/**
 * 详情页文件清单 → 目录树(DETAIL-1,纯函数)。按「/」或「\」拆路径,目录大小为子项之和;
 * 标出主视频(最大视频的 30% 以上,排除 sample)、sample、字幕与附件。输出按先序展平,前端按 depth 缩进。
 */
import type { SiteDetailFile } from "./types.ts";

export type FileRole = "main" | "sample" | "subtitle" | "extra" | "video" | "other";

export interface FileTreeRow {
  /** 完整路径(目录也有),作 key 与折叠状态 */
  path: string;
  name: string;
  depth: number;
  dir: boolean;
  /** 目录:子项之和;有未知大小的子项时仍给已知部分之和 */
  sizeBytes: number | null;
  /** 目录为 null */
  role: FileRole | null;
  /** 目录下的文件数(递归);文件为 null */
  fileCount: number | null;
}

const VIDEO = /\.(mkv|mp4|m2ts|ts|avi|wmv|mov|m4v|iso|rmvb|flv|webm|vob|mpg|mpeg)$/i;
const SUB = /\.(srt|ass|ssa|sup|sub|idx|vtt|smi)$/i;
const EXTRA = /\.(nfo|txt|jpe?g|png|gif|webp|bmp|md5|sfv|sha1|sha256|url|html?|pdf|cue|log|torrent)$/i;
const SAMPLE = /(^|[\\/._\-\s])sample([\\/._\-\s]|$)/i;

interface Node {
  name: string;
  path: string;
  children: Map<string, Node> | null;
  sizeBytes: number | null;
}

export function buildFileTree(files: SiteDetailFile[]): FileTreeRow[] {
  const root: Node = { name: "", path: "", children: new Map(), sizeBytes: null };
  for (const f of files) {
    const parts = f.name.split(/[\\/]+/).filter(Boolean);
    if (!parts.length) continue;
    let node = root;
    parts.forEach((part, i) => {
      const last = i === parts.length - 1;
      const path = node.path ? `${node.path}/${part}` : part;
      let child = node.children!.get(part);
      if (!child) {
        child = { name: part, path, children: last ? null : new Map(), sizeBytes: last ? f.sizeBytes : null };
        node.children!.set(part, child);
      } else if (!last && !child.children) {
        child.children = new Map();
      }
      node = child;
    });
  }

  const videoSizes = files.filter((f) => VIDEO.test(f.name) && !SAMPLE.test(f.name)).map((f) => f.sizeBytes ?? 0);
  const maxVideo = Math.max(0, ...videoSizes);
  const roleOf = (n: Node): FileRole => {
    if (SUB.test(n.name)) return "subtitle";
    if (VIDEO.test(n.name)) {
      if (SAMPLE.test(n.path)) return "sample";
      // 大小未知时所有视频都当主视频;已知时按最大视频的 30% 划线(剧集各集、原盘正片)
      if (!maxVideo || n.sizeBytes === null || n.sizeBytes >= maxVideo * 0.3) return "main";
      return "video";
    }
    if (EXTRA.test(n.name)) return "extra";
    return "other";
  };

  const out: FileTreeRow[] = [];
  const walk = (n: Node, depth: number): { size: number | null; count: number } => {
    const kids = [...n.children!.values()].sort((a, b) =>
      !!a.children === !!b.children ? a.name.localeCompare(b.name, "zh-CN", { numeric: true }) : a.children ? -1 : 1,
    );
    let size: number | null = null;
    let count = 0;
    for (const k of kids) {
      if (k.children) {
        const idx = out.length;
        out.push({ path: k.path, name: k.name, depth, dir: true, sizeBytes: null, role: null, fileCount: null });
        const sub = walk(k, depth + 1);
        out[idx]!.sizeBytes = sub.size;
        out[idx]!.fileCount = sub.count;
        if (sub.size !== null) size = (size ?? 0) + sub.size;
        count += sub.count;
      } else {
        out.push({
          path: k.path,
          name: k.name,
          depth,
          dir: false,
          sizeBytes: k.sizeBytes,
          role: roleOf(k),
          fileCount: null,
        });
        if (k.sizeBytes !== null) size = (size ?? 0) + k.sizeBytes;
        count += 1;
      }
    }
    return { size, count };
  };
  walk(root, 0);
  return out;
}