import { getGameDb } from '@/lib/db/client'
import { parseCrewTeam } from '@/app/api/crew-team'
import { getTechState, checkResearchPreconditions, ResearchError } from '@/lib/game/research'
import { queueStateFromSave, saveInventory, saveTaskRow } from '@/lib/game/save'
import { queueTask, TaskError } from '@/lib/game/tasks'

// Research one tech: assign the crew team (lead + helpers) and queue the RESEARCH task — the
// tech cost is deducted at queue time and the tech is marked researched (unlock effect
// included) when the task completes on the turn tick (runTurn). Body:
// { techId, leadCrewId, helperCrewIds? }. Queueing spends no turn; returns the same fresh
// tech tree state the instant action returned.
export async function POST(req: Request) {
  let body: unknown
  try {
    body = await req.json()
  } catch {
    return Response.json({ error: 'Invalid JSON body' }, { status: 400 })
  }

  const techId = (body as { techId?: unknown }).techId
  if (typeof techId !== 'number' || !Number.isInteger(techId)) {
    return Response.json({ error: 'techId must be an integer' }, { status: 400 })
  }
  const team = parseCrewTeam(body)
  if ('error' in team) {
    return Response.json({ error: team.error }, { status: team.status })
  }

  try {
    const db = await getGameDb()
    await checkResearchPreconditions(db, techId) // existing pre-checks: 404 unknown · 409 already researched / missing prereq
    const state = await queueStateFromSave(db)
    const { task, inventory } = queueTask(state, { type: 'RESEARCH', payload: { techId }, leadCrewId: team.leadCrewId, helperCrewIds: team.helperCrewIds })
    await saveTaskRow(db, task)
    await saveInventory(db, inventory) // the cost was deducted at queue time
    return Response.json(await getTechState(db))
  } catch (err) {
    if (err instanceof ResearchError || err instanceof TaskError) {
      return Response.json({ error: err.message }, { status: err.status })
    }
    throw err
  }
}