# =============================================================================
# Projet : AIR — Accounting Intermediate Representation
# Auteur : Simon-Pierre Boucher
# Contact : contact@spboucher.ai
# Fichier : unit.py
# Description : CompilationUnit — the mutable state threaded through AIC passes.
# =============================================================================
"""The compilation unit: AIR document in, journal entries out.

Passes read the immutable AIR events and accumulate derived state here
(subtotals, tax lines, FX conversions, classifications), all anchored in the
provenance graph. The pass manager verifies the double-entry invariant on
`entries` after every pass.
"""
from __future__ import annotations

from dataclasses import dataclass, field

from aic.diagnostics import Diagnostic
from alsl.model import PolicySet
from core.events import AirDocument, EconomicEvent
from core.journal import JournalEntry
from core.money import Money
from core.provenance import ProvenanceGraph


@dataclass
class TaxLineState:
    """A computed tax amount for one event (transaction currency)."""

    code: str
    amount: Money
    node_id: str
    payable_role: str
    receivable_role: str
    recoverable: bool
    policy: str                       # name of the ALSL policy that produced it


@dataclass
class EventState:
    """Everything the passes derive for a single event."""

    # transaction-currency amounts
    subtotal: Money | None = None
    subtotal_node: str | None = None
    taxes: list[TaxLineState] = field(default_factory=list)

    # classification (purchases): account role for the debit side
    classify_as: str | None = None          # "asset" | "expense"
    classification_role: str | None = None
    classification_policy: str | None = None

    # functional-currency amounts, ready for posting (set by the FX pass)
    post_subtotal: Money | None = None
    post_subtotal_node: str | None = None
    post_taxes: list[TaxLineState] = field(default_factory=list)

    # settlement FX difference (payments): + = more functional units than booked
    fx_diff: Money | None = None
    fx_diff_node: str | None = None
    booked_amount: Money | None = None      # functional value at booking rate


@dataclass
class CompilationUnit:
    document: AirDocument
    policies: PolicySet
    provenance: ProvenanceGraph = field(default_factory=ProvenanceGraph)
    state: dict[str, EventState] = field(default_factory=dict)
    entries: list[JournalEntry] = field(default_factory=list)
    diagnostics: list[Diagnostic] = field(default_factory=list)

    def event_state(self, event_id: str) -> EventState:
        return self.state.setdefault(event_id, EventState())

    def find_event(self, event_id: str) -> EconomicEvent | None:
        for event in self.document.events:
            if event.id == event_id:
                return event
        return None