META_TITLE_MAX else "") + ")",
                          "set meta_title")]
    if len(mt) > META_TITLE_MAX:
        return [Violation("meta_title.too_long", MED,
                          f"meta_title {len(mt)} chars > {META_TITLE_MAX}", "shorten meta_title")]
    return []


def r_meta_description(p):
    md = _s(p.get("meta_description"))
    if _empty(md):
        return [Violation("meta_description.missing", HIGH,
                          "meta_description MISSING (no SERP snippet control)", "write meta_description")]
    if len(md) > META_DESC_MAX:
        return [Violation("meta_description.too_long", MED,
                          f"meta_description {len(md)} chars > {META_DESC_MAX} (will be truncated in SERP)",
                          "shorten meta_description")]
    return []


def r_custom_excerpt(p):
    ce = _s(p.get("custom_excerpt"))
    if ce and len(ce) > CUSTOM_EXCERPT_MAX:
        return [Violation("custom_excerpt.too_long", LOW,
                          f"custom_excerpt {len(ce)} chars > {CUSTOM_EXCERPT_MAX}", "shorten custom_excerpt")]
    return []


def r_social_fields(p):
    """OG/Twitter empties — the safest auto-fixable category (mirror meta_*)."""
    out = []
    fallbacks = {
        "og_title":          "meta_title",
        "og_description":    "meta_description",
        "twitter_title":     "meta_title",
        "twitter_description": "meta_description",
    }
    for field, src in fallbacks.items():
        if _empty(p.get(field)):
            out.append(Violation(f"{field}.empty", LOW,
                                 f"{field} empty", f"mirror from {src}"))
    return out


def r_feature_image(p):
    out = []
    if _empty(p.get("feature_image")):
        out.append(Violation("feature_image.missing", MED,
                             "feature_image missing (no social/share card image)", "add feature image"))
    else:
        if _empty(p.get("feature_image_alt")):
            out.append(Violation("feature_image_alt.missing", LOW,
                                 "feature_image_alt missing (a11y + image SEO)", "add feature image alt text"))
    return out


def r_internal_links(p):
    n = len(internal_links(p))
    if n < MIN_INTERNAL_LINKS:
        return [Violation("internal_links.too_few", MED,
                          f"{n} internal link(s) < {MIN_INTERNAL_LINKS} (weak interlinking)",
                          "add internal links to related articles")]
    return []


def r_title_equals_meta(p):
    mt = _s(p.get("meta_title"))
    title = _s(p.get("title"))
    if mt and mt == title:
        return [Violation("title_eq_meta_title", INFO,
                          "meta_title identical to title (often fine; review)", "")]
    return []


def r_jsonld(p):
    if THEME_HANDLES_JSONLD:
        return []
    return [Violation("jsonld.missing", MED, "no BlogPosting JSON-LD", "add JSON-LD")]


RULES = [
    r_meta_title,
    r_meta_description,
    r_custom_excerpt,
    r_social_fields,
    r_feature_image,
    r_internal_links,
    r_title_equals_meta,
    r_jsonld,
]


def check_post(post):
    """Run every rule against one post dict → list[Violation]."""
    out = []
    for rule in RULES:
        out.extend(rule(post))
    return out


def score(violations):
    """Total severity weight (for ranking posts worst-first); INFO counts 0."""
    return sum(v.severity for v in violations)