#!/usr/bin/env python3
"""Time-aware declaration matching over the FIAM query index."""
from __future__ import annotations
import json

ALLOWED_RELATIONS={
 'rpc':{'fiam.relation.uses','fiam.relation.client-of','fiam.relation.targets'},
 'http':{'fiam.relation.uses','fiam.relation.client-of','fiam.relation.targets'},
 'messaging':{'fiam.relation.uses','fiam.relation.targets','fiam.relation.appends-to','fiam.relation.watches'},
 'database':{'fiam.relation.uses','fiam.relation.reads-from','fiam.relation.writes-to','fiam.relation.targets','fiam.relation.appends-to','fiam.relation.watches'},
}

def canonical(conn,ref,at):
    if not ref:return ref
    r=conn.execute('SELECT preferred_ref FROM working_identity WHERE observed_ref=? AND snapshot_time<=? ORDER BY snapshot_time DESC LIMIT 1',(ref,at)).fetchone()
    return r[0] if r else ref

def latest_declared_exchanges(conn,population_id,at):
    rows=conn.execute("SELECT source_id,exchange_id,population_id,snapshot_time FROM exchange_documents WHERE mode='declared-snapshot' AND snapshot_time<=? AND (population_id IS NULL OR population_id=? ) ORDER BY source_id,snapshot_time DESC",(at,population_id)).fetchall()
    out={}
    for r in rows:
        if r['source_id'] not in out:out[r['source_id']]=r['exchange_id']
    return set(out.values())

def match_edge(conn,row,population_id,at):
    exchanges=latest_declared_exchanges(conn,population_id,at)
    if not exchanges:return {'declared':False,'matches':[],'reason':'no-effective-declaration-snapshot'}
    fr=canonical(conn,row['from_ref'],at)
    targets={canonical(conn,row['target_ref'],at)}
    if row['channel_ref']:targets.add(canonical(conn,row['channel_ref'],at))
    if 'intended_target' in row.keys() and row['intended_target']:targets.add(canonical(conn,row['intended_target'],at))
    rels=ALLOWED_RELATIONS.get(row['domain'],set().union(*ALLOWED_RELATIONS.values()))
    marks=','.join('?'*len(exchanges));params=list(exchanges)
    ds=conn.execute(f'SELECT * FROM declarations WHERE exchange_id IN ({marks})',params).fetchall()
    hits=[]
    for d in ds:
        if d['predicate'] not in rels:continue
        ds_from=canonical(conn,d['subject_owner'] or d['subject_ref'],at)
        if ds_from!=fr:continue
        cands={canonical(conn,d['object_ref'],at),canonical(conn,d['object_owner'],at)}
        common=targets & {x for x in cands if x}
        if not common:continue
        via='channel' if row['channel_ref'] and canonical(conn,row['channel_ref'],at) in common else 'intended-target' if ('intended_target' in row.keys() and row['intended_target'] and canonical(conn,row['intended_target'],at) in common) else 'target'
        hits.append({'declaration_id':d['declaration_id'],'predicate':d['predicate'],'matched_via':via,'matched_ref':sorted(common)[0],'source_id':d['source_id']})
    return {'declared':bool(hits),'matches':hits,'reason':'matched' if hits else 'no-matching-declaration'}