// Pure skill-progression module (spec §6): XP accrual, level→power, titles. No lib/db imports — operates on plain SkillRow data (Task 12's crew_skills table); the frontend imports it for the CREW-tab display.
import type { SkillName } from './crew-costs'
import { POWER_BANDS, XP_THRESHOLDS } from './crew-costs'
export interface SkillRow {
  saveId: string
  crewId: string
  skill: SkillName
  level: number
  xp: number
}
export type CrewIdentity = { name: string; role: string }
// Highest level 0–5 with xp ≥ XP_THRESHOLDS[level−1]; thresholds [5,10,15,20,25], cap 5.
export function levelFromXp(xp: number): number {
  let level = 0
  for (let l = 1; l <= XP_THRESHOLDS.length; l++) if (xp >= XP_THRESHOLDS[l - 1]) level = l
  return level
}
// L0–2 → 1 · L3–4 → 2 · L5 → 3 (direct lookup into crew-costs POWER_BANDS).
export function powerForLevel(level: number): number {
  return POWER_BANDS[level]
}
// From the member's HIGHEST skill level: ≥5 → "MASTER <ROLE>", ≥3 → "SENIOR <ROLE>", below → null.
export function titleFor(member: CrewIdentity, skillRows: SkillRow[]): string | null {
  const highest = skillRows.reduce((max, r) => Math.max(max, r.level), 0)
  if (highest >= 5) return `MASTER ${member.role}`
  if (highest >= 3) return `SENIOR ${member.role}`
  return null
}
// +1 XP to every listed member's row for `skill`; returns updated rows + any level-up events. An event
// fires when the gained skill steps into a titled band (3 → SENIOR, 5 → MASTER), e.g. "BEN OKONKWO is now a SENIOR PILOT — NAVIGATION L3" (title from the member's HIGHEST skill).
export function grantXp(
  skillRows: SkillRow[],
  crewIds: string[],
  skill: SkillName,
  members: Record<string, CrewIdentity>,
): { rows: SkillRow[]; events: string[] } {
  const rows = skillRows.map((r) =>
    r.skill === skill && crewIds.includes(r.crewId)
      ? { ...r, xp: r.xp + 1, level: levelFromXp(r.xp + 1) }
      : r,
  )
  const events: string[] = []
  for (const crewId of crewIds) {
    const member = members[crewId]
    if (!member) continue
    const newLevel = rows.find((r) => r.crewId === crewId && r.skill === skill)?.level ?? 0
    if (newLevel === 3 || newLevel === 5) {
      const title = titleFor(member, rows.filter((r) => r.crewId === crewId))
      if (title) events.push(`${member.name} is now a ${title} — ${skill} L${newLevel}`)
    }
  }
  return { rows, events }
}