# =============================================================================
# Projet : AIR — Accounting Intermediate Representation
# Auteur : Simon-Pierre Boucher
# Contact : contact@spboucher.ai
# Fichier : classification.py
# Description : Classification pass — applies ALSL classification policies (e.g. capitalization).
# =============================================================================
"""Classification pass.

Decides which account role receives the debit side of a Purchase
(expense vs capitalized asset) by evaluating ALSL classification policies —
e.g. "capitalize equipment purchases at or above the policy threshold".
Thresholds live in ALSL, never here.
"""
from __future__ import annotations

from aic.diagnostics import Diagnostic, Severity
from aic.passes.base import Pass
from aic.unit import CompilationUnit
from alsl.evaluator import applicable_classifications
from core.events import EventType


class ClassificationPass(Pass):
    name = "classification"

    def run(self, unit: CompilationUnit) -> list[Diagnostic]:
        diags: list[Diagnostic] = []
        for event in unit.document.events:
            if event.type is not EventType.PURCHASE:
                continue
            state = unit.event_state(event.id)
            if state.subtotal is None:
                continue  # validation already failed this event

            hits = applicable_classifications(unit.policies, event, state.subtotal)
            if not hits:
                continue
            if len(hits) > 1:
                diags.append(Diagnostic(
                    code="AIR-W300", severity=Severity.WARNING,
                    message=(
                        "multiple classification policies match: "
                        + ", ".join(p.name for p in hits)
                        + f"; applying '{hits[0].name}'"
                    ),
                    location=f"event {event.id}",
                    suggestion="tighten the policies' when-clauses so at most one matches",
                    origin_pass=self.name,
                ))
            policy = hits[0]
            state.classify_as = policy.classify_as
            state.classification_role = policy.account_role
            state.classification_policy = policy.name
        return diags