package jnpf.dmsService.search;

import jnpf.dmsEntity.permission.enums.DmsPermissionAction;
import jnpf.dmsEntity.permission.enums.DmsResourceType;
import jnpf.dmsEntity.permission.form.PermissionDecisionForm;
import jnpf.dmsEntity.permission.vo.DmsPermissionDecisionVO;
import jnpf.dmsEntity.search.form.DmsFullTextSearchForm;
import jnpf.dmsEntity.search.vo.DmsFullTextSearchItemVO;
import jnpf.dmsEntity.search.vo.DmsFullTextSearchPageVO;
import jnpf.dmsPermission.DmsCurrentIdentity;
import jnpf.dmsMapper.DmsSearchIndexSourceMapper;
import jnpf.dmsPermission.DmsPermissionError;
import jnpf.dmsPermission.DmsPermissionException;
import jnpf.dmsService.DmsPermissionDecisionService;
import jnpf.dmsService.search.meili.DmsMeilisearchClient;
import jnpf.dmsService.search.meili.DmsMeilisearchSearchHit;
import jnpf.dmsService.search.meili.DmsMeilisearchSearchPage;
import jnpf.dmsService.search.meili.DmsSearchIndexDocument;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

@Service
@RequiredArgsConstructor
public class DmsFullTextSearchService {
    private static final int DEFAULT_PAGE_SIZE = 20;
    private static final int MAX_PAGE_SIZE = 100;
    private static final int CANDIDATE_BATCH_SIZE = 100;
    private static final int MAX_CANDIDATES_PER_REQUEST = 1_000;

    private final DmsCurrentIdentity currentIdentity;
    private final DmsPermissionDecisionService permissionDecisionService;
    private final DmsMeilisearchClient meilisearchClient;
    private final DmsSearchIndexSourceMapper sourceMapper;

    public DmsFullTextSearchPageVO search(DmsFullTextSearchForm form) throws IOException {
        String keyword = form.getKeyword().trim();
        int pageSize = pageSize(form.getPageSize());
        int candidateOffset = cursor(form.getCursor());
        int scanned = 0;
        String tenantId = currentIdentity.tenantId();
        List<DmsFullTextSearchItemVO> results = new ArrayList<>();

        while (scanned < MAX_CANDIDATES_PER_REQUEST) {
            int batchSize = Math.min(CANDIDATE_BATCH_SIZE,
                    MAX_CANDIDATES_PER_REQUEST - scanned);
            DmsMeilisearchSearchPage candidates = meilisearchClient.search(
                    tenantId, keyword, candidateOffset, batchSize);
            if (candidates.getHits().isEmpty()) {
                break;
            }
            List<Boolean> allowed = allowed(candidates.getHits());
            java.util.Set<String> current = new java.util.HashSet<>(sourceMapper.currentVersionIds(tenantId,
                    candidates.getHits().stream().map(hit -> hit.getDocument().getFileVersionId()).toList()));
            for (int index = 0; index < candidates.getHits().size(); index++) {
                int currentOffset = candidateOffset + index;
                if (!allowed.get(index) || !current.contains(candidates.getHits().get(index).getDocument().getFileVersionId())) {
                    continue;
                }
                if (results.size() == pageSize) {
                    return page(results, Integer.toString(currentOffset), true);
                }
                results.add(toItem(candidates.getHits().get(index)));
            }
            int consumed = candidates.getHits().size();
            candidateOffset += consumed;
            scanned += consumed;
            if (candidateOffset >= candidates.getEstimatedTotalHits()
                    || consumed < batchSize) {
                break;
            }
        }
        if (scanned >= MAX_CANDIDATES_PER_REQUEST) {
            return page(results, Integer.toString(candidateOffset), true);
        }
        return page(results, null, false);
    }

    private List<Boolean> allowed(List<DmsMeilisearchSearchHit> hits) {
        List<PermissionDecisionForm> requests = new ArrayList<>();
        for (DmsMeilisearchSearchHit hit : hits) {
            PermissionDecisionForm request = new PermissionDecisionForm();
            request.setResourceType(DmsResourceType.FILE_VERSION);
            request.setResourceId(UUID.fromString(hit.getDocument().getFileVersionId()));
            request.setActionCode(DmsPermissionAction.READ);
            requests.add(request);
        }
        try {
            List<DmsPermissionDecisionVO> decisions = permissionDecisionService.evaluate(requests);
            List<Boolean> result = new ArrayList<>();
            for (DmsPermissionDecisionVO decision : decisions) {
                result.add(decision.isAllowed());
            }
            return result;
        } catch (RuntimeException batchFailure) {
            List<Boolean> result = new ArrayList<>();
            for (PermissionDecisionForm request : requests) {
                try {
                    result.add(permissionDecisionService.evaluate(request).isAllowed());
                } catch (RuntimeException ignored) {
                    result.add(false);
                }
            }
            return result;
        }
    }

    private DmsFullTextSearchItemVO toItem(DmsMeilisearchSearchHit hit) {
        DmsSearchIndexDocument source = hit.getDocument();
        DmsFullTextSearchItemVO item = new DmsFullTextSearchItemVO();
        item.setId(UUID.fromString(source.getFileVersionId()));
        item.setDocumentId(UUID.fromString(source.getDocumentId()));
        item.setFolderId(uuid(source.getFolderId()));
        item.setFolderPath(source.getFolderPath());
        item.setDocumentNo(source.getDocumentNo());
        item.setTitle(source.getTitle());
        item.setHighlightedTitle(highlight(hit.getFormattedTitle()));
        item.setVersionLabel(source.getVersionLabel());
        item.setFileName(source.getFileName());
        item.setMimeType(source.getMimeType());
        item.setLifecycleStatus(source.getLifecycleStatus());
        item.setCreatedAt(source.getCreatedAt());
        item.setHighlightedSnippet(highlight(hit.getFormattedContent()));
        return item;
    }

    private DmsFullTextSearchPageVO page(List<DmsFullTextSearchItemVO> list,
                                         String nextCursor, boolean hasMore) {
        DmsFullTextSearchPageVO page = new DmsFullTextSearchPageVO();
        page.setList(list);
        page.setNextCursor(nextCursor);
        page.setHasMore(hasMore);
        return page;
    }

    private int pageSize(Integer requested) {
        int value = requested == null ? DEFAULT_PAGE_SIZE : requested;
        if (value < 1 || value > MAX_PAGE_SIZE) {
            throw invalid("pageSize 必须在 1 到 " + MAX_PAGE_SIZE + " 之间");
        }
        return value;
    }

    private int cursor(String value) {
        if (value == null || value.trim().isEmpty()) {
            return 0;
        }
        try {
            int offset = Integer.parseInt(value.trim());
            if (offset < 0) {
                throw invalid("cursor 无效");
            }
            return offset;
        } catch (NumberFormatException exception) {
            throw invalid("cursor 无效");
        }
    }

    private UUID uuid(String value) {
        return value == null || value.trim().isEmpty() ? null : UUID.fromString(value);
    }

    private String highlight(String value) {
        String escaped = value == null ? "" : value
                .replace("&", "&amp;")
                .replace("<", "&lt;")
                .replace(">", "&gt;")
                .replace("\"", "&quot;")
                .replace("'", "&#39;");
        return escaped
                .replace(DmsMeilisearchClient.HIGHLIGHT_START, "<mark>")
                .replace(DmsMeilisearchClient.HIGHLIGHT_END, "</mark>");
    }

    private DmsPermissionException invalid(String message) {
        return DmsPermissionException.of(DmsPermissionError.INVALID_REQUEST, message);
    }
}