/** 统一拆分正文中的 [hide] / [timeline] 指令块（忽略代码围栏） */

import {
  splitHideSegments,
  type HideKind,
  type HideSegment,
} from "@/lib/hideBlocks";
import { parseTimelineBody, type TimelineItem } from "@/lib/timelineBlocks";

export type ContentSegment =
  | { type: "md"; text: string }
  | {
      type: "hide";
      kind: HideKind;
      points: number;
      locked: boolean;
      body: string;
    }
  | { type: "timeline"; items: TimelineItem[]; rawBody: string };

function isTimelineClose(line: string): boolean {
  return line.trim().toLowerCase() === "[/timeline]";
}

function isTimelineOpen(trimmed: string): boolean {
  return trimmed.toLowerCase() === "[timeline]";
}

/**
 * 先拆时间线，再对普通 md/hide 段做 hide 拆分。
 * 时间线与 hide 互不嵌套；解析失败时整段当普通 Markdown。
 */
export function splitContentSegments(content: string): ContentSegment[] {
  if (!content) return [{ type: "md", text: "" }];
  const lines = content.replace(/\r\n/g, "\n").replace(/\r/g, "\n").split("\n");
  const raw: Array<{ type: "md"; text: string } | { type: "timeline"; body: string }> = [];
  let buf: string[] = [];
  let inCode = false;
  let i = 0;

  const flushMd = () => {
    if (buf.length === 0) return;
    raw.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;
    }

    if (isTimelineOpen(trimmed)) {
      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 (isTimelineOpen(inner)) {
          // 嵌套视为失败：整段当 md
          buf.push(lines[i]);
          i++;
          found = false;
          break;
        }
        if (isTimelineClose(inner)) {
          found = true;
          break;
        }
        bodyLines.push(lines[j]);
        j++;
      }
      if (!found) {
        buf.push(lines[i]);
        i++;
        continue;
      }
      raw.push({ type: "timeline", body: bodyLines.join("\n") });
      i = j + 1;
      continue;
    }

    buf.push(lines[i]);
    i++;
  }
  flushMd();

  const out: ContentSegment[] = [];
  for (const part of raw) {
    if (part.type === "timeline") {
      out.push({
        type: "timeline",
        items: parseTimelineBody(part.body),
        rawBody: part.body,
      });
      continue;
    }
    const hideSegs = splitHideSegments(part.text) as HideSegment[];
    for (const s of hideSegs) {
      if (s.type === "md") {
        out.push({ type: "md", text: s.text });
      } else {
        out.push({
          type: "hide",
          kind: s.kind,
          points: s.points,
          locked: s.locked,
          body: s.body,
        });
      }
    }
  }
  return out.length > 0 ? out : [{ type: "md", text: content }];
}

/** 光标是否落在某个 [timeline]…[/timeline] 块内；返回块起止与正文 */
export function findTimelineBlockAt(
  content: string,
  cursor: number
): { start: number; end: number; body: string } | null {
  const blocks = listTimelineBlocks(content);
  for (const b of blocks) {
    if (cursor >= b.start && cursor <= b.end) return b;
  }
  return null;
}

/**
 * 编辑器打开时间线面板时的目标块：
 * 1) 光标落在某块内 → 该块
 * 2) 正文恰有一块 → 该块（changelog 页常见：光标在标题区仍应更新已有时间线）
 * 3) 否则 null（新建插入）
 */
export function resolveTimelineBlockForEdit(
  content: string,
  cursor: number
): { start: number; end: number; body: string } | null {
  const at = findTimelineBlockAt(content, cursor);
  if (at) return at;
  const blocks = listTimelineBlocks(content);
  if (blocks.length === 1) return blocks[0];
  return null;
}

function listTimelineBlocks(
  content: string
): Array<{ start: number; end: number; body: string }> {
  const lines = content.replace(/\r\n/g, "\n").replace(/\r/g, "\n").split("\n");
  const out: Array<{ start: number; end: number; body: string }> = [];
  let offset = 0;
  let inCode = false;
  for (let i = 0; i < lines.length; i++) {
    const line = lines[i];
    const lineStart = offset;
    const lineEnd = offset + line.length;
    const trimmed = line.trim();
    if (trimmed.startsWith("```")) inCode = !inCode;
    if (!inCode && isTimelineOpen(trimmed)) {
      const openStart = lineStart;
      let j = i + 1;
      let innerCode = false;
      let closeEnd = -1;
      const bodyLines: string[] = [];
      let pos = lineEnd + 1;
      while (j < lines.length) {
        const l = lines[j];
        const t = l.trim();
        if (t.startsWith("```")) innerCode = !innerCode;
        if (!innerCode && isTimelineClose(t)) {
          closeEnd = pos + l.length;
          break;
        }
        bodyLines.push(l);
        pos += l.length + 1;
        j++;
      }
      if (closeEnd >= 0) {
        out.push({ start: openStart, end: closeEnd, body: bodyLines.join("\n") });
      }
    }
    offset = lineEnd + 1;
  }
  return out;
}