#!/usr/bin/env python3
"""Build a single-page HTML site from README.md for the awesome-python website."""

import json
import re
import shutil
import xml.etree.ElementTree as ET
from collections.abc import Sequence
from datetime import UTC, datetime
from pathlib import Path
from typing import Any

from jinja2 import Environment, FileSystemLoader
from readme_parser import ParsedGroup, ParsedSection, parse_readme, parse_sponsors

GITHUB_REPO_URL_RE = re.compile(r"^https?://github\.com/([^/]+/[^/]+?)(?:\.git)?/?$")
SITE_URL = "https://awesome-python.com/"
SITEMAP_URL = f"{SITE_URL}sitemap.xml"
SITEMAP_NS = "http://www.sitemaps.org/schemas/sitemap/0.9"

SOURCE_TYPE_DOMAINS = {
    "docs.python.org": "Built-in",
    "gitlab.com": "GitLab",
    "bitbucket.org": "Bitbucket",
}


def detect_source_type(url: str) -> str | None:
    """Detect source type from URL domain. Returns None for GitHub URLs."""
    if GITHUB_REPO_URL_RE.match(url):
        return None
    for domain, source_type in SOURCE_TYPE_DOMAINS.items():
        if domain in url:
            return source_type
    if "github.com" not in url:
        return "External"
    return None


def extract_github_repo(url: str) -> str | None:
    """Extract owner/repo from a GitHub repo URL. Returns None for non-GitHub URLs."""
    m = GITHUB_REPO_URL_RE.match(url)
    return m.group(1) if m else None


def load_stars(path: Path) -> dict[str, dict]:
    """Load star data from JSON. Returns empty dict if file doesn't exist or is corrupt."""
    if path.exists():
        try:
            return json.loads(path.read_text(encoding="utf-8"))
        except json.JSONDecodeError:
            return {}
    return {}


def sort_entries(entries: list[dict]) -> list[dict]:
    """Sort entries by stars descending, then name ascending.

    Three tiers: starred entries first, stdlib second, other non-starred last.
    """

    def sort_key(entry: dict) -> tuple[int, int, int, str]:
        stars = entry["stars"]
        name = entry["name"].lower()
        if stars is not None:
            builtin = 1 if entry.get("source_type") == "Built-in" else 0
            return (0, -stars, builtin, name)
        if entry.get("source_type") == "Built-in":
            return (1, 0, 0, name)
        return (2, 0, 0, name)

    return sorted(entries, key=sort_key)


def build_robots_txt() -> str:
    return (
        "User-agent: *\n"
        "Content-Signal: search=yes, ai-input=yes, ai-train=yes\n"
        "Allow: /\n"
        "\n"
        f"Sitemap: {SITEMAP_URL}\n"
    )


def write_sitemap_xml(path: Path, urls: Sequence[tuple[str, str]]) -> None:
    ET.register_namespace("", SITEMAP_NS)
    urlset = ET.Element(f"{{{SITEMAP_NS}}}urlset")
    for url, lastmod in urls:
        url_el = ET.SubElement(urlset, f"{{{SITEMAP_NS}}}url")
        loc_el = ET.SubElement(url_el, f"{{{SITEMAP_NS}}}loc")
        loc_el.text = url
        lastmod_el = ET.SubElement(url_el, f"{{{SITEMAP_NS}}}lastmod")
        lastmod_el.text = lastmod

    ET.ElementTree(urlset).write(path, encoding="utf-8", xml_declaration=True)
    with path.open("ab") as f:
        f.write(b"\n")


def top_level_heading_text(line: str) -> str | None:
    stripped = line.strip()
    if not stripped.startswith("# "):
        return None
    return stripped.removeprefix("#").strip().strip("#").strip().strip("*").strip()


def remove_sponsors_section(markdown: str) -> str:
    lines = markdown.splitlines(keepends=True)
    start_idx = None
    for i, line in enumerate(lines):
        heading = top_level_heading_text(line)
        if heading and heading.lower() == "sponsors":
            start_idx = i
            break

    if start_idx is None:
        return markdown

    end_idx = len(lines)
    for i, line in enumerate(lines[start_idx + 1 :], start=start_idx + 1):
        if top_level_heading_text(line):
            end_idx = i
            break

    return "".join(lines[:start_idx] + lines[end_idx:])


def extract_entries(
    categories: list[ParsedSection],
    groups: list[ParsedGroup],
) -> list[dict]:
    """Flatten categories into individual library entries for table display.

    Entries appearing in multiple categories are merged into a single entry
    with lists of categories and groups.
    """
    cat_to_group = {cat["name"]: group["name"] for group in groups for cat in group["categories"]}

    seen: dict[tuple[str, str], dict[str, Any]] = {}  # (url, name) -> entry
    entries: list[dict[str, Any]] = []
    for cat in categories:
        group_name = cat_to_group.get(cat["name"], "Other")
        for entry in cat["entries"]:
            key = (entry["url"], entry["name"])
            existing: dict[str, Any] | None = seen.get(key)
            if existing is None:
                existing = {
                    "name": entry["name"],
                    "url": entry["url"],
                    "description": entry["description"],
                    "categories": [],
                    "groups": [],
                    "subcategories": [],
                    "stars": None,
                    "owner": None,
                    "last_commit_at": None,
                    "source_type": detect_source_type(entry["url"]),
                    "also_see": entry["also_see"],
                }
                seen[key] = existing
                entries.append(existing)
            if cat["name"] not in existing["categories"]:
                existing["categories"].append(cat["name"])
            if group_name not in existing["groups"]:
                existing["groups"].append(group_name)
            subcat = entry["subcategory"]
            if subcat:
                scoped = f"{cat['name']} > {subcat}"
                if not any(s["value"] == scoped for s in existing["subcategories"]):
                    existing["subcategories"].append({"name": subcat, "value": scoped})
    return entries


def build(repo_root: Path) -> None:
    """Main build: parse README, render single-page HTML via Jinja2 templates."""
    website = repo_root / "website"
    readme_text = (repo_root / "README.md").read_text(encoding="utf-8")

    subtitle = ""
    for line in readme_text.split("\n"):
        stripped = line.strip()
        if stripped and not stripped.startswith("#"):
            subtitle = stripped
            break

    parsed_groups = parse_readme(readme_text)
    sponsors = parse_sponsors(readme_text)

    categories = [cat for g in parsed_groups for cat in g["categories"]]
    total_entries = sum(c["entry_count"] for c in categories)
    entries = extract_entries(categories, parsed_groups)
    build_date = datetime.now(UTC)

    stars_data = load_stars(website / "data" / "github_stars.json")

    repo_self = stars_data.get("vinta/awesome-python", {})
    repo_stars = None
    if "stars" in repo_self:
        stars_val = repo_self["stars"]
        repo_stars = f"{stars_val // 1000}k" if stars_val >= 1000 else str(stars_val)

    for entry in entries:
        repo_key = extract_github_repo(entry["url"])
        if not repo_key and entry.get("source_type") == "Built-in":
            repo_key = "python/cpython"
        if repo_key and repo_key in stars_data:
            sd = stars_data[repo_key]
            entry["stars"] = sd["stars"]
            entry["owner"] = sd["owner"]
            entry["last_commit_at"] = sd.get("last_commit_at", "")

    entries = sort_entries(entries)

    env = Environment(
        loader=FileSystemLoader(website / "templates"),
        autoescape=True,
        trim_blocks=True,
        lstrip_blocks=True,
    )

    site_dir = website / "output"
    if site_dir.exists():
        shutil.rmtree(site_dir)
    site_dir.mkdir(parents=True)

    tpl_index = env.get_template("index.html")
    (site_dir / "index.html").write_text(
        tpl_index.render(
            categories=categories,
            subtitle=subtitle,
            entries=entries,
            total_entries=total_entries,
            total_categories=len(categories),
            repo_stars=repo_stars,
            build_date=build_date.strftime("%B %d, %Y"),
            sponsors=sponsors,
        ),
        encoding="utf-8",
    )

    static_src = website / "static"
    static_dst = site_dir / "static"
    if static_src.exists():
        shutil.copytree(static_src, static_dst, dirs_exist_ok=True)

    markdown_index = remove_sponsors_section(readme_text)
    (site_dir / "robots.txt").write_text(build_robots_txt(), encoding="utf-8")
    write_sitemap_xml(site_dir / "sitemap.xml", [(SITE_URL, build_date.date().isoformat())])
    (site_dir / "index.md").write_text(markdown_index, encoding="utf-8")
    (site_dir / "llms.txt").write_text(markdown_index, encoding="utf-8")

    print(f"Built single page with {len(parsed_groups)} groups, {len(categories)} categories")
    print(f"Total entries: {total_entries}")
    print(f"Output: {site_dir}")


if __name__ == "__main__":
    build(Path(__file__).parent.parent)