/** Routage URL sous `/mail` : dossier, onglet boîte de réception, page, message ouvert. */

import {
  cloneDefaultLabelRows,
  tabbedInboxLabelRows,
} from "@/lib/sidebar-nav-data"

export const DEFAULT_MAIL_FOLDER = "inbox"
export const DEFAULT_INBOX_TAB = "primary"

/** Segments d’URL historiques → ids libellés actuels. */
const LEGACY_INBOX_TAB_SEGMENT: Record<string, string> = {
  updates: "mises-a-jour",
  notifications: "newsletters",
  social: "reseaux-sociaux",
  purchases: "achats",
  travel: "deplacements",
}

export function normalizeInboxTabSegment(tab: string): string {
  return LEGACY_INBOX_TAB_SEGMENT[tab] ?? tab
}

function defaultInboxTabIdSet(): Set<string> {
  const s = new Set<string>([DEFAULT_INBOX_TAB])
  for (const r of tabbedInboxLabelRows(cloneDefaultLabelRows())) {
    s.add(r.id)
  }
  return s
}

/** Onglets boîte de réception reconnus dans l’URL (ids courants + segments legacy). */
export const INBOX_CATEGORY_TAB_IDS = (() => {
  const s = defaultInboxTabIdSet()
  for (const legacy of Object.keys(LEGACY_INBOX_TAB_SEGMENT)) {
    s.add(legacy)
  }
  return s
})()

export type MailRouteState = {
  folderId: string
  /** Onglet catégorie ; pour `folderId !== inbox`, valeur ignorée par le filtre mais peut rester `primary`. */
  inboxTab: string
  page: number
  mailId: string | null
}

const DEFAULT_STATE: MailRouteState = {
  folderId: DEFAULT_MAIL_FOLDER,
  inboxTab: DEFAULT_INBOX_TAB,
  page: 1,
  mailId: null,
}

function decodeSegment(s: string): string {
  try {
    return decodeURIComponent(s)
  } catch {
    return s
  }
}

/**
 * Parse le tableau de segments Next (sans le préfixe `mail`).
 * Ex. `['inbox','promotions','page','2','message','1']`
 */
export function parseMailSegments(
  segments: string[] | undefined | null
): MailRouteState {
  const raw = segments?.filter((x) => x.length > 0) ?? []
  if (raw.length === 0) return { ...DEFAULT_STATE }

  const parts = [...raw]
  let mailId: string | null = null
  let page = 1

  if (parts.length >= 2 && parts[parts.length - 2] === "message") {
    mailId = decodeSegment(parts[parts.length - 1]!)
    parts.length -= 2
  }

  if (parts.length >= 2 && parts[parts.length - 2] === "page") {
    const n = parseInt(parts[parts.length - 1]!, 10)
    page = Number.isFinite(n) && n >= 1 ? n : 1
    parts.length -= 2
  }

  if (parts.length === 0) {
    return { ...DEFAULT_STATE, mailId, page }
  }

  const folderId = parts[0]!
  if (folderId === "inbox") {
    if (parts.length >= 2) {
      const tab = parts[1]!
      if (INBOX_CATEGORY_TAB_IDS.has(tab)) {
        const inboxTab = normalizeInboxTabSegment(tab)
        const valid = defaultInboxTabIdSet()
        return {
          folderId,
          inboxTab: valid.has(inboxTab) ? inboxTab : DEFAULT_INBOX_TAB,
          page,
          mailId,
        }
      }
      return { folderId, inboxTab: DEFAULT_INBOX_TAB, page, mailId }
    }
    return { folderId, inboxTab: DEFAULT_INBOX_TAB, page, mailId }
  }

  return {
    folderId,
    inboxTab: DEFAULT_INBOX_TAB,
    page,
    mailId,
  }
}

function encodePathSegment(s: string): string {
  return encodeURIComponent(s)
}

export function buildMailPath(r: MailRouteState): string {
  const segs: string[] = ["mail", encodeURIComponent(r.folderId)]

  if (r.folderId === "inbox") {
    const tab = normalizeInboxTabSegment(r.inboxTab || DEFAULT_INBOX_TAB)
    if (tab !== DEFAULT_INBOX_TAB) {
      segs.push(tab)
    }
  }

  if (r.page > 1) {
    segs.push("page", String(r.page))
  }

  if (r.mailId) {
    segs.push("message", encodePathSegment(r.mailId))
  }

  return `/${segs.join("/")}`
}