"""
maintenance/agent.py — Maintenance Agent: detects broken links, orphaned documents, stale content.
"""

from __future__ import annotations

import logging
from datetime import datetime, timezone, timedelta

from base_agent import BaseAgent

logger = logging.getLogger('agent.maintenance')


class MaintenanceAgent(BaseAgent):
    agent_type = 'maintenance'

    async def process(self, job_id: str, payload: dict) -> dict:
        report = {}

        async with self.pool.acquire() as conn:
            # 1. Broken WikiLinks (target_doc_id is NULL but target_path exists)
            broken_links = await conn.fetchval(
                """
                SELECT COUNT(*) FROM relations
                WHERE relation_type = 'wikilink' AND target_doc_id IS NULL
                """
            )
            report['broken_wikilinks'] = broken_links

            # 2. Orphaned documents (no incoming links and no outgoing links)
            orphans = await conn.fetch(
                """
                SELECT d.id::text, d.title, d.path
                FROM documents d
                WHERE NOT EXISTS (
                    SELECT 1 FROM relations r WHERE r.target_doc_id = d.id
                )
                AND NOT EXISTS (
                    SELECT 1 FROM relations r WHERE r.source_doc_id = d.id
                )
                LIMIT 20
                """
            )
            report['orphaned_documents'] = len(orphans)
            report['orphan_paths'] = [r['path'] for r in orphans]

            # 3. Documents not re-indexed in >7 days
            stale_cutoff = datetime.now(timezone.utc) - timedelta(days=7)
            stale_count = await conn.fetchval(
                'SELECT COUNT(*) FROM documents WHERE indexed_at < $1 OR indexed_at IS NULL',
                stale_cutoff,
            )
            report['stale_documents'] = stale_count

            # 4. Documents with chunks but no embeddings
            missing_embeddings = await conn.fetchval(
                'SELECT COUNT(*) FROM chunks WHERE embedding IS NULL'
            )
            report['chunks_missing_embeddings'] = missing_embeddings

            # 5. Resolve previously broken WikiLinks that now have matching docs
            resolved = await conn.execute(
                """
                UPDATE relations r
                SET target_doc_id = d.id
                FROM documents d
                WHERE r.target_doc_id IS NULL
                  AND r.relation_type = 'wikilink'
                  AND (d.path LIKE '%' || r.target_path || '%'
                    OR d.title = r.target_path
                    OR r.target_path = ANY(d.aliases))
                """
            )
            report['wikilinks_resolved'] = int(resolved.split()[-1])

        logger.info('Maintenance report: %s', report)
        return report