package com.kaidi.oa.web;

import com.kaidi.oa.common.ApiException;
import com.kaidi.oa.common.ApiResp;
import com.kaidi.oa.domain.Archive;
import com.kaidi.oa.domain.ArchiveAccessLog;
import com.kaidi.oa.repository.ArchiveAccessLogRepository;
import com.kaidi.oa.repository.ArchiveRepository;
import jakarta.servlet.http.HttpServletRequest;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.List;

/**
 * 资料室·Module 3「电子文件管理」批量操作补完。
 *
 * <p>补缺口：「批量下载/转移/修改元数据无专门端点」。
 * 本控制器提供三个批量端点（均 @Transactional，幂等写入）：
 * <ul>
 *   <li>POST /archive-batch/transfer — 批量转移档案分类（targetCategory）；</li>
 *   <li>POST /archive-batch/meta-update — 批量修改元数据（tags / summary / accessLevel / archiveDate）；</li>
 *   <li>POST /archive-batch/download-list — 批量下载清单（返回文件 URL 列表，前端逐一下载）。</li>
 * </ul>
 *
 * 注意：PDF/A 格式转换、OCR 正文识别、区块链哈希存证属外部系统，本轮跳过。
 */
@RestController
@RequestMapping("/api/oa/archive-batch")
public class ArchiveBatchController {

    private static final DateTimeFormatter FMT = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

    private final ArchiveRepository archiveRepo;
    private final ArchiveAccessLogRepository accessLogRepo;
    private final CurrentUserResolver currentUser;

    public ArchiveBatchController(ArchiveRepository archiveRepo,
                                   ArchiveAccessLogRepository accessLogRepo,
                                   CurrentUserResolver currentUser) {
        this.archiveRepo = archiveRepo;
        this.accessLogRepo = accessLogRepo;
        this.currentUser = currentUser;
    }

    // ─────────────────────────────────────────────────────────────────────────
    // 1. 批量转移分类
    // ─────────────────────────────────────────────────────────────────────────

    public record TransferRequest(List<Long> ids, String targetCategory) {}

    public record BatchResult(int total, int affected, String message) {}

    /**
     * 批量将选定档案转移到目标分类。
     * ids 最多 200 条，targetCategory 不可为空。
     */
    @PostMapping("/transfer")
    @Transactional
    public ApiResp<BatchResult> transfer(@RequestBody TransferRequest req,
                                          HttpServletRequest http) {
        validateIds(req.ids());
        if (req.targetCategory() == null || req.targetCategory().isBlank()) {
            throw new ApiException(400, "目标分类不可为空");
        }
        List<Archive> archives = archiveRepo.findAllById(req.ids());
        String operator = resolveOperator(http);
        String now = LocalDateTime.now().format(FMT);
        for (Archive a : archives) {
            String oldCat = a.getCategory();
            a.setCategory(req.targetCategory());
            archiveRepo.save(a);
            writeLog(a.getId(), a.getTitle(), "批量转移",
                    operator, "分类 " + oldCat + " → " + req.targetCategory(), http, now);
        }
        return ApiResp.ok(new BatchResult(req.ids().size(), archives.size(),
                "已将 " + archives.size() + " 条档案转移至【" + req.targetCategory() + "】"));
    }

    // ─────────────────────────────────────────────────────────────────────────
    // 2. 批量修改元数据
    // ─────────────────────────────────────────────────────────────────────────

    /**
     * 批量修改元数据字段。
     * 仅修改非空字段（null 表示不改）。
     * 可修改：tags / summary / accessLevel / archiveDate。
     */
    public record MetaUpdateRequest(
            List<Long> ids,
            String tags,
            String summary,
            String accessLevel,
            String archiveDate) {}

    @PostMapping("/meta-update")
    @Transactional
    public ApiResp<BatchResult> metaUpdate(@RequestBody MetaUpdateRequest req,
                                            HttpServletRequest http) {
        validateIds(req.ids());
        boolean anyField = req.tags() != null || req.summary() != null
                || req.accessLevel() != null || req.archiveDate() != null;
        if (!anyField) {
            throw new ApiException(400, "至少需要指定一个要修改的元数据字段");
        }
        List<Archive> archives = archiveRepo.findAllById(req.ids());
        String operator = resolveOperator(http);
        String now = LocalDateTime.now().format(FMT);
        for (Archive a : archives) {
            if (req.tags() != null) {
                a.setTags(req.tags());
            }
            if (req.summary() != null) {
                a.setSummary(req.summary());
            }
            if (req.accessLevel() != null) {
                a.setAccessLevel(req.accessLevel());
            }
            if (req.archiveDate() != null) {
                a.setArchiveDate(req.archiveDate());
            }
            archiveRepo.save(a);
            writeLog(a.getId(), a.getTitle(), "批量修改元数据",
                    operator, buildMetaDetail(req), http, now);
        }
        return ApiResp.ok(new BatchResult(req.ids().size(), archives.size(),
                "已批量更新 " + archives.size() + " 条档案的元数据"));
    }

    // ─────────────────────────────────────────────────────────────────────────
    // 3. 批量下载清单（返回 fileUrl 列表，前端逐一触发下载）
    // ─────────────────────────────────────────────────────────────────────────

    public record DownloadListRequest(List<Long> ids) {}

    public record DownloadItem(Long id, String title, String fileType, String fileUrl) {}

    public record DownloadListResult(int total, List<DownloadItem> items, String note) {}

    /**
     * 批量下载清单：返回可下载档案的 fileUrl 列表（已有 fileUrl 的条目）。
     * 前端逐条调用浏览器 &lt;a download&gt; 完成下载，避免后端 ZIP 依赖。
     */
    @PostMapping("/download-list")
    @Transactional
    public ApiResp<DownloadListResult> downloadList(@RequestBody DownloadListRequest req,
                                                     HttpServletRequest http) {
        validateIds(req.ids());
        List<Archive> archives = archiveRepo.findAllById(req.ids());
        String operator = resolveOperator(http);
        String now = LocalDateTime.now().format(FMT);
        List<DownloadItem> items = archives.stream()
                .filter(a -> a.getFileUrl() != null && !a.getFileUrl().isBlank())
                .map(a -> {
                    writeLog(a.getId(), a.getTitle(), "批量下载",
                            operator, "批量下载请求", http, now);
                    return new DownloadItem(a.getId(), a.getTitle(), a.getFileType(), a.getFileUrl());
                })
                .toList();
        int noUrl = archives.size() - items.size();
        String note = noUrl > 0
                ? noUrl + " 条档案无文件链接（实体档案或未上传电子版），已跳过"
                : "全部档案均有文件链接";
        return ApiResp.ok(new DownloadListResult(items.size(), items, note));
    }

    // ─────────────────────────────────────────────────────────────────────────
    // helpers
    // ─────────────────────────────────────────────────────────────────────────

    private void validateIds(List<Long> ids) {
        if (ids == null || ids.isEmpty()) {
            throw new ApiException(400, "ids 不可为空");
        }
        if (ids.size() > 200) {
            throw new ApiException(400, "单次批量操作最多 200 条");
        }
    }

    private String resolveOperator(HttpServletRequest http) {
        var u = currentUser.resolve(http);
        return u != null ? u.getDisplayName() : "未知用户";
    }

    private void writeLog(Long archiveId, String title, String action,
                           String operator, String detail,
                           HttpServletRequest http, String now) {
        ArchiveAccessLog log = new ArchiveAccessLog();
        log.setArchiveId(archiveId);
        log.setArchiveTitle(title);
        log.setAction(action);
        log.setOperator(operator);
        log.setIp(http.getRemoteAddr());
        log.setDetail(detail);
        log.setOccurredAt(now);
        accessLogRepo.save(log);
    }

    private String buildMetaDetail(MetaUpdateRequest req) {
        java.util.LinkedHashMap<String, String> m = new java.util.LinkedHashMap<>();
        if (req.tags() != null) m.put("tags", req.tags());
        if (req.summary() != null) m.put("summary", req.summary().length() > 20 ? req.summary().substring(0, 20) + "…" : req.summary());
        if (req.accessLevel() != null) m.put("accessLevel", req.accessLevel());
        if (req.archiveDate() != null) m.put("archiveDate", req.archiveDate());
        StringBuilder sb = new StringBuilder("批量修改:");
        m.forEach((k, v) -> sb.append(" ").append(k).append("=").append(v).append(";"));
        return sb.toString();
    }
}