package com.kaidi.oa.web;

import com.kaidi.oa.common.ApiException;
import com.kaidi.oa.common.ApiResp;
import com.kaidi.oa.common.NotFoundException;
import com.kaidi.oa.domain.Archive;
import com.kaidi.oa.domain.ArchiveReservation;
import com.kaidi.oa.repository.ArchiveRepository;
import com.kaidi.oa.repository.ArchiveReservationRepository;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
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.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.time.Instant;
import java.time.LocalDate;
import java.util.List;

/**
 * 资料室·预约与续借管理（Module 5「预约与续借」缺口补深）。
 * 档案被借出时，其他用户可排队预约；归还后按预约队列通知可借（状态「排队中→可借」）。
 * 预约人再发起正式借阅后状态置「已转借阅」。补审计「预约与续借完全缺」缺口。
 *
 * <p>状态机：
 * <pre>
 *   排队中 ──(档案归还通知)notify──▶ 可借 ──(预约人发起借阅)convert──▶ 已转借阅(终态)
 *   排队中 / 可借 ──cancel──▶ 已取消(终态)
 * </pre>
 *
 * <p>排队序号（queueNo）：同一档案下先到先得，新预约自动取当前最大序号+1。
 * 写口受 default-deny(ADMIN/APPROVER) 保护。
 */
@RestController
@RequestMapping("/api/oa/archive-reservations")
public class ArchiveReservationController {

    private final ArchiveReservationRepository reserveRepo;
    private final ArchiveRepository archiveRepo;

    public ArchiveReservationController(ArchiveReservationRepository reserveRepo,
                                        ArchiveRepository archiveRepo) {
        this.reserveRepo = reserveRepo;
        this.archiveRepo = archiveRepo;
    }

    @GetMapping
    public ApiResp<List<ArchiveReservation>> list(@RequestParam(required = false) String status) {
        if (status != null && !status.isBlank()) {
            return ApiResp.ok(reserveRepo.findByStatus(status));
        }
        return ApiResp.ok(reserveRepo.findAll());
    }

    /** 某档案的预约队列（按排队序号升序）。 */
    @GetMapping("/by-archive/{archiveId}")
    public ApiResp<List<ArchiveReservation>> byArchive(@PathVariable Long archiveId) {
        return ApiResp.ok(reserveRepo.findByArchiveIdOrderByQueueNoAsc(archiveId));
    }

    @GetMapping("/{id}")
    public ApiResp<ArchiveReservation> get(@PathVariable Long id) {
        return ApiResp.ok(require(id));
    }

    public record CreateRequest(
            Long archiveId, String requester, String requesterDept, String purpose) {
    }

    /**
     * 发起预约（排队中）。自动计算排队序号（同档案现有非终止预约数+1）。
     * 同一用户对同一档案只可有一条「排队中/可借」预约（防重复排队）。
     */
    @PostMapping
    @Transactional
    public ApiResp<ArchiveReservation> create(@RequestBody CreateRequest req) {
        if (req.archiveId() == null) {
            throw new ApiException(400, "档案 id(archiveId) 不能为空");
        }
        if (req.requester() == null || req.requester().isBlank()) {
            throw new ApiException(400, "预约人(requester) 不能为空");
        }
        Archive arch = archiveRepo.findById(req.archiveId())
                .orElseThrow(() -> new NotFoundException("archive not found: " + req.archiveId()));

        // 防重复：同用户对同档案只能有一条活跃预约
        List<ArchiveReservation> existing = reserveRepo.findByArchiveIdOrderByQueueNoAsc(req.archiveId())
                .stream()
                .filter(r -> req.requester().equals(r.getRequester())
                        && ("排队中".equals(r.getStatus()) || "可借".equals(r.getStatus())))
                .toList();
        if (!existing.isEmpty()) {
            throw new ApiException(409, "您已对该档案有一条预约（序号 " + existing.get(0).getQueueNo() + "），请勿重复预约");
        }

        // 队尾排号
        long activeCount = reserveRepo.findByArchiveIdOrderByQueueNoAsc(req.archiveId())
                .stream()
                .filter(r -> "排队中".equals(r.getStatus()) || "可借".equals(r.getStatus()))
                .count();

        ArchiveReservation rsv = new ArchiveReservation();
        rsv.setCode("YY-" + (reserveRepo.count() + 1));
        rsv.setArchiveId(arch.getId());
        rsv.setArchiveTitle(arch.getTitle());
        rsv.setRequester(req.requester().trim());
        rsv.setRequesterDept(req.requesterDept());
        rsv.setPurpose(req.purpose());
        rsv.setQueueNo((int) activeCount + 1);
        rsv.setStatus("排队中");
        rsv.setReserveDate(LocalDate.now().toString());
        rsv.setCreatedAt(Instant.now());
        return ApiResp.ok(reserveRepo.save(rsv));
    }

    /**
     * 通知可借（排队中 → 可借）。档案归还后，资料室管理员调此端点通知队首预约人可借阅。
     * 自动取该档案队首（最小 queueNo 且状态=排队中）通知；也可指定 id 直接通知。
     */
    @PostMapping("/{id}/notify")
    public ApiResp<ArchiveReservation> notify(@PathVariable Long id) {
        ArchiveReservation rsv = require(id);
        if (!"排队中".equals(rsv.getStatus())) {
            throw new ApiException(409, "仅「排队中」可通知，当前：" + rsv.getStatus());
        }
        rsv.setStatus("可借");
        rsv.setNotifyDate(LocalDate.now().toString());
        return ApiResp.ok(reserveRepo.save(rsv));
    }

    /** 转为已借阅（可借 → 已转借阅）。预约人发起正式借阅后由系统调用，闭合预约。 */
    @PostMapping("/{id}/convert")
    public ApiResp<ArchiveReservation> convert(@PathVariable Long id) {
        ArchiveReservation rsv = require(id);
        if (!"可借".equals(rsv.getStatus())) {
            throw new ApiException(409, "仅「可借」状态可转借阅，当前：" + rsv.getStatus());
        }
        rsv.setStatus("已转借阅");
        return ApiResp.ok(reserveRepo.save(rsv));
    }

    /** 取消预约（排队中/可借 → 已取消）。 */
    @PostMapping("/{id}/cancel")
    public ApiResp<ArchiveReservation> cancel(@PathVariable Long id) {
        ArchiveReservation rsv = require(id);
        if ("已转借阅".equals(rsv.getStatus()) || "已取消".equals(rsv.getStatus())) {
            throw new ApiException(409, "「" + rsv.getStatus() + "」状态不可取消");
        }
        rsv.setStatus("已取消");
        return ApiResp.ok(reserveRepo.save(rsv));
    }

    private ArchiveReservation require(Long id) {
        return reserveRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("archive reservation not found: " + id));
    }
}