package com.erp.service;

import com.erp.common.BaseService;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.*;
import java.util.stream.Collectors;

@Service
@RequiredArgsConstructor
@Slf4j
public class CodeMergeService extends BaseService {

    private final JdbcTemplate jdbcTemplate;

    private static final String NS = "codeMerge.";

    // ── Tables With Column ────────────────────────────────────────────────────

    /**
     * GET /tables-with-column/:columnName
     * 해당 컬럼과 company_code 컬럼을 함께 가진 public 테이블 목록 반환
     */
    public Map<String, Object> getTablesWithColumn(String columnName) {
        Map<String, Object> params = new HashMap<>();
        params.put("column_name", columnName);
        List<Map<String, Object>> rows = sqlSession.selectList(NS + "getTablesWithColumn", params);

        List<String> tables = rows.stream()
                .map(r -> {
                    Object val = r.get("table_name");
                    return val != null ? val.toString() : null;
                })
                .filter(Objects::nonNull)
                .collect(Collectors.toList());

        Map<String, Object> result = new LinkedHashMap<>();
        result.put("column_name", columnName);
        result.put("tables", tables);
        result.put("count", tables.size());
        return result;
    }

    // ── Preview (column-based) ────────────────────────────────────────────────

    /**
     * POST /preview
     * columnName + oldValue 기준으로 영향받을 테이블/행 수 미리보기 (DB 변경 없음)
     */
    public Map<String, Object> previewCodeMerge(Map<String, Object> body) {
        String columnName  = str(body.get("column_name"));
        String oldValue    = str(body.get("old_value"));
        String companyCode = str(body.get("company_code"));

        if (isBlank(columnName) || isBlank(oldValue)) {
            throw new IllegalArgumentException("필수 필드가 누락되었습니다. (columnName, oldValue)");
        }

        log.info("코드 병합 미리보기: column={}, oldValue={}, company={}", columnName, oldValue, companyCode);

        Map<String, Object> params = new HashMap<>();
        params.put("column_name", columnName);
        List<Map<String, Object>> tableRows = sqlSession.selectList(NS + "getTablesWithColumn", params);

        List<Map<String, Object>> preview = new ArrayList<>();
        int totalRows = 0;

        for (Map<String, Object> tableRow : tableRows) {
            Object nameVal = tableRow.get("table_name");
            if (nameVal == null) continue;
            String tableName = nameVal.toString();

            // 테이블명·컬럼명은 information_schema에서 검증된 값 — SQL 인젝션 위험 없음
            String countSql = String.format(
                    "SELECT COUNT(*) FROM \"%s\" WHERE \"%s\" = ? AND company_code = ?",
                    tableName, columnName);
            try {
                Integer count = jdbcTemplate.queryForObject(countSql, Integer.class, oldValue, companyCode);
                if (count != null && count > 0) {
                    Map<String, Object> item = new LinkedHashMap<>();
                    item.put("table_name", tableName);
                    item.put("affected_rows", count);
                    preview.add(item);
                    totalRows += count;
                }
            } catch (Exception e) {
                log.warn("테이블 {} 조회 실패 (건너뜀): {}", tableName, e.getMessage());
            }
        }

        Map<String, Object> result = new LinkedHashMap<>();
        result.put("column_name", columnName);
        result.put("old_value", oldValue);
        result.put("preview", preview);
        result.put("total_affected_rows", totalRows);
        return result;
    }

    // ── Merge All Tables (column-based) ───────────────────────────────────────

    /**
     * POST /merge-all-tables
     * PostgreSQL 함수 merge_code_all_tables(columnName, oldValue, newValue, companyCode) 호출
     */
    @Transactional
    public Map<String, Object> mergeAllTables(Map<String, Object> body) {
        String columnName  = str(body.get("column_name"));
        String oldValue    = str(body.get("old_value"));
        String newValue    = str(body.get("new_value"));
        String companyCode = str(body.get("company_code"));

        if (isBlank(columnName) || isBlank(oldValue) || isBlank(newValue)) {
            throw new IllegalArgumentException("필수 필드가 누락되었습니다. (columnName, oldValue, newValue)");
        }
        if (oldValue.equals(newValue)) {
            throw new IllegalArgumentException("기존 값과 새 값이 동일합니다.");
        }

        log.info("코드 병합 시작: column={}, {} → {}, company={}", columnName, oldValue, newValue, companyCode);

        List<Map<String, Object>> rows = jdbcTemplate.queryForList(
                "SELECT * FROM merge_code_all_tables(?, ?, ?, ?)",
                columnName, oldValue, newValue, companyCode);

        int totalRows = rows.stream()
                .mapToInt(r -> r.get("rows_updated") != null ? ((Number) r.get("rows_updated")).intValue() : 0)
                .sum();

        List<Map<String, Object>> affectedTables = rows.stream().map(r -> {
            Map<String, Object> item = new LinkedHashMap<>();
            item.put("table_name", r.get("table_name"));
            item.put("rows_updated", r.get("rows_updated") != null ? ((Number) r.get("rows_updated")).intValue() : 0);
            return item;
        }).collect(Collectors.toList());

        log.info("코드 병합 완료: 영향 테이블 {}개, 총 {}행", affectedTables.size(), totalRows);

        Map<String, Object> result = new LinkedHashMap<>();
        result.put("column_name", columnName);
        result.put("old_value", oldValue);
        result.put("new_value", newValue);
        result.put("affected_tables", affectedTables);
        result.put("total_rows_updated", totalRows);
        return result;
    }

    // ── Merge By Value ────────────────────────────────────────────────────────

    /**
     * POST /merge-by-value
     * PostgreSQL 함수 merge_code_by_value(oldValue, newValue, companyCode) 호출
     * 컬럼명에 관계없이 해당 값을 가진 모든 위치를 변경
     */
    @Transactional
    public Map<String, Object> mergeByValue(Map<String, Object> body) {
        String oldValue    = str(body.get("old_value"));
        String newValue    = str(body.get("new_value"));
        String companyCode = str(body.get("company_code"));

        if (isBlank(oldValue) || isBlank(newValue)) {
            throw new IllegalArgumentException("필수 필드가 누락되었습니다. (oldValue, newValue)");
        }
        if (oldValue.equals(newValue)) {
            throw new IllegalArgumentException("기존 값과 새 값이 동일합니다.");
        }

        log.info("값 기반 코드 병합 시작: {} → {}, company={}", oldValue, newValue, companyCode);

        List<Map<String, Object>> rows = jdbcTemplate.queryForList(
                "SELECT * FROM merge_code_by_value(?, ?, ?)",
                oldValue, newValue, companyCode);

        int totalRows = rows.stream()
                .mapToInt(r -> r.get("out_rows_updated") != null ? ((Number) r.get("out_rows_updated")).intValue() : 0)
                .sum();

        List<Map<String, Object>> affectedData = rows.stream().map(r -> {
            Map<String, Object> item = new LinkedHashMap<>();
            item.put("table_name",   r.get("out_table_name"));
            item.put("column_name",  r.get("out_column_name"));
            item.put("rows_updated", r.get("out_rows_updated") != null ? ((Number) r.get("out_rows_updated")).intValue() : 0);
            return item;
        }).collect(Collectors.toList());

        log.info("값 기반 코드 병합 완료: {} → {}, 총 {}행", oldValue, newValue, totalRows);

        Map<String, Object> result = new LinkedHashMap<>();
        result.put("old_value", oldValue);
        result.put("new_value", newValue);
        result.put("affected_data", affectedData);
        result.put("total_rows_updated", totalRows);
        return result;
    }

    // ── Preview By Value ──────────────────────────────────────────────────────

    /**
     * POST /preview-by-value
     * PostgreSQL 함수 preview_merge_code_by_value(oldValue, companyCode) 호출
     */
    public Map<String, Object> previewByValue(Map<String, Object> body) {
        String oldValue    = str(body.get("old_value"));
        String companyCode = str(body.get("company_code"));

        if (isBlank(oldValue)) {
            throw new IllegalArgumentException("필수 필드가 누락되었습니다. (oldValue)");
        }

        log.info("값 기반 코드 병합 미리보기: oldValue={}, company={}", oldValue, companyCode);

        List<Map<String, Object>> rows = jdbcTemplate.queryForList(
                "SELECT * FROM preview_merge_code_by_value(?, ?)",
                oldValue, companyCode);

        int totalRows = rows.stream()
                .mapToInt(r -> r.get("out_affected_rows") != null ? ((Number) r.get("out_affected_rows")).intValue() : 0)
                .sum();

        List<Map<String, Object>> preview = rows.stream().map(r -> {
            Map<String, Object> item = new LinkedHashMap<>();
            item.put("table_name",    r.get("out_table_name"));
            item.put("column_name",   r.get("out_column_name"));
            item.put("affected_rows", r.get("out_affected_rows") != null ? ((Number) r.get("out_affected_rows")).intValue() : 0);
            return item;
        }).collect(Collectors.toList());

        Map<String, Object> result = new LinkedHashMap<>();
        result.put("old_value", oldValue);
        result.put("preview", preview);
        result.put("total_affected_rows", totalRows);
        return result;
    }

    // ── Helpers ───────────────────────────────────────────────────────────────

    private String str(Object val) {
        return val != null ? val.toString() : null;
    }

    private boolean isBlank(String s) {
        return s == null || s.isBlank();
    }
}