import { BaseSchema } from '@adonisjs/lucid/schema'

/**
 * Lease lanes (REBUILD.md, "Voyager 3: window indexing", 1, amended 2026-10-27): a group has two cursors, each with
 * its own holder, window and snapshot. The `history` lane works the ranges the lease bounds hand out (the windows,
 * the history), the `tail` lane the tail planner's (priority at or below the tail's): a thread on the tail never
 * waits behind a group's history, and a held history group's tail isn't stuck behind its days of ranges.
 */
export default class extends BaseSchema {
  async up() {
    this.schema.raw(
      `ALTER TABLE group_leases ADD COLUMN lane varchar(8) NOT NULL DEFAULT 'history'`
    )
    this.schema.raw(`ALTER TABLE group_leases DROP CONSTRAINT group_leases_pkey`)
    this.schema.raw(`ALTER TABLE group_leases ADD PRIMARY KEY (group_id, lane)`)
    // Counts the leases handed out: odd and even ones start from the other half of the order's mix.
    this.schema.raw(`CREATE SEQUENCE group_lease_turns`)
  }

  async down() {
    this.schema.raw(`DROP SEQUENCE IF EXISTS group_lease_turns`)
    this.schema.raw(`DELETE FROM group_leases WHERE lane <> 'history'`)
    this.schema.raw(`ALTER TABLE group_leases DROP CONSTRAINT group_leases_pkey`)
    this.schema.raw(`ALTER TABLE group_leases DROP COLUMN lane`)
    this.schema.raw(`ALTER TABLE group_leases ADD PRIMARY KEY (group_id)`)
  }
}