import { SoftDeleteAudit } from "@tria-plc/api-common/modules/typeorm/audit.entity";
import {
  Check,
  Column,
  Entity,
  Index,
  PrimaryGeneratedColumn,
  Unique,
} from "typeorm";

import { moneyColumn } from "../../../common/money";

/**
 * DRAFT    — being prepared. Editable, and NOT part of any balance.
 * POSTED   — in the ledger. Immutable forever.
 * REVERSED — was posted, then undone by a linked reversing entry. The original
 *            row is still POSTED-immutable; this status only records that a
 *            reversal exists, so a reader is not surprised by the pair.
 *
 * There is deliberately no CANCELLED or DELETED. A posted entry is never
 * removed — that is the difference between a ledger and a spreadsheet.
 */
export const JOURNAL_STATUSES = ["DRAFT", "POSTED", "REVERSED"] as const;
export type JournalStatus = (typeof JOURNAL_STATUSES)[number];

/**
 * Where the entry came from. GENERAL is a human-keyed entry; the rest are
 * written by the automated flows in 4.2–4.5. OPENING carries the cutover
 * balances and REVERSAL is generated, never hand-picked.
 */
export const JOURNAL_TYPES = [
  "GENERAL",
  "SALES",
  "PURCHASE",
  "CASH_RECEIPT",
  "CASH_PAYMENT",
  "PAYROLL",
  "DEPRECIATION",
  "OPENING",
  "REVERSAL",
] as const;
export type JournalType = (typeof JOURNAL_TYPES)[number];

/**
 * The header of one double-entry transaction.
 *
 * Invariants the service enforces inside a single transaction, because a ledger
 * that violates any of them is not repairable after the fact:
 *  1. `total_debit` = `total_credit`, and both > 0.
 *  2. At least two lines.
 *  3. The named period is OPEN at the moment of posting.
 *  4. Once POSTED, neither the header nor its lines may be modified.
 *  5. A correction is a REVERSAL entry, never an edit.
 *
 * `total_debit`/`total_credit` are stored rather than summed on read: they are
 * frozen evidence of what balanced at posting time, so a later change to a line
 * (which cannot happen, but the ledger should not depend on that) could never
 * silently rewrite history.
 */
@Entity({ schema: "finance", name: "journal_entries" })
@Unique("uq_journal_entries_org_number", ["organizationId", "entryNumber"])
@Index("idx_journal_entries_organization_id", ["organizationId"])
@Index("idx_journal_entries_period_id", ["fiscalPeriodId"])
@Index("idx_journal_entries_date", ["entryDate"])
@Index("idx_journal_entries_status", ["status"])
@Index("idx_journal_entries_source", ["sourceModule", "sourceId"])
@Check(
  "ck_journal_entries_status",
  `"status" IN ('DRAFT','POSTED','REVERSED')`,
)
@Check("ck_journal_entries_totals_non_negative", `"total_debit" >= 0 AND "total_credit" >= 0`)
// The balance rule, at the database level as well as in the service. Belt and
// braces on purpose: this is the one invariant whose violation is unrecoverable.
@Check("ck_journal_entries_balanced", `"total_debit" = "total_credit"`)
export class JournalEntry extends SoftDeleteAudit {
  @PrimaryGeneratedColumn("uuid")
  id!: string;

  @Column({ type: "uuid", name: "organization_id" })
  organizationId!: string;

  /** Human-facing sequence, e.g. "JV-2026-000042". Unique per organization. */
  @Column({ type: "varchar", length: 32, name: "entry_number" })
  entryNumber!: string;

  /**
   * The date the transaction is recognised on — NOT when the row was created.
   * It decides which period the entry falls in, so a receipt banked late is
   * still recognised in the month it belongs to.
   */
  @Column({ type: "date", name: "entry_date" })
  entryDate!: string;

  @Column({ type: "uuid", name: "fiscal_period_id" })
  fiscalPeriodId!: string;

  @Column({ type: "varchar", length: 24, name: "journal_type", default: "GENERAL" })
  journalType!: JournalType;

  @Column({ type: "varchar", length: 16, name: "status", default: "DRAFT" })
  status!: JournalStatus;

  @Column({ type: "text", name: "memo" })
  memo!: string;

  /** Free-text pointer to the paper/source document (invoice no., receipt no.). */
  @Column({ type: "varchar", length: 128, name: "reference", nullable: true })
  reference?: string | null;

  /**
   * Which upstream system produced this entry ("freight", "passenger", "hr",
   * "payment"), and its id there. Soft reference, never an FK — Finance must
   * stay readable when a source row is gone. Together they are also the
   * idempotency key for automated posting: one source document posts once.
   */
  @Column({ type: "varchar", length: 32, name: "source_module", nullable: true })
  sourceModule?: string | null;

  @Column({ type: "varchar", length: 128, name: "source_id", nullable: true })
  sourceId?: string | null;

  @Column(moneyColumn({ name: "total_debit", default: 0 }))
  totalDebit!: number;

  @Column(moneyColumn({ name: "total_credit", default: 0 }))
  totalCredit!: number;

  /** ETB unless an entry deliberately records another currency's conversion. */
  @Column({ type: "varchar", length: 8, name: "currency", default: "ETB" })
  currency!: string;

  /** `iam.employees.id` of whoever prepared it. */
  @Column({ type: "uuid", name: "prepared_by", nullable: true })
  preparedBy?: string | null;

  /**
   * `iam.employees.id` of whoever posted it. Separate from `preparedBy` because
   * preparing and posting are separate permissions — see the role matrix.
   */
  @Column({ type: "uuid", name: "posted_by", nullable: true })
  postedBy?: string | null;

  @Column({ type: "timestamptz", name: "posted_at", nullable: true })
  postedAt?: Date | null;

  /** Set on the ORIGINAL, pointing at the entry that reverses it. */
  @Column({ type: "uuid", name: "reversed_by_entry_id", nullable: true })
  reversedByEntryId?: string | null;

  /** Set on the REVERSAL, pointing back at what it undoes. */
  @Column({ type: "uuid", name: "reverses_entry_id", nullable: true })
  reversesEntryId?: string | null;

  @Column({ type: "text", name: "reversal_reason", nullable: true })
  reversalReason?: string | null;
}