books/backend/Books.Api/Database/Migrations/012_Invoices.sql

-- Migration: 012_Invoices.sql
-- Description: Invoice read model for invoicing system
-- Date: 2026-01-18
-- Phase: 2 of Invoicing Implementation

-- Invoice read model table
CREATE TABLE IF NOT EXISTS invoice_read_models (
    -- EventFlow standard fields
    aggregate_id VARCHAR(255) PRIMARY KEY,
    last_aggregate_sequence_number BIGINT NOT NULL DEFAULT 0,
    create_time TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    update_time TIMESTAMP WITH TIME ZONE DEFAULT NOW(),

    -- Company and fiscal year
    company_id VARCHAR(255) NOT NULL,
    fiscal_year_id VARCHAR(255),

    -- Customer reference
    customer_id VARCHAR(255) NOT NULL,
    customer_name VARCHAR(255) NOT NULL,
    customer_number VARCHAR(20) NOT NULL,

    -- Invoice identification (Momsloven §52: Sequential per year)
    invoice_number VARCHAR(50) NOT NULL,
    invoice_date DATE,
    due_date DATE,

    -- Status: draft, sent, partially_paid, paid, voided
    status VARCHAR(20) NOT NULL DEFAULT 'draft',

    -- Amounts (calculated from lines)
    amount_ex_vat DECIMAL(18, 2) NOT NULL DEFAULT 0,
    amount_vat DECIMAL(18, 2) NOT NULL DEFAULT 0,
    amount_total DECIMAL(18, 2) NOT NULL DEFAULT 0,
    amount_paid DECIMAL(18, 2) NOT NULL DEFAULT 0,
    amount_remaining DECIMAL(18, 2) NOT NULL DEFAULT 0,

    -- Currency (default DKK)
    currency VARCHAR(3) NOT NULL DEFAULT 'DKK',

    -- VAT settings
    vat_code VARCHAR(20),

    -- Payment terms
    payment_terms_days INT NOT NULL DEFAULT 30,

    -- Invoice lines as JSONB for flexibility
    -- Structure: [{ lineNumber, description, quantity, unitPrice, vatCode, amountExVat, amountVat, amountTotal, accountId }]
    lines JSONB NOT NULL DEFAULT '[]',

    -- Ledger integration
    ledger_transaction_id VARCHAR(255),

    -- Notes and reference
    notes TEXT,
    reference VARCHAR(255),

    -- Timestamps for status changes
    sent_at TIMESTAMP WITH TIME ZONE,
    paid_at TIMESTAMP WITH TIME ZONE,
    voided_at TIMESTAMP WITH TIME ZONE,
    voided_reason TEXT,
    voided_by VARCHAR(255),

    -- Audit
    created_by VARCHAR(255) NOT NULL,
    updated_by VARCHAR(255)
);

-- Indexes for common queries
CREATE INDEX IF NOT EXISTS idx_invoice_company_id ON invoice_read_models(company_id);
CREATE INDEX IF NOT EXISTS idx_invoice_customer_id ON invoice_read_models(customer_id);
CREATE INDEX IF NOT EXISTS idx_invoice_status ON invoice_read_models(status);
CREATE INDEX IF NOT EXISTS idx_invoice_fiscal_year_id ON invoice_read_models(fiscal_year_id);
CREATE INDEX IF NOT EXISTS idx_invoice_number ON invoice_read_models(company_id, invoice_number);
CREATE INDEX IF NOT EXISTS idx_invoice_date ON invoice_read_models(invoice_date);
CREATE INDEX IF NOT EXISTS idx_invoice_due_date ON invoice_read_models(due_date);

-- Unique constraint on invoice number per company (Momsloven §52 compliance)
CREATE UNIQUE INDEX IF NOT EXISTS idx_invoice_number_unique ON invoice_read_models(company_id, invoice_number);

-- Comment explaining the table
COMMENT ON TABLE invoice_read_models IS 'Invoice read model for the Books accounting system. Supports B2B and B2C invoicing with Danish tax compliance (Momsloven §52).';
COMMENT ON COLUMN invoice_read_models.invoice_number IS 'Sequential invoice number per year, format: INV-YYYY-NNNN (Momsloven §52)';
COMMENT ON COLUMN invoice_read_models.lines IS 'Invoice lines as JSONB array with lineNumber, description, quantity, unitPrice, vatCode, amounts, accountId';
COMMENT ON COLUMN invoice_read_models.ledger_transaction_id IS 'Reference to the Ledger transaction when invoice is sent/posted';