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use super::*;
use std::fmt;
#[derive(PartialEq, Debug)]
pub enum Keyword {
    SELECT,
    FROM,
    WHERE,
    ORDER,
    BY,
    CREATE,
    TABLE,
    TRIGGER,
    DATABASE,
    IF,
    ELSE,
    END,
    DESC,
    ASC,
    AS,
    TOP,
    BOTTOM,
    DISTINCT,
    LIMIT,
    OFFSET,
    GROUP,
    HAVING,
    JOIN,
    LIKE,
    IN,
    AND,
    UNKNOWN,
}

impl Keyword {
    pub fn value_for_command(&self) -> i32 {
        match self {
            Keyword::SELECT => 1,
            _ => 10,
        }
    }

    pub fn needs_data(&self) -> bool {
        match self {
            Keyword::SELECT => true,
            Keyword::FROM => true,
            _ => false,
        }
    }

    pub fn bigger_than(&self, comparator: &Keyword) -> bool {
        if self.compare_command(comparator) != 1 {
            return false;
        }
        true
    }
    /// compare the assigned values to a command in order to check what command has a higher
    /// importance level.
    ///
    /// If the command value of the first element is bigger than the value of the
    /// parameter_keyword, the function will return 1;
    /// If they have the same value, it will return 0;
    /// If the value of the given element is smaller than the parameter_keyword, the function will
    /// return -1;
    pub fn compare_command(&self, comparator: &Keyword) -> i32 {
        if self.value_for_command() > comparator.value_for_command() {
            1
        } else if self.value_for_command() == comparator.value_for_command() {
            0
        } else {
            -1
        }
    }
}

/// convert a given string into a better processable enum-value that can be later used in order
/// to construct the finit expression with the data.
pub fn unwrap_string(mut convertable: String) -> Keyword {
    convertable = convertable.to_lowercase();
    match convertable.as_ref() {
        "select" => Keyword::SELECT,
        "where" => Keyword::WHERE,
        "from" => Keyword::FROM,
        "create" => Keyword::CREATE,
        "table" => Keyword::TABLE,
        "database" => Keyword::DATABASE,
        "order" => Keyword::ORDER,
        "if" => Keyword::IF,
        "else" => Keyword::ELSE,
        "distinct" => Keyword::DISTINCT,
        "top" => Keyword::TOP,
        "end" => Keyword::END,
        "limit" => Keyword::LIMIT,
        "having" => Keyword::HAVING,
        "like" => Keyword::LIKE,
        _ => Keyword::UNKNOWN,
    }
}

impl fmt::Display for Keyword {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Debug::fmt(self, f)
    }
}

pub fn identifiy_data_after_keyword(_expression: expression::Expression) {}

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn return_enum_value_for_keyword_string() {
        let keyword_strings = vec!["SELECT", "FROM", "WHERE"];
        let result_return = vec![Keyword::SELECT, Keyword::FROM, Keyword::WHERE];
        let mut returned_result_vec: Vec<Keyword> = Vec::new();
        for i in 0..keyword_strings.len() {
            returned_result_vec.push(grammar::unwrap_string(keyword_strings[i].to_string()));
        }
        assert_eq!(result_return, returned_result_vec);
    }

    #[test]
    fn get_wheiht_for_enum_value() {
        let enum_value = Keyword::SELECT;
        let expected_result = 1;
        assert_eq!(expected_result, enum_value.value_for_command());
    }

    #[test]
    fn keyword_needs_values() {
        assert_eq!(Keyword::SELECT.needs_data(), true);
        assert_eq!(Keyword::FROM.needs_data(), true);
        assert_eq!(Keyword::ORDER.needs_data(), false);
    }

}