"""Decision qualification engine.

Pure functions — no database, no I/O.
Takes a QualificationInput + QualificationConfig and returns a QualificationResult.

LLM integration (suggest_modalities_from_context) is stubbed pending local Qwen deployment.
"""

from __future__ import annotations

from dataclasses import dataclass, field
from enum import Enum


class DecisionType(str, Enum):
    INDIVIDUAL = "individual"
    COLLECTIVE = "collective"


# ---------------------------------------------------------------------------
# Configuration (thresholds — stored as a QualificationProtocol in DB)
# ---------------------------------------------------------------------------


@dataclass
class QualificationConfig:
    """Configurable thresholds for the qualification engine.

    These defaults will be seeded as a QualificationProtocol record so they
    can be adjusted through the admin interface without code changes.

    individual_max:      affected_count <= this → always individual
    small_group_max:     affected_count <= this → individual recommended, collective available
    collective_wot_min:  affected_count > this  → collective required (WoT formula applies)

    Default modalities shown when collective is chosen (ordered by relevance).
    """
    individual_max: int = 1
    small_group_max: int = 5
    collective_wot_min: int = 50

    default_modalities: list[str] = field(default_factory=lambda: [
        "vote_wot",
        "vote_smith",
        "consultation_avis",
        "election",
    ])


# ---------------------------------------------------------------------------
# Input / Output
# ---------------------------------------------------------------------------


@dataclass
class QualificationInput:
    within_mandate: bool = False
    affected_count: int | None = None
    is_structural: bool = False
    context_description: str | None = None  # reserved for LLM suggestion


@dataclass
class QualificationResult:
    decision_type: DecisionType
    process: str
    recommended_modalities: list[str]
    recommend_onchain: bool
    confidence: str          # "required" | "recommended" | "optional"
    collective_available: bool
    reasons: list[str]
    onchain_reason: str | None = None


# ---------------------------------------------------------------------------
# LLM stub
# ---------------------------------------------------------------------------


def suggest_modalities_from_context(
    context: str,
    config: QualificationConfig,
) -> list[str]:
    """Suggest voting modalities based on a natural-language context description.

    Stub — returns empty list until local Qwen (qwen3.6) is integrated.
    When implemented, this will call the LLM API and return an ordered list
    of modality slugs from config.default_modalities.
    """
    return []


# ---------------------------------------------------------------------------
# Core engine
# ---------------------------------------------------------------------------


def qualify(inp: QualificationInput, config: QualificationConfig) -> QualificationResult:
    """Qualify a decision and recommend a type, process, and modalities.

    Rules (in priority order):
      R1/R2  within_mandate → individual + consultation_avis, no modalities
      R3     affected_count == 1 → individual + personal
      R4     affected_count ≤ small_group_max → individual recommended, collective available
      R5     small_group_max < affected_count ≤ collective_wot_min → collective recommended
      R6     affected_count > collective_wot_min → collective required (WoT)
      R7/R8  is_structural → recommend_onchain with reason
    """
    reasons: list[str] = []

    # ── R1/R2: mandate scope overrides everything ───────────────────────────
    if inp.within_mandate:
        reasons.append("Décision dans le périmètre d'un mandat existant.")
        return QualificationResult(
            decision_type=DecisionType.INDIVIDUAL,
            process="consultation_avis",
            recommended_modalities=[],
            recommend_onchain=_onchain(inp, reasons),
            confidence="required",
            collective_available=False,
            reasons=reasons,
            onchain_reason=_onchain_reason(inp),
        )

    count = inp.affected_count if inp.affected_count is not None else 1

    # ── R3: single person ───────────────────────────────────────────────────
    if count <= config.individual_max:
        reasons.append("Une seule personne concernée.")
        return QualificationResult(
            decision_type=DecisionType.INDIVIDUAL,
            process="personal",
            recommended_modalities=[],
            recommend_onchain=_onchain(inp, reasons),
            confidence="required",
            collective_available=False,
            reasons=reasons,
            onchain_reason=_onchain_reason(inp),
        )

    # ── R4: small group → individual recommended, collective available ───────
    if count <= config.small_group_max:
        reasons.append(
            f"{count} personnes concernées : décision individuelle recommandée, "
            "vote collectif possible."
        )
        modalities = _collect_modalities(inp, config)
        return QualificationResult(
            decision_type=DecisionType.INDIVIDUAL,
            process="personal",
            recommended_modalities=[],
            recommend_onchain=_onchain(inp, reasons),
            confidence="recommended",
            collective_available=True,
            reasons=reasons,
            onchain_reason=_onchain_reason(inp),
        )

    # ── R5/R6: medium or large group → collective ────────────────────────────
    modalities = _collect_modalities(inp, config)

    if count <= config.collective_wot_min:
        reasons.append(
            f"{count} personnes concernées : vote collectif recommandé."
        )
        confidence = "recommended"
    else:
        reasons.append(
            f"{count} personnes concernées : vote collectif obligatoire "
            "(formule WoT applicable)."
        )
        confidence = "required"
        if "vote_wot" not in modalities:
            modalities = ["vote_wot"] + modalities

    return QualificationResult(
        decision_type=DecisionType.COLLECTIVE,
        process="vote_collective",
        recommended_modalities=modalities,
        recommend_onchain=_onchain(inp, reasons),
        confidence=confidence,
        collective_available=True,
        reasons=reasons,
        onchain_reason=_onchain_reason(inp),
    )


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------


def _onchain(inp: QualificationInput, reasons: list[str]) -> bool:
    if inp.is_structural:
        reasons.append(
            "Décision structurante : gravure on-chain recommandée "
            "(a force de loi ou déclenche une action machine)."
        )
    return inp.is_structural


def _onchain_reason(inp: QualificationInput) -> str | None:
    if not inp.is_structural:
        return None
    return (
        "Cette décision est structurante : elle a valeur de loi au sein de la "
        "communauté ou déclenche une action machine (ex : runtime upgrade). "
        "La gravure on-chain (IPFS + system.remark) garantit son immuabilité "
        "et sa vérifiabilité publique."
    )


def _collect_modalities(
    inp: QualificationInput,
    config: QualificationConfig,
) -> list[str]:
    """Combine default modalities with any LLM suggestions (stub for now)."""
    llm_suggestions = []
    if inp.context_description:
        llm_suggestions = suggest_modalities_from_context(inp.context_description, config)

    seen: set[str] = set()
    result: list[str] = []
    for m in llm_suggestions + config.default_modalities:
        if m not in seen:
            seen.add(m)
            result.append(m)
    return result