/* eslint @typescript-eslint/no-unused-vars: 0 */

import sqlite3 from 'sqlite3'
import crypto from 'crypto'
import { instrument } from 'succinct-async'
import { now } from '@welshman/lib'
import type { Subscription } from './alert.js'

const db = new sqlite3.Database('mailship.db')

type Param = number | string | boolean

type Row = Record<string, any>

const run = (query: string, params: Param[] = []) =>
  new Promise((resolve, reject) => {
    db.run(query, params, function (err) {
      return err ? reject(err) : resolve(this.changes > 0)
    })
  })

// prettier-ignore
const all = <T=Row>(query: string, params: Param[] = []) =>
  new Promise<T[]>((resolve, reject) => {
    db.all(query, params, (err, rows: T[]) => (err ? reject(err) : resolve(rows)))
  })

// prettier-ignore
const get = <T=Row>(query: string, params: Param[] = []) =>
  new Promise<T | undefined>((resolve, reject) => {
    db.get(query, params, (err, row) => {
      if (err) {
        reject(err)
      } else if (row) {
        resolve(row as T)
      } else {
        resolve(undefined)
      }
    })
  })

async function assertResult<T>(p: T | Promise<T>) {
  return (await p)!
}

// Migrations

export const migrate = () =>
  new Promise<void>(async (resolve, reject) => {
    try {
      db.serialize(async () => {
        await run(
          `
          CREATE TABLE IF NOT EXISTS subscriptions (
            id TEXT PRIMARY KEY,
            key TEXT NOT NULL UNIQUE,
            pubkey TEXT NOT NULL,
            email TEXT NOT NULL,
            frequency TEXT NOT NULL DEFAULT 'daily',
            created_at INTEGER NOT NULL,
            confirmed_at INTEGER,
            unsubscribed_at INTEGER,
            last_digest_at INTEGER
          )
        `,
        )
        await run(
          `
          CREATE TABLE IF NOT EXISTS events (
            id TEXT NOT NULL,
            subscription_id TEXT NOT NULL,
            event JSON NOT NULL,
            relay TEXT NOT NULL,
            received_at INTEGER NOT NULL,
            PRIMARY KEY (id, subscription_id)
          )
        `,
        )
        await run(
          `CREATE INDEX IF NOT EXISTS idx_events_subscription_received ON events (subscription_id, received_at)`,
        )
        resolve()
      })
    } catch (err) {
      reject(err)
    }
  })

// Subscriptions

const parseSubscription = (row: any): Subscription | undefined => {
  if (row) {
    return row as Subscription
  }
}

export const insertSubscription = instrument(
  'database.insertSubscription',
  async (pubkey: string, email: string, frequency: string) => {
    const existing = await getSubscriptionByPubkey(pubkey)

    if (existing) {
      // Update existing
      return assertResult(
        parseSubscription(
          await get(
            `UPDATE subscriptions SET email = ?, frequency = ?, confirmed_at = NULL, unsubscribed_at = NULL
             WHERE pubkey = ? RETURNING *`,
            [email, frequency, pubkey],
          ),
        ),
      )
    }

    // Create new
    return assertResult(
      parseSubscription(
        await get(
          `INSERT INTO subscriptions (id, key, pubkey, email, frequency, created_at)
           VALUES (?, ?, ?, ?, ?, ?) RETURNING *`,
          [
            crypto.randomUUID(),
            crypto.randomBytes(32).toString('hex'),
            pubkey,
            email,
            frequency,
            now(),
          ],
        ),
      ),
    )
  },
)

export const confirmSubscription = instrument(
  'database.confirmSubscription',
  async (key: string) => {
    return parseSubscription(
      await get(
        `UPDATE subscriptions SET confirmed_at = unixepoch()
         WHERE key = ? AND confirmed_at IS NULL RETURNING *`,
        [key],
      ),
    )
  },
)

export const unsubscribeSubscription = instrument(
  'database.unsubscribeSubscription',
  async (key: string) => {
    return parseSubscription(
      await get(
        `UPDATE subscriptions SET unsubscribed_at = unixepoch() WHERE key = ? RETURNING *`,
        [key],
      ),
    )
  },
)

export const getSubscriptionById = instrument(
  'database.getSubscriptionById',
  async (id: string) => {
    return parseSubscription(await get(`SELECT * FROM subscriptions WHERE id = ?`, [id]))
  },
)

export const getSubscriptionByKey = instrument(
  'database.getSubscriptionByKey',
  async (key: string) => {
    return parseSubscription(await get(`SELECT * FROM subscriptions WHERE key = ?`, [key]))
  },
)

export const getSubscriptionByPubkey = instrument(
  'database.getSubscriptionByPubkey',
  async (pubkey: string) => {
    return parseSubscription(
      await get(
        `SELECT * FROM subscriptions WHERE pubkey = ? AND unsubscribed_at IS NULL`,
        [pubkey],
      ),
    )
  },
)

export const getActiveSubscriptions = instrument('database.getActiveSubscriptions', async () => {
  const rows = await all(
    `SELECT * FROM subscriptions
     WHERE confirmed_at IS NOT NULL
       AND unsubscribed_at IS NULL`,
  )

  return rows.map(parseSubscription) as Subscription[]
})

export const updateLastDigestAt = instrument(
  'database.updateLastDigestAt',
  async (id: string, timestamp: number) => {
    await run(`UPDATE subscriptions SET last_digest_at = ? WHERE id = ?`, [timestamp, id])
  },
)

// Events

export type StoredEvent = {
  id: string
  subscription_id: string
  event: any
  relay: string
  received_at: number
}

export const insertEvent = instrument(
  'database.insertEvent',
  async (eventId: string, subscriptionId: string, event: any, relay: string) => {
    try {
      await run(
        `INSERT INTO events (id, subscription_id, event, relay, received_at)
         VALUES (?, ?, ?, ?, ?)`,
        [eventId, subscriptionId, JSON.stringify(event), relay, now()],
      )
      return true
    } catch (err: any) {
      // PRIMARY KEY collision = dedup, not an error
      if (err.message?.includes('UNIQUE constraint')) {
        return false
      }
      throw err
    }
  },
)

export const getEventsForSubscription = instrument(
  'database.getEventsForSubscription',
  async (subscriptionId: string, since: number) => {
    const rows = await all<StoredEvent>(
      `SELECT * FROM events
       WHERE subscription_id = ? AND received_at > ?
       ORDER BY received_at DESC`,
      [subscriptionId, since],
    )

    return rows.map((row) => ({
      ...row,
      event: JSON.parse(row.event as any),
    }))
  },
)

export const deleteEventsForSubscription = instrument(
  'database.deleteEventsForSubscription',
  async (subscriptionId: string, since: number) => {
    await run(
      `DELETE FROM events WHERE subscription_id = ? AND received_at > ?`,
      [subscriptionId, since],
    )
  },
)

export const purgeEventsOlderThan = instrument(
  'database.purgeEventsOlderThan',
  async (timestamp: number) => {
    await run(`DELETE FROM events WHERE received_at < ?`, [timestamp])
  },
)