/**
 * Personal-report generation progress: the shared vocabulary between the API
 * route (which reads durable section rows) and the waiting screen.
 *
 * The waiting screen exists because a full report takes minutes. Everything
 * here is derived from state the worker already persists — nothing is
 * interpolated, smoothed, or extrapolated. If the backend has not moved, the
 * screen does not move either.
 *
 * Privacy boundary, drawn against BUG-043 (a rectification surface that
 * re-rendered backend evidence state as a panel the user had to manage):
 * chapter names and per-chapter state are the reader's own deliverable
 * structure on a read-only waiting screen, so they may be shown. Attempt
 * counts, raw error codes, lease tokens, job ids and payloads are backend
 * state and must never cross into the response.
 * `deriveSectionProgressState` is the one place attemptCount is read, and it
 * runs on the server.
 */

/** Chapter titles shown to the reader; shared with the report document view. */
export const REPORT_THEME_LABELS: Readonly<Record<string, string>> = {
  general: "综合",
  career: "事业",
  wealth: "财富",
  marriage: "婚恋",
  health: "健康",
  education: "教育",
  timing: "应期",
};

export function reportThemeLabel(theme: string): string {
  return REPORT_THEME_LABELS[theme] ?? theme;
}

/**
 * Per-chapter state as the reader sees it.
 * - `done`    section row is `ready`
 * - `failed`  section row is `blocked` (attempts exhausted); still counts as
 *             finished work, so the bar advances rather than stalling
 * - `writing` row is `pending` but has been claimed at least once
 * - `waiting` row is `pending` and untouched
 */
export type ReportSectionProgressState = "done" | "failed" | "writing" | "waiting";

export type ReportSectionProgress = Readonly<{
  id: string;
  state: ReportSectionProgressState;
}>;

/**
 * Server-side mapping from a durable section row to reader-visible state.
 *
 * `start_personal_report_section` bumps `attempt_count` and leaves `status`
 * at `pending`, so a claimed-but-unfinished chapter is exactly
 * `pending && attemptCount > 0`. That makes "which chapter is being written"
 * an observed fact rather than an inference from the completed count — the
 * section list arrives ordered by section_id, not by write order, so counting
 * forward from the finished chapters would name the wrong one.
 */
export function deriveSectionProgressState(
  status: string,
  attemptCount: number,
): ReportSectionProgressState {
  if (status === "ready") return "done";
  if (status === "blocked") return "failed";
  return attemptCount > 0 ? "writing" : "waiting";
}

/**
 * Stage of the generation run, read from the job's progress phase.
 * The worker ladder is queued(0) → loading_context(10) → generating_report(30)
 * → section:<id>(30..85, one step per finished chapter) → persisting_report(90)
 * → ready(100).
 */
export type ReportProgressStage = "preparing" | "writing" | "finishing";

export function classifyReportProgressStage(phase: string | undefined): ReportProgressStage {
  if (phase === "persisting_report") return "finishing";
  if (phase !== undefined && phase.startsWith("section:")) return "writing";
  return "preparing";
}

/**
 * How long one unchanged progress signature may last before the screen says
 * so. A chapter that fails is retried (max_attempts 2) with no change to the
 * job's phase or percent, so this is the only signal the reader gets that a
 * chapter is taking two passes. We say it is slow; we do not claim to know
 * which attempt it is, because attemptCount never reaches the client.
 */
export const REPORT_PROGRESS_STALL_MS = 90_000;

export type ReportProgressChapter = Readonly<{
  id: string;
  label: string;
  state: ReportSectionProgressState;
  statusText: string;
}>;

export type ReportProgressView = Readonly<{
  stage: ReportProgressStage;
  /** Sentence for the status line; always present. */
  headline: string;
  /** Empty until the run reaches the writing stage. */
  chapters: readonly ReportProgressChapter[];
  finished: number;
  total: number;
  /** True when at least one chapter is blocked; the run can still finish. */
  hasFailure: boolean;
}>;

const STATE_TEXT: Readonly<Record<ReportSectionProgressState, string>> = {
  done: "已完成",
  failed: "写作失败",
  writing: "正在写",
  waiting: "待写",
};

/**
 * Build the reader-facing view. `stalled` is passed in rather than computed
 * from a clock so this stays a pure function the tests can drive.
 */
export function describeReportProgress(input: Readonly<{
  phase?: string;
  sections?: readonly ReportSectionProgress[];
  stalled?: boolean;
}>): ReportProgressView {
  const stage = classifyReportProgressStage(input.phase);
  const sections = input.sections ?? [];
  const chapters = sections.map((section) => ({
    id: section.id,
    label: reportThemeLabel(section.id),
    state: section.state,
    statusText: section.state === "writing" && input.stalled
      ? "用时较长，仍在写"
      : STATE_TEXT[section.state],
  }));
  const finished = chapters.filter(
    (chapter) => chapter.state === "done" || chapter.state === "failed",
  ).length;
  const total = chapters.length;
  const hasFailure = chapters.some((chapter) => chapter.state === "failed");

  if (stage === "finishing") {
    return { stage, headline: "正在整理成文", chapters, finished, total, hasFailure };
  }
  if (stage === "writing" && total > 0) {
    return {
      stage,
      headline: `已完成 ${finished} / ${total} 章`,
      chapters,
      finished,
      total,
      hasFailure,
    };
  }
  // Either the run has not reached the chapters yet, or the section rows are
  // not readable this poll. Both are "preparing" as far as the reader is
  // concerned; we never invent a chapter count.
  return {
    stage: "preparing",
    headline: "正在准备你的星盘证据",
    chapters: [],
    finished: 0,
    total: 0,
    hasFailure: false,
  };
}

/**
 * A signature that changes exactly when observable progress changes. The
 * waiting screen restarts its stall timer on a new signature, so a chapter
 * being retried (phase and percent unchanged) is what trips the slow notice.
 */
export function reportProgressSignature(input: Readonly<{
  phase?: string;
  percent?: number;
  sections?: readonly ReportSectionProgress[];
}>): string {
  const sections = (input.sections ?? [])
    .map((section) => `${section.id}:${section.state}`)
    .join(",");
  return `${input.phase ?? ""}|${input.percent ?? ""}|${sections}`;
}