<?php
/**
 * EE_Model_Parser
 *
 * @package         Event Espresso
 * @subpackage
 * @author              Mike Nelson
 */
class EE_Model_Parser
{
    const table_alias_model_relation_chain_separator = '__';
    const table_alias_model_relation_chain_prefix_end = '___';
    /**
     * Adds a period onto the front and end of the string. This often helps in searching.
     * For example, if we want to find the model name "Event", it can be tricky when the following are possible
     * "","Event.EVT_ID","Event","Event_Venue.Venue.VNU_ID",etc. It's easier to look for ".Event." in
     * "..",".Event.EVT_ID.", ".Event.", and ".Event_Venue.Venue.VNU_ID", especially when the last example should NOT
     * be found because the "Event" model isn't mentioned- it's just a string that has a model name that coincidentally
     * has it as a substring
     * @param string $string_to_pad
     * @return string
     */
    public static function pad_with_periods($string_to_pad)
    {
        return ".".$string_to_pad.".";
    }
    /**
     * Basically undoes _pad_with_periods
     * @param string $string_to_trim
     * @return string
     */
    public static function trim_periods($string_to_trim)
    {
        return trim($string_to_trim, '.');
    }



    /**
     * Gets the calculated table's alias
     * @param string $model_relation_chain or query param
     * @param        $this_model_name
     * @return string which can be added onto table aliases to make them unique
     */
    public static function extract_table_alias_model_relation_chain_prefix($model_relation_chain, $this_model_name)
    {
        // eg $model_relation_chain = 'Venue.Event_Venue.Event.Registration", and $this_model_name = 'Event'
        $model_relation_chain = self::pad_with_periods($model_relation_chain);
        $this_model_name = self::pad_with_periods($this_model_name);
        // eg '.Venue.Event_Venue.Event.Registration." and '.Event.'
        // remove this model name and everything afterwards
        $pos_of_model_name = strpos($model_relation_chain, $this_model_name);
        $model_relation_chain = substr($model_relation_chain, 0, $pos_of_model_name);
        // eg '.Venue.Event_Venue.'
        // trim periods
        $model_relation_chain = self::trim_periods($model_relation_chain);
        // eg 'Venue.Event_Venue'
        // replace periods with double-underscores
        $model_relation_chain = str_replace(".", self::table_alias_model_relation_chain_separator, $model_relation_chain);
        // eg 'Venue__Event_Venue'
        if ($model_relation_chain !='') {
            $model_relation_chain = $model_relation_chain.self::table_alias_model_relation_chain_prefix_end;
        }
        // eg 'Venue_Event_Venue___'
        return $model_relation_chain;
    }
    /**
     * Gets the table's alias (without prefix or anything)
     * @param string $table_alias_with_model_relation_chain_prefix which CAN have a table alias model relation chain prefix (or not)
     * @return string
     */
    public static function remove_table_alias_model_relation_chain_prefix($table_alias_with_model_relation_chain_prefix)
    {
        // does this actually have a table alias model relation chain prefix?
        $pos = strpos($table_alias_with_model_relation_chain_prefix, self::table_alias_model_relation_chain_prefix_end);
        if ($pos !== false) {
            // yes
            // find that triple underscore and remove it and everything before it
            $table_alias = substr($table_alias_with_model_relation_chain_prefix, $pos + strlen(self::table_alias_model_relation_chain_prefix_end));
        } else {
            $table_alias = $table_alias_with_model_relation_chain_prefix;
        }
        return $table_alias;
    }
    /**
     * Gets the table alias model relation chain prefix from the table alias already containing it
     * @param string $table_alias_with_model_relation_chain_prefix
     * @return string
     */
    public static function get_prefix_from_table_alias_with_model_relation_chain_prefix($table_alias_with_model_relation_chain_prefix)
    {
        // does this actually have a table alias model relation chain prefix?
        $pos = strpos($table_alias_with_model_relation_chain_prefix, self::table_alias_model_relation_chain_prefix_end);
        if ($pos !== false) {
            // yes
            // find that triple underscore and remove it and everything before it
            $prefix = substr($table_alias_with_model_relation_chain_prefix, 0, $pos + strlen(self::table_alias_model_relation_chain_prefix_end));
        } else {
            $prefix = '';
        }
        return $prefix;
    }

    /**
     * Gets the table alias model relation chain prefix (ie, what can be prepended onto
     * EE_Model_Field::get_qualified_column() to get the proper column name for that field
     * in a specific query) from teh query param (eg 'Registration.Event.EVT_ID').
     *
     * @param string $model_name of the model on which the related query param was found to be belong
     * @param string $original_query_param
     * @return string
     */
    public static function extract_table_alias_model_relation_chain_from_query_param($model_name, $original_query_param)
    {
        $relation_chain = self::extract_model_relation_chain($model_name, $original_query_param);
        $table_alias_with_model_relation_chain_prefix = EE_Model_Parser::extract_table_alias_model_relation_chain_prefix($relation_chain, $model_name);
        return $table_alias_with_model_relation_chain_prefix;
    }
    /**
     * Gets the model relation chain to $model_name from the $original_query_param.
     * Eg, if $model_name were 'Payment', and $original_query_param were 'Registration.Transaction.Payment.PAY_ID',
     * this would return 'Registration.Transaction.Payment'. Also if the query param were 'Registration.Transaction.Payment'
     * and $model_name were 'Payment', it should return 'Registration.Transaction.Payment'
     * @param string $model_name
     * @param string $original_query_param
     * @return string
     */
    public static function extract_model_relation_chain($model_name, $original_query_param)
    {
        // prefix and postfix both with a period, as this facilitates searching
        $model_name = EE_Model_Parser::pad_with_periods($model_name);
        $original_query_param = EE_Model_Parser::pad_with_periods($original_query_param);
        $pos_of_model_string = strpos($original_query_param, $model_name);
        // eg, if we're looking for the model relation chain from Event to Payment, the original query param is probably something like
        // "Registration.Transaction.Payment.PAY_ID", $pos_of_model_string points to the 'P' or Payment. We want the string
        // "Registration.Transaction.Payment"
        $model_relation_chain = substr($original_query_param, 0, $pos_of_model_string+strlen($model_name));
        return EE_Model_Parser::trim_periods($model_relation_chain);
    }

    /**
     * Replaces the specified model in teh model relation chain with teh join model.
     * Eg EE_Model_Parser::replace_model_name_with_join_model_name_in_model_relation_chain(
     * "Ticket", "Datetime_Ticket", "Datetime.Ticket" ) will return
     * "Datetime.Datetime_Ticket" which can be used to find the table alias model relation chain prefix
     * using EE_Model_Parser::extract_table_alias_model_relation_chain_prefix
     * @param string $model_name
     * @param string $join_model_name
     * @param string $model_relation_chain
     * @return string
     */
    public static function replace_model_name_with_join_model_name_in_model_relation_chain($model_name, $join_model_name, $model_relation_chain)
    {
        $model_name = EE_Model_Parser::pad_with_periods($model_name);
        $join_model_name = EE_Model_Parser::pad_with_periods($join_model_name);
        $model_relation_chain = EE_Model_Parser::pad_with_periods($model_relation_chain);
        $replaced_with_periods = str_replace($model_name, $join_model_name, $model_relation_chain);
        return EE_Model_Parser::trim_periods($replaced_with_periods);
    }
}
