/*
* Copyright (C) 2016-2022 ActionTech.
* based on code by MyCATCopyrightHolder Copyright (c) 2013, OpenCloudDB/MyCAT.
* License: http://www.gnu.org/licenses/gpl.html GPL version 2 or higher.
*/
package com.actiontech.dble.route.parser;

import com.actiontech.dble.route.parser.util.ParseUtil;

/**
 * @author mycat
 */
public final class ManagerParseClear {
    private ManagerParseClear() {
    }

    public static final int OTHER = -1;
    public static final int SLOW_SCHEMA = 1;
    public static final int SLOW_DATANODE = 2;

    public static int parse(String stmt, int offset) {
        int i = offset;
        for (; i < stmt.length(); i++) {
            switch (stmt.charAt(i)) {
                case ' ':
                    continue;
                case '/':
                case '#':
                    i = ParseUtil.comment(stmt, i);
                    continue;
                case '@':
                    return clear2Check(stmt, i);
                default:
                    return OTHER;
            }
        }
        return OTHER;
    }

    // CLEAR @@SLOW
    static int clear2Check(String stmt, int offset) {
        if (stmt.length() > ++offset && stmt.charAt(offset) == '@' &&
                stmt.length() > offset + "SLOW ".length()) {
            char c1 = stmt.charAt(++offset);
            char c2 = stmt.charAt(++offset);
            char c3 = stmt.charAt(++offset);
            char c4 = stmt.charAt(++offset);
            char c5 = stmt.charAt(++offset);
            if ((c1 == 'S' || c1 == 's') && (c2 == 'L' || c2 == 'l') && (c3 == 'O' || c3 == 'o') &&
                    (c4 == 'W' || c4 == 'w') && (c5 == ' ')) {
                while (stmt.length() > ++offset) {
                    switch (stmt.charAt(offset)) {
                        case ' ':
                            continue;
                        case 'W':
                        case 'w':
                            return clear2WhereCheck(stmt, offset);
                        default:
                            return OTHER;
                    }
                }
            }
        }
        return OTHER;
    }

    // CLEAR @@SLOW WHERE
    static int clear2WhereCheck(String stmt, int offset) {
        if (stmt.length() > offset + "HERE ".length()) {
            char c1 = stmt.charAt(++offset);
            char c2 = stmt.charAt(++offset);
            char c3 = stmt.charAt(++offset);
            char c4 = stmt.charAt(++offset);
            char c5 = stmt.charAt(++offset);
            if ((c1 == 'H' || c1 == 'h') && (c2 == 'E' || c2 == 'e') && (c3 == 'R' || c3 == 'r') &&
                    (c4 == 'E' || c4 == 'e') && (c5 == ' ')) {
                while (stmt.length() > ++offset) {
                    switch (stmt.charAt(offset)) {
                        case ' ':
                            continue;
                        case 'D':
                        case 'd':
                            return clear2DCheck(stmt, offset);
                        case 'S':
                        case 's':
                            return clear2SCheck(stmt, offset);
                        default:
                            return OTHER;
                    }
                }
            }
        }
        return OTHER;
    }

    // CLEAR @@SLOW WHERE DATANODE = XXXXXX
    static int clear2DCheck(String stmt, int offset) {
        if (stmt.length() > offset + "ATANODE".length()) {
            char c1 = stmt.charAt(++offset);
            char c2 = stmt.charAt(++offset);
            char c3 = stmt.charAt(++offset);
            char c4 = stmt.charAt(++offset);
            char c5 = stmt.charAt(++offset);
            char c6 = stmt.charAt(++offset);
            char c7 = stmt.charAt(++offset);
            if ((c1 == 'A' || c1 == 'a') && (c2 == 'T' || c2 == 't') && (c3 == 'A' || c3 == 'a') &&
                    (c4 == 'N' || c4 == 'n') && (c5 == 'O' || c5 == 'o') && (c6 == 'D' || c6 == 'd') &&
                    (c7 == 'E' || c7 == 'e')) {
                while (stmt.length() > ++offset) {
                    switch (stmt.charAt(offset)) {
                        case ' ':
                            continue;
                        case '=':
                            while (stmt.length() > ++offset) {
                                switch (stmt.charAt(offset)) {
                                    case ' ':
                                        continue;
                                    default:
                                        return (offset << 8) | SLOW_DATANODE;
                                }
                            }
                            return OTHER;
                        default:
                            return OTHER;
                    }
                }
            }
        }
        return OTHER;
    }

    // CLEAR @@SLOW WHERE SCHEMA = XXXXXX
    static int clear2SCheck(String stmt, int offset) {
        if (stmt.length() > offset + "CHEMA".length()) {
            char c1 = stmt.charAt(++offset);
            char c2 = stmt.charAt(++offset);
            char c3 = stmt.charAt(++offset);
            char c4 = stmt.charAt(++offset);
            char c5 = stmt.charAt(++offset);
            if ((c1 == 'C' || c1 == 'c') && (c2 == 'H' || c2 == 'h') && (c3 == 'E' || c3 == 'e') &&
                    (c4 == 'M' || c4 == 'm') && (c5 == 'A' || c5 == 'a')) {
                while (stmt.length() > ++offset) {
                    switch (stmt.charAt(offset)) {
                        case ' ':
                            continue;
                        case '=':
                            while (stmt.length() > ++offset) {
                                switch (stmt.charAt(offset)) {
                                    case ' ':
                                        continue;
                                    default:
                                        return (offset << 8) | SLOW_SCHEMA;
                                }
                            }
                            return OTHER;
                        default:
                            return OTHER;
                    }
                }
            }
        }
        return OTHER;
    }

}
