import type { SqliteDb } from './types'
import schemaV1 from './schema-v1.sql?raw'
import schemaV2 from './schema-v2.sql?raw'

const CURRENT_VERSION = 2

function tryAlter(db: SqliteDb, sql: string): void {
  try {
    db.exec(sql)
  } catch (err) {
    const msg = err instanceof Error ? err.message : String(err)
    if (!msg.includes('duplicate column')) throw err
  }
}

function applyV2(db: SqliteDb): void {
  tryAlter(db, "ALTER TABLE chapters ADD COLUMN publish_status TEXT NOT NULL DEFAULT 'draft'")
  tryAlter(db, 'ALTER TABLE chapters ADD COLUMN pov_character_id TEXT DEFAULT NULL')
  tryAlter(db, "ALTER TABLE chapters ADD COLUMN summary TEXT DEFAULT ''")
  tryAlter(db, 'ALTER TABLE chapters ADD COLUMN story_time TEXT DEFAULT NULL')
  db.exec(schemaV2)
}

export function migrate(db: SqliteDb): void {
  db.exec(`CREATE TABLE IF NOT EXISTS schema_version (
    version INTEGER PRIMARY KEY,
    applied_at TEXT NOT NULL DEFAULT (datetime('now')),
    description TEXT
  )`)

  const row = db.prepare('SELECT MAX(version) AS v FROM schema_version').get() as { v: number | null }
  let current = row?.v ?? 0
  if (current >= CURRENT_VERSION) return

  if (current < 1) {
    db.exec(schemaV1)
    db.prepare('INSERT INTO schema_version (version, description) VALUES (?, ?)').run(1, 'initial schema')
    current = 1
  }

  if (current < 2) {
    applyV2(db)
    db.prepare('INSERT INTO schema_version (version, description) VALUES (?, ?)').run(2, 'P2 schema')
  }
}