import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

/**
 * 数据库直连小工具。用法见 printUsage()。
 * 运行：bash sql/db.sh "SELECT 1"
 */
public class DbTool {

    private static final String DEFAULT_URL =
            "jdbc:mysql://localhost:3306/product-inventory-management-rbhb"
                    + "?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull"
                    + "&serverTimezone=GMT%2B8&sslMode=DISABLED&allowPublicKeyRetrieval=true";
    private static final String DEFAULT_USER = "root";
    private static final String DEFAULT_PASS = "123456";

    public static void main(String[] args) throws Exception {
        String url = DEFAULT_URL;
        String user = DEFAULT_USER;
        String pass = DEFAULT_PASS;
        String sqlText = null;
        Path scriptFile = null;

        List<String> positional = new ArrayList<>();
        for (int i = 0; i < args.length; i++) {
            String arg = args[i];
            switch (arg) {
                case "-url" -> url = args[++i];
                case "-user" -> user = args[++i];
                case "-pass" -> pass = args[++i];
                case "-f" -> scriptFile = Path.of(args[++i]);
                case "-h", "--help" -> {
                    printUsage();
                    return;
                }
                default -> positional.add(arg);
            }
        }

        if (scriptFile != null) {
            sqlText = Files.readString(scriptFile, StandardCharsets.UTF_8);
        } else if (!positional.isEmpty()) {
            sqlText = String.join(" ", positional);
        } else if (System.console() != null) {
            printUsage();
            return;
        } else {
            Scanner scanner = new Scanner(System.in, StandardCharsets.UTF_8).useDelimiter("\\A");
            sqlText = scanner.hasNext() ? scanner.next() : null;
        }

        if (sqlText == null || sqlText.isBlank()) {
            printUsage();
            return;
        }

        List<String> statements = splitStatements(sqlText);
        if (statements.isEmpty()) {
            printUsage();
            return;
        }

        try (Connection conn = DriverManager.getConnection(url, user, pass)) {
            for (String sql : statements) {
                runOne(conn, sql);
            }
        }
    }

    private static void runOne(Connection conn, String sql) throws Exception {
        long start = System.currentTimeMillis();
        try (Statement stmt = conn.createStatement()) {
            boolean hasResultSet = stmt.execute(sql);
            long cost = System.currentTimeMillis() - start;
            if (hasResultSet) {
                try (ResultSet rs = stmt.getResultSet()) {
                    printResultSet(rs);
                }
                System.out.println("耗时 " + cost + " ms");
            } else {
                System.out.println("受影响行数: " + stmt.getUpdateCount() + "  耗时 " + cost + " ms");
            }
        } catch (Exception e) {
            System.out.println("执行失败: " + e.getMessage());
            System.out.println("SQL: " + sql);
            throw e;
        }
    }

    private static void printResultSet(ResultSet rs) throws Exception {
        ResultSetMetaData meta = rs.getMetaData();
        int columnCount = meta.getColumnCount();
        String[] headers = new String[columnCount];
        int[] widths = new int[columnCount];
        for (int i = 0; i < columnCount; i++) {
            headers[i] = meta.getColumnLabel(i + 1);
            widths[i] = displayWidth(headers[i]);
        }

        List<String[]> rows = new ArrayList<>();
        while (rs.next()) {
            String[] row = new String[columnCount];
            for (int i = 0; i < columnCount; i++) {
                Object value = rs.getObject(i + 1);
                row[i] = value == null ? "NULL" : String.valueOf(value);
                widths[i] = Math.max(widths[i], displayWidth(row[i]));
            }
            rows.add(row);
        }

        StringBuilder separator = new StringBuilder();
        for (int width : widths) {
            separator.append('-').append("-".repeat(width)).append('-');
        }
        System.out.println(separator);
        System.out.println(joinRow(headers, widths));
        System.out.println(separator);
        for (String[] row : rows) {
            System.out.println(joinRow(row, widths));
        }
        System.out.println(separator);
        System.out.println("共 " + rows.size() + " 行");
    }

    private static String joinRow(String[] cells, int[] widths) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < cells.length; i++) {
            sb.append("| ").append(cells[i]);
            sb.append(" ".repeat(Math.max(0, widths[i] - displayWidth(cells[i]) + 1)));
        }
        return sb.append('|').toString();
    }

    /**
     * 全角字符占两个终端宽度，按 2 计算以保证表格对齐。
     */
    private static int displayWidth(String text) {
        int width = 0;
        for (int i = 0; i < text.length(); i++) {
            width += text.charAt(i) > 0x2E80 ? 2 : 1;
        }
        return width;
    }

    /**
     * 按分号切分语句，忽略空语句与纯注释行。
     * 简单实现：不支持字符串字面量中包含分号的极端场景。
     */
    private static List<String> splitStatements(String sqlText) {
        List<String> statements = new ArrayList<>();
        for (String part : sqlText.split(";")) {
            String trimmed = part.trim();
            if (trimmed.isEmpty() || isCommentOnly(trimmed)) {
                continue;
            }
            statements.add(trimmed);
        }
        return statements;
    }

    private static boolean isCommentOnly(String sql) {
        for (String line : sql.split("\\R")) {
            String stripped = line.trim();
            if (!stripped.isEmpty() && !stripped.startsWith("--") && !stripped.startsWith("#")) {
                return false;
            }
        }
        return true;
    }

    private static void printUsage() {
        System.out.println("""
                数据库直连工具

                用法:
                  bash sql/db.sh "SQL语句"
                  bash sql/db.sh -f 脚本.sql
                  echo "SQL语句" | bash sql/db.sh

                可覆盖连接参数:
                  -url jdbc:mysql://host:3306/db?...   -user root   -pass 123456
                """);
    }
}