"""Local passage retrieval and source-grounded claim validation."""
import json
import re
from pathlib import Path
from .schema import Evidence, ToolResult


def search_local(path, query, limit=8):
    """Rank source passages by query token overlap and retain complete records."""
    terms=set(re.findall(r"[a-z0-9]+",query.lower()))
    records=[Evidence.model_validate(json.loads(x)) for x in Path(path).read_text().splitlines() if x.strip()]
    scored=[(len(terms & set(re.findall(r"[a-z0-9]+",r.passage.lower()+" "+r.claim.lower()))),r) for r in records]
    return [r for s,r in sorted(scored,key=lambda x:(-x[0],x[1].id))[:limit] if s>0]


def retrieval_tool(path):
    def run(arguments,state):
        records=search_local(path,arguments["query"],int(arguments.get("limit",8)))
        return ToolResult(evidence=records,message=f"Retrieved {len(records)} source records")
    return run


def validate_claim(evidence: Evidence, source_text: str):
    """Require the stored passage to occur verbatim in its retained source."""
    if evidence.passage not in source_text:
        raise ValueError("evidence passage is absent from the source snapshot")
    return evidence