/**
 * cli:audit-ba — corpus/conventions.ts
 *
 * Requirement 8 of the audit-ba mandate: massive, measured corpus conventions
 * are ACCEPTED as-is — the tooling adapts to the project, never the reverse.
 * Detection is a pure function of the corpus (≥90% share decides), zero
 * config, zero mutable state. The divergence from the canonical doc form is
 * ONE project-scoped warn (CONV-001 / CONV-002), never an error per
 * occurrence (1 538 flat-kebab error codes = 1 warn, not 1 538 errs).
 */
import type { ProjectConventions } from '../types.js'
import type { ModuleModel } from './model.js'

const SHARE_THRESHOLD = 0.9

/** True when the UC code's section segments (between MOD and NNN) carry any
 *  lowercase letter — the corpus-lowercase form. */
function ucSectionIsLower(ucCode: string): boolean {
  const middle = ucCode.split('-').slice(3, -1).join('-')
  return /[a-z]/.test(middle)
}

/** BR-011 canonical: `lower.dotted` ≥3 segments. Kebab flat = no dot at all. */
function errorCodeIsKebabFlat(code: string): boolean {
  return !code.includes('.')
}

export function detectConventions(modules: ModuleModel[]): ProjectConventions {
  const ucs = modules.flatMap((m) => m.ucs)
  const lowerCount = ucs.filter((u) => ucSectionIsLower(u.ucCode)).length
  const ucShare = ucs.length === 0 ? 0 : lowerCount / ucs.length

  const codes = modules.flatMap((m) => m.rules.map((r) => r.errorCode)).filter((c): c is string => !!c)
  const kebabCount = codes.filter(errorCodeIsKebabFlat).length
  const codeShare = codes.length === 0 ? 0 : kebabCount / codes.length

  return {
    ucSectionCase:
      ucs.length === 0 ? 'upper' : ucShare >= SHARE_THRESHOLD ? 'lower' : ucShare <= 1 - SHARE_THRESHOLD ? 'upper' : 'mixed',
    ucSectionLowerShare: Math.round(ucShare * 1000) / 1000,
    errorCodeShape:
      codes.length === 0 ? 'dotted' : codeShare >= SHARE_THRESHOLD ? 'kebab' : codeShare <= 1 - SHARE_THRESHOLD ? 'dotted' : 'mixed',
    errorCodeKebabShare: Math.round(codeShare * 1000) / 1000,
  }
}

/** Modules on the MINORITY side of the detected UC-case convention. */
export function ucCaseMinorityModules(modules: ModuleModel[], convention: 'lower' | 'upper'): string[] {
  const out: string[] = []
  for (const m of modules) {
    if (m.ucs.length === 0) continue
    const lower = m.ucs.filter((u) => ucSectionIsLower(u.ucCode)).length
    const majorityLower = lower * 2 >= m.ucs.length
    if ((convention === 'lower') !== majorityLower) out.push(`${m.app}/${m.module}`)
  }
  return out
}