"""Generator strategies and registry."""
from __future__ import annotations

from collections.abc import Iterable
from typing import Any

from query_planning.domain import (
    GenerationRequest,
    GeneratorKind,
    GeneratorOutput,
    KnowledgeNeedDraft,
    QueryCandidate,
)
from query_planning.errors import UnsupportedGeneratorError
from query_planning.ports import QueryGenerator


def _candidate(value: Any, position: int, kind: GeneratorKind) -> QueryCandidate:
    if isinstance(value, QueryCandidate):
        if value.original_position == 0 and position:
            value.original_position = position
        return value
    if isinstance(value, str):
        return QueryCandidate(
            query_text=value,
            original_position=position,
            source_refs=[{"generator_kind": kind.value}],
        )
    if not isinstance(value, dict):
        return QueryCandidate(query_text="", original_position=position)
    source_refs = value.get("source_refs") or []
    if not source_refs:
        source_refs = [{"generator_kind": kind.value}]
    filter_reason = (
        value.get("filter_reason")
        if "filter_reason" in value
        else value.get("reason")
    )
    return QueryCandidate(
        query_text=str(value.get("query_text") or value.get("query") or ""),
        axes=dict(value.get("axes") or value.get("parts") or {}),
        priority=int(value.get("priority") or 0),
        original_position=int(value.get("original_position", position)),
        source_refs=[dict(ref) for ref in source_refs if isinstance(ref, dict)],
        knowledge_need_keys=[str(key) for key in value.get("knowledge_need_keys") or []],
        metadata=dict(value.get("metadata") or {}),
        filter_reason=filter_reason,
    )


def _need(value: Any) -> KnowledgeNeedDraft | None:
    if isinstance(value, KnowledgeNeedDraft):
        return value
    if not isinstance(value, dict):
        return None
    need_key = str(value.get("need_key") or "").strip()
    if not need_key:
        return None
    return KnowledgeNeedDraft(
        need_key=need_key,
        decision_context=str(value.get("decision_context") or ""),
        unknown_information=str(value.get("unknown_information") or ""),
        source_ref=dict(value.get("source_ref") or {}),
        priority=int(value.get("priority") or 0),
        metadata=dict(value.get("metadata") or {}),
    )


class _PayloadQueryGenerator:
    kind: GeneratorKind

    def generate(self, request: GenerationRequest) -> GeneratorOutput:
        raw_candidates: Iterable[Any] = request.payload.get("candidates") or ()
        candidates = tuple(_candidate(value, index, self.kind) for index, value in enumerate(raw_candidates))
        needs = tuple(
            need
            for raw in request.payload.get("knowledge_needs") or ()
            if (need := _need(raw)) is not None
        )
        return GeneratorOutput(
            candidates=candidates,
            knowledge_needs=needs,
            generator_config=dict(request.payload.get("generator_config") or {}),
        )


class CartesianQueryGenerator(_PayloadQueryGenerator):
    kind = GeneratorKind.CARTESIAN


class ManualQueryGenerator(_PayloadQueryGenerator):
    kind = GeneratorKind.MANUAL


class TopicTableQueryGenerator(_PayloadQueryGenerator):
    """Consumes candidates already derived from a topic snapshot by the LLM planner."""

    kind = GeneratorKind.TOPIC_TABLE


class QueryGeneratorRegistry:
    def __init__(self, generators: Iterable[QueryGenerator] = ()) -> None:
        self._generators: dict[GeneratorKind, QueryGenerator] = {}
        for generator in generators:
            self.register(generator)

    def register(self, generator: QueryGenerator) -> None:
        self._generators[generator.kind] = generator

    def get(self, kind: GeneratorKind) -> QueryGenerator:
        try:
            return self._generators[kind]
        except KeyError as exc:
            raise UnsupportedGeneratorError(f"query generator is not registered: {kind.value}") from exc


def default_generator_registry() -> QueryGeneratorRegistry:
    return QueryGeneratorRegistry(
        (CartesianQueryGenerator(), ManualQueryGenerator(), TopicTableQueryGenerator())
    )