# topology_api/queries/snapshot_queries.py
"""Snapshot resolution and data fetching logic."""
from topology_api.db import read_cursor


def resolve_snapshot_time(requested_mission=None, requested_at=None):
    """Determine the snapshot timestamp per spec.

    Returns: (snapshot_at: str | None, anchor_source: str)
    """
    with read_cursor() as cur:
        if requested_at is not None:
            return requested_at, "explicit_time"

        if requested_mission is not None:
            cur.execute("""
                SELECT id, occurrence_status
                FROM missions
                WHERE code = %(code)s
            """, {"code": requested_mission})
            mission = cur.fetchone()
            if mission is None:
                return None, "mission_not_found"

            cur.execute("""
                SELECT effective_at
                FROM mission_events
                WHERE mission_id = %(mid)s
                ORDER BY effective_at DESC, event_order DESC
                LIMIT 1
            """, {"mid": mission["id"]})
            event = cur.fetchone()
            if event is None:
                return None, "mission_has_no_timed_event"

            return event["effective_at"].isoformat(), "mission_latest_event"

        # Neither provided: latest event across all occurred missions
        cur.execute("""
            SELECT me.effective_at
            FROM mission_events me
            JOIN missions m ON m.id = me.mission_id
            WHERE m.occurrence_status = 'occurred'
            ORDER BY me.effective_at DESC, me.event_order DESC
            LIMIT 1
        """)
        event = cur.fetchone()
        if event is None:
            return None, "no_events"
        return event["effective_at"].isoformat(), "latest_recorded_state"


def fetch_snapshot(snapshot_at):
    """Fetch complete base topology at a given point in time.

    Returns dict with keys: base, components, connections
    """
    result = {"base": None, "components": [], "connections": []}
    params = {"at": snapshot_at}

    with read_cursor() as cur:
        # --- base ---
        cur.execute("SELECT code, name FROM bases WHERE code = 'guanghan'")
        base = cur.fetchone()
        if base is None:
            return result
        result["base"] = dict(base)

        # --- components present at snapshot_at ---
        cur.execute("""
            SELECT
                c.id,
                c.component_key,
                c.component_type,
                cv.display_name,
                cv.summary,
                cv.description,
                cv.length_m,
                cv.width_m,
                cv.height_m,
                cv.diameter_m,
                cv.mass_t,
                cv.detail_url,
                cv.properties
            FROM components c
            JOIN mission_events e_intro
                ON e_intro.id = c.introduced_by_event_id
            LEFT JOIN mission_events e_retire
                ON e_retire.id = c.retired_by_event_id
            LEFT JOIN LATERAL (
                SELECT cv_sub.*
                FROM component_versions cv_sub
                WHERE cv_sub.component_id = c.id
                  AND cv_sub.valid_from <= %(at)s::timestamptz
                  AND (cv_sub.valid_to IS NULL OR %(at)s::timestamptz < cv_sub.valid_to)
                ORDER BY cv_sub.valid_from DESC
                LIMIT 1
            ) cv ON true
            WHERE c.base_id = (SELECT id FROM bases WHERE code = 'guanghan')
              AND e_intro.effective_at <= %(at)s::timestamptz
              AND (c.retired_by_event_id IS NULL
                   OR (SELECT effective_at FROM mission_events WHERE id = c.retired_by_event_id) > %(at)s::timestamptz)
            ORDER BY c.component_key
        """, params)
        component_rows = cur.fetchall()

        component_map = {}
        for row in component_rows:
            comp = {
                "key": row["component_key"],
                "type": row["component_type"],
                "name": row["display_name"],
                "summary": row["summary"],
                "description": row["description"],
                "detailUrl": row["detail_url"],
                "dimensions": {},
                "properties": row["properties"] or {},
                "ports": [],
                "states": {},
            }
            for dim in ["length_m", "width_m", "height_m", "diameter_m"]:
                val = row[dim]
                if val is not None:
                    comp["dimensions"][dim.replace("_m", "M")] = float(val)
            if row["mass_t"] is not None:
                comp["dimensions"]["massT"] = float(row["mass_t"])
            result["components"].append(comp)
            component_map[row["id"]] = comp

        if not component_map:
            return result

        # --- ports ---
        component_ids = tuple(component_map.keys())
        cur.execute("""
            SELECT id, component_id, port_key, display_name, direction, interface_type
            FROM ports
            WHERE component_id IN %(ids)s
            ORDER BY component_id, port_key
        """, {"ids": component_ids})
        port_map = {}
        for row in cur.fetchall():
            port = {
                "key": row["port_key"],
                "displayName": row["display_name"],
                "direction": row["direction"],
                "interfaceType": row["interface_type"],
            }
            cid = row["component_id"]
            if cid in component_map:
                component_map[cid]["ports"].append(port)
            port_map[row["id"]] = {
                "component_key": component_map.get(cid, {}).get("key"),
                **port,
            }

        # --- states ---
        cur.execute("""
            SELECT component_id, state_kind, state_value, details
            FROM component_states
            WHERE component_id IN %(ids)s
              AND valid_from <= %(at)s::timestamptz
              AND (valid_to IS NULL OR %(at)s::timestamptz < valid_to)
            ORDER BY component_id, state_kind
        """, {"ids": component_ids, "at": snapshot_at})
        for row in cur.fetchall():
            comp = component_map.get(row["component_id"])
            if comp:
                comp["states"][row["state_kind"]] = row["state_value"]
                if row["details"]:
                    comp["states"][row["state_kind"] + "Details"] = row["details"]

        # --- connections ---
        cur.execute("""
            SELECT
                tc.connection_type,
                tc.properties,
                pa.component_id AS comp_a_id,
                pa.port_key AS port_a_key,
                pb.component_id AS comp_b_id,
                pb.port_key AS port_b_key
            FROM topology_connections tc
            JOIN ports pa ON pa.id = tc.port_a_id
            JOIN ports pb ON pb.id = tc.port_b_id
            WHERE tc.base_id = (SELECT id FROM bases WHERE code = 'guanghan')
              AND tc.valid_from <= %(at)s::timestamptz
              AND (tc.valid_to IS NULL OR %(at)s::timestamptz < tc.valid_to)
              AND pa.component_id IN %(ids)s
              AND pb.component_id IN %(ids)s
            ORDER BY tc.connection_type, pa.port_key
        """, {"ids": component_ids, "at": snapshot_at})
        for row in cur.fetchall():
            comp_a = component_map.get(row["comp_a_id"])
            comp_b = component_map.get(row["comp_b_id"])
            if comp_a and comp_b:
                result["connections"].append({
                    "type": row["connection_type"],
                    "fromPort": f"{comp_a['key']}.{row['port_a_key']}",
                    "toPort": f"{comp_b['key']}.{row['port_b_key']}",
                    "properties": row["properties"],
                })

    return result