/*
 * Copyright 2004-2011 H2 Group.
 * Copyright 2011 James Moger.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.iciql;

import com.iciql.TableDefinition.FieldDefinition;
import com.iciql.util.StringUtils;

import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.text.DateFormat;
import java.text.MessageFormat;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.regex.Pattern;

import static com.iciql.util.StringUtils.isNullOrEmpty;

/**
 * Utility methods for models related to type mapping, default value validation,
 * and class or field name creation.
 */
class ModelUtils {

    /**
     * The list of supported data types. It is used by the runtime mapping for
     * CREATE statements.
     */
    private static final Map<Class<?>, String> SUPPORTED_TYPES = new HashMap<Class<?>, String>();

    static {
        Map<Class<?>, String> m = SUPPORTED_TYPES;
        m.put(String.class, "VARCHAR");
        m.put(Boolean.class, "BOOLEAN");
        m.put(Byte.class, "TINYINT");
        m.put(Short.class, "SMALLINT");
        m.put(Integer.class, "INT");
        m.put(Long.class, "BIGINT");
        m.put(Float.class, "REAL");
        m.put(Double.class, "DOUBLE");
        m.put(BigDecimal.class, "DECIMAL");
        m.put(java.sql.Timestamp.class, "TIMESTAMP");
        m.put(java.util.Date.class, "TIMESTAMP");
        m.put(java.sql.Date.class, "DATE");
        m.put(java.sql.Time.class, "TIME");
        m.put(byte[].class, "BLOB");
        m.put(UUID.class, "UUID");

        // map primitives
        m.put(boolean.class, m.get(Boolean.class));
        m.put(byte.class, m.get(Byte.class));
        m.put(short.class, m.get(Short.class));
        m.put(int.class, m.get(Integer.class));
        m.put(long.class, m.get(Long.class));
        m.put(float.class, m.get(Float.class));
        m.put(double.class, m.get(Double.class));
    }

    /**
     * Convert SQL type aliases to the list of supported types. This map is used
     * by generation and validation.
     */
    private static final Map<String, String> SQL_TYPES = new HashMap<String, String>();

    static {
        Map<String, String> m = SQL_TYPES;
        m.put("CHAR", "VARCHAR");
        m.put("CHARACTER", "VARCHAR");
        m.put("NCHAR", "VARCHAR");
        m.put("VARCHAR_CASESENSITIVE", "VARCHAR");
        m.put("VARCHAR_IGNORECASE", "VARCHAR");
        m.put("LONGVARCHAR", "VARCHAR");
        m.put("VARCHAR2", "VARCHAR");
        m.put("NVARCHAR", "VARCHAR");
        m.put("NVARCHAR2", "VARCHAR");
        m.put("TEXT", "VARCHAR");
        m.put("NTEXT", "VARCHAR");
        m.put("TINYTEXT", "VARCHAR");
        m.put("MEDIUMTEXT", "VARCHAR");
        m.put("LONGTEXT", "VARCHAR");
        m.put("CLOB", "VARCHAR");
        m.put("NCLOB", "VARCHAR");

        // logic
        m.put("BIT", "BOOLEAN");
        m.put("BOOL", "BOOLEAN");

        // numeric
        m.put("BYTE", "TINYINT");
        m.put("INT2", "SMALLINT");
        m.put("YEAR", "SMALLINT");
        m.put("INTEGER", "INT");
        m.put("MEDIUMINT", "INT");
        m.put("INT4", "INT");
        m.put("SIGNED", "INT");
        m.put("INT8", "BIGINT");
        m.put("IDENTITY", "BIGINT");
        m.put("SERIAL", "INT");
        m.put("BIGSERIAL", "BIGINT");

        // decimal
        m.put("NUMBER", "DECIMAL");
        m.put("DEC", "DECIMAL");
        m.put("NUMERIC", "DECIMAL");
        m.put("FLOAT", "DOUBLE");
        m.put("FLOAT4", "DOUBLE");
        m.put("FLOAT8", "DOUBLE");
        m.put("DOUBLE PRECISION", "DOUBLE");

        // date
        m.put("DATETIME", "TIMESTAMP");
        m.put("SMALLDATETIME", "TIMESTAMP");

        // binary types
        m.put("TINYBLOB", "BLOB");
        m.put("MEDIUMBLOB", "BLOB");
        m.put("LONGBLOB", "BLOB");
        m.put("IMAGE", "BLOB");
        m.put("OID", "BLOB");
    }

    private static final List<String> KEYWORDS = Arrays.asList("abstract", "assert", "boolean", "break",
            "byte", "case", "catch", "char", "class", "const", "continue", "default", "do", "double", "else",
            "enum", "extends", "final", "finally", "float", "for", "goto", "if", "implements", "import",
            "instanceof", "int", "interface", "long", "native", "new", "package", "private", "protected",
            "public", "return", "short", "static", "strictfp", "super", "switch", "synchronized", "this",
            "throw", "throws", "transient", "try", "void", "volatile", "while", "false", "null", "true");

    /**
     * Returns a SQL type mapping for a Java class.
     *
     * @param fieldDef the field to map
     * @return
     */
    static String getDataType(FieldDefinition fieldDef) {
        Class<?> fieldClass = fieldDef.field.getType();
        if (fieldClass.isEnum()) {
            switch (fieldDef.enumType) {
                case ORDINAL:
                    return "INT";
                case ENUMID:
                    String sqlType = SUPPORTED_TYPES.get(fieldDef.enumTypeClass);
                    if (sqlType == null) {
                        throw new IciqlException("Unsupported enum mapping type {0} for {1}",
                                fieldDef.enumTypeClass, fieldDef.columnName);
                    }
                    return sqlType;
                case NAME:
                default:
                    return "VARCHAR";
            }
        }
        if (SUPPORTED_TYPES.containsKey(fieldClass)) {
            return SUPPORTED_TYPES.get(fieldClass);
        }
        throw new IciqlException("Unsupported type " + fieldClass.getName());
    }

    /**
     * Returns the Java class for a given SQL type.
     *
     * @param sqlType
     * @param dateTimeClass the preferred date class (java.util.Date or
     *                      java.sql.Timestamp)
     * @return
     */
    static Class<?> getClassForSqlType(String sqlType, Class<? extends java.util.Date> dateTimeClass) {
        sqlType = sqlType.toUpperCase();
        // XXX dropping "UNSIGNED" or parts like that could be trouble
        sqlType = sqlType.split(" ")[0].trim();
        if (sqlType.indexOf('(') > -1) {
            // strip out length or precision
            sqlType = sqlType.substring(0, sqlType.indexOf('('));
        }

        if (SQL_TYPES.containsKey(sqlType)) {
            // convert the sqlType to a standard type
            sqlType = SQL_TYPES.get(sqlType);
        }
        Class<?> mappedClass = null;
        for (Class<?> clazz : SUPPORTED_TYPES.keySet()) {
            if (clazz.isPrimitive()) {
                // do not map from SQL TYPE to primitive type
                continue;
            }
            if (SUPPORTED_TYPES.get(clazz).equalsIgnoreCase(sqlType)) {
                mappedClass = clazz;

                break;
            }
        }
        if (mappedClass != null) {
            if (mappedClass.equals(java.util.Date.class) || mappedClass.equals(java.sql.Timestamp.class)) {
                return dateTimeClass;
            }
            return mappedClass;
        }
        return null;
    }

    /**
     * Tries to create a convert a SQL table name to a camel case class name.
     *
     * @param tableName the SQL table name
     * @return the class name
     */
    static String convertTableToClassName(String tableName) {
        String[] chunks = StringUtils.arraySplit(tableName, '_', false);
        StringBuilder className = new StringBuilder();
        for (String chunk : chunks) {
            if (chunk.length() == 0) {
                // leading or trailing _
                continue;
            }
            String[] subchunks = StringUtils.arraySplit(chunk, ' ', false);
            for (String subchunk : subchunks) {
                if (subchunk.length() == 0) {
                    // leading or trailing space
                    continue;
                }
                className.append(Character.toUpperCase(subchunk.charAt(0)));
                className.append(subchunk.substring(1).toLowerCase());
            }
        }
        return className.toString();
    }

    /**
     * Ensures that SQL column names don't collide with Java keywords.
     *
     * @param columnName the column name
     * @return the Java field name
     */
    static String convertColumnToFieldName(String columnName) {
        String lower = columnName.toLowerCase();
        if (KEYWORDS.contains(lower)) {
            lower += "Value";
        }
        return lower;
    }

    /**
     * Converts a DEFAULT clause value into an object.
     *
     * @param field definition
     * @return object
     */
    static Object getDefaultValue(FieldDefinition def, Class<? extends Date> dateTimeClass) {
        Class<?> valueType = getClassForSqlType(def.dataType, dateTimeClass);
        if (String.class.isAssignableFrom(valueType)) {
            if (StringUtils.isNullOrEmpty(def.defaultValue)) {
                // literal default must be specified within single quotes
                return null;
            }
            if (def.defaultValue.charAt(0) == '\''
                    && def.defaultValue.charAt(def.defaultValue.length() - 1) == '\'') {
                // strip leading and trailing single quotes
                return def.defaultValue.substring(1, def.defaultValue.length() - 1).trim();
            }
            return def.defaultValue;
        }

        if (StringUtils.isNullOrEmpty(def.defaultValue)) {
            // can not create object from empty string
            return null;
        }

        // strip leading and trailing single quotes
        String content = def.defaultValue;
        if (content.charAt(0) == '\'') {
            content = content.substring(1);
        }
        if (content.charAt(content.length() - 1) == '\'') {
            content = content.substring(0, content.length() - 2);
        }

        if (StringUtils.isNullOrEmpty(content)) {
            // can not create object from empty string
            return null;
        }

        if (Boolean.class.isAssignableFrom(valueType) || boolean.class.isAssignableFrom(valueType)) {
            return Boolean.parseBoolean(content);
        }

        if (Number.class.isAssignableFrom(valueType)) {
            try {
                // delegate to static valueOf() method to parse string
                Method m = valueType.getMethod("valueOf", String.class);
                return m.invoke(null, content);
            } catch (NumberFormatException e) {
                throw new IciqlException(e, "Failed to parse {0} as a number!", def.defaultValue);
            } catch (Throwable t) {
            }
        }

        String dateRegex = "[0-9]{1,4}[-/\\.][0-9]{1,2}[-/\\.][0-9]{1,2}";
        String timeRegex = "[0-2]{1}[0-9]{1}:[0-5]{1}[0-9]{1}:[0-5]{1}[0-9]{1}";

        if (java.sql.Date.class.isAssignableFrom(valueType)) {
            // this may be a little loose....
            // 00-00-00
            // 00/00/00
            // 00.00.00
            Pattern pattern = Pattern.compile(dateRegex);
            if (pattern.matcher(content).matches()) {
                DateFormat df = DateFormat.getDateInstance();
                try {
                    return df.parse(content);
                } catch (Exception e) {
                    throw new IciqlException(e, "Failed to parse {0} as a date!", def.defaultValue);
                }
            }
        }

        if (java.sql.Time.class.isAssignableFrom(valueType)) {
            // 00:00:00
            Pattern pattern = Pattern.compile(timeRegex);
            if (pattern.matcher(content).matches()) {
                DateFormat df = DateFormat.getTimeInstance();
                try {
                    return df.parse(content);
                } catch (Exception e) {
                    throw new IciqlException(e, "Failed to parse {0} as a time!", def.defaultValue);
                }
            }
        }

        if (java.util.Date.class.isAssignableFrom(valueType)) {
            // this may be a little loose....
            // 00-00-00 00:00:00
            // 00/00/00T00:00:00
            // 00.00.00T00:00:00
            Pattern pattern = Pattern.compile(dateRegex + "." + timeRegex);
            if (pattern.matcher(content).matches()) {
                DateFormat df = DateFormat.getDateTimeInstance();
                try {
                    return df.parse(content);
                } catch (Exception e) {
                    throw new IciqlException(e, "Failed to parse {0} as a datetimestamp!", def.defaultValue);
                }
            }
        }
        return content;
    }

    /**
     * Converts the object into a DEFAULT clause value.
     *
     * @param o the default object
     * @return the value formatted for a DEFAULT clause
     */
    static String formatDefaultValue(Object o) {
        Class<?> objectClass = o.getClass();
        String value = null;
        if (Number.class.isAssignableFrom(objectClass)) {
            // NUMBER
            return ((Number) o).toString();
        } else if (Boolean.class.isAssignableFrom(objectClass)) {
            // BOOLEAN
            return o.toString();
        } else if (java.sql.Date.class.isAssignableFrom(objectClass)) {
            // DATE
            value = new SimpleDateFormat("yyyy-MM-dd").format((Date) o);
        } else if (java.sql.Time.class.isAssignableFrom(objectClass)) {
            // TIME
            value = new SimpleDateFormat("HH:mm:ss").format((Date) o);
        } else if (Date.class.isAssignableFrom(objectClass)) {
            // DATETIME
            value = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format((Date) o);
        } else if (String.class.isAssignableFrom(objectClass)) {
            // STRING
            value = o.toString();
        }
        if (value == null) {
            return "''";
        }
        return MessageFormat.format("''{0}''", value);
    }

    /**
     * Checks the formatting of IQColumn.defaultValue().
     *
     * @param defaultValue the default value
     * @return true if it is
     */
    static boolean isProperlyFormattedDefaultValue(String defaultValue) {
        if (isNullOrEmpty(defaultValue)) {
            return true;
        }
        Pattern literalDefault = Pattern.compile("'.*'");
        Pattern functionDefault = Pattern.compile("[^'].*[^']");
        return literalDefault.matcher(defaultValue).matches()
                || functionDefault.matcher(defaultValue).matches();
    }

    /**
     * Checks to see if the default value matches the class.
     *
     * @param modelClass   the class
     * @param defaultValue the value
     * @return true if it does
     */
    static boolean isValidDefaultValue(Class<?> modelClass, String defaultValue) {

        if (defaultValue == null) {
            // NULL
            return true;
        }
        if (defaultValue.trim().length() == 0) {
            // NULL (effectively)
            return true;
        }

        // function / variable
        Pattern functionDefault = Pattern.compile("[^'].*[^']");
        if (functionDefault.matcher(defaultValue).matches()) {
            // hard to validate this since its in the database
            // assume it is good
            return true;
        }

        // STRING
        if (modelClass == String.class) {
            Pattern stringDefault = Pattern.compile("'(.|\\n)*'");
            return stringDefault.matcher(defaultValue).matches();
        }

        String dateRegex = "[0-9]{1,4}[-/\\.][0-9]{1,2}[-/\\.][0-9]{1,2}";
        String timeRegex = "[0-2]{1}[0-9]{1}:[0-5]{1}[0-9]{1}:[0-5]{1}[0-9]{1}";

        // TIMESTAMP
        if (modelClass == java.util.Date.class || modelClass == java.sql.Timestamp.class) {
            // this may be a little loose....
            // 00-00-00 00:00:00
            // 00/00/00T00:00:00
            // 00.00.00T00:00:00
            Pattern pattern = Pattern.compile("'" + dateRegex + "." + timeRegex + "'");
            return pattern.matcher(defaultValue).matches();
        }

        // DATE
        if (modelClass == java.sql.Date.class) {
            // this may be a little loose....
            // 00-00-00
            // 00/00/00
            // 00.00.00
            Pattern pattern = Pattern.compile("'" + dateRegex + "'");
            return pattern.matcher(defaultValue).matches();
        }

        // TIME
        if (modelClass == java.sql.Time.class) {
            // 00:00:00
            Pattern pattern = Pattern.compile("'" + timeRegex + "'");
            return pattern.matcher(defaultValue).matches();
        }

        // NUMBER
        if (Number.class.isAssignableFrom(modelClass)) {
            // strip single quotes
            String unquoted = defaultValue;
            if (unquoted.charAt(0) == '\'') {
                unquoted = unquoted.substring(1);
            }
            if (unquoted.charAt(unquoted.length() - 1) == '\'') {
                unquoted = unquoted.substring(0, unquoted.length() - 1);
            }

            try {
                // delegate to static valueOf() method to parse string
                Method m = modelClass.getMethod("valueOf", String.class);
                m.invoke(null, unquoted);
            } catch (NumberFormatException ex) {
                return false;
            } catch (Throwable t) {
            }
        }
        return true;
    }
}