use nom::branch::alt;
use nom::bytes::complete::tag_no_case;
use nom::character::complete::{multispace0, multispace1};
use nom::combinator::{map, opt};
use nom::sequence::{terminated, tuple};
use nom::IResult;
use std::fmt::{write, Display, Formatter};

use base::algorithm_type::AlgorithmType;
use base::error::ParseSQLError;
use base::index_option::IndexOption;
use base::index_type::IndexType;
use base::lock_type::LockType;
use base::table::Table;
use base::{CommonParser, KeyPart};

/// parse `CREATE [UNIQUE | FULLTEXT | SPATIAL] INDEX index_name
///     [index_type]
///     ON tbl_name (key_part,...)
///     [index_option]
///     [algorithm_option | lock_option] ...`
///
/// `key_part: {col_name [(length)] | (expr)} [ASC | DESC]`
///
/// `index_option: {
///     KEY_BLOCK_SIZE [=] value
///   | index_type
///   | WITH PARSER parser_name
///   | COMMENT 'string'
///   | {VISIBLE | INVISIBLE}
///   | ENGINE_ATTRIBUTE [=] 'string'
///   | SECONDARY_ENGINE_ATTRIBUTE [=] 'string'
/// }`
///
/// `index_type:
///     USING {BTREE | HASH}`
///
/// `algorithm_option:
///     ALGORITHM [=] {DEFAULT | INPLACE | COPY}`
///
/// `lock_option:
///     LOCK [=] {DEFAULT | NONE | SHARED | EXCLUSIVE}`
#[derive(Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
pub struct CreateIndexStatement {
    pub opt_index: Option<Index>,
    pub index_name: String,
    pub index_type: Option<IndexType>,
    pub table: Table,
    pub key_part: Vec<KeyPart>,
    pub index_option: Option<Vec<IndexOption>>,
    pub algorithm_option: Option<AlgorithmType>,
    pub lock_option: Option<LockType>,
}

impl Display for CreateIndexStatement {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        write!(f, "CREATE");
        if let Some(opt_index) = &self.opt_index {
            write!(f, " {}", opt_index);
        }
        write!(f, " INDEX {}", self.index_name);
        if let Some(index_type) = &self.index_type {
            write!(f, " {}", index_type);
        }
        write!(f, " ON {}", self.table);
        write!(f, " {}", KeyPart::format_list(&self.key_part));
        if let Some(index_option) = &self.index_option {
            write!(f, " {}", IndexOption::format_list(index_option));
        }
        if let Some(algorithm_option) = &self.algorithm_option {
            write!(f, " {}", algorithm_option);
        }
        if let Some(lock_option) = &self.lock_option {
            write!(f, " {}", lock_option);
        }
        Ok(())
    }
}

impl CreateIndexStatement {
    pub fn parse(i: &str) -> IResult<&str, CreateIndexStatement, ParseSQLError<&str>> {
        map(
            tuple((
                tuple((tag_no_case("CREATE"), multispace1)),
                opt(terminated(Index::parse, multispace1)),
                tuple((tag_no_case("INDEX"), multispace1)),
                map(tuple((CommonParser::sql_identifier, multispace1)), |x| {
                    String::from(x.0)
                }),
                opt(terminated(IndexType::parse, multispace1)),
                terminated(tag_no_case("ON"), multispace1),
                terminated(Table::without_alias, multispace1), // tbl_name
                KeyPart::parse,                                // (key_part,...)
                IndexOption::opt_index_option,
                multispace0, // [index_option]
                opt(terminated(AlgorithmType::parse, multispace0)),
                opt(terminated(LockType::parse, multispace0)),
                CommonParser::statement_terminator,
            )),
            |(
                _,
                opt_index,
                _,
                index_name,
                index_type,
                _,
                table,
                key_part,
                index_option,
                _,
                algorithm_option,
                lock_option,
                _,
            )| CreateIndexStatement {
                opt_index,
                index_name,
                index_type,
                table,
                key_part,
                index_option,
                algorithm_option,
                lock_option,
            },
        )(i)
    }
}

/// `[UNIQUE | FULLTEXT | SPATIAL]`
#[derive(Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
pub enum Index {
    Unique,
    Fulltext,
    Spatial,
}

impl Display for Index {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match *self {
            Index::Unique => write!(f, "UNIQUE"),
            Index::Fulltext => write!(f, "FULLTEXT"),
            Index::Spatial => write!(f, "SPATIAL"),
        }
    }
}

impl Index {
    fn parse(i: &str) -> IResult<&str, Index, ParseSQLError<&str>> {
        alt((
            map(tag_no_case("UNIQUE"), |_| Index::Unique),
            map(tag_no_case("FULLTEXT"), |_| Index::Fulltext),
            map(tag_no_case("SPATIAL"), |_| Index::Spatial),
        ))(i)
    }
}

#[cfg(test)]
mod tests {
    use base::{KeyPart, KeyPartType};
    use dds::create_index::CreateIndexStatement;

    #[test]
    fn parse_create_index() {
        let sqls = [
            "create index idx_1 on tbl_foo (age);",
            "create index idx_2 on tbl_bar (name, age);",
        ];
        let exp_statements = [
            CreateIndexStatement {
                opt_index: None,
                index_name: "idx_1".to_string(),
                index_type: None,
                table: "tbl_foo".into(),
                key_part: vec![KeyPart {
                    r#type: KeyPartType::ColumnNameWithLength {
                        col_name: "age".to_string(),
                        length: None,
                    },
                    order: None,
                }],
                index_option: None,
                algorithm_option: None,
                lock_option: None,
            },
            CreateIndexStatement {
                opt_index: None,
                index_name: "idx_2".to_string(),
                index_type: None,
                table: "tbl_bar".into(),
                key_part: vec![
                    KeyPart {
                        r#type: KeyPartType::ColumnNameWithLength {
                            col_name: "name".to_string(),
                            length: None,
                        },
                        order: None,
                    },
                    KeyPart {
                        r#type: KeyPartType::ColumnNameWithLength {
                            col_name: "age".to_string(),
                            length: None,
                        },
                        order: None,
                    },
                ],
                index_option: None,
                algorithm_option: None,
                lock_option: None,
            },
        ];

        for i in 0..sqls.len() {
            let res = CreateIndexStatement::parse(sqls[i]);
            assert!(res.is_ok());
            assert_eq!(res.unwrap().1, exp_statements[i]);
        }
    }
}