"""Separate, version-bound Neo4j content graph; never clears the metadata graph."""
from __future__ import annotations

import json
from pathlib import Path
from tools.knowledge.sources import identifier
from tools.graphrag.graph_db import create_neo4j_driver, get_neo4j_settings
from tools.answer_evaluation.context_policy import normalized

SCOPE = 'zpwiki-content-v1'


def write_graph(index: dict) -> None:
    settings = get_neo4j_settings()
    rows = []
    for unit in index['units']:
        rows.append({**{k: v for k, v in unit.items() if k not in {'concepts', 'relations'}},
                     'concepts': [{'id': identifier(normalized(c)), 'name': c} for c in unit['concepts']],
                     'relations_json': json.dumps(unit['relations'], ensure_ascii=False)})
    with create_neo4j_driver(settings) as driver, driver.session(database=settings.database) as session:
        driver.verify_connectivity()
        for name,label,field in [('evidence','KnowledgeEvidence','id'),('concept','KnowledgeConcept','id'),
                                 ('person','KnowledgePerson','source_path')]:
            session.run(f'CREATE CONSTRAINT zp_content_{name} IF NOT EXISTS '
                        f'FOR (n:{label}) REQUIRE (n.graph_scope,n.{field}) IS UNIQUE').consume()
        session.run('CREATE CONSTRAINT zp_content_state IF NOT EXISTS '
                    'FOR (n:KnowledgeState) REQUIRE n.scope IS UNIQUE').consume()
        with session.begin_transaction() as tx:
            tx.run('MATCH (n:KnowledgeRelation {graph_scope:$scope}) DETACH DELETE n', scope=SCOPE).consume()
            tx.run('MATCH (n:KnowledgeEvidence {graph_scope:$scope}) DETACH DELETE n', scope=SCOPE).consume()
            tx.run('MATCH (n:KnowledgeConcept {graph_scope:$scope}) DETACH DELETE n', scope=SCOPE).consume()
            tx.run('MATCH (n:KnowledgePerson {graph_scope:$scope}) DETACH DELETE n', scope=SCOPE).consume()
            # Copy only scalar evidence properties. Dynamic labels/Cypher from
            # the model are never executed; all relationships have fixed types.
            evidence_rows = [{'evidence': {k:v for k,v in row.items() if k != 'concepts'} | {'graph_scope':SCOPE},
                              'concepts':row['concepts']} for row in rows]
            tx.run('''UNWIND $rows AS row
                    CREATE (e:KnowledgeEvidence) SET e=row.evidence
                    MERGE (p:KnowledgePerson {source_path:row.evidence.source_path,graph_scope:$scope})
                    SET p.name=row.evidence.person
                    MERGE (p)-[:HAS_EVIDENCE]->(e)
                    FOREACH (concept IN row.concepts |
                        MERGE (c:KnowledgeConcept {id:concept.id,graph_scope:$scope})
                        SET c.name=concept.name MERGE (e)-[:ABOUT]->(c))''',rows=evidence_rows,scope=SCOPE).consume()
            relations = [{'left':identifier(normalized(r['subject'])), 'right':identifier(normalized(r['object'])),
                          'evidence':row['id'], 'predicate':r['predicate']}
                         for row in rows for r in json.loads(row['relations_json'])]
            tx.run('''UNWIND $rows AS row
                MATCH (a:KnowledgeConcept {id:row.left,graph_scope:$scope}),
                      (b:KnowledgeConcept {id:row.right,graph_scope:$scope}),
                      (e:KnowledgeEvidence {id:row.evidence,graph_scope:$scope})
                CREATE (r:KnowledgeRelation {graph_scope:$scope,predicate:row.predicate,origin:'llm'})
                CREATE (r)-[:SUBJECT]->(a), (r)-[:OBJECT]->(b), (r)-[:EVIDENCED_BY]->(e)''',
                rows=relations,scope=SCOPE).consume()
            tx.run('MERGE (s:KnowledgeState {scope:$scope}) SET s.version=$version',
                   scope=SCOPE, version=index['version']).consume()
            tx.commit()


def read_graph(index: dict) -> list[dict]:
    settings = get_neo4j_settings()
    with create_neo4j_driver(settings) as driver, driver.session(database=settings.database) as session:
        with session.begin_transaction() as tx:
            state = tx.run('MATCH (s:KnowledgeState {scope:$scope}) RETURN s.version AS version', scope=SCOPE).single()
            if not state or state['version'] != index['version']:
                raise RuntimeError('Content graph and extraction checkpoint differ.')
            rows = tx.run('''MATCH (p:KnowledgePerson {graph_scope:$scope})-[:HAS_EVIDENCE]->(e)
                OPTIONAL MATCH (e)-[:ABOUT]->(c:KnowledgeConcept)
                RETURN properties(e) AS evidence, collect(c.name) AS concepts ORDER BY evidence.source_path,evidence.line''', scope=SCOPE)
            result = [{**dict(r['evidence']), 'concepts': list(r['concepts'])} for r in rows]
            tx.commit()
            return result


def load_index(data_dir: Path, version: dict | None) -> dict | None:
    path = data_dir / 'knowledge/index.json'
    if not path.exists():
        return None
    index = json.loads(path.read_text())
    if not version or index.get('index_version') != version:
        raise RuntimeError('Content extraction belongs to another source snapshot. Rebuild it.')
    return index