import { Context, Effect, Layer } from "effect"
import { Database } from "./storage/db"
import { DataMigrationTable } from "./data-migration.sql"
import * as Log from "@opencode-ai/core/util/log"
import { eq } from "drizzle-orm"

export type Migration<R = never> = {
  name: string
  run: Effect.Effect<void, unknown, R>
}

const log = Log.create({ service: "data-migration" })

export interface Interface {}

export class Service extends Context.Service<Service, Interface>()("@opencode/DataMigration") {}

export const layer = Layer.effect(
  Service,
  Effect.gen(function* () {
    const migrations: Migration[] = []

    yield* Effect.gen(function* () {
      if (migrations.length === 0) return

      // Migrations run in a background fiber, so they must be resumable until
      // their completion row is written.
      for (const migration of migrations) {
        const completed = Database.use((db) =>
          db
            .select({ name: DataMigrationTable.name })
            .from(DataMigrationTable)
            .where(eq(DataMigrationTable.name, migration.name))
            .get(),
        )
        if (completed) continue

        log.info("running data migration", { name: migration.name })
        yield* migration.run.pipe(Effect.withSpan("DataMigration", { attributes: { name: migration.name } }))
        Database.use((db) =>
          db
            .insert(DataMigrationTable)
            .values({ name: migration.name, time_completed: Date.now() })
            .onConflictDoNothing()
            .run(),
        )
      }
    }).pipe(
      Effect.tapCause((cause) => Effect.logError("failed to run data migrations", { cause })),
      Effect.ignore,
      Effect.forkScoped,
    )
    return Service.of({})
  }),
)

export const defaultLayer = layer

export * as DataMigration from "./data-migration"