#!/usr/bin/env python3
"""
Offline CDMS index builder — the reproducible source of truth.

Ingests every PDF in data/pdfs/cdms/, extracts + chunks + BATCH-embeds them,
writes the SQLite metadata DB (data/cdms_metadata.db) and the Qdrant vector
index, then exports a portable Qdrant snapshot (data/qdrant_snapshots/) that is
committed and restored into the served Docker Qdrant at deploy.

This replaces the ad-hoc reprocess_pdfs.py. Unlike the old script it:
  * points at the real CDMS folder (data/pdfs/cdms, not data/pdfs),
  * injects the filename->cdms.net URL manifest so citations keep the source link,
  * validates that PDFs == documents == distinct Qdrant docs and points == chunks,
  * exports a server-format snapshot for the two-process Docker deploy.

Usage:
    # Build into a running Docker Qdrant (recommended) and export a snapshot:
    docker run -d -p 6333:6333 -v "$PWD/data/qdrant_snapshots:/qdrant/snapshots" qdrant/qdrant
    python scripts/build_index.py --force

    # Build into the on-disk local store instead (single-process only, no snapshot):
    python scripts/build_index.py --force --local

Flags:
    --force   reprocess every PDF from scratch (REQUIRED for the first real build,
              because the shipped index is stale/partial: 26 of 53 PDFs indexed).
    --local   build into the on-disk Qdrant (QDRANT_FORCE_LOCAL) instead of Docker.
              No portable snapshot is produced in this mode.
"""

import argparse
import json
import sqlite3
import sys
from pathlib import Path

PROJECT_ROOT = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(PROJECT_ROOT))


def load_url_manifest(manifest_path: Path) -> dict:
    """Return {filename: cdms.net URL}; empty (with a warning) if absent."""
    if not manifest_path.exists():
        print(f"⚠️  No URL manifest at {manifest_path}")
        print("   Citations will fall back to filename + page (no source link).")
        return {}
    try:
        data = json.loads(manifest_path.read_text())
        print(f"🔗 Loaded {len(data)} URL mapping(s) from {manifest_path.name}")
        return data
    except Exception as e:
        print(f"⚠️  Could not read URL manifest ({e}); continuing without URLs.")
        return {}


def build(force: bool, local: bool):
    import os

    # A build must never trip the served-mode fail-fast.
    os.environ.pop("QDRANT_REQUIRE_DOCKER", None)
    if local:
        os.environ["QDRANT_FORCE_LOCAL"] = "1"

    from src.config.paths import PDF_DIR, URL_MANIFEST_PATH
    from src.cdms.document_loader import DocumentLoader

    if not PDF_DIR.exists():
        sys.exit(f"❌ PDF folder not found: {PDF_DIR}")

    pdfs = sorted(PDF_DIR.glob("*.pdf"))
    if not pdfs:
        sys.exit(f"❌ No PDFs in {PDF_DIR}")

    urls = load_url_manifest(URL_MANIFEST_PATH)
    missing_urls = [p.name for p in pdfs if p.name not in urls]

    loader = DocumentLoader(pdf_folder=str(PDF_DIR))
    if loader.embedding_service is None:
        sys.exit("❌ OpenAI embeddings unavailable (check OPENAI_API_KEY in .env).")
    if loader.vector_store is None:
        sys.exit("❌ Qdrant vector store unavailable.")

    print(f"\n📚 Building index from {len(pdfs)} PDF(s) in {PDF_DIR}")
    print(f"   Mode: {'on-disk (local)' if local else 'Docker Qdrant'} | force={force}")
    print("-" * 70)

    results = []
    for pdf in pdfs:
        res = loader.load_pdf(str(pdf), force_reprocess=force, pdf_url=urls.get(pdf.name))
        results.append((pdf.name, res))
        if res.get("skipped"):
            print(f"⏭️  {pdf.name}: already processed (use --force to rebuild)")
        elif res.get("success"):
            print(f"✅ {pdf.name}: {res.get('chunks_stored', 0)} chunks, "
                  f"{res.get('embeddings_generated', 0)} embeddings")
        else:
            print(f"❌ {pdf.name}: {res.get('error', 'failed')}")

    if missing_urls:
        print(f"\n⚠️  {len(missing_urls)} PDF(s) have no URL in the manifest "
              f"(citations degrade to filename+page): {', '.join(missing_urls[:8])}"
              f"{' ...' if len(missing_urls) > 8 else ''}")

    return loader


def validate(loader) -> bool:
    """Assert PDFs == docs == distinct-Qdrant-docs and points == chunks."""
    from src.config.paths import PDF_DIR, DB_PATH
    from src.cdms.product_catalog import ProductCatalog

    print("\n" + "=" * 70)
    print("VALIDATION")
    print("=" * 70)

    n_pdfs = len(list(PDF_DIR.glob("*.pdf")))

    conn = sqlite3.connect(str(DB_PATH))
    n_docs = conn.execute("SELECT COUNT(*) FROM documents WHERE processed=1").fetchone()[0]
    n_chunks = conn.execute("SELECT COUNT(*) FROM document_chunks").fetchone()[0]
    per_pdf = conn.execute(
        """SELECT d.filename, COUNT(dc.id)
           FROM documents d LEFT JOIN document_chunks dc ON dc.document_id = d.id
           GROUP BY d.id ORDER BY d.filename"""
    ).fetchall()
    conn.close()

    zero_chunk = [fn for fn, n in per_pdf if n == 0]

    info = loader.vector_store.get_collection_info()
    points = info.get("cdms_documents", {}).get("points_count", None)

    print(f"  PDFs on disk .............. {n_pdfs}")
    print(f"  Documents (processed) ..... {n_docs}")
    print(f"  Chunks (SQLite) ........... {n_chunks}")
    print(f"  Points (Qdrant) ........... {points}")

    ok = True
    if n_docs != n_pdfs:
        print(f"  ⚠️  documents ({n_docs}) != PDFs ({n_pdfs}) — run with --force.")
        ok = False
    if points is not None and points != n_chunks:
        print(f"  ❌ Qdrant points ({points}) != SQLite chunks ({n_chunks}).")
        ok = False

    if zero_chunk:
        # Known-empty (corrupted / scanned) PDFs are expected, not failures.
        expected_empty = {"ACQUIT.pdf", "asenra_g.pdf"}
        unexpected = [z for z in zero_chunk if z not in expected_empty]
        print(f"  ℹ️  0-chunk PDFs ({len(zero_chunk)}): {', '.join(zero_chunk)}")
        print(f"     (expected-empty: {', '.join(sorted(expected_empty))} — corrupted/scanned)")
        if unexpected:
            print(f"  ⚠️  Unexpected 0-chunk PDFs (investigate): {', '.join(unexpected)}")

    products = sorted(ProductCatalog().available_products())
    print(f"\n  🟢 Answerable products ({len(products)}):")
    print("     " + ", ".join(products))

    print("\n  " + ("✅ VALIDATION PASSED" if ok else "❌ VALIDATION FAILED"))
    return ok


def export_snapshot(loader) -> bool:
    """Create + download a portable Qdrant snapshot into data/qdrant_snapshots/."""
    from src.config.paths import SNAPSHOT_DIR

    store = loader.vector_store
    if not store.using_docker:
        print("\n⚠️  Snapshot export skipped: build ran against the on-disk store, "
              "not Docker.\n   The server-format snapshot needs a Docker Qdrant. "
              "For a single-process deploy you may commit data/qdrant_local instead.")
        return False

    print("\n" + "=" * 70)
    print("SNAPSHOT EXPORT")
    print("=" * 70)
    try:
        snap = store.client.create_snapshot(collection_name="cdms_documents")
        name = snap.name
        print(f"  Created snapshot on server: {name}")

        import requests
        url = f"http://{store.host}:{store.port}/collections/cdms_documents/snapshots/{name}"
        resp = requests.get(url, timeout=120)
        resp.raise_for_status()

        SNAPSHOT_DIR.mkdir(parents=True, exist_ok=True)
        out = SNAPSHOT_DIR / "cdms_documents.snapshot"
        out.write_bytes(resp.content)
        mb = len(resp.content) / (1024 * 1024)
        print(f"  📦 Saved {mb:.1f} MB -> {out}")
        print("  Commit this file (Git LFS). Restore it at deploy with "
              "scripts/restore_snapshot.py.")
        return True
    except Exception as e:
        print(f"  ⚠️  Snapshot export failed ({e}).")
        print("     If the Qdrant container was started with "
              "'-v \"$PWD/data/qdrant_snapshots:/qdrant/snapshots\"', the .snapshot "
              "file is already on disk under data/qdrant_snapshots/.")
        return False


def main():
    ap = argparse.ArgumentParser(description="Build the committed CDMS index.")
    ap.add_argument("--force", action="store_true",
                    help="reprocess every PDF (required for the first real build)")
    ap.add_argument("--local", action="store_true",
                    help="build into the on-disk Qdrant instead of Docker (no snapshot)")
    ap.add_argument("--no-snapshot", action="store_true", help="skip snapshot export")
    args = ap.parse_args()

    loader = build(force=args.force, local=args.local)
    valid = validate(loader)
    if not args.local and not args.no_snapshot:
        export_snapshot(loader)

    sys.exit(0 if valid else 1)


if __name__ == "__main__":
    main()