import Database from 'better-sqlite3'
import fs from 'node:fs'
import path from 'node:path'

/** HQ console DB — SQLite behind portable repositories, S3 backup at deploy time. */
export type DB = Database.Database

const SCHEMA = `
CREATE TABLE IF NOT EXISTS staff_user (
  id TEXT PRIMARY KEY, email TEXT NOT NULL UNIQUE, display_name TEXT NOT NULL,
  role TEXT NOT NULL CHECK (role IN ('owner','staff')),
  pw_salt TEXT NOT NULL, pw_hash TEXT NOT NULL, active INTEGER NOT NULL DEFAULT 1
);
CREATE TABLE IF NOT EXISTS session (
  token TEXT PRIMARY KEY, staff_id TEXT NOT NULL, expires_at TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS client (
  id TEXT PRIMARY KEY, code TEXT NOT NULL UNIQUE, name TEXT NOT NULL,
  gstin TEXT, state_code TEXT NOT NULL DEFAULT '32', address TEXT NOT NULL DEFAULT '',
  contacts TEXT NOT NULL DEFAULT '[]', -- JSON [{name,phone,email,role}]
  status TEXT NOT NULL DEFAULT 'active' CHECK (status IN ('lead','active','dormant','lost')),
  notes TEXT NOT NULL DEFAULT '', source TEXT NOT NULL DEFAULT 'hq', created_at TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS module (
  id TEXT PRIMARY KEY, code TEXT NOT NULL UNIQUE, name TEXT NOT NULL,
  sac TEXT NOT NULL DEFAULT '998313', -- IT services default; CA session confirms per module
  allowed_kinds TEXT NOT NULL DEFAULT '["one_time","monthly","yearly","usage"]',
  multi_subscription INTEGER NOT NULL DEFAULT 0, active INTEGER NOT NULL DEFAULT 1,
  quote_content TEXT NOT NULL DEFAULT '[]' -- JSON string[]: "what's included" lines on quotes
);
CREATE TABLE IF NOT EXISTS module_price_book (
  id TEXT PRIMARY KEY, module_id TEXT NOT NULL, edition TEXT NOT NULL DEFAULT 'standard',
  kind TEXT NOT NULL, price_paise INTEGER NOT NULL, effective_from TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS client_module (
  id TEXT PRIMARY KEY, client_id TEXT NOT NULL, module_id TEXT NOT NULL,
  status TEXT NOT NULL DEFAULT 'quoted' CHECK (status IN
    ('quoted','ordered','installing','installed','trained','live','expired','cancelled')),
  kind TEXT NOT NULL, edition TEXT NOT NULL DEFAULT 'standard',
  installed_on TEXT, completed_on TEXT, trained_on TEXT,
  next_renewal TEXT, active INTEGER NOT NULL DEFAULT 1
);
CREATE TABLE IF NOT EXISTS tax_class (
  class_code TEXT NOT NULL, rate_pct_bp INTEGER NOT NULL,
  cess_pct_bp INTEGER NOT NULL DEFAULT 0, effective_from TEXT NOT NULL, effective_to TEXT
);
CREATE TABLE IF NOT EXISTS doc_series (
  doc_type TEXT NOT NULL, fy TEXT NOT NULL, prefix TEXT NOT NULL, next_seq INTEGER NOT NULL,
  PRIMARY KEY (doc_type, fy)
);
CREATE TABLE IF NOT EXISTS document (
  id TEXT PRIMARY KEY, doc_type TEXT NOT NULL CHECK (doc_type IN
    ('QUOTATION','PROFORMA','INVOICE','RECEIPT','CREDIT_NOTE')),
  doc_no TEXT, fy TEXT NOT NULL, client_id TEXT NOT NULL, doc_date TEXT NOT NULL,
  status TEXT NOT NULL DEFAULT 'draft' CHECK (status IN
    ('draft','sent','accepted','invoiced','part_paid','paid','lost','cancelled')),
  ref_doc_id TEXT, -- QT→PI→INV chain; CN → the invoice it amends
  taxable_paise INTEGER NOT NULL, cgst_paise INTEGER NOT NULL, sgst_paise INTEGER NOT NULL,
  igst_paise INTEGER NOT NULL, round_off_paise INTEGER NOT NULL, payable_paise INTEGER NOT NULL,
  payload TEXT NOT NULL, -- JSON { lines: BillLine[], totals: BillTotals, terms?: string }
  source TEXT NOT NULL DEFAULT 'hq', -- 'apex' rows keep legacy numbers, exempt from series
  created_by TEXT NOT NULL, created_at TEXT NOT NULL,
  UNIQUE (doc_no)
);
CREATE TABLE IF NOT EXISTS document_event (
  id TEXT PRIMARY KEY, document_id TEXT NOT NULL, at_wall TEXT NOT NULL,
  kind TEXT NOT NULL, meta TEXT NOT NULL DEFAULT '{}'
);
CREATE TABLE IF NOT EXISTS payment (
  id TEXT PRIMARY KEY, client_id TEXT NOT NULL, received_on TEXT NOT NULL,
  mode TEXT NOT NULL CHECK (mode IN ('bank','upi','cheque','cash','other')),
  reference TEXT NOT NULL DEFAULT '', amount_paise INTEGER NOT NULL,
  tds_paise INTEGER NOT NULL DEFAULT 0, created_by TEXT NOT NULL, created_at TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS payment_allocation (
  id TEXT PRIMARY KEY, payment_id TEXT NOT NULL, document_id TEXT NOT NULL,
  amount_paise INTEGER NOT NULL -- includes this allocation's TDS share
);
CREATE TABLE IF NOT EXISTS email_account (
  id TEXT PRIMARY KEY, address TEXT NOT NULL, refresh_token_enc TEXT NOT NULL,
  status TEXT NOT NULL DEFAULT 'active' CHECK (status IN ('active','dead')), updated_at TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS email_log (
  id TEXT PRIMARY KEY, document_id TEXT, to_addr TEXT NOT NULL, subject TEXT NOT NULL,
  status TEXT NOT NULL CHECK (status IN ('sent','failed')), gmail_message_id TEXT,
  error TEXT, at_wall TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS setting (
  key TEXT PRIMARY KEY, value TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS audit_log (
  id TEXT PRIMARY KEY, at_wall TEXT NOT NULL, user_id TEXT NOT NULL, action TEXT NOT NULL,
  entity TEXT NOT NULL, entity_id TEXT NOT NULL, before_json TEXT, after_json TEXT
);
CREATE TABLE IF NOT EXISTS stg_client (
  row_no INTEGER PRIMARY KEY, code TEXT, name TEXT, gstin TEXT, state_code TEXT,
  address TEXT, phone TEXT, email TEXT, status TEXT, problems TEXT NOT NULL DEFAULT '[]'
);
CREATE TABLE IF NOT EXISTS stg_invoice (
  row_no INTEGER PRIMARY KEY, client_code TEXT, doc_no TEXT, doc_date TEXT,
  taxable_paise INTEGER, tax_paise INTEGER, total_paise INTEGER, paid INTEGER,
  problems TEXT NOT NULL DEFAULT '[]'
);
CREATE TABLE IF NOT EXISTS recurring_plan (
  id TEXT PRIMARY KEY, client_id TEXT NOT NULL,
  client_module_id TEXT, -- source of the invoice line's module; required for generation in HQ-2
  cadence TEXT NOT NULL CHECK (cadence IN ('monthly','yearly')),
  amount_paise INTEGER, -- NULL = price from module_price_book at generation time
  next_run TEXT NOT NULL,
  policy TEXT NOT NULL DEFAULT 'manual' CHECK (policy IN ('auto','manual')),
  active INTEGER NOT NULL DEFAULT 1
);
CREATE TABLE IF NOT EXISTS amc_contract (
  id TEXT PRIMARY KEY, client_id TEXT NOT NULL, coverage TEXT NOT NULL DEFAULT '',
  period_from TEXT NOT NULL, period_to TEXT NOT NULL, amount_paise INTEGER NOT NULL,
  renewal_reminder_days INTEGER NOT NULL DEFAULT 30,
  legacy_paid INTEGER, -- manual flag for imported contracts only; else paid derives from invoice_doc_id
  invoice_doc_id TEXT, active INTEGER NOT NULL DEFAULT 1
);
CREATE TABLE IF NOT EXISTS interaction_type (
  code TEXT PRIMARY KEY, label TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS interaction (
  id TEXT PRIMARY KEY, client_id TEXT NOT NULL, type_code TEXT NOT NULL,
  on_date TEXT NOT NULL, staff_id TEXT NOT NULL, notes TEXT NOT NULL DEFAULT '',
  outcome TEXT CHECK (outcome IN ('positive','neutral','negative')),
  follow_up_on TEXT, created_at TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS reminder (
  id TEXT PRIMARY KEY,
  rule_kind TEXT NOT NULL CHECK (rule_kind IN
    ('invoice_overdue','renewal_due','amc_expiring','follow_up','recurring_generated','email_bounced')),
  subject_id TEXT NOT NULL, due_period TEXT NOT NULL, client_id TEXT NOT NULL,
  doc_id TEXT, -- the document this reminder concerns (overdue/recurring/amc invoice); NULL otherwise
  status TEXT NOT NULL DEFAULT 'queued' CHECK (status IN ('queued','sent','failed','dismissed')),
  policy_applied TEXT NOT NULL DEFAULT 'manual' CHECK (policy_applied IN ('auto','manual')),
  error TEXT, created_at TEXT NOT NULL, sent_at TEXT,
  UNIQUE (rule_kind, subject_id, due_period) -- the idempotency key: at-most-once per due-period
);
`

export function openDb(dataDir?: string): DB {
  let db: DB
  if (dataDir === ':memory:') {
    db = new Database(':memory:')
  } else {
    const dir = dataDir ?? path.resolve(process.cwd(), 'data')
    fs.mkdirSync(dir, { recursive: true })
    db = new Database(path.join(dir, 'hq.db'))
    db.pragma('journal_mode = WAL')
  }
  db.exec(SCHEMA)
  migrate(db)
  return db
}

/** Additive, idempotent column adds for DBs created before a schema change. */
function migrate(db: DB): void {
  const moduleCols = db.prepare(`PRAGMA table_info(module)`).all() as { name: string }[]
  if (!moduleCols.some((c) => c.name === 'quote_content')) {
    db.exec(`ALTER TABLE module ADD COLUMN quote_content TEXT NOT NULL DEFAULT '[]'`)
  }
  const emailCols = db.prepare(`PRAGMA table_info(email_log)`).all() as { name: string }[]
  if (!emailCols.some((c) => c.name === 'bounced')) {
    db.exec(`ALTER TABLE email_log ADD COLUMN bounced INTEGER NOT NULL DEFAULT 0`)
  }
}