"""
Export the Narada knowledge graph to Neo4j Cypher format.

Generates two files:
  neo4j_nodes.cypher    — CREATE constraints + MERGE node statements
  neo4j_rels.cypher     — MERGE relationship statements

Import into Neo4j Aura (free tier, 50MB) or Desktop:
  neo4j-admin database import ...   OR paste into Neo4j Browser

Usage:
    PYTHONPATH=src/envs python scripts/export_neo4j.py
    PYTHONPATH=src/envs python scripts/export_neo4j.py --limit 5000
"""

from __future__ import annotations

import argparse
import os
import sys

# Make sure graph module is importable
_src = os.path.join(os.path.dirname(__file__), "..", "src", "envs")
if _src not in sys.path:
    sys.path.insert(0, _src)

from narada.graph import get_graph


def escape(s: str) -> str:
    return s.replace("\\", "\\\\").replace("'", "\\'").replace("\n", " ").replace("\r", "")


def export(limit: int) -> None:
    print("Loading graph...", flush=True)
    g = get_graph()
    nodes = list(g.nodes.items())
    if limit:
        nodes = nodes[:limit]

    node_ids = {nid for nid, _ in nodes}

    print(f"Exporting {len(nodes)} nodes...", flush=True)
    with open("neo4j_nodes.cypher", "w", encoding="utf-8") as f:
        f.write("// Narada knowledge graph — nodes\n")
        f.write("// Generated by scripts/export_neo4j.py\n\n")
        f.write("CREATE CONSTRAINT IF NOT EXISTS FOR (n:NaradaNode) REQUIRE n.id IS UNIQUE;\n\n")

        for nid, nd in nodes:
            label = nd.get("type", "unknown").capitalize()
            name = escape(nd.get("name", nid))
            desc = escape(nd.get("description", ""))[:200]
            f.write(
                f"MERGE (n:NaradaNode:{label} {{id: '{escape(nid)}'}}) "
                f"SET n.name = '{name}', n.description = '{desc}';\n"
            )

    print("Exporting relationships...", flush=True)
    rel_count = 0
    with open("neo4j_rels.cypher", "w", encoding="utf-8") as f:
        f.write("// Narada knowledge graph — relationships\n\n")
        for nid, _ in nodes:
            for neighbor in g.get_neighbors(nid):
                if neighbor in node_ids:
                    f.write(
                        f"MATCH (a:NaradaNode {{id: '{escape(nid)}'}}), "
                        f"(b:NaradaNode {{id: '{escape(neighbor)}'}}) "
                        f"MERGE (a)-[:CONNECTS]->(b);\n"
                    )
                    rel_count += 1

    print(f"Done. {len(nodes)} nodes, {rel_count} relationships.")
    print("Files: neo4j_nodes.cypher, neo4j_rels.cypher")
    print()
    print("To import into Neo4j Browser (Aura / Desktop):")
    print("  1. Open Neo4j Browser → run neo4j_nodes.cypher")
    print("  2. Run neo4j_rels.cypher")
    print("  3. MATCH (n:NaradaNode) RETURN n LIMIT 100  — to visualise")
    print()
    print("Useful Cypher queries:")
    print("  // Show 2-hop subgraph from a disease node")
    print("  MATCH p=(d:Disease)-[*1..2]-(x) WHERE d.name CONTAINS 'Marfan' RETURN p LIMIT 50")
    print()
    print("  // Find path from phenotype to variant")
    print("  MATCH p=shortestPath((ph:Phenotype {id:'HP:0001250'})-[*]-(v:Variant))")
    print("  RETURN p LIMIT 10")


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument("--limit", type=int, default=0, help="Node limit (0 = all)")
    args = parser.parse_args()
    export(args.limit)