# File Objective  : Build the Vantage Knowledge Graph end-to-end.
# Scope           : Dev script — run after ingest + tag_topics to populate Neo4j.
# What it does    : 1. Coverage  — reads topic_coverage.csv (written by tag_topics.py).
#                   2. Signals   — Google Trends volume + velocity per topic (anchor=calculator).
#                   3. Gap score — Demand × (1 − Coverage) per topic.
#                   4. Push      — (:Topic){gap metadata} + (:Topic)-[:COVERED_BY]->(:Document).
#                   5. Prints top gaps with covered documents.
# What it does not: Wipe the graph (run wipe_graph.py first) or re-ingest.
#
# Usage            : python scripts/build_graph.py            # all topics
#                    SAMPLE=10 python scripts/build_graph.py  # first N topics only

from __future__ import annotations

import csv
import json
import os
from collections import defaultdict
from pathlib import Path

from vantage_core.adapters.graph_neo4j import Neo4jGraphRepo
from vantage_core.adapters.signals_pytrends import fetch_signals
from vantage_core.domain.gap import compute_gaps
from vantage_core.models import SignalRecord
from vantage_core.topic_seeds import load_topics

SAMPLE        = int(os.environ.get("SAMPLE", 0))                       # >0 → first N topics
TOPICS_ENV    = os.environ.get("TOPICS", "")                           # comma-separated override
_SIG_CACHE    = Path("data/signals.json")
_COVERAGE_CSV = Path("data/topic_coverage.csv")


def load_coverage() -> dict[str, list[str]]:
    """Read topic_coverage.csv → {topic: [doc_id, ...]}. Written by tag_topics.py."""
    coverage: dict[str, list[str]] = defaultdict(list)
    with _COVERAGE_CSV.open(encoding="utf-8") as f:
        for row in csv.DictReader(f):
            coverage[row["topic"]].append(row["doc_id"])
    return dict(coverage)


def load_signals(topics: list[str]) -> list[SignalRecord]:
    """Return signals from disk cache if present; otherwise fetch live and save cache."""
    if _SIG_CACHE.exists():
        print(f"  Using cached signals ({_SIG_CACHE})")
        data = json.loads(_SIG_CACHE.read_text(encoding="utf-8"))
        cached = {r["keyword"]: SignalRecord(**r) for r in data["signals"]}
        # fetch any topics missing from cache
        missing = [t for t in topics if t not in cached]
        if missing:
            print(f"  {len(missing)} topics not in cache — fetching live...")
            fresh = fetch_signals(missing)
            for s in fresh:
                cached[s.keyword] = s
            _save_signals_cache(list(cached.values()))
        return [cached[t] for t in topics if t in cached]
    signals = fetch_signals(topics)
    _save_signals_cache(signals)
    return signals


def _save_signals_cache(signals: list[SignalRecord]) -> None:
    _SIG_CACHE.parent.mkdir(parents=True, exist_ok=True)
    _SIG_CACHE.write_text(
        json.dumps({"signals": [s.model_dump() for s in signals]}, indent=2),
        encoding="utf-8",
    )
    print(f"  Signals cached → {_SIG_CACHE} ({len(signals)} records)")


def main() -> None:
    graph = Neo4jGraphRepo()

    # ── 0. Load coverage CSV, pre-filter to topics with ≥1 doc ───────────────
    print(f"Loading coverage from {_COVERAGE_CSV}...")
    raw_coverage = load_coverage()                                       # topic → [doc_id]

    if TOPICS_ENV:
        candidates = [t.strip() for t in TOPICS_ENV.split(",")]
    elif SAMPLE:
        candidates = load_topics()[:SAMPLE]
    else:
        candidates = load_topics()

    topics = [t for t in candidates if t in raw_coverage]
    print(f"  {len(topics)}/{len(candidates)} topics have ≥1 doc\n")

    # cover: topic → list of {doc_id} dicts
    cover: dict[str, list[dict]] = {t: [{"doc_id": d} for d in raw_coverage[t]] for t in topics}

    print(f"Building graph for {len(topics)} topics\n")

    # ── 1. Signals ────────────────────────────────────────────────────────────
    print("Loading signals...")
    signals = load_signals(topics)

    # ── 2. Gap scores ─────────────────────────────────────────────────────────
    counts = {t: len(docs) for t, docs in cover.items()}
    gaps   = compute_gaps(signals, counts)

    # ── 3. Push to Neo4j: Topic nodes + COVERED_BY edges ──────────────────────
    print("\nPushing to Neo4j...")
    graph.build(gaps)
    edges = [
        {"topic": g.topic, "doc_id": d["doc_id"], "title": ""}
        for g in gaps
        for d in cover.get(g.topic, [])
    ]
    graph.link_coverage(edges)
    print(f"  {len(gaps)} Topic nodes + {len(edges)} COVERED_BY edges\n")

    # ── 4. Sample output ──────────────────────────────────────────────────────
    print("── Top 10 gaps ──────────────────────────────────────────────────────")
    for g in gaps[:10]:
        print(f"  gap={g.gap_score:.4f}  {g.label:<13} vol={g.volume:.2f} vel={g.velocity:+.2f} "
              f"cov={g.coverage_count}docs  {g.topic}")
        for d in graph.docs_for_topic(g.topic, limit=2):
            print(f"      └─ [{d['doc_id']}] {d['title'][:60]}")

    graph.close()


if __name__ == "__main__":
    main()