#!/usr/bin/env python3
"""Build a JSON index from Markdown frontmatter."""

from __future__ import annotations

import json
from collections import Counter, defaultdict
from pathlib import Path


ROOT = Path(__file__).resolve().parents[2]
COLLECTIONS = ("jobs", "papers", "industry")


def parse_scalar(value: str):
    value = value.strip()
    if value == "":
        return None
    return value


def parse_frontmatter(text: str) -> dict:
    start = text.find("\n---\n")
    if text.startswith("---\n"):
        start = -1
        body_start = 4
    elif start != -1:
        body_start = start + 5
    else:
        return {}
    end = text.find("\n---", body_start)
    if end == -1:
        return {}
    lines = text[body_start:end].splitlines()
    data: dict[str, object] = {}
    current_key: str | None = None
    for raw in lines:
        line = raw.rstrip()
        if not line:
            continue
        if line.startswith("  -"):
            if current_key:
                item = line[3:].strip()
                if item:
                    data.setdefault(current_key, [])
                    assert isinstance(data[current_key], list)
                    data[current_key].append(item)
            continue
        if ":" in line:
            key, value = line.split(":", 1)
            key = key.strip()
            value = value.strip()
            current_key = key
            data[key] = [] if value == "" else parse_scalar(value)
    return data


def iter_items():
    for collection in COLLECTIONS:
        item_dir = ROOT / collection / "items"
        for path in sorted(item_dir.glob("*.md")):
            if path.name == "README.md":
                continue
            text = path.read_text(encoding="utf-8")
            meta = parse_frontmatter(text)
            yield {
                "collection": collection,
                "path": str(path.relative_to(ROOT)),
                "title": meta.get("title") or meta.get("role") or path.stem,
                "type": meta.get("type") or collection.rstrip("s"),
                "meta": meta,
            }


def main() -> int:
    items = list(iter_items())
    data_dir = ROOT / "data"
    data_dir.mkdir(exist_ok=True)
    (data_dir / "index.json").write_text(
        json.dumps(items, ensure_ascii=False, indent=2) + "\n",
        encoding="utf-8",
    )

    by_collection = Counter(item["collection"] for item in items)
    by_status = defaultdict(Counter)
    topics = Counter()
    skills = Counter()
    companies = Counter()
    for item in items:
        meta = item["meta"]
        by_status[item["collection"]][meta.get("status") or "unknown"] += 1
        for topic in meta.get("topics") or []:
            topics[topic] += 1
        for skill in meta.get("skills") or []:
            skills[skill] += 1
        company = meta.get("company")
        if company:
            companies[str(company)] += 1

    summary = {
        "total": len(items),
        "by_collection": dict(by_collection),
        "by_status": {key: dict(value) for key, value in by_status.items()},
        "top_topics": topics.most_common(20),
        "top_skills": skills.most_common(20),
        "top_companies": companies.most_common(20),
    }
    (data_dir / "summary.json").write_text(
        json.dumps(summary, ensure_ascii=False, indent=2) + "\n",
        encoding="utf-8",
    )
    print(json.dumps(summary, ensure_ascii=False, indent=2))
    return 0


if __name__ == "__main__":
    raise SystemExit(main())