import { readCurrentSubjectId } from "@/lib/current-subject";
import { isConsultationSubjectProfileComplete } from "@/lib/consultation-subject-resolver";
import { sessionChartLabel } from "@/lib/home-profile";
import type { ChartLibraryRecord, ChatSession } from "@/lib/home-types";

export type ChatProfileCatalogStatus = "idle" | "loading" | "ready" | "failed" | "degraded";

/** New ordinary chats follow the current person, not a fixed self id. */
export function NEW_CHAT_SUBJECT_ID(): string {
  return readCurrentSubjectId();
}

export type ChatProfileChoice =
  | { readonly action: "bind"; readonly chartProfileId: string }
  | { readonly action: "open-new"; readonly chartProfileId: string }
  | { readonly action: "ignore" };

export type ChatProfilePickerRow = {
  readonly id: string;
  readonly role: "self" | "other";
  readonly name: string;
  readonly detail: string;
  readonly complete: boolean;
  readonly selected: boolean;
};

type SubjectSession = Pick<ChatSession, "chartProfileId" | "chartProfileName" | "chartProfileRole" | "sessionType" | "messagesHydrated" | "messages">;

export function chatSessionSubjectLocked(session: {
  sessionType: string;
  messagesHydrated: boolean;
  messages: readonly unknown[];
}): boolean {
  if (session.sessionType !== "consultation") return true;
  if (!session.messagesHydrated) return true;
  return session.messages.length > 0;
}

export function sessionMatchesSubject(
  session: Pick<ChatSession, "chartProfileId" | "chartProfileRole">,
  subjectId: string,
): boolean {
  const id = session.chartProfileId?.trim() || null;
  if (!subjectId || subjectId === "self") {
    return id == null || id === "self" || session.chartProfileRole === "self";
  }
  return id === subjectId;
}

export function chatProfileSelectedId(session: Pick<ChatSession, "chartProfileId" | "chartProfileRole">): string {
  if (session.chartProfileRole === "other" || (session.chartProfileId && session.chartProfileId !== "self")) {
    return session.chartProfileId ?? "";
  }
  return "self";
}

export function chatProfileDisplayName(input: {
  session: Pick<ChatSession, "chartProfileId" | "chartProfileName" | "chartProfileRole">;
  status: ChatProfileCatalogStatus;
  library: readonly ChartLibraryRecord[];
}): string {
  if (input.status !== "ready") {
    const snapshot = input.session.chartProfileName?.trim();
    if (snapshot) return snapshot;
    if (!input.session.chartProfileId || input.session.chartProfileId === "self" || input.session.chartProfileRole !== "other") {
      return "我";
    }
    return "未命名资料";
  }
  return sessionChartLabel(input.session, input.library);
}

export function chatSubjectSendBlocked(input: {
  session: Pick<ChatSession, "sessionType" | "chartProfileId" | "chartProfileRole"> | undefined;
  status: ChatProfileCatalogStatus;
  library: readonly ChartLibraryRecord[];
}): boolean {
  if (!input.session || input.session.sessionType !== "consultation") return false;
  if (input.status !== "ready") return false;
  const id = input.session.chartProfileId;
  if (!id || id === "self" || input.session.chartProfileRole === "self") return false;
  return !input.library.some((record) => record.id === id && record.role === "other");
}

function rowName(record: ChartLibraryRecord): string {
  return record.profile.name.trim() || (record.role === "self" ? "我" : "未命名资料");
}

export function chatProfilePickerRows(input: {
  status: ChatProfileCatalogStatus;
  library: readonly ChartLibraryRecord[];
  selectedId: string;
}): ChatProfilePickerRow[] {
  if (input.status !== "ready" && input.status !== "degraded") return [];
  const self = input.library.find((record) => record.role === "self" || record.id === "self");
  const others = input.library.filter((record) => record.role === "other" && record.id !== "self");
  const rows: ChatProfilePickerRow[] = [];
  if (self) rows.push(toRow(self, input.selectedId));
  else {
    rows.push({
      id: "self",
      role: "self",
      name: "我",
      detail: "这份资料还不完整",
      complete: false,
      selected: input.selectedId === "self",
    });
  }
  if (input.status === "degraded") return rows;
  for (const record of others) rows.push(toRow(record, input.selectedId));
  return rows;
}

function toRow(record: ChartLibraryRecord, selectedId: string): ChatProfilePickerRow {
  const complete = isConsultationSubjectProfileComplete(record.profile);
  const id = record.role === "self" ? "self" : record.id;
  return {
    id,
    role: record.role,
    name: rowName(record),
    detail: complete
      ? (record.role === "self" ? "本人" : (record.profile.date || "其他人"))
      : "这份资料还不完整",
    complete,
    selected: id === selectedId,
  };
}

export function chatProfileChoice(input: {
  session: Pick<SubjectSession, "sessionType" | "messagesHydrated" | "messages" | "chartProfileId">;
  chartProfileId: string;
  requestInFlight: boolean;
  libraryReady: boolean;
  selectable: boolean;
}): ChatProfileChoice {
  if (!input.libraryReady || !input.selectable || !input.chartProfileId) return { action: "ignore" };
  if (input.session.sessionType !== "consultation") return { action: "ignore" };
  if (chatSessionSubjectLocked(input.session)) {
    if (input.chartProfileId === (input.session.chartProfileId || "self")) return { action: "ignore" };
    if (input.requestInFlight) return { action: "ignore" };
    return { action: "open-new", chartProfileId: input.chartProfileId };
  }
  if (input.chartProfileId === input.session.chartProfileId) return { action: "ignore" };
  return { action: "bind", chartProfileId: input.chartProfileId };
}

/** Empty-session PATCH body. The server fills the name; the client does not send one. */
export function emptySessionBindingWrite(chartProfileId: string, role: "self" | "other"): {
  chart_profile_id: string;
  chart_profile_role: "self" | "other";
} {
  return {
    chart_profile_id: role === "self" ? "self" : chartProfileId,
    chart_profile_role: role,
  };
}