/** 正文 [timeline]…[/timeline] 块解析与序列化 */

export type TimelineItem = {
  date: string;
  title: string;
  body: string;
  sourceUrl?: string;
  /** 导入勾选；手填项默认 true */
  selected?: boolean;
};

export type TimelineDayGroup = {
  date: string;
  items: TimelineItem[];
};

const GIT_COMMENT_RE = /^<!--\s*git:\s*(https?:\/\/\S+)\s*-->\s*$/i;
const HEADING_RE = /^##\s+(\d{4}-\d{2}-\d{2})\s+(.+)$/;

/** 去掉控制字符与 RTL 覆盖，截断长度 */
export function sanitizeTimelineText(raw: string, max: number): string {
  let s = raw
    .replace(/[\u0000-\u0008\u000B\u000C\u000E-\u001F\u007F]/g, "")
    .replace(/[\u202A-\u202E\u2066-\u2069]/g, "");
  if ([...s].length > max) {
    s = [...s].slice(0, max).join("");
  }
  return s;
}

function isDirectiveLine(t: string): boolean {
  const lower = t.toLowerCase();
  return (
    lower === "[/hide]" ||
    lower === "[/timeline]" ||
    lower === "[timeline]" ||
    lower.startsWith("[hide") ||
    t.startsWith("<!-- git:")
  );
}

/** 避免导入文本拆坏指令块：危险独立行加前缀空格 */
export function neutralizeDirectiveLines(text: string): string {
  return text
    .split("\n")
    .map((line) => {
      const t = line.trim();
      if (isDirectiveLine(t)) {
        return " " + line;
      }
      return line;
    })
    .join("\n");
}

/** 标题行：去掉换行，防止拆项 */
export function sanitizeTimelineTitle(title: string): string {
  return sanitizeTimelineText(title.replace(/[\r\n]+/g, " ").trim(), 200);
}

export function parseTimelineBody(body: string): TimelineItem[] {
  const lines = body.replace(/\r\n/g, "\n").replace(/\r/g, "\n").split("\n");
  const items: TimelineItem[] = [];
  let cur: TimelineItem | null = null;
  let bodyBuf: string[] = [];

  const flush = () => {
    if (!cur) return;
    let sourceUrl: string | undefined;
    const kept: string[] = [];
    for (const line of bodyBuf) {
      const m = line.trim().match(GIT_COMMENT_RE);
      if (m) {
        sourceUrl = m[1];
        continue;
      }
      kept.push(line);
    }
    cur.body = kept.join("\n").replace(/^\n+/, "").replace(/\n+$/, "");
    if (sourceUrl) cur.sourceUrl = sourceUrl;
    items.push(cur);
    cur = null;
    bodyBuf = [];
  };

  for (const line of lines) {
    const m = line.match(HEADING_RE);
    if (m) {
      flush();
      cur = {
        date: m[1],
        title: sanitizeTimelineTitle(m[2]),
        body: "",
        selected: true,
      };
      continue;
    }
    if (cur) bodyBuf.push(line);
  }
  flush();
  return items;
}

export function serializeTimelineBlock(items: TimelineItem[]): string {
  const parts = items
    .filter((it) => it.selected !== false)
    .map((it) => {
      const date = /^\d{4}-\d{2}-\d{2}$/.test(it.date)
        ? it.date
        : new Date().toISOString().slice(0, 10);
      const title = sanitizeTimelineTitle(it.title) || "未命名";
      const body = neutralizeDirectiveLines(sanitizeTimelineText(it.body || "", 2000));
      const lines = [`## ${date} ${title}`];
      if (body.trim()) lines.push(body.trimEnd());
      if (it.sourceUrl && /^https:\/\//i.test(it.sourceUrl)) {
        lines.push(`<!-- git: ${it.sourceUrl} -->`);
      }
      return lines.join("\n");
    });
  return `[timeline]\n${parts.join("\n\n")}\n[/timeline]`;
}

export function groupTimelineByDate(items: TimelineItem[]): TimelineDayGroup[] {
  const map = new Map<string, TimelineItem[]>();
  const order: string[] = [];
  for (const it of items) {
    const d = it.date || "未知日期";
    if (!map.has(d)) {
      map.set(d, []);
      order.push(d);
    }
    map.get(d)!.push(it);
  }
  order.sort((a, b) => (a < b ? 1 : a > b ? -1 : 0));
  return order.map((date) => ({ date, items: map.get(date)! }));
}

export function isLikelyMergeCommit(title: string): boolean {
  return /^merge\b/i.test(title.trim()) || /^合并\b/.test(title.trim());
}