/** 正文 :::hide 块解析（与 backend/markdown/hide.go 契约一致） */

export type HideKind = "login" | "reply" | "points" | "password";

export type HideSegment =
  | { type: "md"; text: string }
  | {
      type: "hide";
      kind: HideKind;
      points: number;
      locked: boolean;
      body: string;
    };

const HIDE_KINDS = new Set<HideKind>(["login", "reply", "points", "password"]);

function isClose(line: string): boolean {
  return line.trim() === ":::";
}

/** 与 Go parseOpenMarker 对齐：:::hide <kind> [points|password] [locked] */
function parseOpen(trimmed: string): {
  kind: HideKind;
  points: number;
  locked: boolean;
} | null {
  if (!trimmed.startsWith(":::hide")) return null;
  const parts = trimmed
    .slice(":::hide".length)
    .trim()
    .split(/\s+/)
    .filter(Boolean);
  if (parts.length === 0) return null;
  const kind = parts[0] as HideKind;
  if (!HIDE_KINDS.has(kind)) return null;

  let idx = 1;
  let points = 0;
  let locked = false;

  if (kind === "points") {
    if (idx >= parts.length) return null;
    const n = Number(parts[idx]);
    if (!Number.isFinite(n) || n < 1 || n > 100000) return null;
    points = n;
    idx++;
  } else if (kind === "password") {
    // 脱敏：:::hide password locked；原文：:::hide password <pwd> [locked]
    if (idx < parts.length && parts[idx] !== "locked") {
      idx++;
    }
  }

  for (; idx < parts.length; idx++) {
    if (parts[idx] === "locked") locked = true;
    else return null;
  }
  return { kind, points, locked };
}

/**
 * 将正文拆成公开 Markdown 段与隐藏块（忽略代码围栏内伪语法）。
 * 解析失败时整篇当作普通 Markdown，避免渲染崩溃。
 */
export function splitHideSegments(content: string): HideSegment[] {
  if (!content) return [{ type: "md", text: "" }];
  const lines = content.replace(/\r\n/g, "\n").replace(/\r/g, "\n").split("\n");
  const out: HideSegment[] = [];
  let buf: string[] = [];
  let inCode = false;
  let i = 0;

  const flushMd = () => {
    if (buf.length === 0) return;
    out.push({ type: "md", text: buf.join("\n") });
    buf = [];
  };

  while (i < lines.length) {
    const trimmed = lines[i].trim();
    if (trimmed.startsWith("```")) {
      inCode = !inCode;
      buf.push(lines[i]);
      i++;
      continue;
    }
    if (inCode) {
      buf.push(lines[i]);
      i++;
      continue;
    }

    const open = parseOpen(trimmed);
    if (open) {
      flushMd();
      const bodyLines: string[] = [];
      let j = i + 1;
      let innerCode = false;
      let found = false;
      while (j < lines.length) {
        const inner = lines[j].trim();
        if (inner.startsWith("```")) {
          innerCode = !innerCode;
          bodyLines.push(lines[j]);
          j++;
          continue;
        }
        if (innerCode) {
          bodyLines.push(lines[j]);
          j++;
          continue;
        }
        if (parseOpen(inner)) {
          buf.push(lines[i]);
          i++;
          found = false;
          break;
        }
        if (isClose(inner)) {
          found = true;
          break;
        }
        bodyLines.push(lines[j]);
        j++;
      }
      if (!found) {
        buf.push(lines[i]);
        i++;
        continue;
      }
      out.push({
        type: "hide",
        kind: open.kind,
        points: open.points,
        locked: open.locked,
        body: bodyLines.join("\n"),
      });
      i = j + 1;
      continue;
    }

    buf.push(lines[i]);
    i++;
  }
  flushMd();
  return out.length > 0 ? out : [{ type: "md", text: content }];
}

/** 去掉锁块与标记后，供 SEO / TOC / description 使用的公开纯文本片段 */
export function publicMarkdownForSeo(content: string): string {
  const segs = splitHideSegments(content);
  return segs
    .filter((s): s is Extract<HideSegment, { type: "md" }> => s.type === "md")
    .map((s) => s.text)
    .concat(
      segs
        .filter(
          (s): s is Extract<HideSegment, { type: "hide" }> =>
            s.type === "hide" && !s.locked
        )
        .map((s) => s.body)
    )
    .join("\n\n")
    .trim();
}

export function hideKindLabel(kind: HideKind): string {
  switch (kind) {
    case "login":
      return "登录可见";
    case "reply":
      return "回复可见";
    case "points":
      return "积分可见";
    case "password":
      return "密码可见";
  }
}