/**
 * 文件：gallery-processor.ts
 * 作用：处理文章中的图库短代码
 * 
 * 职责：
 * 1. 解析和转换 gallery 短代码
 * 2. 处理本地图片目录扫描
 * 3. 生成 wikilink 格式的图片引用
 */

import { stat, readdir } from 'fs/promises';
import * as path from 'path';
import { NMPSettings } from '../settings';

// gallery 配置迁移到 NMPSettings（galleryPrePath, galleryNumPic）
// 匹配示例：{{<gallery dir="/img/guanzhan/1" figcaption="毕业展" mppickall=1/>}}{{<load-photoswipe>}}
// 支持可选 figcaption 以及 mppickall=1/0（无引号数字或布尔），若 mppickall=1 则选取目录内全部图片
const GALLERY_SHORTCODE_REGEX = /{{<gallery\s+dir="([^"]+)"(?:\s+figcaption="([^"]*)")?(?:\s+mppickall=(?:"(1|0)"|'(1|0)'|(1|0)))?\s*\/?>}}\s*{{<load-photoswipe>}}/g;

// 块级 gallery：
// {{<gallery>}}\n{{<figure src="/img/a.png" caption=".." >}}\n...\n{{</gallery>}}
// 需要提取所有 figure 的 src basename 生成多行 wikilink
const GALLERY_BLOCK_REGEX = /{{<gallery>}}([\s\S]*?){{<\/gallery>}}/g;

// figure 支持 src 或 link 属性，两者取其一
const FIGURE_IN_GALLERY_REGEX = /{{<figure\s+(?:src|link)="([^"]+)"[^>]*>}}/g;

/**
 * 列出本地图片目录中的图片文件
 */
async function listLocalImages(dirAbs: string): Promise<string[]> {
    try {
        const stats = await stat(dirAbs);
        if (!stats.isDirectory()) return [];
    } catch { 
        return []; 
    }
    
    try {
        const files = await readdir(dirAbs);
        return files.filter(f => /(png|jpe?g|gif|bmp|webp|svg)$/i.test(f)).sort();
    } catch { 
        return []; 
    }
}

/**
 * 从图片列表中选择指定数量的图片
 */
function pickImages(all: string[], limit: number): string[] {
    if (all.length <= limit) return all;
    
    // 均匀采样
    const step = all.length / limit;
    const picked: string[] = [];
    for (let i = 0; i < limit; i++) {
        const index = Math.floor(i * step);
        picked.push(all[index]);
    }
    return picked;
}

/**
 * 图库处理器类
 */
export class GalleryProcessor {
    private settings: NMPSettings;

    constructor(settings: NMPSettings) {
        this.settings = settings;
    }

    /**
     * 处理文章中的图库短代码
     */
    async processGalleryShortcodes(content: string): Promise<string> {
        // 处理目录式 gallery
        content = await this.processDirectoryGalleries(content);
        
        // 处理块级 gallery
        content = await this.processBlockGalleries(content);
        
        return content;
    }

    /**
     * 处理目录式图库短代码
     */
    private async processDirectoryGalleries(content: string): Promise<string> {
        const matches = Array.from(content.matchAll(GALLERY_SHORTCODE_REGEX));
        
        for (const match of matches) {
            const [fullMatch, dir, figcaption = '', pickall1, pickall2, pickall3] = match;
            const pickall = pickall1 || pickall2 || pickall3;
            const shouldPickAll = pickall === '1';
            
            try {
                const galleryPrePath = this.settings.galleryPrePath;
                const dirAbs = path.join(galleryPrePath, dir);
                const allImages = await listLocalImages(dirAbs);
                
                if (allImages.length === 0) {
                    console.warn(`[GalleryProcessor] 目录 ${dirAbs} 中没有找到图片`);
                    continue;
                }
                
                const selectedImages = shouldPickAll 
                    ? allImages 
                    : pickImages(allImages, this.settings.galleryNumPic);
                
                // 生成 wikilink 格式的图片引用
                const wikilinks = selectedImages.map(img => {
                    const imgPath = path.join(dir, img).replace(/\\/g, '/');
                    return `![[${imgPath}]]`;
                });
                
                let replacement = wikilinks.join('\n');
                if (figcaption) {
                    replacement = `> ${figcaption}\n\n${replacement}`;
                }
                
                content = content.replace(fullMatch, replacement);
            } catch (error) {
                console.error(`[GalleryProcessor] 处理图库失败: ${dir}`, error);
            }
        }
        
        return content;
    }

    /**
     * 处理块级图库短代码
     */
    private processBlockGalleries(content: string): Promise<string> {
        return Promise.resolve(content.replace(GALLERY_BLOCK_REGEX, (match, blockContent) => {
            const figureMatches = Array.from(blockContent.matchAll(FIGURE_IN_GALLERY_REGEX));
            
            if (figureMatches.length === 0) {
                return match; // 保持原样
            }
            
            const wikilinks = figureMatches.map(([, src]) => {
                const basename = path.basename(src);
                return `![[${basename}]]`;
            });
            
            return wikilinks.join('\n');
        }));
    }
}