/**
 * Ordinary-chat subject truth.
 *
 * `self` is the current user's `profiles` row. `other` is a `chart_profiles`
 * row owned by that user. Session name/role snapshots and client birth fields
 * are not chart truth. A failed other lookup never falls back to self.
 */

export const consultationSubjectErrorCodes = [
  "subject_not_found",
  "subject_role_mismatch",
  "subject_incomplete",
  "subject_unavailable",
  "subject_locked",
] as const;

export type ConsultationSubjectErrorCode = (typeof consultationSubjectErrorCodes)[number];

export class ConsultationSubjectError extends Error {
  readonly code: ConsultationSubjectErrorCode;

  constructor(code: ConsultationSubjectErrorCode) {
    super(`Consultation subject rejected: ${code}`);
    this.name = "ConsultationSubjectError";
    this.code = code;
  }
}

export type ConsultationSubjectBinding = Readonly<{
  chartProfileId: string | null;
  chartProfileRole: "self" | "other" | null;
  chartProfileName: string | null;
}>;

export type OwnedChartProfile = Readonly<{
  id: string;
  userId: string;
  role: string;
  profile: unknown;
}>;

export type ResolvedConsultationSubject = Readonly<{
  role: "self" | "other";
  chartProfileId: string | null;
  name: string;
  profile: unknown;
}>;

export type ConsultationSubjectFailureBody = Readonly<{
  error: string;
  message: string;
  code: "subject_incomplete" | "subject_unavailable" | "subject_locked";
}>;

const bindingKeys = ["chart_profile_id", "chart_profile_name", "chart_profile_role"] as const;

const emptyBinding: ConsultationSubjectBinding = {
  chartProfileId: null,
  chartProfileRole: null,
  chartProfileName: null,
};

function textOrNull(value: unknown): string | null {
  if (typeof value !== "string") return null;
  const trimmed = value.trim();
  return trimmed ? trimmed : null;
}

function recordOf(value: unknown): Record<string, unknown> | null {
  return value !== null && typeof value === "object" && !Array.isArray(value)
    ? value as Record<string, unknown>
    : null;
}

function pickText(row: Record<string, unknown>, keys: readonly string[]): string | null {
  for (const key of keys) {
    const value = textOrNull(row[key]);
    if (value) return value;
  }
  return null;
}

function pickNumber(row: Record<string, unknown>, keys: readonly string[]): number | null {
  for (const key of keys) {
    const value = row[key];
    if (typeof value === "number" && Number.isFinite(value)) return value;
  }
  return null;
}

function profileName(value: unknown): string {
  const row = recordOf(value);
  const name = row ? pickText(row, ["name"]) : null;
  return name ? name.slice(0, 80) : "";
}

/**
 * Library rows are camelCase `Profile` objects. Consultation truth is the
 * snake_case account shape. Client request keys (`year`, `lat`, `city`, …)
 * are not read, so they cannot fill gaps.
 */
export function chartProfileToConsultationRow(value: unknown): Record<string, unknown> | null {
  const row = recordOf(value);
  if (!row) return null;
  const status = pickText(row, ["birth_time_status", "birthTimeStatus"]);
  const verified = status === "accepted" || status === "confirmed";
  const activeTime = verified
    ? pickText(row, ["active_birth_time", "time"])
    : pickText(row, ["active_birth_time"]);
  return {
    name: pickText(row, ["name"]),
    birth_date: pickText(row, ["birth_date", "date"]),
    active_birth_date: pickText(row, ["active_birth_date", "activeDate"]),
    reported_birth_time: pickText(row, ["reported_birth_time", "reportedTime"]),
    active_birth_time: activeTime,
    birth_time_source: pickText(row, ["birth_time_source", "birthTimeSource"]),
    birth_time_period: pickText(row, ["birth_time_period", "birthTimePeriod"]),
    declared_window_start: pickText(row, ["declared_window_start", "declaredWindowStart"]),
    declared_window_end: pickText(row, ["declared_window_end", "declaredWindowEnd"]),
    birth_time_status: status,
    country_code: pickText(row, ["country_code", "countryCode"]),
    province_code: pickText(row, ["province_code", "provinceCode"]),
    city_code: pickText(row, ["city_code", "cityCode"]),
    district_code: pickText(row, ["district_code", "districtCode"]),
    latitude: pickNumber(row, ["latitude"]),
    longitude: pickNumber(row, ["longitude"]),
    timezone_offset: pickNumber(row, ["timezone_offset", "timezoneOffset"]),
    active_birth_timezone_offset: pickNumber(row, ["active_birth_timezone_offset", "activeTimezoneOffset"]),
    birth_place_label: pickText(row, ["birth_place_label", "birthPlaceLabel"]),
    birth_place_type: pickText(row, ["birth_place_type", "birthPlaceType"]),
    birth_place_provider: pickText(row, ["birth_place_provider", "birthPlaceProvider"]),
    birth_place_provider_id: pickText(row, ["birth_place_provider_id", "birthPlaceProviderId"]),
    timezone_id: pickText(row, ["timezone_id", "timezoneId"]),
    timezone_source: pickText(row, ["timezone_source", "timezoneSource"]),
    ayanamsa: pickText(row, ["ayanamsa"]),
  };
}

function otherProfileComplete(row: Record<string, unknown>): boolean {
  const name = typeof row.name === "string" && row.name.trim();
  const birthDate = typeof row.birth_date === "string" && row.birth_date.trim();
  const source = typeof row.birth_time_source === "string" && row.birth_time_source.trim();
  const status = typeof row.birth_time_status === "string" && row.birth_time_status.trim();
  const latitude = typeof row.latitude === "number" && Number.isFinite(row.latitude);
  const longitude = typeof row.longitude === "number" && Number.isFinite(row.longitude);
  const label = typeof row.birth_place_label === "string" && row.birth_place_label.trim();
  const timezoneOffset = typeof row.timezone_offset === "number" && Number.isFinite(row.timezone_offset);
  const timezoneId = typeof row.timezone_id === "string" && row.timezone_id.trim();
  return Boolean(name && birthDate && source && status && latitude && longitude && label && (timezoneOffset || timezoneId));
}

export function consultationSubjectBindingFromSession(row: {
  chart_profile_id?: unknown;
  chart_profile_name?: unknown;
  chart_profile_role?: unknown;
}): ConsultationSubjectBinding {
  const role = row.chart_profile_role === "self" || row.chart_profile_role === "other"
    ? row.chart_profile_role
    : null;
  return {
    chartProfileId: textOrNull(row.chart_profile_id),
    chartProfileRole: role,
    chartProfileName: textOrNull(row.chart_profile_name),
  };
}

export function sessionHasMessages(messages: unknown): boolean {
  if (messages == null) return false;
  if (Array.isArray(messages)) return messages.length > 0;
  return true;
}

export function sessionBindingRequested(values: object): boolean {
  return bindingKeys.some((key) => Object.prototype.hasOwnProperty.call(values, key));
}

export function sameSessionBinding(
  left: ConsultationSubjectBinding,
  right: ConsultationSubjectBinding,
): boolean {
  return textOrNull(left.chartProfileId) === textOrNull(right.chartProfileId)
    && (left.chartProfileRole ?? null) === (right.chartProfileRole ?? null)
    && textOrNull(left.chartProfileName) === textOrNull(right.chartProfileName);
}

async function readOwnedChart(
  load: (chartProfileId: string) => Promise<OwnedChartProfile | null>,
  userId: string,
  chartProfileId: string,
): Promise<OwnedChartProfile | null> {
  try {
    const row = await load(chartProfileId);
    if (row === null) return null;
    if (!row || typeof row.id !== "string" || typeof row.userId !== "string" || typeof row.role !== "string") {
      throw new ConsultationSubjectError("subject_unavailable");
    }
    if (row.userId !== userId) throw new ConsultationSubjectError("subject_not_found");
    return row;
  } catch (error) {
    if (error instanceof ConsultationSubjectError) throw error;
    throw new ConsultationSubjectError("subject_unavailable");
  }
}

async function resolveOther(
  input: {
    userId: string;
    loadOwnedChartProfile: (chartProfileId: string) => Promise<OwnedChartProfile | null>;
  },
  chartProfileId: string,
): Promise<ResolvedConsultationSubject> {
  const row = await readOwnedChart(input.loadOwnedChartProfile, input.userId, chartProfileId);
  if (!row) throw new ConsultationSubjectError("subject_not_found");
  if (row.role !== "other") throw new ConsultationSubjectError("subject_role_mismatch");
  const profile = chartProfileToConsultationRow(row.profile);
  if (!profile || !otherProfileComplete(profile)) {
    throw new ConsultationSubjectError("subject_incomplete");
  }
  return Object.freeze({
    role: "other",
    chartProfileId: row.id,
    name: profileName(profile),
    profile: Object.freeze({ ...profile }),
  });
}

export async function resolveConsultationSubject(input: {
  userId: string;
  binding: ConsultationSubjectBinding;
  loadSelfProfile: (userId: string) => Promise<unknown>;
  loadOwnedChartProfile: (chartProfileId: string) => Promise<OwnedChartProfile | null>;
  /** Present so callers can pass the request body. Never read for chart truth. */
  clientBirth?: unknown;
}): Promise<ResolvedConsultationSubject> {
  const id = textOrNull(input.binding.chartProfileId);
  const role = input.binding.chartProfileRole ?? null;
  const explicitOtherId = Boolean(id && id !== "self");

  if (role === "other") {
    if (!explicitOtherId) throw new ConsultationSubjectError("subject_role_mismatch");
    return resolveOther(input, id as string);
  }

  if (explicitOtherId && role !== "self") {
    return resolveOther(input, id as string);
  }

  if (role === "self" && explicitOtherId) {
    const row = await readOwnedChart(input.loadOwnedChartProfile, input.userId, id as string);
    if (!row) throw new ConsultationSubjectError("subject_not_found");
    if (row.role !== "self") throw new ConsultationSubjectError("subject_role_mismatch");
  }

  const selfRow = await input.loadSelfProfile(input.userId);
  return Object.freeze({
    role: "self",
    chartProfileId: "self",
    name: profileName(selfRow),
    profile: selfRow,
  });
}

function mergedBinding(
  requested: object,
  existing: ConsultationSubjectBinding | null,
): ConsultationSubjectBinding {
  const record = requested as Record<string, unknown>;
  const base = existing ?? emptyBinding;
  const role = record.chart_profile_role;
  return {
    chartProfileId: Object.prototype.hasOwnProperty.call(record, "chart_profile_id")
      ? textOrNull(record.chart_profile_id)
      : base.chartProfileId,
    chartProfileRole: Object.prototype.hasOwnProperty.call(record, "chart_profile_role")
      ? role === "self" || role === "other" ? role : null
      : base.chartProfileRole,
    chartProfileName: Object.prototype.hasOwnProperty.call(record, "chart_profile_name")
      ? textOrNull(record.chart_profile_name)
      : base.chartProfileName,
  };
}

export async function authoritativeSessionBinding(input: {
  userId: string;
  requested: object;
  existingMessages: unknown;
  existingBinding: ConsultationSubjectBinding | null;
  loadSelfProfile: (userId: string) => Promise<unknown>;
  loadOwnedChartProfile: (chartProfileId: string) => Promise<OwnedChartProfile | null>;
}): Promise<{
  chart_profile_id: string | null;
  chart_profile_name: string | null;
  chart_profile_role: "self" | "other" | null;
} | null> {
  if (!sessionBindingRequested(input.requested)) return null;
  const requestedBinding = mergedBinding(input.requested, input.existingBinding);
  const existing = input.existingBinding ?? emptyBinding;
  if (sessionHasMessages(input.existingMessages)) {
    if (!sameSessionBinding(requestedBinding, existing)) {
      throw new ConsultationSubjectError("subject_locked");
    }
    return {
      chart_profile_id: existing.chartProfileId,
      chart_profile_name: existing.chartProfileName,
      chart_profile_role: existing.chartProfileRole,
    };
  }
  const resolved = await resolveConsultationSubject({
    userId: input.userId,
    binding: requestedBinding,
    loadSelfProfile: input.loadSelfProfile,
    loadOwnedChartProfile: input.loadOwnedChartProfile,
    clientBirth: {
      name: requestedBinding.chartProfileName,
    },
  });
  return {
    chart_profile_id: resolved.role === "self" ? "self" : resolved.chartProfileId,
    chart_profile_name: resolved.name || null,
    chart_profile_role: resolved.role,
  };
}

export function ownedChartProfileFromResult(result: {
  data: unknown;
  error: unknown;
}): OwnedChartProfile | null {
  if (result.error) throw new ConsultationSubjectError("subject_unavailable");
  const row = recordOf(result.data);
  if (!row) return null;
  if (typeof row.id !== "string" || typeof row.user_id !== "string" || typeof row.role !== "string") {
    throw new ConsultationSubjectError("subject_unavailable");
  }
  return { id: row.id, userId: row.user_id, role: row.role, profile: row.profile };
}

export function selfNameFromResult(result: { data: unknown; error: unknown }): unknown {
  if (result.error) throw new ConsultationSubjectError("subject_unavailable");
  return result.data;
}

export function consultationSubjectFailureResponse(error: ConsultationSubjectError): {
  status: number;
  body: ConsultationSubjectFailureBody;
} {
  if (error.code === "subject_locked") {
    return {
      status: 409,
      body: {
        error: "不能更换这段对话的人物",
        message: "这段对话已经开始。要换一个人，请新建对话。",
        code: "subject_locked",
      },
    };
  }
  if (error.code === "subject_incomplete") {
    return {
      status: 409,
      body: {
        error: "这份人物资料还不完整",
        message: "请补全出生日期、时间和地点后再发送，本次不会扣点。",
        code: "subject_incomplete",
      },
    };
  }
  if (error.code === "subject_unavailable") {
    return {
      status: 503,
      body: {
        error: "暂时无法核对人物资料",
        message: "请稍后重试，本次不会扣点。",
        code: "subject_unavailable",
      },
    };
  }
  return {
    status: 409,
    body: {
      error: "无法使用这份人物资料",
      message: "这份资料不存在、已删除，或与当前会话不一致。请新建对话后再试，本次不会扣点。",
      code: "subject_unavailable",
    },
  };
}