"""
AR roll-forward (movement) and ledger, built from the journal decomposition + payouts.

    Closing AR = Opening AR + Net Revenue − Payouts received
                (payouts are stored negative, so Closing = Opening + NetRev + received_payouts)

Net Revenue is the sum of the non-transfer journal lines. Gross Revenue is the Sales line
(product sales + shipping + gift-wrap). This ties to both the Journal Entry and the
settlement-based receivable.
"""
from __future__ import annotations


def compute_movement(journal: dict, received_payouts: float, all_payouts: float,
                     opening: float, settlement_closing: float | None = None,
                     currency: str = "USD") -> dict:
    periods = journal.get("periods", [])
    lines = journal.get("lines", [])
    n = len(periods)

    net_rev_per = [0.0] * n
    gross_per = [0.0] * n
    revenue_lines = []
    for ln in lines:
        if ln["key"] == "Transfer":
            continue
        for i in range(n):
            net_rev_per[i] += ln["values"][i]
        if ln["key"] == "Sales":
            for i in range(n):
                gross_per[i] += ln["values"][i]
        revenue_lines.append(ln)

    net_revenue = round(sum(net_rev_per), 2)
    gross_revenue = round(sum(gross_per), 2)
    closing = round(opening + net_revenue + received_payouts, 2)

    # Ledger (debits raise AR, credits reduce it)
    ledger = [{"period": "Opening", "description": "Previous month closing balance",
               "debit": None, "credit": None, "balance": round(opening, 2)}]
    bal = opening
    for i, p in enumerate(periods):
        bal += net_rev_per[i]
        ledger.append({"period": p["label"], "description": "Net revenue (accrued)",
                       "debit": round(net_rev_per[i], 2), "credit": None, "balance": round(bal, 2)})
    bal += received_payouts
    ledger.append({"period": "Settlement", "description": "Amazon payout received",
                   "debit": None, "credit": round(-received_payouts, 2), "balance": round(bal, 2)})
    ledger.append({"period": "Closing", "description": "Month-end receivable",
                   "debit": None, "credit": None, "balance": round(bal, 2)})

    diff_vs_settlement = (round(closing - settlement_closing, 2)
                          if settlement_closing is not None else None)

    return {
        "currency": currency,
        "opening": round(opening, 2),
        "gross_revenue": gross_revenue,
        "net_revenue": net_revenue,
        "net_revenue_per_period": [round(x, 2) for x in net_rev_per],
        "total_receivable": round(opening + net_revenue, 2),
        "received_payouts": round(received_payouts, 2),
        "all_payouts": round(all_payouts, 2),
        "in_transit_payouts": round(all_payouts - received_payouts, 2),
        "closing": closing,
        "settlement_closing": settlement_closing,
        "difference_vs_settlement": diff_vs_settlement,
        "period_labels": [p["label"] for p in periods],
        "revenue_lines": revenue_lines,     # per-period + total revenue/fee breakdown
        "ledger": ledger,
    }