package com.xuqm.tenant.controller;

import com.xuqm.tenant.config.PrivateDeploymentProperties;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/api/system/database")
public class DatabaseController {

    private final PrivateDeploymentProperties deployProps;
    private final DataSource dataSource;

    public DatabaseController(PrivateDeploymentProperties deployProps, DataSource dataSource) {
        this.deployProps = deployProps;
        this.dataSource = dataSource;
    }

    @GetMapping("/tables")
    public ResponseEntity<?> listTables() {
        if (!deployProps.isPrivate()) {
            return ResponseEntity.status(403).body(Map.of("message", "此接口仅在私有化部署可用"));
        }
        try (Connection conn = dataSource.getConnection()) {
            DatabaseMetaData meta = conn.getMetaData();
            String catalog = conn.getCatalog();
            ResultSet rs = meta.getTables(catalog, null, "%", new String[]{"TABLE"});
            List<Map<String, Object>> tables = new ArrayList<>();
            while (rs.next()) {
                Map<String, Object> t = new LinkedHashMap<>();
                t.put("name", rs.getString("TABLE_NAME"));
                t.put("comment", rs.getString("REMARKS"));
                tables.add(t);
            }
            return ResponseEntity.ok(Map.of("data", tables));
        } catch (SQLException e) {
            return ResponseEntity.status(500).body(Map.of("message", "查询表列表失败: " + e.getMessage()));
        }
    }

    @GetMapping("/tables/{tableName}/columns")
    public ResponseEntity<?> listColumns(@PathVariable String tableName) {
        if (!deployProps.isPrivate()) {
            return ResponseEntity.status(403).body(Map.of("message", "此接口仅在私有化部署可用"));
        }
        if (!isAllowedTable(tableName)) {
            return ResponseEntity.status(403).body(Map.of("message", "不允许访问该表"));
        }
        try (Connection conn = dataSource.getConnection()) {
            DatabaseMetaData meta = conn.getMetaData();
            String catalog = conn.getCatalog();
            ResultSet rs = meta.getColumns(catalog, null, tableName, "%");
            List<Map<String, Object>> columns = new ArrayList<>();
            while (rs.next()) {
                Map<String, Object> c = new LinkedHashMap<>();
                c.put("name", rs.getString("COLUMN_NAME"));
                c.put("type", rs.getString("TYPE_NAME"));
                c.put("size", rs.getInt("COLUMN_SIZE"));
                c.put("nullable", rs.getInt("NULLABLE") == DatabaseMetaData.columnNullable);
                c.put("comment", rs.getString("REMARKS"));
                columns.add(c);
            }
            return ResponseEntity.ok(Map.of("data", columns));
        } catch (SQLException e) {
            return ResponseEntity.status(500).body(Map.of("message", "查询列信息失败: " + e.getMessage()));
        }
    }

    @GetMapping("/tables/{tableName}/data")
    public ResponseEntity<?> queryData(
            @PathVariable String tableName,
            @RequestParam(defaultValue = "0") int page,
            @RequestParam(defaultValue = "50") int size,
            @RequestParam(required = false) String keyword,
            @RequestParam(required = false) String sortColumn,
            @RequestParam(required = false, defaultValue = "ASC") String sortDirection) {
        if (!deployProps.isPrivate()) {
            return ResponseEntity.status(403).body(Map.of("message", "此接口仅在私有化部署可用"));
        }
        if (!isAllowedTable(tableName)) {
            return ResponseEntity.status(403).body(Map.of("message", "不允许访问该表"));
        }
        if (size > 200) size = 200;

        try (Connection conn = dataSource.getConnection()) {
            // Get columns info for keyword search
            List<String> textColumns = new ArrayList<>();
            DatabaseMetaData meta = conn.getMetaData();
            String catalog = conn.getCatalog();
            ResultSet colRs = meta.getColumns(catalog, null, tableName, "%");
            List<String> allColumns = new ArrayList<>();
            while (colRs.next()) {
                String colName = colRs.getString("COLUMN_NAME");
                String typeName = colRs.getString("TYPE_NAME");
                allColumns.add(colName);
                if (typeName != null && (typeName.contains("CHAR") || typeName.contains("TEXT") || typeName.contains("VARCHAR"))) {
                    textColumns.add(colName);
                }
            }

            // Build WHERE clause for keyword search
            StringBuilder whereClause = new StringBuilder();
            List<Object> params = new ArrayList<>();
            if (keyword != null && !keyword.isBlank() && !textColumns.isEmpty()) {
                whereClause.append(" WHERE ");
                for (int i = 0; i < textColumns.size(); i++) {
                    if (i > 0) whereClause.append(" OR ");
                    String safeCol = sanitizeIdentifier(textColumns.get(i));
                    whereClause.append(safeCol).append(" LIKE ?");
                    params.add("%" + keyword + "%");
                }
            }

            // Count total
            String countSql = "SELECT COUNT(*) FROM " + sanitizeIdentifier(tableName) + whereClause;
            long total = 0;
            try (PreparedStatement ps = conn.prepareStatement(countSql)) {
                for (int i = 0; i < params.size(); i++) ps.setObject(i + 1, params.get(i));
                try (ResultSet rs = ps.executeQuery()) {
                    if (rs.next()) total = rs.getLong(1);
                }
            }

            // Build ORDER BY
            String orderClause = "";
            if (sortColumn != null && !sortColumn.isBlank() && allColumns.contains(sortColumn)) {
                String dir = "DESC".equalsIgnoreCase(sortDirection) ? "DESC" : "ASC";
                orderClause = " ORDER BY " + sanitizeIdentifier(sortColumn) + " " + dir;
            }

            // Query data with pagination
            String dataSql = "SELECT * FROM " + sanitizeIdentifier(tableName) + whereClause + orderClause
                    + " LIMIT ? OFFSET ?";
            List<Map<String, Object>> rows = new ArrayList<>();
            try (PreparedStatement ps = conn.prepareStatement(dataSql)) {
                int idx = 1;
                for (Object p : params) ps.setObject(idx++, p);
                ps.setInt(idx++, size);
                ps.setInt(idx, page * size);
                try (ResultSet rs = ps.executeQuery()) {
                    ResultSetMetaData rsmd = rs.getMetaData();
                    int colCount = rsmd.getColumnCount();
                    while (rs.next()) {
                        Map<String, Object> row = new LinkedHashMap<>();
                        for (int i = 1; i <= colCount; i++) {
                            row.put(rsmd.getColumnName(i), rs.getObject(i));
                        }
                        rows.add(row);
                    }
                }
            }

            int totalPages = size > 0 ? (int) Math.ceil((double) total / size) : 0;
            Map<String, Object> result = new LinkedHashMap<>();
            result.put("columns", allColumns);
            result.put("rows", rows);
            result.put("total", total);
            result.put("totalPages", totalPages);
            result.put("page", page);
            result.put("size", size);
            return ResponseEntity.ok(Map.of("data", result));
        } catch (SQLException e) {
            return ResponseEntity.status(500).body(Map.of("message", "查询数据失败: " + e.getMessage()));
        }
    }

    private boolean isAllowedTable(String tableName) {
        // Allow any table in the current database - the table name comes from our own listTables() API
        return tableName != null && tableName.matches("[a-zA-Z0-9_]+");
    }

    private static String sanitizeIdentifier(String identifier) {
        // Backtick-quote to prevent SQL injection
        return "`" + identifier.replace("`", "``") + "`";
    }
}