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','manager','staff')),
  phone TEXT, title TEXT, -- D18 WS-E: contact + designation shown on Employees/profile; nothing routes on them
  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')),
  owner_id TEXT, -- account/enquiry owner → staff_user.id; NULL = unassigned (routing, D-EMP A4)
  -- D18 WS-F: support-access data from the APEX book. db_password_enc is AES-256-GCM
  -- (HQ_SECRET_KEY) and never appears in list/get payloads — reveal-only, audited.
  anydesk TEXT, os TEXT, district TEXT, sector TEXT, db_password_enc TEXT,
  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,
  due_date TEXT, -- INVOICE only: stamped at issue from billing.payment_terms_days when absent (D18)
  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 document_share (
  id TEXT PRIMARY KEY, document_id TEXT NOT NULL, token TEXT NOT NULL UNIQUE,
  created_by TEXT NOT NULL, created_at TEXT NOT NULL,
  expires_at TEXT, -- NULL = never expires
  revoked INTEGER NOT NULL DEFAULT 0
);
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,
  anydesk TEXT, os TEXT, district TEXT, sector 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','quote_followup')),
  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
);
CREATE TABLE IF NOT EXISTS reminder_schedule (
  id TEXT PRIMARY KEY, rule_kind TEXT NOT NULL,    -- 'quote_followup' | 'invoice_overdue' (validated in repo)
  effective_from TEXT NOT NULL, effective_to TEXT, -- dated config window (rule 3): active when from<=today AND (to IS NULL OR to>today)
  day_offsets TEXT NOT NULL,                       -- CSV day milestones since anchor, e.g. '3,7,14'
  subject TEXT, body TEXT                          -- dated message text (quote_followup); NULL = code-constant fallback
);
CREATE TABLE IF NOT EXISTS aws_usage (
  id TEXT PRIMARY KEY, client_id TEXT NOT NULL,
  month TEXT NOT NULL,                       -- 'YYYY-MM'
  storage_gb REAL NOT NULL DEFAULT 0,        -- GB stored, month-end snapshot (manual or CloudWatch later)
  transfer_gb REAL NOT NULL DEFAULT 0,       -- GB transferred over the month
  cost_paise INTEGER NOT NULL DEFAULT 0,     -- Cost Explorer UnblendedCost for the 'client' tag, in paise (INR)
  source TEXT NOT NULL DEFAULT 'auto' CHECK (source IN ('auto','manual')),
  updated_at TEXT NOT NULL,
  UNIQUE (client_id, month)                  -- one row per client per month; the pull upserts on this key
);
`

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`)
  }
  const docCols = db.prepare(`PRAGMA table_info(document)`).all() as { name: string }[]
  if (!docCols.some((c) => c.name === 'due_date')) {
    db.exec(`ALTER TABLE document ADD COLUMN due_date TEXT`)
  }
  const staffCols = db.prepare(`PRAGMA table_info(staff_user)`).all() as { name: string }[]
  if (!staffCols.some((c) => c.name === 'phone')) {
    db.exec(`ALTER TABLE staff_user ADD COLUMN phone TEXT`)
  }
  if (!staffCols.some((c) => c.name === 'title')) {
    db.exec(`ALTER TABLE staff_user ADD COLUMN title TEXT`)
  }
  const clientCols = db.prepare(`PRAGMA table_info(client)`).all() as { name: string }[]
  if (!clientCols.some((c) => c.name === 'owner_id')) {
    db.exec(`ALTER TABLE client ADD COLUMN owner_id TEXT`)
  }
  // D18 WS-F: support-access fields from the APEX client book.
  for (const col of ['anydesk', 'os', 'district', 'sector', 'db_password_enc']) {
    if (!clientCols.some((c) => c.name === col)) {
      db.exec(`ALTER TABLE client ADD COLUMN ${col} TEXT`)
    }
  }
  // …and the same fields on the import staging table so the cutover carries them.
  const stgClientCols = db.prepare(`PRAGMA table_info(stg_client)`).all() as { name: string }[]
  for (const col of ['anydesk', 'os', 'district', 'sector']) {
    if (!stgClientCols.some((c) => c.name === col)) {
      db.exec(`ALTER TABLE stg_client ADD COLUMN ${col} TEXT`)
    }
  }
  rebuildStaffUserRoleCheck(db)
  rebuildReminderRuleKindCheck(db)
}

/**
 * Rebuild a table whose CHECK constraint must change — SQLite cannot ALTER a CHECK in
 * place, so the table is recreated and rows copied with an explicit column list.
 * Guarded: a no-op unless `guardToken` (a fragment of the OLD constraint) is still
 * present in the live DDL, so fresh DBs (born correct from SCHEMA) and re-runs skip it.
 * The whole rebuild runs in one transaction (crash-safe).
 * SQLite-only migration path — on Postgres (prod, D15) this is a one-line
 * ALTER TABLE … DROP/ADD CONSTRAINT in the prod migration set.
 */
export function rebuildTable(
  db: DB, table: string, newDdl: string, guardToken: string, columns: string[],
): void {
  const row = db.prepare(`SELECT sql FROM sqlite_master WHERE type='table' AND name=?`)
    .get(table) as { sql: string } | undefined
  if (!row || !row.sql.includes(guardToken)) return
  const cols = columns.join(', ')
  db.transaction(() => {
    db.exec(newDdl)
    db.exec(`INSERT INTO ${table}__new (${cols}) SELECT ${cols} FROM ${table}`)
    db.exec(`DROP TABLE ${table}`)
    db.exec(`ALTER TABLE ${table}__new RENAME TO ${table}`)
  })()
}

/** Widen staff_user.role CHECK to allow 'manager' on DBs created before the employee slice. */
export function rebuildStaffUserRoleCheck(db: DB): void {
  rebuildTable(
    db,
    'staff_user',
    `CREATE TABLE staff_user__new (
  id TEXT PRIMARY KEY, email TEXT NOT NULL UNIQUE, display_name TEXT NOT NULL,
  role TEXT NOT NULL CHECK (role IN ('owner','manager','staff')),
  pw_salt TEXT NOT NULL, pw_hash TEXT NOT NULL, active INTEGER NOT NULL DEFAULT 1
)`,
    `('owner','staff')`,
    ['id', 'email', 'display_name', 'role', 'pw_salt', 'pw_hash', 'active'],
  )
}

/**
 * Widen reminder.rule_kind CHECK to allow 'quote_followup' on DBs created before the
 * quote-follow-up slice (spec §4). The status/policy_applied CHECKs and the
 * UNIQUE (rule_kind, subject_id, due_period) idempotency key are preserved verbatim.
 * Guard token: the old list ends "...'email_bounced')" — the new DDL continues
 * ",'quote_followup')" instead, so the fragment vanishes once rebuilt (idempotent).
 */
export function rebuildReminderRuleKindCheck(db: DB): void {
  rebuildTable(
    db,
    'reminder',
    `CREATE TABLE reminder__new (
  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','quote_followup')),
  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; the quote for quote_followup); 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
)`,
    `'email_bounced')`,
    ['id', 'rule_kind', 'subject_id', 'due_period', 'client_id', 'doc_id',
      'status', 'policy_applied', 'error', 'created_at', 'sent_at'],
  )
}