"""Full simulation tick — the autonomous world engine."""

from __future__ import annotations

import json
import random
from collections import defaultdict
from datetime import datetime

from ai.events import generate_dream_fragment, generate_world_event, update_entity_memory
from ai.interaction import generate_interaction
from world.book_of_ages import create_entry
from world.database import db_session
from world.entities import (
    get_active_entities,
    increment_days_in_realm,
    increment_interaction_count,
    update_memory,
)
from world.events import create_interaction, create_world_event
from world.locations import get_all_locations, get_location_by_id, update_entity_counts
from world.relationships import upsert_relationship
from world.quests import get_entities_with_quests, complete_quest
from simulation.lifecycle import process_lifecycle_updates
from simulation.location_effects import (
    apply_moon_market_memory_trade,
    process_library_memory_fragments,
    process_mirror_contradictions,
)


EMBER_CROSSROADS_SLUG = "crossroads"


def execute_simulation_tick() -> dict:
    """Run one complete simulation tick. Returns summary."""
    from world.database import ensure_database_ready

    ensure_database_ready()

    summary = {
        "world_event": None,
        "world_event_title": None,
        "interactions": 0,
        "interactions_run": 0,
        "memories_updated": 0,
        "milestones": [],
        "day": None,
    }

    with db_session() as conn:
        world = conn.execute("SELECT * FROM world_state WHERE id = 1").fetchone()
        world_day = world["current_day"]

    increment_days_in_realm()

    try:
        event_result = generate_world_event(world_day)
        event_id = create_world_event(event_result.model_dump(), world_day)
        create_entry(
            world_day=world_day,
            entry_type="world_event",
            content=event_result.book_of_ages_entry,
            title=event_result.title,
            is_milestone=False,
        )
        summary["world_event"] = event_result.title
        summary["world_event_title"] = event_result.title
        current_event = {
            "title": event_result.title,
            "description": event_result.description,
            "affected_locations": event_result.affected_locations,
        }
    except Exception as e:
        current_event = None
        summary["world_event"] = f"failed: {e}"

    active_entities = get_active_entities()
    entities_by_location = defaultdict(list)
    for e in active_entities:
        entities_by_location[e["location_id"]].append(e)

    # Load active quests so they can influence interactions
    active_quests = get_entities_with_quests()

    pairs = _select_interaction_pairs(
        entities_by_location, active_entities, num_pairs=random.randint(2, 4)
    )
    interacted_entities: dict[str, list[str]] = defaultdict(list)
    moon_market_pairs: list[tuple[dict, dict]] = []
    seen_pairs: set[tuple[str, str]] = set()

    for entity_a, entity_b, meet_location_id in pairs:
        if entity_a["id"] == entity_b["id"]:
            continue

        pair_key = tuple(sorted((entity_a["id"], entity_b["id"])))
        if pair_key in seen_pairs:
            continue
        seen_pairs.add(pair_key)

        location = get_location_by_id(meet_location_id)
        if not location:
            continue

        try:
            # Inject quest context into entity data if they have active quests
            ea_with_quest = dict(entity_a)
            eb_with_quest = dict(entity_b)
            if entity_a["id"] in active_quests:
                q = active_quests[entity_a["id"]]
                ea_with_quest["active_quest"] = q["title"]
            if entity_b["id"] in active_quests:
                q = active_quests[entity_b["id"]]
                eb_with_quest["active_quest"] = q["title"]

            result = generate_interaction(ea_with_quest, eb_with_quest, location, current_event)

            create_interaction(
                entity_a["id"],
                entity_b["id"],
                location["id"],
                result.model_dump(),
                world_day,
            )

            create_entry(
                world_day=world_day,
                entry_type="interaction",
                content=result.book_of_ages_entry,
                entity_ids=[entity_a["id"], entity_b["id"]],
                location_id=location["id"],
            )

            upsert_relationship(
                entity_a["id"],
                entity_b["id"],
                result.relationship_change,
                result.new_relationship_description,
                world_day,
            )

            increment_interaction_count(entity_a["id"])
            increment_interaction_count(entity_b["id"])

            interacted_entities[entity_a["id"]].append(result.entity_a_memory_addition)
            interacted_entities[entity_b["id"]].append(result.entity_b_memory_addition)

            if location.get("slug") == "moon-market":
                moon_market_pairs.append((entity_a, entity_b))

            summary["interactions"] += 1
            summary["interactions_run"] = summary["interactions"]
        except Exception:
            continue

    for entity_id, memory_additions in interacted_entities.items():
        from world.entities import get_entity
        entity = get_entity(entity_id)
        if not entity:
            continue

        world_events_for_entity = []
        if current_event and entity:
            loc = get_location_by_id(entity["location_id"])
            if loc and loc["name"] in (current_event.get("affected_locations") or []):
                world_events_for_entity.append(current_event["description"])

        try:
            new_memory = update_entity_memory(
                entity,
                memory_additions,
                world_events_for_entity,
            )
            update_memory(entity_id, new_memory)
            summary["memories_updated"] += 1
        except Exception:
            pass

    for entity_a, entity_b in moon_market_pairs:
        from world.entities import get_entity
        ea = get_entity(entity_a["id"])
        eb = get_entity(entity_b["id"])
        if not ea or not eb:
            continue
        ma, mb = apply_moon_market_memory_trade(
            ea, eb, "moon-market",
            ea.get("memory_summary") or "",
            eb.get("memory_summary") or "",
        )
        update_memory(ea["id"], ma)
        update_memory(eb["id"], mb)

    _process_dream_fragments(world_day)
    summary["library_fragments"] = process_library_memory_fragments(world_day)
    summary["mirror_contradictions"] = process_mirror_contradictions(world_day)
    milestones = process_lifecycle_updates(world_day)
    summary["milestones"] = milestones

    with db_session() as conn:
        conn.execute(
            """
            UPDATE world_state SET
                current_day = current_day + 1,
                last_simulation_run = ?,
                updated_at = datetime('now')
            WHERE id = 1
            """,
            (datetime.now().isoformat(),),
        )

    update_entity_counts()

    # Get updated world day for summary
    with db_session() as conn:
        ws = conn.execute("SELECT current_day FROM world_state WHERE id=1").fetchone()
        summary["day"] = ws["current_day"] if ws else "?"

    try:
        from persistence.backup import backup_database
        backup_database()
    except Exception:
        pass

    return summary


def _select_interaction_pairs(
    entities_by_location: dict,
    active_entities: list[dict] | None = None,
    num_pairs: int = 3,
) -> list[tuple]:
    """Select distinct, fresh entity pairs to interact this tick.

    Two kinds of encounters are possible:

    * **Within a place** — two souls that share a location simply meet.
    * **At the Ember Crossroads** — "every road eventually passes through the
      Crossroads", so each tick a rotating set of souls from anywhere in the
      Realm travels through it and can meet whoever else is passing. This keeps
      the hub lively and stops history from looping on the same co-located pair.

    Each returned tuple is ``(entity_a, entity_b, meet_location_id)``.
    """
    locations = get_all_locations()
    loc_by_id = {loc["id"]: loc for loc in locations}
    crossroads = next((l for l in locations if l["slug"] == EMBER_CROSSROADS_SLUG), None)
    crossroads_id = crossroads["id"] if crossroads else None
    recent = _recently_interacted_pairs()

    # candidate -> (entity_a, entity_b, meet_location_id, weight)
    candidates: dict[tuple[str, str], tuple] = {}

    def _consider(a: dict, b: dict, meet_id: int, base_weight: float) -> None:
        key = tuple(sorted((a["id"], b["id"])))
        freshness = 0.12 if key in recent else 1.0
        weight = base_weight * freshness
        # Keep the higher-weighted venue if the pair could meet in two places.
        if key not in candidates or candidates[key][3] < weight:
            candidates[key] = (a, b, meet_id, weight)

    # 1. Souls that already share a place.
    for loc_id, entities in entities_by_location.items():
        if len(entities) < 2:
            continue
        loc = loc_by_id.get(loc_id)
        base = loc["interaction_multiplier"] if loc else 1.0
        for i in range(len(entities)):
            for j in range(i + 1, len(entities)):
                _consider(entities[i], entities[j], loc_id, base)

    # 2. The Crossroads convergence: residents + a rotating set of travellers.
    if crossroads_id and active_entities:
        residents = [e for e in active_entities if e["location_id"] == crossroads_id]
        travellers_pool = [e for e in active_entities if e["location_id"] != crossroads_id]
        random.shuffle(travellers_pool)
        travellers = travellers_pool[: random.randint(3, 5)]
        gathering = residents + travellers
        for i in range(len(gathering)):
            for j in range(i + 1, len(gathering)):
                # Crossroads meetings are weighted up (the lively hub) but a
                # touch below same-place pairs at their home so places still matter.
                _consider(gathering[i], gathering[j], crossroads_id, 2.0)

    if not candidates:
        return []

    selected: list[tuple] = []
    pool = list(candidates.values())
    attempts = 0
    while pool and len(selected) < num_pairs and attempts < num_pairs * 10:
        attempts += 1
        weights = [c[3] for c in pool]
        chosen = random.choices(pool, weights=weights, k=1)[0]
        a, b, meet_id, _ = chosen
        selected.append((a, b, meet_id))
        chosen_key = tuple(sorted((a["id"], b["id"])))
        pool = [c for c in pool if tuple(sorted((c[0]["id"], c[1]["id"]))) != chosen_key]

    return selected


def _recently_interacted_pairs(within_days: int = 2) -> set[tuple[str, str]]:
    """Pairs that have interacted within the last `within_days` world-days."""
    with db_session() as conn:
        current_day = conn.execute(
            "SELECT current_day FROM world_state WHERE id = 1"
        ).fetchone()["current_day"]
        rows = conn.execute(
            "SELECT entity_a_id, entity_b_id FROM interactions WHERE world_day >= ?",
            (current_day - within_days,),
        ).fetchall()
    return {tuple(sorted((r["entity_a_id"], r["entity_b_id"]))) for r in rows}


def _process_dream_fragments(world_day: int) -> None:
    with db_session() as conn:
        rows = conn.execute(
            """
            SELECT e.* FROM entities e
            JOIN locations l ON e.location_id = l.id
            WHERE e.status = 'dormant' AND l.slug = 'valley'
            """
        ).fetchall()

    for row in rows:
        entity = dict(row)
        entity["personality_traits"] = json.loads(entity["personality_traits"])
        last_active = datetime.fromisoformat(entity["last_active"])
        days_dormant = (datetime.now() - last_active).days

        if days_dormant >= 7 and random.random() < 0.3:
            try:
                fragment = generate_dream_fragment(entity, days_dormant)
                content = f'*From the dreams of {entity["name"]}: {fragment}*'
                create_entry(
                    world_day=world_day,
                    entry_type="dream_fragment",
                    content=content,
                    entity_ids=[entity["id"]],
                )
            except Exception:
                pass